tag:theconversation.com,2011:/ca/topics/life-on-mars-6975/articlesLife on Mars – The Conversation2024-03-12T12:29:40Ztag:theconversation.com,2011:article/2076982024-03-12T12:29:40Z2024-03-12T12:29:40ZNASA’s search for life on Mars: a rocky road for its rovers, a long slog for scientists – and back on Earth, a battle of the budget<p>Is or was there life on Mars? That profound question is so complex that it will not be fully answered by the <a href="https://mars.nasa.gov/">two NASA rovers now exploring it</a>. </p>
<p>But because of the literal groundwork the rovers are performing, scientists are finally investigating, in-depth and in unprecedented detail, the planet’s evidence for life, known as its “<a href="https://astrobiology.nasa.gov/education/alp/what-is-a-biosignature/">biosignatures</a>.” This search is remarkably complicated, and in the case of Mars, it is spanning decades. </p>
<p><a href="https://geology.ufl.edu/people/faculty/dr-amy-j-williams-2/">As a geologist</a>, I have had the extraordinary opportunity to work on both the Curiosity and Perseverance rover missions. Yet as much as scientists are learning from them, it will take another robotic mission to figure out if Mars has ever hosted life. That mission will bring Martian rocks back to Earth for analysis. Then – hopefully – we will have an answer. </p>
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<a href="https://images.theconversation.com/files/578822/original/file-20240229-16-zmsstx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A photograph of the planet Mars, showing white caps and the reddish Martian surface." src="https://images.theconversation.com/files/578822/original/file-20240229-16-zmsstx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/578822/original/file-20240229-16-zmsstx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=564&fit=crop&dpr=1 600w, https://images.theconversation.com/files/578822/original/file-20240229-16-zmsstx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=564&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/578822/original/file-20240229-16-zmsstx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=564&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/578822/original/file-20240229-16-zmsstx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=708&fit=crop&dpr=1 754w, https://images.theconversation.com/files/578822/original/file-20240229-16-zmsstx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=708&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/578822/original/file-20240229-16-zmsstx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=708&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">A photograph of Mars, the fourth planet from the Sun, taken by the Hubble Space Telescope in 2017.</span>
<span class="attribution"><a class="source" href="https://science.nasa.gov/image-detail/amf-gsfc_20171208_archive_e000019/">NASA</a></span>
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<h2>From habitable to uninhabitable</h2>
<p>While so much remains mysterious about Mars, there is one thing I am confident about. Amid the thousands of pictures both rovers are taking, I’m quite sure no alien bears or meerkats will show up in any of them. Most scientists doubt the surface of Mars, or its near-surface, could currently sustain even single-celled organisms, much less complex forms of life. </p>
<p>Instead, the rovers are acting as extraterrestrial detectives, hunting for clues that life may have existed eons ago. That includes evidence of long-gone liquid surface water, life-sustaining minerals and organic molecules. To find this evidence, <a href="https://mars.nasa.gov/msl/home/">Curiosity</a> and <a href="https://mars.nasa.gov/mars2020/">Perseverance</a> are treading very different paths on Mars, more than 2,000 miles (3,200 kilometers) from each other. </p>
<p>These two rovers will help scientists answer some big questions: Did life ever exist on Mars? Could it exist today, perhaps deep under the surface? And would it be only microbial life, or is there any possibility it might be more complex? </p>
<p>The Mars of today is nothing like the <a href="https://www.nasa.gov/solar-system/nasa-funded-study-extends-period-when-mars-could-have-supported-life/#:%7E">Mars of several billion years ago</a>. In its infancy, Mars was far more Earth-like, with a thicker atmosphere, rivers, lakes, maybe even oceans of water, and the essential elements needed for life. But this period was cut short when Mars <a href="https://mgs-mager.gsfc.nasa.gov/#:%7E">lost its magnetic field</a> and nearly all of its atmosphere – now only 1% as dense as the Earth’s. </p>
<p>The change from habitable to uninhabitable took time, perhaps hundreds of millions of years; if life ever existed on Mars, it likely died out a few billion years ago. Gradually, Mars became the cold and dry desert that it is today, with a landscape comparable to <a href="https://www.alluringworld.com/mcmurdo-dry-valleys/">the dry valleys of Antarctica</a>, without glaciers and plant or animal life. The average Martian temperature is minus 80 degrees Fahrenheit (minus 62 degrees Celsius), and its meager atmosphere is nearly all carbon dioxide. </p>
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<span class="caption">The Mars rover Perseverance has taken over 200,000 pictures, including this selfie from April, 2021.</span>
<span class="attribution"><a class="source" href="https://mars.nasa.gov/resources/25790/perseverances-selfie-with-ingenuity/">NASA/JPL-Caltech/MSSS</a></span>
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<h2>Early exploration</h2>
<p>Robotic exploration of the Martian surface began in the 1970s, when life-detection experiments on the <a href="https://mars.nasa.gov/mars-exploration/missions/viking-1-2/">Viking missions</a> failed to find any conclusive evidence for life. </p>
<p><a href="https://www.jpl.nasa.gov/missions/mars-pathfinder-sojourner-rover">Sojourner, the first rover</a>, landed in 1997 and demonstrated that a moving robot could perform experiments. In 2004, <a href="https://mars.nasa.gov/mer/">Spirit and Opportunity</a> followed; both found evidence that liquid water once existed on the Martian surface. </p>
<p>The Curiosity rover <a href="https://mars.nasa.gov/msl/home/">landed in 2012</a> and began ascending Mount Sharp, the 18,000-foot-high mountain located inside Gale crater. There is a reason why NASA chose it as an exploration site: The mountain’s rock layers show <a href="https://www.jpl.nasa.gov/news/mars-rover-views-spectacular-layered-rock-formations">a dramatic shift in climate</a>, from one with abundant liquid water to the dry environment of today. </p>
<p>So far, Curiosity has found evidence in several locations of past liquid water, minerals that may provide chemical energy, and intriguingly, a <a href="https://doi.org/10.1029/2021JE007107">variety of organic carbon molecules</a>. </p>
<p>While organic carbon is not itself alive, it is a building block <a href="https://www.nasa.gov/solar-system/nasas-curiosity-takes-inventory-of-key-life-ingredient-on-mars/">for all life as we know it</a>. Does its presence mean that life once existed on Mars?</p>
<p>Not necessarily. Organic carbon can be abiotic – that is, unrelated to a living organism. For example, maybe the organic carbon came from a <a href="https://www.livescience.com/tissint-meteorite-organic-compounds">meteorite that crashed on Mars</a>. And though the rovers carry wonderfully sophisticated instruments, they can’t definitively tell us if these organic molecules are related to past life on Mars.</p>
<p>But laboratories here on Earth likely can. By collecting rock and soil samples from the Martian surface, and then returning them to Earth for detailed analysis with our state-of-the-art instruments, scientists may finally have the answer to an age-old question.</p>
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<figcaption><span class="caption">An animation of the proposed Mars Sample Return mission.</span></figcaption>
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<h2>Perseverance</h2>
<p>Enter Perseverance, NASA’s <a href="https://mars.nasa.gov/mars2020/">newest flagship mission to Mars</a>. For the past three years – it landed in February 2021 – Perseverance has been searching for signs of bygone microbial life in the rocks within Jezero crater, selected as the landing site because it once contained a large lake. </p>
<p>Perseverance is the first step of the <a href="https://mars.nasa.gov/msr/">Mars Sample Return</a> mission, an international effort to collect Martian rock and soil for return to Earth.</p>
<p>The instrument suite onboard Perseverance will help the science team choose the rocks that seem to promise the most scientific return. This will be a careful process; after all, there would be only <a href="https://mars.nasa.gov/msr/multimedia/videos/?v=523">30 seats on the ride back to Earth</a> for these geological samples.</p>
<h2>Budget woes</h2>
<p>NASA’s original plan called for returning those samples to Earth by 2033. But work on the mission – now estimated to cost between US$8 billion to $11 billion – has slowed <a href="https://www.cbsnews.com/losangeles/news/jpl-to-lay-off-more-than-500-employees/">due to budget cuts and layoffs</a>. The cuts are severe; a request for $949 million to fund the mission for fiscal 2024 <a href="https://www.latimes.com/science/story/2024-03-06/nasa-budget-deal-hope-for-mars-sample-return-mission-jpl">was trimmed to $300 million</a>, although efforts are underway to <a href="https://spacenews.com/congressional-letter-asks-white-house-to-reverse-msr-spending-cuts/">restore at least some of the funding</a>. </p>
<p>The Mars Sample Return mission is critical to better understand the potential for life beyond Earth. The science and the technology that will enable it are both novel and expensive. But if NASA discovers life once existed on Mars – even if it’s by finding a microbe dead for a billion years – that will tell scientists that life is not a fluke one-time event that only happened on Earth, but a more common phenomenon that could occur on many planets.</p>
<p>That knowledge would revolutionize the way human beings see ourselves and our place in the universe. There is far more to this endeavor than just returning some rocks.</p><img src="https://counter.theconversation.com/content/207698/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Amy J. Williams receives funding from NASA Participating Scientist grants associated with the Mars 2020 Perseverance rover and the Mars Science Laboratory Curiosity rover. </span></em></p>Determining whether or not life exists on another planet is an extraordinarily complicated – and expensive – scientific endeavor.Amy J. Williams, Assistant Professor of Geology, University of FloridaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2210332024-01-16T17:47:56Z2024-01-16T17:47:56ZFor All Mankind’s Happy Valley: why a Martian city could well extend below the surface<figure><img src="https://images.theconversation.com/files/569044/original/file-20240112-27-4on00f.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The entrance to For All Mankind's Happy Valley.</span> <span class="attribution"><a class="source" href="https://www.apple.com/uk/tv-pr/originals/for-all-mankind/episodes-images/">Apple</a></span></figcaption></figure><p>Apple TV+‘s alternate space race, <a href="https://theconversation.com/for-all-mankind-space-dramas-alternate-history-constructs-a-better-vision-of-nasa-214935">For All Mankind</a>, imagines what would have have happened if USSR cosmonauts, and not Nasa’s astronauts, had been the first to land on the Moon. Rather than the waning of interest in space that followed the Moon landings in our reality, over the four seasons of the show to date, the race has continued towards lunar and then Martian settlement. </p>
<p>In the <a href="https://www.youtube.com/watch?v=j1WX0FOKh5k">latest season</a>, the finale of which aired on January 12 2024, initial colonisation efforts on Mars have developed to the point where an international alliance supports and maintains a single large colony. Dubbed “Happy Valley”, the Martian city <a href="https://for-all-mankind.fandom.com/wiki/Happy_Valley?file=FAM_406_52.07_Happy_Valley_aerial.png">features</a> an array of interconnected modules. </p>
<p>Tubular corridors run between bigger geodesic and half-pipe structures housing control rooms, laboratories, meeting rooms and eating and living quarters for the base commander and other higher ups. Most residents live below ground.</p>
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<img alt="Two people on either side of an octogonal window." src="https://images.theconversation.com/files/569043/original/file-20240112-27-vaphcv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/569043/original/file-20240112-27-vaphcv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=300&fit=crop&dpr=1 600w, https://images.theconversation.com/files/569043/original/file-20240112-27-vaphcv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=300&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/569043/original/file-20240112-27-vaphcv.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=300&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/569043/original/file-20240112-27-vaphcv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=377&fit=crop&dpr=1 754w, https://images.theconversation.com/files/569043/original/file-20240112-27-vaphcv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=377&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/569043/original/file-20240112-27-vaphcv.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=377&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">Happy Valley’s surface level habitats are for the top-tier residents of the base.</span>
<span class="attribution"><a class="source" href="https://www.apple.com/uk/tv-pr/originals/for-all-mankind/episodes-images/">Apple</a></span>
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<p>With its Artemis programme, Nasa <a href="https://www.theguardian.com/science/2024/jan/10/nasa-postpones-plans-to-send-humans-to-moon-artemis">plans</a> to have humans living outside Earth’s orbit. This would including a lunar base camp, as well as a space station that circles the Moon, in the view of ultimately sending people to Mars. Quite in what <a href="https://eprints.gla.ac.uk/159428/">structures</a> such Martian explorers would live has long had people <a href="https://theconversation.com/our-long-fascination-with-the-journey-to-mars-106541">dreaming</a> – and scientists <a href="https://www.bas.ac.uk/data/our-data/publication/antarctic-ecosystems-as-models-for-extraterrestrial-surface-habitats/">experimenting</a>.</p>
<h2>Life on Mars?</h2>
<p>In the early 20th century, sufficient uncertainty remained to allow for planetary romances such as the <a href="https://www.nasa.gov/image-article/barsoom/">Barsoom</a> novels of Edgar Rice Burroughs. Written between 1912 and 1946, these tell the story of a 19th-century US veteran transported to Mars, and were brought to life in the 2012 action film, John Carter. These fantasies paved the way for more serious consideration of <a href="https://warwick.ac.uk/fac/sci/physics/research/astro/people/stanway/sciencefiction/cosmicstories/survival_on_mars/">survival on Mars</a> as our understanding developed. </p>
<p>However, astronomers were already establishing that the planet’s surface was arid, cold and toxic. Long before Burroughs completed his series, <a href="https://ui.adsabs.harvard.edu/abs/1926ApJ....63...48M/abstract">it was clear</a> that Barsoom’s great cities, open to a breathable atmosphere, could never exist.</p>
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<p>One of the earliest stories to seriously consider the scientifically understood conditions on Mars, and the life that might result from it, was Stanley Weinbaum’s 1934 novella, <a href="https://www.gutenberg.org/files/23731/23731-h/23731-h.htm">A Martian Odyssey</a>. In keeping with telescopic observations of the planet’s cold, thin air and spectra indicating a lack of both water and vegetation, this was a Mars devoid of cityscapes, but not of life. Salvaging what he can from a crashed shuttle, the protagonist treks across 800 miles of Martian landscape, encountering a variety of interesting Martian forms. </p>
<p>In the early 20th century, it was believed that Mars’s atmosphere was thin, but not necessarily beyond the range of human adaptability. After all, settlements on Earth exist at altitudes of up to 5,000m – where the atmospheric pressure is less than half that at the surface. Early estimates for Martian surface pressure were in this ballpark (rather than <a href="https://marsed.asu.edu/mep/atmosphere">less than 1%</a>, <a href="https://theconversation.com/could-people-breathe-the-air-on-mars-180504#:%7E:text=The%20Martian%20atmosphere%20is%20thin,gases%20from%20escaping%20into%20space">as we now know</a>. Thus Weinbaum speaks of “months spent in acclimatisation chambers”, but otherwise frees his explorer (and any Mars settlement) from the needs of atmosphere management.</p>
<h2>Going underground</h2>
<p>By the middle of the 20th century, Earth-based observations and the first of the Mariner probe missions had removed any doubt about the <a href="https://ui.adsabs.harvard.edu/abs/1964CoLPL...2..113O">hostility of Mars’s atmosphere</a>. The cities envisaged by mid-century sci-fi writers were encased in vast protective domes. These could contain an Earth-like environment and allow humans to breathe and move freely without protective equipment. </p>
<p>Such domed surface cities can be found in examples ranging from childrens’ fare such as <a href="https://wrap.warwick.ac.uk/168958/">Dan Dare: Pilot of the Future</a>, to the work of established authors including Larry Niven (see his 1966 story, How the Heroes Die). Some saw these domes as fully urbanised. Others imagined a more scattered settlement amid a managed landscape. </p>
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<img alt="A vintage magazine comic." src="https://images.theconversation.com/files/569053/original/file-20240112-23-43lw93.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/569053/original/file-20240112-23-43lw93.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=832&fit=crop&dpr=1 600w, https://images.theconversation.com/files/569053/original/file-20240112-23-43lw93.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=832&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/569053/original/file-20240112-23-43lw93.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=832&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/569053/original/file-20240112-23-43lw93.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1046&fit=crop&dpr=1 754w, https://images.theconversation.com/files/569053/original/file-20240112-23-43lw93.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1046&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/569053/original/file-20240112-23-43lw93.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1046&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">Dan Dare: Pilot of the Future.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/ausdew/22678711382">Ausdew|Flickr</a></span>
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<p>This dominant image of cities on Mars persists to the current day, in imagery from Mars colonisation enthusiasts including the international <a href="https://www.marssociety.org/why-mars/">Mars Society</a> and <a href="https://www.spacex.com/humanspaceflight/mars/">SpaceX</a>. Research suggests, however, that as long-term habitation, a domed environment would have significant flaws. </p>
<p>Since the 1960s, scientific understanding of the <a href="https://journals.lww.com/health-physics/abstract/2000/11000/radiation_exposure_for_human_mars_exploration.8.aspx">impact of radiation</a> on humans and their offspring has advanced. The planet lacks the protection, afforded by Earth’s thick atmosphere and its strong magnetic field, to our DNA, from a rain of ionising particles from the Sun and beyond. Smart dome materials might filter some of this, but could not protect astronauts from the <a href="https://ui.adsabs.harvard.edu/abs/2021A&ARv..29....8G/abstract">cumulative effects of penetrating particles</a>, leaving its occupants vulnerable to cancer. </p>
<p>As pointed out by many writers (including Niven in the story already mentioned), large domes would leave a city on Mars vulnerable to air leaks too, as well as the extreme fluctuations in day-night temperature the planet experiences (from -125C to 20C). Further, the material would be abraded over time by sandstorms so extreme, they are visible from Earth. </p>
<p>Instead, many <a href="https://www.newscientist.com/article/2288037-martian-cave-entrances-may-offer-a-life-friendly-radiation-shield/">researchers</a> now consider <a href="https://www.sciencedirect.com/science/article/abs/pii/S0012825220303342">underground</a> or cave <a href="https://ui.adsabs.harvard.edu/abs/2023AcAau.204..157M/">settlements</a> as sites for human settlement on Mars. Here protection from temperature, radiation, sandstorms and air leaks are all provided by a thick layer of <a href="https://ui.adsabs.harvard.edu/abs/2022P&SS..21805517L/abstract">regolith</a> (soil or rock), reducing the cumulative exposure any settlers would face. </p>
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<p>While the red planet is now devoid of surface water, <a href="https://www.usgs.gov/news/caves-mars">it is likely</a> to have cave systems dating from its wetter, tectonically active youth, and – unlike Earth – its surface quakes are rare and weak. If natural caves are unavailable, tunnelling, or even using surface rock powder to make a form of Martian concrete may be good alternatives. Indeed, partly with Mars-prototyping in mind, <a href="https://blogs.nasa.gov/artemis/2020/10/28/lunar-living-nasas-artemis-base-camp-concept/">Nasa</a> and ESA <a href="https://www.esa.int/Enabling_Support/Space_Engineering_Technology/Building_a_lunar_base_with_3D_printing">have explored</a> the idea of <a href="https://ascelibrary.org/doi/abs/10.1061/(ASCE)AS.1943-5525.0001359">3D printing</a> and then burying habitation modules on the Moon, which experiences many of the same risks.</p>
<p>For All Mankind has been <a href="https://www.space.com/for-all-mankind-season-3-space-history">noted</a> for its realistic physics. The production team include a NASA technical advisor. </p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1135661336908537858"}"></div></p>
<p>Perhaps unsurprisingly its Happy Valley colony, descending several levels into the Martian subsurface, represents a plausible vision for future Martian cities. Contrary to the series though, underground levels might well be sought after, by real-world Martian residents, for the increased protection they provide. </p>
<p>Planetary settlement remains an increasingly distant prospect in our reality, but science fiction has always played a role in shaping public understanding of our planetary neighbours and in fostering enthusiasm for their exploration. Just as Burroughs’ Barsoom novel <a href="https://warwick.ac.uk/fac/sci/physics/research/astro/people/stanway/sciencefiction/cosmicstories/the_echo_of/">inspired the scientists</a> working on the Mars landers of the 1960s-70s, today’s viewers of For All Mankind might include the engineers and scientists that one day bring its vision of a Martian city to fruition.</p><img src="https://counter.theconversation.com/content/221033/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Elizabeth Stanway receives funding from the Science and Technology Facilities Council for her astrophysics research </span></em></p>In sci-fi depictions, extraterrestrial habitats have evolved tandem with scientific understanding of conditions on planetsElizabeth Stanway, Reader in Astronomy and Astrophysics, University of WarwickLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1805042022-05-16T12:15:00Z2022-05-16T12:15:00ZCould people breathe the air on Mars?<figure><img src="https://images.theconversation.com/files/461626/original/file-20220505-16-gls54w.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C4992%2C2986&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">An artist's concept of an astronaut walking on Mars. But what would happen if the astronaut weren't wearing a space helmet?</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/astronaut-walking-on-mars-royalty-free-image/1276723596?adppopup=true">cokada/E+ via Getty Images</a></span></figcaption></figure><figure class="align-left ">
<img alt="" src="https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=293&fit=crop&dpr=1 600w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=293&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=293&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=368&fit=crop&dpr=1 754w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=368&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/281719/original/file-20190628-76743-26slbc.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=368&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<p><em><a href="https://theconversation.com/us/topics/curious-kids-us-74795">Curious Kids</a> is a series for children of all ages. If you have a question you’d like an expert to answer, send it to <a href="mailto:curiouskidsus@theconversation.com">curiouskidsus@theconversation.com</a>.</em></p>
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<blockquote>
<p><strong>Could people breathe on Mars? – Jack J., age 7, Alexandria, Virginia</strong></p>
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<hr>
<p>Let’s suppose you were an astronaut who just landed on <a href="https://spaceplace.nasa.gov/all-about-mars/en/">the planet Mars</a>. What would you need to survive? </p>
<p>For starters, here’s a short list: Water, food, shelter – and oxygen. </p>
<p>Oxygen is in the air we breathe here on Earth. Plants and some kinds of bacteria provide it for us. </p>
<p>But oxygen is not the only gas in the Earth’s atmosphere. It’s not even the most abundant. In fact, only 21% of our air is made up of oxygen. Almost all the rest is nitrogen – about 78%. </p>
<p>Now you might be wondering: If there’s more nitrogen in the air, why do we breathe oxygen? </p>
<p>Here’s how it works: Technically, when you breathe in, you take in everything that’s in the atmosphere. But your body uses only the oxygen; you get rid of the rest when you exhale.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/460682/original/file-20220502-24-sonuz8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Empty landscape with rocks in the foreground and sandy hills in the background." src="https://images.theconversation.com/files/460682/original/file-20220502-24-sonuz8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/460682/original/file-20220502-24-sonuz8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=340&fit=crop&dpr=1 600w, https://images.theconversation.com/files/460682/original/file-20220502-24-sonuz8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=340&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/460682/original/file-20220502-24-sonuz8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=340&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/460682/original/file-20220502-24-sonuz8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=427&fit=crop&dpr=1 754w, https://images.theconversation.com/files/460682/original/file-20220502-24-sonuz8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=427&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/460682/original/file-20220502-24-sonuz8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=427&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">NASA’s Perseverance Mars rover captured this image of the bleak and barren Martian landscape.</span>
<span class="attribution"><a class="source" href="https://mars.nasa.gov/resources/25904/mastcam-z-views-santa-cruz-on-mars/">NASA/JPL-Caltech/ASU/MSSS</a></span>
</figcaption>
</figure>
<h2>The air on Mars</h2>
<p>The Martian atmosphere is thin – its volume is only 1% of the Earth’s atmosphere. To put it another way, there’s 99% less air on Mars than on Earth. </p>
<p>That’s partly because Mars is about half the size of Earth. Its gravity isn’t strong enough to keep atmospheric gases from escaping into space. </p>
<p>And the most abundant gas in that thin air is carbon dioxide. For people on Earth, that’s a poisonous gas at high concentrations. Fortunately, it makes up far less than 1% of our atmosphere. But on Mars, carbon dioxide is 96% of the air! </p>
<p>Meanwhile, Mars has almost no oxygen; it’s only one-tenth of one percent of the air, not nearly enough for humans to survive. </p>
<p>If you tried to breathe on the surface of Mars without a spacesuit supplying your oxygen – bad idea – you would die in an instant. You would suffocate, and <a href="https://www.cnet.com/science/features/the-terrifying-reality-of-actually-living-on-mars/">because of the low atmospheric pressure</a>, your blood would boil, both at about the same time. </p>
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<iframe width="440" height="260" src="https://www.youtube.com/embed/yOplTCgnJFQ?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Billions of years ago, Mars’ Jezero Crater hosted an ancient lake.</span></figcaption>
</figure>
<h2>Life without oxygen</h2>
<p>So far, researchers have not found any evidence of life on Mars. But the search is just beginning; our robotic probes have barely scratched the surface.</p>
<p>Without question, Mars is an extreme environment. And it’s not just the air. Very little liquid water is <a href="https://www.nasa.gov/press-release/nasa-confirms-evidence-that-liquid-water-flows-on-today-s-mars">on the Martian surface</a>. <a href="https://mars.nasa.gov/mars2020/weather/">Temperatures are incredibly cold</a> – at night, it’s more than -100 degrees Fahrenheit (-73 degrees Celsius).</p>
<p>But plenty of organisms on Earth <a href="https://astrobiology.nasa.gov/news/the-message-of-really-really-extreme-life/">survive extreme environments</a>. Life has been found in the Antarctic ice, at the bottom of the ocean and miles below the Earth’s surface. Many of those places have extremely hot or cold temperatures, almost no water and little to no oxygen.</p>
<p>And even if life no longer exists on Mars, maybe it did billions of years ago, when it had a thicker atmosphere, <a href="https://www.space.com/33296-mars-atmosphere-oxygen-curiosity-rover.html">more oxygen</a>, <a href="https://www.space.com/ancient-mars-intermittently-warm-wet">warmer temperatures</a> and significant amounts of liquid water <a href="https://www.nasa.gov/feature/jpl/nasa-s-mro-finds-water-flowed-on-mars-longer-than-previously-thought">on the surface</a>. </p>
<p>That’s one of the goals of <a href="https://mars.nasa.gov/mars2020/">NASA’s Mars Perseverance rover mission</a> – to look for signs of ancient Martian life. That’s why Perseverance is searching within the Martian rocks for fossils of organisms that once lived – most likely, primitive life, like Martian microbes. </p>
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<a href="https://images.theconversation.com/files/460659/original/file-20220501-19-ls0chw.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A rocky, rust-colored landscape surrounds NASA's Perseverance Mars rover as it sits Martian soil." src="https://images.theconversation.com/files/460659/original/file-20220501-19-ls0chw.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/460659/original/file-20220501-19-ls0chw.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/460659/original/file-20220501-19-ls0chw.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/460659/original/file-20220501-19-ls0chw.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/460659/original/file-20220501-19-ls0chw.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/460659/original/file-20220501-19-ls0chw.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/460659/original/file-20220501-19-ls0chw.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">On the 198th day of its mission, NASA’s Perseverance Mars rover took this selfie.</span>
<span class="attribution"><a class="source" href="https://mars.nasa.gov/resources/26253/perseverances-selfie-at-rochette/#:~:text=NASA's%20Perseverance%20Mars%20rover%20took,to%20drill%20rock%20core%20samples.">NASA/JPL-Caltech/MSSS</a></span>
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<h2>Do-it-yourself oxygen</h2>
<p>Among the <a href="https://mars.nasa.gov/mars2020/spacecraft/instruments/">seven instruments on board</a> the Perseverance rover is <a href="https://mars.nasa.gov/mars2020/spacecraft/instruments/moxie/">MOXIE</a>, an incredible device that takes carbon dioxide out of the Martian atmosphere and turns it into oxygen.</p>
<p>If MOXIE works the way that scientists hope it will, future astronauts will not only make their own oxygen; they could use it as a component in the rocket fuel they’ll need to fly back to Earth. The more oxygen people are able to make on Mars, the less they’ll need to bring from Earth – and the easier it becomes for visitors to go there. But even with “homegrown” oxygen, astronauts will still need a spacesuit. </p>
<p>Right now, NASA is working on the new technologies needed to <a href="https://www.nasa.gov/topics/moon-to-mars/overview">send humans to Mars</a>. That could happen in the next decade, perhaps sometime during the late 2030s. By then, you’ll be an adult – and maybe one of the first to take a step on Mars.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/sioX2bbkZms?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">See what a human mission to Mars would be like.</span></figcaption>
</figure>
<hr>
<p><em>Hello, curious kids! Do you have a question you’d like an expert to answer? Ask an adult to send your question to <a href="mailto:curiouskidsus@theconversation.com">CuriousKidsUS@theconversation.com</a>. Please tell us your name, age and the city where you live.</em></p>
<p><em>And since curiosity has no age limit – adults, let us know what you’re wondering, too. We won’t be able to answer every question, but we will do our best.</em></p><img src="https://counter.theconversation.com/content/180504/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Phylindia Gant is a student collaborator on the M2020 rover. She receives funding through the University of Central Florida's NASA Florida Space Grant Consortium. She is a first year Geology PhD student at the University of Florida.</span></em></p><p class="fine-print"><em><span>Amy J. Williams receives relevant funding from NASA's Mars Science Laboratory rover and M2020 rover Participating Scientist Programs, as well as through the University of Central Florida's NASA Florida Space Grant Consortium and Space Florida, and the Florida Space Institute. She is an assistant professor of Earth & Planetary Science at the University of Florida.</span></em></p>Mars is the fourth planet from the Sun and one of our closest neighbors in space. But it’s not a very welcoming place for an Earthling to visit.Phylindia Gant, Ph.D. Student in Geological Sciences, University of FloridaAmy J. Williams, Assistant Professor of Geology, University of FloridaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1554592021-02-18T22:14:35Z2021-02-18T22:14:35ZAs the Perseverance rover lands on Mars, there’s a lot we already know about the red planet from meteorites found on Earth<figure><img src="https://images.theconversation.com/files/385148/original/file-20210218-23-z4qqk.jpg?ixlib=rb-1.1.0&rect=199%2C245%2C10025%2C5503&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">NASA</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span></figcaption></figure><p>NASA’s <a href="https://mars.nasa.gov/mars2020/">Perseverance rover</a> <a href="https://www.nytimes.com/live/2021/02/18/science/nasa-mars-landing">successfully touched down on Mars</a> this morning, and has already begun beaming back images.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1362507436611956736"}"></div></p>
<p>But people might be surprised to learn there have been <a href="https://en.wikipedia.org/wiki/List_of_missions_to_Mars">another 48 missions</a> to the red planet so far. Of these, more than half failed at stages from take-off to deployment — including the 1999 Mars Climate Orbiter, destroyed on Mars entry after someone <a href="https://solarsystem.nasa.gov/missions/mars-climate-orbiter/in-depth/">failed to convert</a> imperial measurements to metric.</p>
<p>Successful missions include <a href="https://mars.nasa.gov/news/8858/insight-is-meeting-the-challenge-of-winter-on-dusty-mars/?site=insight">Mars Insight</a>, which is studying the interior via measurement of “marsquakes”, and the <a href="https://mars.nasa.gov/news/8832/nasas-curiosity-rover-reaches-its-3000th-day-on-mars/?site=msl">Curiosity rover</a>, which touched down in 2012 and has been examining the geology of Mt Sharp. </p>
<figure class="align-center ">
<img alt="NASA's Curiosity Mars rover on Vera Rubin Ridge, with Mt Sharp in the background." src="https://images.theconversation.com/files/385152/original/file-20210218-18-1pbalj4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/385152/original/file-20210218-18-1pbalj4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=429&fit=crop&dpr=1 600w, https://images.theconversation.com/files/385152/original/file-20210218-18-1pbalj4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=429&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/385152/original/file-20210218-18-1pbalj4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=429&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/385152/original/file-20210218-18-1pbalj4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=539&fit=crop&dpr=1 754w, https://images.theconversation.com/files/385152/original/file-20210218-18-1pbalj4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=539&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/385152/original/file-20210218-18-1pbalj4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=539&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">This selfie of NASA’s Curiosity Mars rover shows the vehicle on Vera Rubin Ridge, with Mt Sharp in the background.</span>
<span class="attribution"><span class="source">NASA</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>Although there have been no return missions, there is a lot we can learn without travelling to Mars — from the more than 260 <a href="https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2020JE006523">Martian meteorites</a> that have fallen on Earth. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/as-new-probes-reach-mars-heres-what-we-know-so-far-from-trips-to-the-red-planet-153791">As new probes reach Mars, here's what we know so far from trips to the red planet</a>
</strong>
</em>
</p>
<hr>
<p>Images taken by orbiters reveal Mars has more than 40,000 craters, each formed by an asteroid colliding with the surface. You can explore these craters yourself by going to Google Earth, toggling the Google Mars mode and zooming in. </p>
<p>If some of the debris from the large impacts reached <a href="https://en.wikipedia.org/wiki/Escape_velocity">escape velocity</a> (about 5 km/s on Mars), it would be able to leave the planet’s gravitational field. Eventually, some of the ejected Martian material has intercepted Earth’s trajectory, flashing through the atmosphere until it either burned up or came to rest on the surface.</p>
<p>Although Martian meteorites have been found across Earth, most have been collected from Antarctica or the deserts of northwest Africa. In both cases, the black crust that forms as the meteorite partially burns up passing through Earth’s atmosphere stands out clearly against ice or sand. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/385144/original/file-20210218-13-184u7fx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A fragment of a Martian meteorite." src="https://images.theconversation.com/files/385144/original/file-20210218-13-184u7fx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/385144/original/file-20210218-13-184u7fx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=379&fit=crop&dpr=1 600w, https://images.theconversation.com/files/385144/original/file-20210218-13-184u7fx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=379&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/385144/original/file-20210218-13-184u7fx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=379&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/385144/original/file-20210218-13-184u7fx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=476&fit=crop&dpr=1 754w, https://images.theconversation.com/files/385144/original/file-20210218-13-184u7fx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=476&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/385144/original/file-20210218-13-184u7fx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=476&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A fragment of the NWA7397 meteorite, found in the Sahara desert in 2012.</span>
<span class="attribution"><span class="source">Wikimedia/Gozitano</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<p>This mode of interplanetary travel is important because it raises the possibility that life could inadvertently travel from one planet to another. Back in 1996, one Martian meteorite, <a href="https://science.sciencemag.org/content/273/5277/864.full">ALH84001</a>, was controversially thought to contain fossilised bacteria. </p>
<p>Some of the older landers have almost certainly taken Earth bacteria to Mars, since they were not purified before launch. </p>
<h2>A bubble of Martian atmosphere</h2>
<p>Small planets cool quickly and it has long been suspected that Mars’s core has largely but not totally <a href="https://mars.nasa.gov/news/453/scientists-say-mars-has-a-liquid-iron-core/">crystallised</a>. This means Mars has mostly lost the protective magnetic field that deflects cosmic radiation.</p>
<p>But we are confident Mars once had an ocean, containing water as we know it. The temperature was above freezing and conditions were suitable for life. The stripping away of the magnetic field early in Mars’s history means this ocean is long gone and the average temperature is now -65°C, but frosts, clouds and ice caps remain. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/385149/original/file-20210218-15-11zf8hg.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="An aerial image of the Mars surface showing the crate where the probe has landed." src="https://images.theconversation.com/files/385149/original/file-20210218-15-11zf8hg.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/385149/original/file-20210218-15-11zf8hg.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=568&fit=crop&dpr=1 600w, https://images.theconversation.com/files/385149/original/file-20210218-15-11zf8hg.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=568&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/385149/original/file-20210218-15-11zf8hg.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=568&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/385149/original/file-20210218-15-11zf8hg.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=714&fit=crop&dpr=1 754w, https://images.theconversation.com/files/385149/original/file-20210218-15-11zf8hg.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=714&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/385149/original/file-20210218-15-11zf8hg.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=714&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The remains of an ancient delta in Mars’s Jezero Crater, which NASA’s Perseverance Mars rover will now explore for signs of fossilised microbial life.</span>
<span class="attribution"><a class="source" href="https://mars.nasa.gov/resources/25264/jezero-crater-as-seen-by-esas-mars-express-orbiter/">ESA/DLR/FU-Berlin</a></span>
</figcaption>
</figure>
<p>Not being fortunate enough to roam the deserts of Africa or the icy plateaus of Antarctica, I instead found my first Martian meteorite sitting in a cabinet in a gem store in the small New Zealand town of Akaroa. </p>
<p>Using a scanning electron microscope, my examination revealed it was a shergottite, one of the <a href="https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2020JE006523">most common Martian meteorites</a> — equivalent to what we know on Earth as basalt. If it’s basalt, though, how do we know it’s from Mars? </p>
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Read more:
<a href="https://theconversation.com/how-to-spot-mars-see-the-red-planet-in-the-sky-the-day-nasas-perseverance-rover-lands-155078">How to spot Mars: See the red planet in the sky the day Nasa's Perseverance rover lands</a>
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<p>There are several ways of recognising a Martian meteorite. One is from its gas content. When a meteorite strikes the surface of Mars, the “target” rocks are subject to such great pressures they partly melt and trap Martian atmosphere within gas bubbles. Some of these rocks are then ejected from the planet — becoming meteorites themselves. </p>
<p>The gases in these meteorites can be measured back on Earth and compared to the known Martian atmosphere, which comprises <a href="https://nssdc.gsfc.nasa.gov/planetary/factsheet/marsfact.html">95% carbon dioxide</a> and distinct <a href="https://www.sciencedaily.com/terms/noble_gas.htm">noble gas</a> concentrations. </p>
<p>The thousands of craters scarring Mars’s surface mean it is ancient. This was confirmed when one meteorite was dated to be <a href="https://www.nature.com/articles/nature12764">4.4 billion years old</a>. Properties of some other Martian meteorites show Mars <a href="https://www.nature.com/articles/nature00982">formed within 13 million years</a> of the formation of the Solar System. This in turn means some of the first planetary crust that formed on Mars likely still exists at the surface. </p>
<figure class="align-center ">
<img alt="Martian meteorite" src="https://images.theconversation.com/files/385154/original/file-20210218-12-1tml0a5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/385154/original/file-20210218-12-1tml0a5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=555&fit=crop&dpr=1 600w, https://images.theconversation.com/files/385154/original/file-20210218-12-1tml0a5.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=555&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/385154/original/file-20210218-12-1tml0a5.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=555&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/385154/original/file-20210218-12-1tml0a5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=697&fit=crop&dpr=1 754w, https://images.theconversation.com/files/385154/original/file-20210218-12-1tml0a5.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=697&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/385154/original/file-20210218-12-1tml0a5.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=697&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Some Martian meteorites capture samples of the red planet’s atmosphere in gas bubbles.</span>
<span class="attribution"><span class="source">Wikimedia</span>, <a class="license" href="http://creativecommons.org/licenses/by-nd/4.0/">CC BY-ND</a></span>
</figcaption>
</figure>
<h2>Old and cold — but not dead</h2>
<p>This inference, along with some meteorite mineral and isotopic properties, implies Mars has not been shaped by plate tectonics — the global process that formed the continents, mountain ranges and ocean basins on Earth. </p>
<p>And, as most dated Martian meteorites are less than 1.5 billion years old, volcanism has continued throughout its history. Mars may be cold but it is not dead.</p>
<p>Martian meteorites also hold clues about how people may one day be able to survive on the planet. </p>
<p>While living in hollowed out lava tubes in Martian basalt may appeal to some hopeful interplanetary settlers, we’ll ultimately need to build shelters to protect us from the cosmic radiation and vast dust storms that engulf the planet. </p>
<p>Martian meteorites show olivine, a magnesium-silicate mineral, is common. Experiments are underway to assess the use of a breakdown component, magnesium carbonate, to form a concrete binder from which we could fashion buildings. </p>
<p>Martian meteorites show that big insights can be gleaned from little rocks and reveal what Mars is made of.</p><img src="https://counter.theconversation.com/content/155459/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>James Scott is president of the Geoscience Society of New Zealand</span></em></p>NASA’s successful Mars landing will reveal yet more secrets from the red planet. But there is much we already know from Martian fragments that found their way to Earth.James Scott, Associate Professor in Geology, University of OtagoLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1549822021-02-16T10:38:40Z2021-02-16T10:38:40ZPerseverance Mars rover: how to prove whether there’s life on the red planet<figure><img src="https://images.theconversation.com/files/384291/original/file-20210215-19-s5qrjf.jpg?ixlib=rb-1.1.0&rect=23%2C21%2C1573%2C876&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Perseverance in action.</span> <span class="attribution"><span class="source">NASA/JPL-Caltech</span></span></figcaption></figure><p>We’ll soon be able to properly start asking the question: “Are we alone in the universe?” Nasa’s next major mission, the <a href="https://mars.nasa.gov/mars2020/">Mars 2020 Perseverance rover</a>, will land on the surface on <a href="https://youtu.be/tITni_HY1Bk">February 18</a>. Following a <a href="https://theconversation.com/mars-perseverance-rover-set-for-nail-biting-landing-heres-the-rocket-science-154886">complex landing procedure</a>, it will get started on one of its main goals – searching for life on Mars. </p>
<p>The rover has two ways of gathering samples. It can either analyse them with its <a href="https://mars.nasa.gov/mars2020/spacecraft/instruments/">on-board laboratory</a> or it can <a href="https://theconversation.com/bringing-mars-rocks-back-to-earth-perseverance-rover-lands-on-feb-18-a-lead-scientist-explains-the-tech-and-goals-153851">save them for return</a> to Earth by future missions. But what exactly is it looking for, and what would it need to find to convince us that there is indeed past or present life? </p>
<p>If the landing is successful, this will be the first mission <a href="https://mars.nasa.gov/mars-exploration/missions/viking-1-2/">in decades</a> to actively search for direct evidence of life on Mars. This life – if it exists – will most likely take the form of extinct microbes. </p>
<p>We have recently found some tantalising hints at the possibility for current life in the <a href="https://theconversation.com/methane-on-mars-a-new-discovery-or-just-a-lot-of-hot-air-114656">form of methane gas</a> in the atmosphere. On Earth, a large percentage of methane in the atmosphere is produced by biological processes. This means that methane could be considered a biological signature. But it can also be readily produced by geological processes, so it is not proof of life. </p>
<figure class="align-center ">
<img alt="Diagram showin different ways methane could end up in Mars' atmosphere." src="https://images.theconversation.com/files/384231/original/file-20210215-23-1f81efk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/384231/original/file-20210215-23-1f81efk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/384231/original/file-20210215-23-1f81efk.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/384231/original/file-20210215-23-1f81efk.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/384231/original/file-20210215-23-1f81efk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/384231/original/file-20210215-23-1f81efk.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/384231/original/file-20210215-23-1f81efk.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Are living organisms producing methane on Mars?</span>
<span class="attribution"><span class="source">Nasa</span></span>
</figcaption>
</figure>
<p>There are many molecules that are only made by terrestrial biology, such as <a href="https://www.britannica.com/science/isoprene">isoprene</a> or DNA. So finding something like those would allow us to move toward the conclusion that life exists or existed on Mars. If Perseverance does find such molecules, we will have the harder job of proving it was native to Mars and not a microbial hitchhiker from Earth. To help us work that out, the rover will first run “control experiments” with no sample. If the molecules are there in these experiments, they are likely to be terrestrial contamination on the rover itself.</p>
<h2>Sophisticated instruments</h2>
<p>That said, if we find molecules that are not readily produced by standard chemical reactions on Mars, we might be onto something biologically alien. One of the instruments that will be used to search for biosignatures on Mars is <a href="https://mars.nasa.gov/mars2020/spacecraft/instruments/sherloc/">SHERLOC</a> (Scanning Habitable Environments with Raman & Luminescence for Organics & Chemicals). It will use an ultraviolet laser light to probe samples from a safe distance of about 5cm. This way it reduces the chance of contaminating the samples while measuring the reflected light for evidence of biological molecules. </p>
<p>This works because each molecule type reflects the light in a unique way, allowing us to determine with a high degree of certainty that we have found something like <a href="https://en.wikipedia.org/wiki/Amino_acid">amino acids</a> (which build proteins) or <a href="https://en.wikipedia.org/wiki/Lipid">lipids</a> (which build cell walls). These molecules are known to persist in the environment after other biological molecules like DNA have been broken down and are no longer detectable. </p>
<p>Perseverance will also carry the <a href="https://mars.nasa.gov/mars2020/spacecraft/instruments/supercam/">SuperCam</a> instrument, which can shoot a laser to a distance of around seven metres. It can analyse the resulting dust cloud for evidence of rock types that could preserve clues to past life. This helps narrow down locations that might be best to investigate more fully without having to take the time to drive to them.</p>
<figure class="align-center ">
<img alt="Artist's impression showing the rover on Mars with sample tubes around it on the ground." src="https://images.theconversation.com/files/384233/original/file-20210215-23-16mg383.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/384233/original/file-20210215-23-16mg383.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/384233/original/file-20210215-23-16mg383.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/384233/original/file-20210215-23-16mg383.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/384233/original/file-20210215-23-16mg383.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/384233/original/file-20210215-23-16mg383.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/384233/original/file-20210215-23-16mg383.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The rover will store rock and soil samples in sealed tubes on the planet’s surface for future missions to retrieve.</span>
<span class="attribution"><span class="source">Nasa/JPL-Caltech</span></span>
</figcaption>
</figure>
<p>Rock samples from a depth of around 5cm will also be collected and stored in sealed containers for a future mission to collect. The analysis we can conduct on Earth is many times more precise and detailed than the instruments we can send to Mars. Plus we can do multiple kinds of analysis in multiple labs around the world, allowing for better overall results. For example, if evidence for extinct life is suspected to be preserved in a sample, we could use <a href="https://theconversation.com/startling-images-show-strange-and-beautiful-science-up-close-25129">electron microscopy</a> (which uses electrons rather than light to probe a sample) to try and see if it contains <a href="https://www.newscientist.com/article/2217747-fossilised-microbes-from-3-5-billion-years-ago-are-oldest-yet-found/">fossilised microbial cells</a>.</p>
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<strong>
Read more:
<a href="https://theconversation.com/could-invisible-aliens-really-exist-among-us-an-astrobiologist-explains-129419">Could invisible aliens really exist among us? An astrobiologist explains</a>
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<p>All of this depends on our very narrow understanding of what life is. We only know about one kind of life – the terrestrial kind. Our experiments are searching for life within our current knowledge. It is always possible that life beyond our current understanding exists, perhaps silicon-based rather than carbon-based. Perseverance isn’t likely to detect such life even if it’s thriving on Mars.</p>
<p>Unless something gets up and moves in front of the camera, obtaining conclusive evidence likely be a long process, especially while we wait to analyse those cached samples. If we find even a hint of evidence for life, the next steps will be to detect it with multiple analytical techniques, show that it isn’t contamination from Earth and work out whether the evidence make sense in the context of the environment and data from the other instruments. </p>
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<em>
<strong>
Read more:
<a href="https://theconversation.com/our-rover-could-discover-life-on-mars-heres-what-it-would-take-to-prove-it-89625">Our rover could discover life on Mars – here's what it would take to prove it</a>
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<p>Any evidence for life will have to go through the rigorous scientific process of testing, re-testing and peer review. What’s more, Perseverance is only conducting analysis in <a href="https://en.wikipedia.org/wiki/Jezero_(crater)">one crater</a> on Mars. </p>
<p>But other missions in the search for life, including the European Space Agency’s <a href="https://www.esa.int/Science_Exploration/Human_and_Robotic_Exploration/Exploration/ExoMars">Rosalind Franklin rover</a>, aren’t far behind. Excitingly, Rosalind Franklin will be the first to drill up to 2m under the harsh, freezing Martian surface. If there is any current life on Mars, we might be more likely to find it deeper below the surface, which is constantly bombarded with <a href="https://theconversation.com/mars-mission-how-increasing-levels-of-space-radiation-may-halt-human-visitors-94052">harmful radiation</a>.</p>
<p><em>You can hear more about the three Mars missions arriving at the red planet in February in the first episode of our new podcast, <a href="https://theconversation.com/uk/topics/the-conversation-weekly-98901">The Conversation Weekly</a> – the world explained by experts. Subscribe wherever you get your podcasts.</em></p>
<iframe src="https://player.acast.com/60087127b9687759d637bade/episodes/a-big-month-for-mars?theme=default&cover=1&latest=1" frameborder="0" width="100%" height="110px" allow="autoplay"></iframe><img src="https://counter.theconversation.com/content/154982/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Samantha Rolfe does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Methane gas in the atmosphere is a tantalising hint suggesting that life could exists on Mars.Samantha Rolfe, Lecturer in Astrobiology and Principal Technical Officer at Bayfordbury Observatory, University of HertfordshireLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1548862021-02-15T10:24:02Z2021-02-15T10:24:02ZMars: Perseverance rover set for nail-biting landing – here’s the rocket science<figure><img src="https://images.theconversation.com/files/384083/original/file-20210213-19-d4wxwz.jpg?ixlib=rb-1.1.0&rect=10%2C7%2C1187%2C662&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Landing on Mars is extremely difficult.</span> <span class="attribution"><span class="source">NASA/JPL-Caltech</span></span></figcaption></figure><p>Following “seven minutes of terror” after it reaches Mars’ upper atmosphere, <a href="https://mars.nasa.gov/mars2020/">Nasa’s Perseverance rover</a> is expected to land on the surface of the red planet at 20:55 GMT on February 18. This is <a href="https://theconversation.com/decades-of-attempts-show-how-hard-it-is-to-land-on-mars-heres-how-we-plan-to-succeed-in-2021-69734">incredibly hard to do</a>, with <a href="https://theconversation.com/mars-missions-from-china-and-uae-are-set-to-go-into-orbit-heres-what-they-could-discover-154408">only about 40% of missions</a> succeeding. </p>
<p>As a member of the team that built the European Space Agency’s <a href="https://www.bbc.co.uk/news/science-environment-51844030">Rosalind Franklin rover</a> (we made the <a href="https://www.ucl.ac.uk/planetary-sciences/news/2020/jan/exciting-times-pancam-science-eyes-rosalind-franklin-exomars-rover">PanCam</a>, the camera “eyes” of the rover), which will set off for Mars next year, I will be holding my breath during the landing. There’s so much at stake. Not only could the mission unveil some of Mars’ best-kept secrets, and be a key part of future exploration to return a Mars sample back to Earth, it could also have important lessons for landing Rosalind Franklin.</p>
<p>The appropriately named Perseverance <a href="https://mars.nasa.gov/mars2020/">soared into the Florida morning sky</a> on an Atlas V rocket on July 30 2020, in the midst of a global pandemic for Earthlings. This was the start of a nearly 500 million kilometre journey to the red planet, with the car-sized rover, and a helicopter called Ingenuity, aboard. </p>
<p>Its destination is the <a href="https://mars.nasa.gov/mars2020/mission/science/landing-site/">Jezero crater</a> – a 45km-wide basin, with an old, dry river delta, cliffs, dunes and boulder fields - where it will search for signs of ancient, primitive life on the martian surface. Of course it’s not impossible it could find current life too, if there is any. Perseverance will also <a href="https://theconversation.com/plan-to-bring-back-rocks-from-mars-is-our-best-bet-for-finding-clues-of-past-life-95797">collect samples</a> that another mission will retrieve and return to Earth in the late 2020s. This will be the first attempt to take off from the surface of another planet.</p>
<h2>Landing sequence</h2>
<p>The reason it is hard to land on Mars is that the atmospheric pressure is so low that spacecraft move through it at enormous speeds unless they are slowed down. What’s more, the landing has to be done autonomously, without real-time contact with Earth. The landing sequence for Perseverance is an improved, more accurately targeted version of the “Skycrane” technique, which <a href="https://www.space.com/17963-mars-curiosity.html">safely landed Nasa’s Curiosity rover in 2012</a>. </p>
<p>The “seven minutes of terror” will start at 20:48 GMT when a protective “aeroshell” containing Perseverance, Ingenuity and a descent vehicle called “Skycrane” enters the Mars atmosphere at 19,500 km/h. Just over a minute later, the aeroshell will reach its maximum outer temperature, 1,300°C, due to friction with the upper atmosphere. Luckily, the front of the aeroshell is a protective heat shield.</p>
<p>At 20:52, a 21.5-metre parachute will deploy, and the heat shield will be ejected. Two minutes later, the back part of the shell will separate too. The Skycrane, descending at 2.7 km/h and powered by eight throttleable retrorockets, will then lower the rover on 7.6m nylon cords, from about 20m above the ground. When its speed has slowed down to 2.5km/h and the rover touches the surface, the cords will be severed. At 20:55 GMT Perseverance should land while Skycrane flies off into the sunset to a safe distance.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/383078/original/file-20210208-15-18auzvi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/383078/original/file-20210208-15-18auzvi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/383078/original/file-20210208-15-18auzvi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=354&fit=crop&dpr=1 600w, https://images.theconversation.com/files/383078/original/file-20210208-15-18auzvi.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=354&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/383078/original/file-20210208-15-18auzvi.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=354&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/383078/original/file-20210208-15-18auzvi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=445&fit=crop&dpr=1 754w, https://images.theconversation.com/files/383078/original/file-20210208-15-18auzvi.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=445&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/383078/original/file-20210208-15-18auzvi.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=445&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Perseverance rover’s entry, descent and landing.</span>
<span class="attribution"><span class="source">Nasa</span></span>
</figcaption>
</figure>
<p>Although Skycrane has been used before, features known as “Range Trigger” and “Terrain-Relative Navigation” have been added this time as the landing terrain is much less flat. Range Trigger determines the deployment time for the parachute based on the rover’s position with respect to the target landing area, which is ten times smaller than Curiosity’s. The Terrain Relative Navigation initially uses radar and later live images of the surface to determine the best, precise landing site within a 600 metres range. </p>
<h2>Next steps</h2>
<p>Safely on the ground, Perseverance can begin its mission. The first 30 “sols” (a sol is a Mars day - 23 hours, 39 minutes and 40 seconds) on Mars will be used for initial commissioning, including checkouts of the science instruments and short test drives. The next up to 30 sols will be used for test flights of the Ingenuity helicopter. Following this, the surface operations of the rover can begin.</p>
<p>In addition to cameras, radars and other instruments, the rover has a drill to collect samples, up to 6cm long, from rocks or soil. These will be analysed right away to search for signs of life, or collected in one of 38 metal tubes for later return to labs on Earth. This will provide a key step in Mars exploration, as <a href="https://theconversation.com/plan-to-bring-back-rocks-from-mars-is-our-best-bet-for-finding-clues-of-past-life-95797">much more detailed analysis</a> can be done in labs on Earth. What’s more, we will know the detailed context of the samples, unlike for the Mars meteorites we have already.</p>
<p>We are also keenly looking forward to the launch of the Rosalind Franklin rover (ExoMars 2022) at the next launch opportunity, currently September 21 2022 – with landing expected on June 10 2023. We will be closely monitoring the landing of Perseverance as we too will use an aeroshell for descent, along with two parachutes and a retrorocket-powered landing platform called Kazochok. One of the parachutes is 35m in diameter, making it the largest to be sent to Mars ever. </p>
<p>Rosalind Franklin will be the first to drill up to two metres under the harsh, freezing Martian surface, which is bombarded by harmful radiation, to retrieve samples from below. If there is any life on Mars, it is more likely to survive below the surface. The rover will visit an even older site with evidence of past water, Oxia Planum. These deep samples will be analysed in the rover, with the results radioed back to Earth. </p>
<p>Some of our PanCam team members and other ExoMars scientists will also participate in the Perseverance and Hope missions, and we are lucky to have the opportunity to learn what we can from all of these missions ahead of our own – both in planetary mission operations and in science. The search for past or even present life on Mars is beginning in earnest, and it’s a truly international endeavour.</p>
<p><em>You can hear more about the three Mars missions arriving at the red planet in February in the first episode of our new podcast, <a href="https://theconversation.com/uk/topics/the-conversation-weekly-98901">The Conversation Weekly</a> – the world explained by experts. Subscribe wherever you get your podcasts.</em></p>
<iframe src="https://player.acast.com/60087127b9687759d637bade/episodes/a-big-month-for-mars?theme=default&cover=1&latest=1" frameborder="0" width="100%" height="110px" allow="autoplay"></iframe><img src="https://counter.theconversation.com/content/154886/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Andrew Coates receives funding from UK Space Agency and UKRI/STFC, UK.. </span></em></p>Scientists preparing to land the Rosalind Franklin rover in a few years are nervously awaiting the landing of Nasa’s Perseverance rover.Andrew Coates, Professor of Physics, Deputy Director (Solar System) at the Mullard Space Science Laboratory, UCLLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1537912021-02-09T19:07:45Z2021-02-09T19:07:45ZAs new probes reach Mars, here’s what we know so far from trips to the red planet<figure><img src="https://images.theconversation.com/files/381867/original/file-20210202-23-jt4fc5.jpg?ixlib=rb-1.1.0&rect=0%2C13%2C2281%2C1149&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://mars.nasa.gov/resources/6564/rover-tracks-in-northward-view-along-west-rim-of-endeavour-false-color/">NASA/JPL-Caltech/Cornell University/Arizona State University</a></span></figcaption></figure><p>Three new spacecraft are due to arrive at Mars this month, ending their seven-month journey through space. </p>
<p>The first, the United Arab Emirates’ <a href="https://www.emiratesmarsmission.ae/">Hope Probe</a>, should have made it to the red planet this week. It will stay in orbit and study its atmosphere for one complete Martian year (687 Earth days). </p>
<p>China’s <a href="https://www.planetary.org/space-missions/tianwen-1">Tianwen-1 mission</a> also enters orbit this month and will begin scouting the potential landing site for its Mars rover, due to be deployed in May.</p>
<p>If successful, China will become the second country to land a rover on Mars. </p>
<p>These two missions will join six orbiting spacecraft actively studying the red planet from above:</p>
<ul>
<li>NASA’s <a href="https://mars.nasa.gov/odyssey/">Mars Odyssey</a>, Mars Reconnaissance Orbiter (<a href="https://mars.nasa.gov/mro/">MRO</a>) and <a href="https://mars.nasa.gov/maven/">MAVEN Orbiter</a></li>
<li>Europe’s <a href="https://sci.esa.int/web/mars-express">Mars Express</a></li>
<li>India’s Mars Orbiter Mission (<a href="https://www.isro.gov.in/pslv-c25-mars-orbiter-mission">MOM</a>)</li>
<li>the European and Russian partnership <a href="https://exploration.esa.int/web/mars/-/46475-trace-gas-orbiter">ExoMars Trace Gas Orbiter</a>.</li>
</ul>
<p>The oldest active probe - Mars Odyssey - has been orbiting the planet for 20 years.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/how-to-get-people-from-earth-to-mars-and-safely-back-again-150167">How to get people from Earth to Mars and safely back again</a>
</strong>
</em>
</p>
<hr>
<p>The third spacecraft to reach Mars this month is NASA’s <a href="https://mars.nasa.gov/mars2020/">Perseverance rover</a>, scheduled to land on February 18. It will search for signs of ancient microbial life but its mission also looks ahead, testing <a href="https://mars.nasa.gov/mars2020/spacecraft/instruments/moxie/">new technologies</a> that may support humans visiting Mars one day.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/tITni_HY1Bk?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Now NASA hopes Perseverance will land on Mars.</span></figcaption>
</figure>
<h2>Laboratories on wheels</h2>
<p>NASA has an impressive track record for landing on Mars. It has operated all eight successful missions to the Martian surface. </p>
<p>What began with the two <a href="https://mars.nasa.gov/mars-exploration/missions/viking-1-2/">Viking landers</a> in the 1970s continues today with the <a href="https://mars.nasa.gov/insight/">InSight lander</a>, which has studied the <a href="https://mars.nasa.gov/insight/weather/">daily weather on Mars</a> and <a href="https://www.nature.com/articles/d41586-019-03796-7">detected Marsquakes</a> for the past two years. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/381605/original/file-20210201-17-1q5j86p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A rock strewn field and the foot of the Viking 1 lander appears in one corner." src="https://images.theconversation.com/files/381605/original/file-20210201-17-1q5j86p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/381605/original/file-20210201-17-1q5j86p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=213&fit=crop&dpr=1 600w, https://images.theconversation.com/files/381605/original/file-20210201-17-1q5j86p.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=213&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/381605/original/file-20210201-17-1q5j86p.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=213&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/381605/original/file-20210201-17-1q5j86p.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=268&fit=crop&dpr=1 754w, https://images.theconversation.com/files/381605/original/file-20210201-17-1q5j86p.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=268&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/381605/original/file-20210201-17-1q5j86p.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=268&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Just minutes after landing, Viking 1 captured the first ever photograph taken from the Martian surface.</span>
<span class="attribution"><a class="source" href="https://rps.nasa.gov/resources/16/first-picture-from-the-surface-of-mars/">NASA/JPL</a></span>
</figcaption>
</figure>
<p>Perseverance will be the fifth rover to arrive on Mars that’s capable of venturing across the surface of another planet. </p>
<p>These amazing laboratories on wheels have extended our knowledge of a faraway world. Here’s what they’ve told us so far. </p>
<h2>The first rover - Sojourner</h2>
<p>Twenty years after Viking 1 & 2 landed stationary probes on Mars, a third spacecraft finally reached the planet, but this one could move.</p>
<p>On July 4, 1997, NASA’s <a href="https://mars.nasa.gov/mars-exploration/missions/pathfinder/">Pathfinder</a> literally bounced onto the Martian surface, safely enclosed in a giant set of airbags. Once stable, the lander released the Sojourner rover. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/9HGRReKUzfU?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">See the Sojourner probe from Pathfinder’s viewpoint.</span></figcaption>
</figure>
<p>The first rover on Mars could move at a maximum speed of 1cm a second and was about as long (63cm) as a skateboard — smaller than some of the boulders it encountered. </p>
<p>Sojourner explored 16 locations near the Pathfinder lander, including the volcanic rock “Yogi”. Pictures of its landing site, Ares Vallis, showed it was littered with rounded pebbles and conglomerate rocks, evidence of ancient flood plains. </p>
<h2>The geologists - Spirit and Opportunity</h2>
<p>A pair of upsized rovers arrived on Mars in early 2004. <a href="https://mars.nasa.gov/mars-exploration/missions/mars-exploration-rovers/">Spirit and Opportunity</a> were geologists, searching for minerals within the rocks and soil, hidden clues that dry, cold Mars may once have been wet and warm.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/381608/original/file-20210201-23-14r6qkk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Looking down on Spirit rover." src="https://images.theconversation.com/files/381608/original/file-20210201-23-14r6qkk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/381608/original/file-20210201-23-14r6qkk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/381608/original/file-20210201-23-14r6qkk.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/381608/original/file-20210201-23-14r6qkk.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/381608/original/file-20210201-23-14r6qkk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/381608/original/file-20210201-23-14r6qkk.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/381608/original/file-20210201-23-14r6qkk.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">This overhead ‘selfie’ was combined with Spirit’s largest ever panorama - it contains hundreds of individual images of Gusev Crater taken over three Martian days.</span>
<span class="attribution"><a class="source" href="https://mars.nasa.gov/mro/multimedia/images/?ImageID=5835">NASA/JPL-Caltech/Cornell</a></span>
</figcaption>
</figure>
<p>Spirit landed in Gusev Crater, a 150km-wide crater created billions of years ago when an asteroid crashed into Mars. </p>
<p>Spirit discovered evidence of an ancient volcanic explosion, caused by hot lava meeting water. Small rocks had been thrown skyward but then fell back to Mars. Examination of the impact or “<a href="http://redplanet.asu.edu/?p=1216">bomb sag</a>” showed the rock had landed on wet soil. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/381847/original/file-20210202-19-z79fs3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A small crater on Mars." src="https://images.theconversation.com/files/381847/original/file-20210202-19-z79fs3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/381847/original/file-20210202-19-z79fs3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/381847/original/file-20210202-19-z79fs3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/381847/original/file-20210202-19-z79fs3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/381847/original/file-20210202-19-z79fs3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/381847/original/file-20210202-19-z79fs3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/381847/original/file-20210202-19-z79fs3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The arrow points to a small crater or bomb sag, just 4cm across, that formed in the soaking wet ground when an ejected rock fell back to Mars.</span>
<span class="attribution"><a class="source" href="http://redplanet.asu.edu/?p=1216">NASA/JPL-Caltech/USGS/Cornell</a></span>
</figcaption>
</figure>
<p>Even when things went wrong, Spirit made new discoveries. While dragging a <a href="https://www.newscientist.com/article/dn8944-mars-rovers-broken-wheel-is-beyond-repair/">broken front wheel</a>, Spirit churned up a track of soil revealing a <a href="https://www.newscientist.com/article/dn11914-mars-rovers-disability-leads-to-major-water-discovery/">patch of white silica</a>. </p>
<p>This mineral usually exists in hot springs or steam vents, ideal environments where life on Earth tends to flourish. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/381609/original/file-20210201-15-boa9dl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Track of disturbed red soil revealing white silica." src="https://images.theconversation.com/files/381609/original/file-20210201-15-boa9dl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/381609/original/file-20210201-15-boa9dl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/381609/original/file-20210201-15-boa9dl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/381609/original/file-20210201-15-boa9dl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/381609/original/file-20210201-15-boa9dl.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/381609/original/file-20210201-15-boa9dl.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/381609/original/file-20210201-15-boa9dl.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A 20cm track revealing white silica and a clue that Mars was once wet and warm.</span>
<span class="attribution"><a class="source" href="https://www.jpl.nasa.gov/news/mars-rover-spirit-unearths-surprise-evidence-of-wetter-past">NASA/JPL/Cornell</a></span>
</figcaption>
</figure>
<h2>The rover that kept on going</h2>
<p>Opportunity arrived on Mars three weeks after Spirit. Its original three-month mission was extended to 14 years as it travelled almost 50km across the Martian terrain. </p>
<p>Landing in the small Eagle Crater, Opportunity went on to visit more than 100 impact craters. It also found a handful of meteorites, <a href="https://mars.nasa.gov/mer/newsroom/pressreleases/20050119a.html">the first to be studied on another planet</a>. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/382476/original/file-20210204-22-oxoad8.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Opportunity’s journey mapped on an aerial view of Mars" src="https://images.theconversation.com/files/382476/original/file-20210204-22-oxoad8.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/382476/original/file-20210204-22-oxoad8.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=463&fit=crop&dpr=1 600w, https://images.theconversation.com/files/382476/original/file-20210204-22-oxoad8.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=463&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/382476/original/file-20210204-22-oxoad8.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=463&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/382476/original/file-20210204-22-oxoad8.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=582&fit=crop&dpr=1 754w, https://images.theconversation.com/files/382476/original/file-20210204-22-oxoad8.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=582&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/382476/original/file-20210204-22-oxoad8.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=582&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Outlined in yellow is Opportunity’s journey from Eagle Crater towards its final resting spot on the rim of Endeavour Crater. The blue outline of Victoria’s Phillip Island is included for scale.</span>
<span class="attribution"><span class="source">NASA/JPL-Caltech/MSSS/Museums Victoria</span></span>
</figcaption>
</figure>
<p>The rover was descending into Endeavour Crater when a dust storm <a href="https://mars.nasa.gov/news/8413/nasas-opportunity-rover-mission-on-mars-comes-to-end/">ended its mission</a>. But it was along the crater’s edge that Opportunity made its biggest discoveries. </p>
<p>It found signs of ancient water flows and discovered the crater walls are <a href="https://mars.nasa.gov/mer/newsroom/pressreleases/20110901a.html">made of clays</a> that can only form where freshwater is available — more evidence that Mars could well have been a place for life. </p>
<h2>The chemist - Curiosity</h2>
<p><a href="https://mars.nasa.gov/mars-exploration/missions/mars-science-laboratory/">Curiosity</a> landed in Gale Crater on August 6, 2012, and continues to explore the region today. During the coronavirus pandemic, scientists and engineers have been commanding the rover from their homes.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/381858/original/file-20210202-19-11bt6t4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="The Curiosity rover lowered to Mars." src="https://images.theconversation.com/files/381858/original/file-20210202-19-11bt6t4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/381858/original/file-20210202-19-11bt6t4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=337&fit=crop&dpr=1 600w, https://images.theconversation.com/files/381858/original/file-20210202-19-11bt6t4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=337&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/381858/original/file-20210202-19-11bt6t4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=337&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/381858/original/file-20210202-19-11bt6t4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/381858/original/file-20210202-19-11bt6t4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/381858/original/file-20210202-19-11bt6t4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">An artist’s impression of Curiosity as it descends from the top of the Martian atmosphere to softly touchdown on the planet’s surface.</span>
<span class="attribution"><a class="source" href="https://www.nasa.gov/mission_pages/msl/multimedia/gallery/pia14839.html">NASA/JPL-Caltech</a></span>
</figcaption>
</figure>
<p>In a first for space exploration, NASA’s Curiosity was lowered to the Martian surface using a “sky crane”. After a successful soft landing, the crane’s cables were cut and the spacecraft’s descent stage flew away to crash elsewhere.</p>
<p>Curiosity is a fully equipped chemical laboratory. It can shoot lasers at rocks and also drill into the soil to collect samples. It’s confirmed ancient Mars once had the right chemistry to <a href="https://www.nasa.gov/mission_pages/msl/news/msl20130312.html">support microbial life</a>. </p>
<p>Curiosity also found evidence of ancient freshwater rivers and lakes. It seems that water once flowed towards a basin at Mount Sharp, a central peak that rises 5.5km from within Gale Crater. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/381861/original/file-20210202-17-kqxcbk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="The Curiosity rover on the Martian surface." src="https://images.theconversation.com/files/381861/original/file-20210202-17-kqxcbk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/381861/original/file-20210202-17-kqxcbk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=337&fit=crop&dpr=1 600w, https://images.theconversation.com/files/381861/original/file-20210202-17-kqxcbk.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=337&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/381861/original/file-20210202-17-kqxcbk.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=337&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/381861/original/file-20210202-17-kqxcbk.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/381861/original/file-20210202-17-kqxcbk.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/381861/original/file-20210202-17-kqxcbk.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Curiosity takes a picture of itself, working through the COVID-19 pandemic and drilling holes in a possible ancient riverbed.</span>
<span class="attribution"><a class="source" href="https://www.nasa.gov/feature/jpl/nasas-curiosity-takes-selfie-with-mary-anning-on-the-red-planet">NASA/JPL-Caltech/MSSS</a></span>
</figcaption>
</figure>
<p>From being on the surface of Mars, we’ve learned it was once very different to the dry, dusty planet it is today.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/the-conversation-weekly-podcast-ep-1-transcript-why-its-a-big-month-for-mars-154500">The Conversation Weekly podcast Ep #1 transcript: Why it's a big month for Mars</a>
</strong>
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</p>
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<p>With flowing water, possible oceans, volcanic activity and an abundance of key ingredients necessary for life, the red planet was once much more Earth-like. What happened to make it change so dramatically? </p>
<p>It’s exciting to consider what the Perseverance and Taiwen-1 rovers may discover as they explore their own patch of Mars. They might even lead us to the day when humans are exploring the red planet for ourselves.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/381611/original/file-20210201-17-jy1jiy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A Martian rocky landscape." src="https://images.theconversation.com/files/381611/original/file-20210201-17-jy1jiy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/381611/original/file-20210201-17-jy1jiy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=275&fit=crop&dpr=1 600w, https://images.theconversation.com/files/381611/original/file-20210201-17-jy1jiy.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=275&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/381611/original/file-20210201-17-jy1jiy.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=275&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/381611/original/file-20210201-17-jy1jiy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=346&fit=crop&dpr=1 754w, https://images.theconversation.com/files/381611/original/file-20210201-17-jy1jiy.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=346&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/381611/original/file-20210201-17-jy1jiy.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=346&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The colours in this image from Gale Crater have been adjusted to match conditions on Earth – this helps geologists interpret the rocks but it also changes the natural pink Martian sky to an Earth-like blue.</span>
<span class="attribution"><a class="source" href="https://mars.nasa.gov/resources/7505/strata-at-base-of-mount-sharp/">NASA/JPL-Caltech</a></span>
</figcaption>
</figure><img src="https://counter.theconversation.com/content/153791/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Tanya Hill does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Of the three probes to reach Mars this month, only two will land. But they will add to our growing knowledge of the red planet, and the search for evidence of life.Tanya Hill, Honorary Fellow of the University of Melbourne and Senior Curator (Astronomy), Museums Victoria Research InstituteLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1501672020-12-20T21:12:25Z2020-12-20T21:12:25ZHow to get people from Earth to Mars and safely back again<figure><img src="https://images.theconversation.com/files/372184/original/file-20201201-21-qplwcp.jpg?ixlib=rb-1.1.0&rect=758%2C353%2C1158%2C724&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://images.nasa.gov/details-PIA24032">NASA</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span></figcaption></figure><p>There are many things humanity must overcome before any return journey to Mars is launched.</p>
<p>The two major players are NASA and SpaceX, which work together intimately on missions to the International Space Station but have competing ideas of what a crewed Mars mission would look like.</p>
<h2>Size matters</h2>
<p>The biggest challenge (or constraint) is the mass of the payload (spacecraft, people, fuel, supplies etc) needed to make the journey.</p>
<p>We still talk about launching something into space being like launching its weight in gold.</p>
<p>The payload mass is usually just a small percentage of the total mass of the launch vehicle.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/buried-lakes-of-salty-water-on-mars-may-provide-conditions-for-life-146928">Buried lakes of salty water on Mars may provide conditions for life</a>
</strong>
</em>
</p>
<hr>
<p>For example, the <a href="https://solarsystem.nasa.gov/news/382/10-things-rockets-we-love-saturn-v/">Saturn V</a> rocket that launched <a href="https://www.nasa.gov/mission_pages/apollo/apollo-11.html">Apollo 11</a> to the Moon weighed 3,000 tonnes.</p>
<p>But it could launch only 140 tonnes (5% of its initial launch mass) to low Earth orbit, and 50 tonnes (less than 2% of its initial launch mass) to the Moon.</p>
<p>Mass constrains the size of a Mars spacecraft and what it can do in space. Every manoeuvre costs fuel to fire rocket motors, and this fuel must currently be carried into space on the spacecraft.</p>
<p>SpaceX’s plan is for its crewed <a href="https://www.spacex.com/vehicles/starship/">Starship</a> vehicle to be <a href="https://spaceflightnow.com/2020/10/16/nasa-selects-companies-to-demonstrate-in-space-refueling-and-propellant-depot-tech/">refuelled in space</a> by a separately launched fuel tanker. That means much more fuel can be carried into orbit than could be carried on a single launch.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/374113/original/file-20201210-18-15bl8cf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A rocket capsule just about to land on Mars." src="https://images.theconversation.com/files/374113/original/file-20201210-18-15bl8cf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/374113/original/file-20201210-18-15bl8cf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/374113/original/file-20201210-18-15bl8cf.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/374113/original/file-20201210-18-15bl8cf.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/374113/original/file-20201210-18-15bl8cf.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/374113/original/file-20201210-18-15bl8cf.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/374113/original/file-20201210-18-15bl8cf.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Concept art of SpaceX’s Dragon landing on Mars.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/spacex/21424800115/">Official SpaceX Photos/Flickr</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc/4.0/">CC BY-NC</a></span>
</figcaption>
</figure>
<h2>Time matters</h2>
<p>Another challenge, intimately connected with fuel, is time.</p>
<p>Missions that send spacecraft with no crew to the outer planets often travel complex trajectories around the Sun. They use what are called <a href="https://solarsystem.nasa.gov/basics/primer/">gravity assist manoeuvres</a> to effectively slingshot around different planets to gain enough momentum to reach their target.</p>
<p>This saves a lot of fuel, but can result in missions that take years to reach their destinations. Clearly this is something humans would not want to do. </p>
<p>Both Earth and Mars have (almost) circular orbits and a manoeuvre known as the <a href="https://solarsystem.nasa.gov/basics/chapter4-1/">Hohmann transfer</a> is the most fuel-efficient way to travel between two planets. Basically, without going into too much detail, this is where a spacecraft does a single burn into an elliptical transfer orbit from one planet to the other.</p>
<p>A Hohmann transfer between Earth and Mars takes around 259 days (between eight and nine months) and is only possible approximately every two years due to the different orbits around the Sun of Earth and Mars.</p>
<p>A spacecraft could reach Mars in a shorter time (SpaceX is claiming <a href="https://www.space.com/spacex-plans-journey-to-mars.html">six months</a>) but — you guessed it — it would cost more fuel to do it that way.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/372132/original/file-20201201-13-1s1mkcn.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C3361%2C2212&q=45&auto=format&w=1000&fit=clip"><img alt="Mars, the red planet." src="https://images.theconversation.com/files/372132/original/file-20201201-13-1s1mkcn.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C3361%2C2212&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/372132/original/file-20201201-13-1s1mkcn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/372132/original/file-20201201-13-1s1mkcn.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/372132/original/file-20201201-13-1s1mkcn.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/372132/original/file-20201201-13-1s1mkcn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/372132/original/file-20201201-13-1s1mkcn.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/372132/original/file-20201201-13-1s1mkcn.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Mars and Earth have few similarities.</span>
<span class="attribution"><a class="source" href="https://solarsystem.nasa.gov/resources/683/valles-marineris-the-grand-canyon-of-mars/">NASA/JPL-Caltech</a></span>
</figcaption>
</figure>
<h2>Safe landing</h2>
<p>Suppose our spacecraft and crew get to Mars. The next challenge is landing.</p>
<p>A spacecraft entering Earth is able to use the drag generated by interaction with the atmosphere to slow down. This allows the craft to land safely on the Earth’s surface (provided it can survive the related heating).</p>
<p>But the atmosphere on Mars is about 100 times thinner than Earth’s. That means less potential for drag, so it isn’t possible to land safely without some kind of aid. </p>
<p>Some missions have landed on airbags (such as NASA’s <a href="https://mars.nasa.gov/mars-exploration/missions/pathfinder/">Pathfider</a> mission) while others have used thrusters (NASA’s <a href="https://www.nasa.gov/mission_pages/phoenix/overview">Phoenix</a> mission). The latter, once again, requires more fuel.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/5TaP8YMM524?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">A thruster landing on Mars.</span></figcaption>
</figure>
<h2>Life on Mars</h2>
<p>A Martian day lasts 24 hours and 37 minutes but the similarities with Earth stop there.</p>
<p>The thin atmosphere on Mars means it can’t retain heat as well as Earth does, so life on Mars is characterised by large extremes in temperature during the day/night cycle.</p>
<p>Mars has a maximum temperature of 30°C, which sounds quite pleasant, but its minimum temperature is -140°C, and its average temperature is <a href="https://mars.nasa.gov/all-about-mars/facts/">-63°C</a>. The average winter temperature at the Earth’s South Pole is <a href="https://niwa.co.nz/education-and-training/schools/resources/climate/antarctic">about -49°C</a>.</p>
<p>So we need to be very selective about where we choose to live on Mars and how we manage temperature during the night.</p>
<p>The gravity on Mars is 38% of Earth’s (so you’d feel lighter) but the air is principally carbon dioxide (CO₂) with several percent of nitrogen, so it’s completely unbreathable. We would need to build a climate-controlled place just to live there.</p>
<p>SpaceX <a href="https://www.spacex.com/human-spaceflight/mars/">plans</a> to <a href="https://www.space.com/spacex-plans-journey-to-mars.html">launch several cargo flights</a> including critical infrastructure such as greenhouses, solar panels and — you guessed it — a fuel-production facility for return missions to Earth.</p>
<p>Life on Mars would be possible and several simulation <a href="https://theconversation.com/dear-diary-the-sun-never-set-on-the-arctic-mars-simulation-84597">trials</a> have <a href="https://www.bbc.com/news/world-us-canada-34092770">already</a> been <a href="https://www.nationalgeographic.com/science/2019/01/see-how-astronauts-simulate-mars-mission-on-earth/">done</a> on Earth to see how people would cope with such an existence.</p>
<h2>Return to Earth</h2>
<p>The final challenge is the return journey and getting people safely back to Earth.</p>
<p>Apollo 11 entered Earth’s atmosphere at about 40,000km/h, which is just below the velocity required to escape Earth’s orbit.</p>
<p>Spacecraft returning from Mars will have re-entry velocities from 47,000km/h to 54,000km/h, depending on the orbit they use to arrive at Earth.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/dear-diary-the-sun-never-set-on-the-arctic-mars-simulation-84597">Dear diary: the Sun never set on the Arctic Mars simulation</a>
</strong>
</em>
</p>
<hr>
<p>They could slow down into low orbit around Earth to around 28,800km/h before entering our atmosphere but — you guessed it — they’d need extra fuel to do that.</p>
<p>If they just barrel into the atmosphere, it will do all of the deceleration for them. We just need to make sure we don’t kill the astronauts with G-forces or burn them up due to excess heating.</p>
<p>These are just some of the challenges facing a Mars mission and all of the technological building blocks to achieve this are there. We just need to spend the time and the money and bring it all together.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/374120/original/file-20201210-23-xkn5nb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="The view of sunrise over Earth as seen from the International Space Station" src="https://images.theconversation.com/files/374120/original/file-20201210-23-xkn5nb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/374120/original/file-20201210-23-xkn5nb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=300&fit=crop&dpr=1 600w, https://images.theconversation.com/files/374120/original/file-20201210-23-xkn5nb.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=300&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/374120/original/file-20201210-23-xkn5nb.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=300&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/374120/original/file-20201210-23-xkn5nb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=377&fit=crop&dpr=1 754w, https://images.theconversation.com/files/374120/original/file-20201210-23-xkn5nb.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=377&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/374120/original/file-20201210-23-xkn5nb.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=377&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">And we need to return people safely back to Earth, mission accomplished.</span>
<span class="attribution"><a class="source" href="https://www.nasa.gov/image-feature/good-morning-from-the-international-space-station-1">NASA</a></span>
</figcaption>
</figure><img src="https://counter.theconversation.com/content/150167/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Chris James receives funding from the Australian Research Council. </span></em></p>We’ve already sent probes to land on Mars. The challenge now is to get people there and bring them home again.Chris James, Lecturer, Centre for Hypersonics, The University of QueenslandLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1467322020-09-28T15:05:29Z2020-09-28T15:05:29ZMars: mounting evidence for subglacial lakes, but could they really host life?<figure><img src="https://images.theconversation.com/files/360265/original/file-20200928-20-1qo7icm.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C1397%2C785&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">There seems to be a network of underground bodies of liquid water at Mars' south pole.</span> <span class="attribution"><a class="source" href="https://www.jpl.nasa.gov/news/news.php?feature=7200">NASA/JPL/Malin Space Science Systems</a></span></figcaption></figure><p>Venus <a href="https://theconversation.com/venus-could-it-really-harbour-life-new-study-springs-a-surprise-145981">may harbour life</a> some 50km above its surface, we learned a couple of weeks ago. Now a new paper, <a href="https://www.nature.com/articles/s41550-020-1200-6">published in Nature Astronomy</a>, reveals that the best place for life on Mars might be more than a kilometre <em>below</em> its surface, where an entire network of subglacial lakes has been discovered.</p>
<p>Mars was not always so cold and dry as it is now. There are abundant signs that water flowed across its surface in the distant past, but today you’d struggle to find even any crevices that you could call moist.</p>
<p>There is nevertheless plenty of water on Mars today, but it’s virtually all frozen, so not much use for life. Even in places where the noon-time temperature creeps above freezing, <a href="https://theconversation.com/nasa-streaks-of-salt-on-mars-mean-flowing-water-and-raise-new-hopes-of-finding-life-48182">surface signs of liquid water</a> are frustratingly rare. This is because the atmospheric pressure on Mars is too slight to confine water in its liquid state, so ice usually
turns directly into vapour when heated.</p>
<h2>Lakes beneath ice</h2>
<p>It is beginning to look as if the most favourable place for liquid water on Mars is beneath its vast south polar ice cap. On Earth, such lakes began to be <a href="http://www.antarcticglaciers.org/glacier-processes/glacial-lakes/subglacial-lakes/">discovered in Antarctica</a> in the 1970s, where nearly 400 are now known. Most of these have been found by “radio echo sounding” (essentially radar), in which equipment on a survey aircraft emits radio pulses. </p>
<p>Part of the signal reflects back from the ice surface, but some is reflected from further below – especially strongly where there is a boundary between ice and underlying liquid water. Antarctica’s largest subglacial lake is Lake Vostok – which is 240km long, 50km wide and hundreds of metres deep – located 4km below the surface.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/359439/original/file-20200922-20-1uzlet7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Radar image of Lake Vostok below the Antarctic ice." src="https://images.theconversation.com/files/359439/original/file-20200922-20-1uzlet7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/359439/original/file-20200922-20-1uzlet7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/359439/original/file-20200922-20-1uzlet7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/359439/original/file-20200922-20-1uzlet7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/359439/original/file-20200922-20-1uzlet7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/359439/original/file-20200922-20-1uzlet7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/359439/original/file-20200922-20-1uzlet7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Radar satellite image revealing Lake Vostok below the Antarctic ice. The area shown is about 300km across.</span>
<span class="attribution"><span class="source">NASA</span></span>
</figcaption>
</figure>
<p>Indications of similar lakes below the southern polar ice cap of Mars were <a href="https://theconversation.com/discovered-a-huge-liquid-water-lake-beneath-the-southern-pole-of-mars-100523">first suggested</a> by radar reflections 1.5km below the ice surface in a region named Ultimi Scopuli. These were detected between May 2012 and December 2015 by <a href="https://mars.nasa.gov/express/mission/sc_science_marsis01.html">MARSIS</a> (Mars Advanced Radar for Subsurface and Ionosphere Sounding), an instrument carried by the European Space Agency’s <a href="https://sci.esa.int/web/mars-express/">Mars Express</a> that has been orbiting the planet since 2003. </p>
<figure class="align-center ">
<img alt="Image of Ultimi Scopuli, a region of Mars’s south polar ice cap." src="https://images.theconversation.com/files/359455/original/file-20200922-20-625wz7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/359455/original/file-20200922-20-625wz7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=415&fit=crop&dpr=1 600w, https://images.theconversation.com/files/359455/original/file-20200922-20-625wz7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=415&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/359455/original/file-20200922-20-625wz7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=415&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/359455/original/file-20200922-20-625wz7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=521&fit=crop&dpr=1 754w, https://images.theconversation.com/files/359455/original/file-20200922-20-625wz7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=521&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/359455/original/file-20200922-20-625wz7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=521&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A 4km wide area in Ultimi Scopuli: strange ice texture gives no clue as to presence of liquid water 1.5km below.</span>
<span class="attribution"><span class="source">NASA/JPL/University of Arizona</span></span>
</figcaption>
</figure>
<p>The new study of MARSIS data using signal processing techniques that take account of both the intensity and the sharpness (“acuity”) of the reflections has demonstrated that the previously detected region does indeed mark the top of a liquid body. This is the Ultimi Scopuli subglacial lake, and there seem also to be smaller patches of liquid nearby in the 250km by 300km area covered by the survey. The authors suggest that the liquid bodies consist of hypersaline solutions, in which high concentrations of salts are dissolved in water. </p>
<p>They point out that salts of calcium, magnesium, sodium and potassium are known to be ubiquitous in the martian soil, and that dissolved salts could help to explain how subglacial lakes on Mars can remain liquid despite the low temperature at the base of the ice cap. The weight of the overlying ice would supply the pressure necessary to keep the water in liquid state rather than turning to vapour.</p>
<h2>Life in subglacial lakes?</h2>
<p>Lake Vostok is touted as a <a href="https://theconversation.com/first-direct-evidence-of-microbial-life-under-1km-of-antarctic-ice-30695">possible habitat for life</a> that has been isolated from the Earth’s surface for millions of years, and as an analogue for proposed environments habitable by microbes (and possibly more complex organisms) in the internal oceans of icy moons such as Jupiter’s <a href="https://theconversation.com/new-water-plumes-from-jupiters-moon-europa-raise-hopes-of-detecting-microbial-life-66019">Europa</a> and Saturn’s <a href="https://theconversation.com/nasa-saturn-moon-enceladus-is-able-to-host-life-its-time-for-a-new-mission-76102">Enceladus</a>.</p>
<figure class="align-center ">
<img alt="The white ice cap at the south pole of Mars, seen from space." src="https://images.theconversation.com/files/359858/original/file-20200924-25-kki0ri.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/359858/original/file-20200924-25-kki0ri.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=343&fit=crop&dpr=1 600w, https://images.theconversation.com/files/359858/original/file-20200924-25-kki0ri.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=343&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/359858/original/file-20200924-25-kki0ri.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=343&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/359858/original/file-20200924-25-kki0ri.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=431&fit=crop&dpr=1 754w, https://images.theconversation.com/files/359858/original/file-20200924-25-kki0ri.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=431&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/359858/original/file-20200924-25-kki0ri.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=431&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Mars’s south polar ice cap as seen by the Mars Global Surveyor (MGS) Mars Orbiter Camera (MOC) on April 17, 2000.</span>
<span class="attribution"><a class="source" href="https://www.nasa.gov/centers/ames/multimedia/images/2005/marscap.html">NASA</a></span>
</figcaption>
</figure>
<p>Although hypersaline water would give microbes a place to live below Mars’ south polar cap, without an energy (food) source of some kind they could not survive. Chemical reactions between water and rock might release some energy but probably not enough; it would help if there was an occasional volcanic eruption, or at least hot spring, feeding into lake. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/what-on-earth-could-live-in-a-salt-water-lake-on-mars-an-expert-explains-101148">What on Earth could live in a salt water lake on Mars? An expert explains</a>
</strong>
</em>
</p>
<hr>
<p>We lack evidence of this on Mars, unlike on Europa and Enceladus. Although the new findings make Mars even more interesting than before, they haven’t advanced its ranking in the <a href="https://theconversation.com/water-water-everywhere-where-to-drink-in-the-solar-system-46153">list of solar system bodies</a> most likely to host life.</p>
<p>That said, the salty water could act as a <a href="https://theconversation.com/what-on-earth-could-live-in-a-salt-water-lake-on-mars-an-expert-explains-101148">preservation chamber</a> – helping us find alien organisms that are now extinct but once <a href="https://www.youtube.com/watch?time_continue=56&v=SIkvVQrOpMM&feature=emb_logo">came to Mars</a> from other parts of the solar system.</p><img src="https://counter.theconversation.com/content/146732/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>David Rothery is Professor of Planetary Geosciences at the Open University. He is co-leader of the European Space Agency's Mercury Surface and Composition Working Group, and a Co-Investigator on MIXS (Mercury Imaging X-ray Spectrometer) that is now on its way to Mercury on board the European Space Agency's Mercury orbiter BepiColombo. He has received funding from the UK Space Agency and the Science & Technology Facilities Council for work related to Mercury and BepiColombo, and is currently funded by the European Commission under its Horizon 2020 programme for work on planetary geological mapping (776276 Planmap). He is author of Planet Mercury - from Pale Pink Dot to Dynamic World (Springer, 2015), Moons: A Very Short Introduction (Oxford University Press, 2015) and Planets: A Very Short Introduction (Oxford University Press, 2010). He is Educator on the Open University's free learning Badged Open Course (BOC) on Moons and its equivalent FutureLearn Moons MOOC, and chair of the Open University's level 2 course on Planetary Science and the Search for Life.</span></em></p>New findings boost chances of finding life on Mars, but there are better candidates in the solar system.David Rothery, Professor of Planetary Geosciences, The Open UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1415902020-07-29T19:54:56Z2020-07-29T19:54:56ZPerseverance: the Mars rover searching for ancient life, and the Aussie scientists who helped build it<figure><img src="https://images.theconversation.com/files/349447/original/file-20200725-19-1j979lo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The Perseverance Rover (Mars 2020) installed within the upper stage of the United Launch Alliance rocket that will send it to Mars from Florida this week.</span> </figcaption></figure><p>Every two years or so, when Mars passes close to Earth in its orbit around the Sun, conditions are right to launch a spacecraft to the red planet. Launches during this period can complete the seven-month voyage using a minimum of energy. </p>
<p>We are in the middle of one such period right now, and three separate missions are taking advantage of it. The <a href="https://www.emiratesmarsmission.ae/">United Arab Emirates’ Hope mission</a> and <a href="https://www.nature.com/articles/d41586-020-02187-7">China’s Tianwen-1</a> have already launched. NASA’s Perseverance mission is set to take flight tonight (on July 30, at 9:50pm AEST).</p>
<p>Between them, the missions will study the atmosphere and surface of Mars in unprecedented detail, collect samples that may one day come back to Earth, and tell scientists more about whether our neighbouring planet ever held life.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/349450/original/file-20200725-37-qpanf6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/349450/original/file-20200725-37-qpanf6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/349450/original/file-20200725-37-qpanf6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/349450/original/file-20200725-37-qpanf6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/349450/original/file-20200725-37-qpanf6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/349450/original/file-20200725-37-qpanf6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/349450/original/file-20200725-37-qpanf6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/349450/original/file-20200725-37-qpanf6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Instruments carried aboard NASA’s Perseverance Rover.</span>
<span class="attribution"><span class="source">NASA JPL/Caltech</span></span>
</figcaption>
</figure>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/our-long-fascination-with-the-journey-to-mars-106541">Our long fascination with the journey to Mars</a>
</strong>
</em>
</p>
<hr>
<h2>What do the Mars missions aim to achieve?</h2>
<p>The UAE’s Hope orbiter will study the atmosphere of Mars using <a href="https://www.emiratesmarsmission.ae/hope-probe/instruments/">infrared and ultraviolet light</a>. </p>
<p>In a truly international effort, Hope’s instruments were developed by scientists at the Mohammed Bin Rashid Space Centre in Dubai, working with the University of Colorado, Boulder, and Arizona State University in the United States. Hope was carried from Dubai to Japan by a Russian-operated Antonov aircraft, and launched from Tanegashima Island on July 19.</p>
<p>Hope has no doubt already achieved its primary goal of inspiring the youth of the Arab world. Like most deep space missions, Hope’s goals are a combination of cutting-edge science, technology demonstration, and stimulating the local knowledge economy.</p>
<p>Although accompanied by less fanfare, China’s Tianwen-1 mission is also an extraordinarily ambitious effort driven by clear scientific goals. Building on the success of China’s lunar exploration program, Tianwen is the country’s first attempt at a Mars rover. If Tianwen succeeds, the China National Space Administration (CNSA) will become the second space agency after NASA to operate a rover on Mars.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/349448/original/file-20200725-35-167xupf.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/349448/original/file-20200725-35-167xupf.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/349448/original/file-20200725-35-167xupf.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=664&fit=crop&dpr=1 600w, https://images.theconversation.com/files/349448/original/file-20200725-35-167xupf.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=664&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/349448/original/file-20200725-35-167xupf.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=664&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/349448/original/file-20200725-35-167xupf.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=834&fit=crop&dpr=1 754w, https://images.theconversation.com/files/349448/original/file-20200725-35-167xupf.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=834&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/349448/original/file-20200725-35-167xupf.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=834&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Tianwen-1 undergoing testing in China.</span>
</figcaption>
</figure>
<p>Both the rover and accompanying orbiter will bring instruments that address key questions of the global scientific community. </p>
<p>Tianwen will carry a ground-penetrating radar that will let geologists peer beneath the dusty surface to examine the rock beneath the landing site. It will also carry the first mobile instrument that can sense variations in the magnetic field, which may tell scientists a lot about how fit for life Mars was in the past.</p>
<p>Tianwen-1 launched on July 23 from Hainan Island. Unfortunately, mission scientists were forbidden from talking to media beforehand, and live videos of the launch were banned (though some snuck out online). </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/349442/original/file-20200725-31-13zqicx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/349442/original/file-20200725-31-13zqicx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=586&fit=crop&dpr=1 600w, https://images.theconversation.com/files/349442/original/file-20200725-31-13zqicx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=586&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/349442/original/file-20200725-31-13zqicx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=586&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/349442/original/file-20200725-31-13zqicx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=737&fit=crop&dpr=1 754w, https://images.theconversation.com/files/349442/original/file-20200725-31-13zqicx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=737&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/349442/original/file-20200725-31-13zqicx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=737&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The launch of China’s Tianwen-1 Mars mission on the 23rd of July, 2020.</span>
</figcaption>
</figure>
<p>China has now demonstrated a super heavy launch system to deep space, and if it succeeds with a soft landing on Mars and deep space operations, it will be close on NASA’s heels in Mars sample return. The idea of a Chinese Mars mission getting the first answers to big questions in planetary science, which would have seemed unlikely only a few years ago, may well become reality in the coming months. Both the Chinese and American programs have plans to return Martian samples to Earth in the 2030s.</p>
<h2>Perseverance and the search for ancient life</h2>
<p>For now, NASA is still the player with the most experience and the best resources. The <a href="https://mars.nasa.gov/mars2020/">Perseverance rover</a>, scheduled for launch from Florida on July 30 at 9:50pm AEST, will be the most complex object ever sent to Mars. The new rover will search for evidence of ancient microbial life in Jezero Crater.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/ancient-life-in-greenland-and-the-search-for-life-on-mars-64895">Ancient life in Greenland and the search for life on Mars</a>
</strong>
</em>
</p>
<hr>
<p>Perseverance is the first in a series of missions that NASA hopes will culminate in bringing samples of the Martian surface back to Earth. A <a href="https://mars.nasa.gov/mars2020/spacecraft/rover/sample-handling/">novel system will collect samples</a> selected by a globally distributed team of experts and cache them for future collection. These rocks will likely be studied for decades, like the <a href="https://curator.jsc.nasa.gov/lunar/lun-fac.cfm">samples of Moon rock</a> brought home by the Apollo missions.</p>
<p><a href="https://mars.nasa.gov/mars2020/spacecraft/instruments/meda/">Italy</a>, <a href="https://mars.nasa.gov/mars2020/spacecraft/instruments/rimfax/">Norway</a> and <a href="https://www.dtu.dk/english/news/2019/05/dtu-equipment-on-board-nasas-next-big-mission-to-mars?id=749083ee-d765-4f06-9279-725b45070b73">Denmark</a> are among the smaller nations contributing hardware to Perseverance. The scientists and engineers who participate gain experience with deep space systems, share in discoveries and increase the overall scientific gains of the project. </p>
<h2>How Australians are involved</h2>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/349445/original/file-20200725-35-5gq9xt.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/349445/original/file-20200725-35-5gq9xt.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=336&fit=crop&dpr=1 600w, https://images.theconversation.com/files/349445/original/file-20200725-35-5gq9xt.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=336&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/349445/original/file-20200725-35-5gq9xt.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=336&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/349445/original/file-20200725-35-5gq9xt.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=422&fit=crop&dpr=1 754w, https://images.theconversation.com/files/349445/original/file-20200725-35-5gq9xt.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=422&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/349445/original/file-20200725-35-5gq9xt.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=422&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Artists impression of the Planetary Instrument of X-ray Lithochemistry aboard the Perserverance Rover, led by Australian scientists, analysing rocks on Mars.</span>
</figcaption>
</figure>
<figure class="align-left zoomable">
<a href="https://images.theconversation.com/files/349446/original/file-20200725-21-1nl14pc.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/349446/original/file-20200725-21-1nl14pc.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/349446/original/file-20200725-21-1nl14pc.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=316&fit=crop&dpr=1 600w, https://images.theconversation.com/files/349446/original/file-20200725-21-1nl14pc.PNG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=316&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/349446/original/file-20200725-21-1nl14pc.PNG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=316&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/349446/original/file-20200725-21-1nl14pc.PNG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=397&fit=crop&dpr=1 754w, https://images.theconversation.com/files/349446/original/file-20200725-21-1nl14pc.PNG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=397&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/349446/original/file-20200725-21-1nl14pc.PNG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=397&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Microbial fossil stromatolite in Western Australia (left) sampled by prototype rover drill hardware in a collaboration with NASA JPL. The stable carbon isotope composition of microfossils captured in the drill core was measured using secondary ion mass spectrometry (right).</span>
</figcaption>
</figure>
<p>Several Australians are also involved in the Perseverance mission. </p>
<p>Brisbane-born geologist Abigail Allwood, based at NASA Jet Propulsion Laboratory (JPL) in California, leads the team who developed an <a href="https://mars.nasa.gov/mars2020/spacecraft/instruments/pixl/">instrument on the rover’s arm</a> capable of detecting signs of past life. Australian planetary scientist Adrian Brown is also working on the mission, bringing his experience using remote sensing to study Australian rocks that resemble those on Mars. </p>
<p>I worked on this mission at NASA JPL for several years and, although I have returned to Australia, I continue to serve as a long-term planner leading the mission’s science team and as an instrument co-investigator. The Queensland University of Technology is contributing software that will analyse data returned from the rover, with <a href="https://www.qut.edu.au/news?id=166153">opportunities for Australian students</a> and academics to contribute to the science investigation.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/349444/original/file-20200725-31-14afrde.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/349444/original/file-20200725-31-14afrde.png?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/349444/original/file-20200725-31-14afrde.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=385&fit=crop&dpr=1 600w, https://images.theconversation.com/files/349444/original/file-20200725-31-14afrde.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=385&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/349444/original/file-20200725-31-14afrde.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=385&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/349444/original/file-20200725-31-14afrde.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=484&fit=crop&dpr=1 754w, https://images.theconversation.com/files/349444/original/file-20200725-31-14afrde.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=484&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/349444/original/file-20200725-31-14afrde.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=484&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The geology of Jezero Crater mapped by the Perseverance mission science team including Australians bringing expertise studying similar rocks in Western Australia.</span>
<span class="attribution"><span class="source">NASA JPL/Caltech</span></span>
</figcaption>
</figure>
<h2>The future</h2>
<p>Australia is well placed to make important contributions to the future of Mars exploration. But to do so we must collaborate across national borders and find our place in the international scientific framework.</p>
<p>The planning of the nascent Australian Space Agency has largely focused on creating jobs and nurturing industry, but it needs a list of scientific priorities to guide investment in space missions. Otherwise, we risk building a car that is missing the driver’s seat.</p>
<p>At successful space agencies overseas, engineers and private industry work with scientists who conceive and operate spacecraft in pursuit of truth. Employment and innovation come from scientific projects, not the other way around. By following this model, Australia too may join the exploration of the universe, spurring technological innovation and inspiring the next generation of humans in the process.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/why-isnt-australia-in-deep-space-119533">Why isn't Australia in deep space?</a>
</strong>
</em>
</p>
<hr>
<img src="https://counter.theconversation.com/content/141590/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>David Flannery works and/or consults for NASA and the Queensland University of Technology.</span></em></p>Australian scientists have been working on NASA’s latest Mars mission for years.David Flannery, Planetary Scientist, Queensland University of TechnologyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1427052020-07-29T12:20:02Z2020-07-29T12:20:02ZNASA’s big move to search for life on Mars – and to bring rocks home<figure><img src="https://images.theconversation.com/files/349732/original/file-20200727-37-6cwj5m.jpg?ixlib=rb-1.1.0&rect=0%2C36%2C8238%2C5438&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">In a clean room at NASA's Jet Propulsion Laboratory in Pasadena, Calif., engineers observed the first driving test for the Mars rover, Perseverance. Perseverance will search for signs of past microbial life, characterize Mars' climate and geology, and collect samples for a future return to Earth. </span> <span class="attribution"><a class="source" href="https://mars.nasa.gov/resources/24732/mars-2020-rover-is-roving/">NASA/JPL-Caltech</a></span></figcaption></figure><p>NASA just took the next giant leap in the search for signs of life beyond Earth.</p>
<p>On July 30, <a href="https://mars.nasa.gov/mars2020/">NASA launched</a> its most sophisticated and ambitious spacecraft to Mars: the aptly named Perseverance rover. This will be the third launch to Mars this month, following the UAE’s <a href="https://theconversation.com/the-uaes-mars-mission-seeks-to-bring-hope-to-more-places-than-the-red-planet-142439">Hope</a> and China’s <a href="https://www.nature.com/articles/d41586-020-02187-7">Tianwen-1</a> spacecraft. Perseverance will look for signatures of ancient life preserved in Mars rocks. And, for the first time, this rover will collect rock samples that will be brought back to Earth, where they can be scrutinized in laboratories for decades to come.</p>
<p>Mars is one the few destinations in the Solar System that has had <a href="https://science.sciencemag.org/content/343/6169/1242777.abstract">conditions suitable for life</a> as we know it. There is a chance that Perseverance will collect the sample from Mars that answers the question: “Are we alone in the universe?” This question is especially relevant right now. During the coronavirus pandemic, the mission has remarkably stayed on track for launch in spite of <a href="https://www.jpl.nasa.gov/news/news.php?feature=7645">disruptions</a> and <a href="https://spaceflightnow.com/2020/06/30/nasa-delays-mars-rover-launch-to-no-earlier-than-july-30/">delays</a>, and we have been reminded that life on Earth is vulnerable and precious.</p>
<p>As <a href="https://scholar.google.com/citations?user=FzghC1EAAAAJ&hl=en">two</a> <a href="https://scholar.google.com/citations?user=rixGXz8AAAAJ&hl=en">experts</a> in planetary science and members of the Perseverance science team, we expect that this mission will be the best chance – within our own lifetimes at least – to create a scientific revolution in astrobiology. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/350021/original/file-20200728-35-gym6lh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/350021/original/file-20200728-35-gym6lh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=481&fit=crop&dpr=1 600w, https://images.theconversation.com/files/350021/original/file-20200728-35-gym6lh.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=481&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/350021/original/file-20200728-35-gym6lh.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=481&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/350021/original/file-20200728-35-gym6lh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=604&fit=crop&dpr=1 754w, https://images.theconversation.com/files/350021/original/file-20200728-35-gym6lh.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=604&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/350021/original/file-20200728-35-gym6lh.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=604&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">NASA’s Mars 2020 will land in Jezero Crater, pictured here. On ancient Mars, water carved channels and transported sediments to form fans and deltas within lake basins. Green colors indicate detections of carbonate minerals that may have formed in the ancient lake.</span>
<span class="attribution"><a class="source" href="https://www.nasa.gov/image-feature/jezero-crater-mars-2020s-landing-site">NASA/JPL-Caltech/ASU</a></span>
</figcaption>
</figure>
<h2>Searching for life in Jezero crater</h2>
<p>On Feb. 18, 2021, if all goes according to plan, Perseverance will enter the Martian atmosphere at 13,000 mph, and <a href="https://www.jpl.nasa.gov/video/details.php?id=1090">seven nerve-racking minutes later</a>, will be lowered gently onto the surface by a <a href="https://mars.nasa.gov/mars2020/timeline/landing/">jetpack</a>. The rover will land in <a href="https://www.jpl.nasa.gov/spaceimages/details.php?id=PIA23239">Jezero crater</a>, a site that NASA hopes will provide a window to a time when rain fell and rivers flowed on ancient Mars.</p>
<p>Over the past 30 years, a <a href="https://www.planetary.org/space-missions/every-mars-mission">fleet of rovers and orbiters</a> have built a picture of an Earth-like ancient Mars. Between 3 and 4 billion years ago, Mars hosted vast river networks <a href="https://www.jpl.nasa.gov/spaceimages/details.php?id=PIA00414">as long as the Mississippi</a>, deep lakes that contained <a href="https://mars.nasa.gov/news/8347/nasa-finds-ancient-organic-material-mysterious-methane-on-mars/">the building blocks of life</a>, and hot springs that <a href="https://astrobiology.nasa.gov/news/looking-for-life-on-mars-in-chile/">bubbled with potential</a> for life. These watery environments were able to exist because ancient Mars had a thick atmosphere. However, that atmosphere has been <a href="https://www.nasa.gov/press-release/nasas-maven-reveals-most-of-mars-atmosphere-was-lost-to-space">leaking away</a>, leaving the surface today cold, dry and inhospitable.</p>
<p>After <a href="https://www.nytimes.com/2020/07/28/science/nasa-jezero-perseverance.html">five years of debate</a>, Jezero crater was selected as the site on Mars that is most likely to preserve <a href="https://en.wikipedia.org/wiki/Biosignature">signs of life</a> that might have inhabited Mars billions of years ago, when microbial life was <a href="https://www.livescience.com/earliest-signs-of-life-on-earth.html">first starting on Earth</a>. <a href="https://www.jpl.nasa.gov/spaceimages/details.php?id=PIA23511">Satellite images of Jezero</a> show a river leading into the crater and ending in a large delta, which must have formed in a long-lived ancient lake. A bathtub ring of <a href="https://doi.org/10.1016/j.icarus.2019.113526">carbonate minerals</a> around the edge of the crater might have formed along ancient <a href="https://www.newscientist.com/article/2087612-super-salty-turkish-lakes-may-hold-key-to-spotting-life-on-mars/">beaches</a>, and may preserve rocks with microbial textures known as <a href="https://www.smithsonianmag.com/smart-news/what-happened-to-the-stromatolites-the-most-ancient-visible-lifeforms-on-earth-84714880/">stromatolites</a>. Stromatolites record some of the earliest <a href="https://spacescience.arc.nasa.gov/microbes/about/stromatolites.html">signs of life on Earth</a>, and Perseverance will search for similar signs of life on Mars.</p>
<h2>Advanced exploration technology</h2>
<p>Perseverance will have many new capabilities that will transform how we explore Mars. The rover carries Ingenuity, a small <a href="https://www.nasa.gov/feature/jpl/6-things-to-know-about-nasas-ingenuity-mars-helicopter/">helicopter</a> that will be the first aircraft to fly on another planet. Because Mars’ atmosphere today is so thin – only 1% of the Earth’s – Ingenuity has to be extremely lightweight (4 lbs) with very large blades (4 feet tip-to-tip) to get off the ground. Ingenuity will take images of the distant landscape and help us scout the rover’s traverse; future Mars missions could adopt this model of rovers and aircraft working in tandem.</p>
<p>Looking even further ahead, Perseverance will help prepare for future human missions to Mars. One of many <a href="https://www.wired.com/2016/02/space-is-cold-vast-and-deadly-humans-will-explore-it-anyway/">challenges</a> for astronauts will be the packing list for a two-year roundtrip journey, which includes air, water and rocket fuel to get home. If these resources could be harvested on Mars, human missions would be much more feasible. Perseverance will test <a href="https://mars.nasa.gov/mars2020/spacecraft/instruments/moxie/">a process for creating oxygen</a> from Mars’ carbon dioxide atmosphere. In the future, similar instruments could be sent ahead of astronauts, so that breathable air and liquid oxygen rocket propellant are waiting when they arrive.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/350024/original/file-20200728-27-k7e4r1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/350024/original/file-20200728-27-k7e4r1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/350024/original/file-20200728-27-k7e4r1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/350024/original/file-20200728-27-k7e4r1.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/350024/original/file-20200728-27-k7e4r1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/350024/original/file-20200728-27-k7e4r1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/350024/original/file-20200728-27-k7e4r1.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">In this illustration, NASA’s Mars 2020 rover uses its drill to core a rock sample on Mars.
The rover will collect and store rock and soil samples on the planet’s surface that future missions will retrieve and return to Earth.</span>
<span class="attribution"><a class="source" href="https://www.nasa.gov/image-feature/jpl/mars-2020-collecting-sample-artists-concept">NASA/JPL-Caltech</a></span>
</figcaption>
</figure>
<h2>Getting the samples back to Earth</h2>
<p>The most immediate goal of the mission is to search for evidence of past life, and Perseverance’s <a href="https://mars.nasa.gov/mars2020/spacecraft/instruments/">science payload</a> will allow the rover to search for organic materials and microbial textures at the scale of a grain of salt. However, finding definitive evidence of microbial life is <a href="https://www.livescience.com/earliest-signs-of-life-on-earth.html">extremely difficult</a>. Ultimately, we will need to look at samples from Jezero with advanced instruments on Earth. This is why Perseverance will also collect pencil-sized rock cores that will be returned to Earth by a <a href="https://www.nature.com/articles/d41586-020-01114-0">series of missions</a> in the late 2020s.</p>
<p>[<em>Deep knowledge, daily.</em> <a href="https://theconversation.com/us/newsletters/the-daily-3?utm_source=TCUS&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=deepknowledge">Sign up for The Conversation’s newsletter</a>.]</p>
<p>By <a href="https://www.thespacereview.com/article/3930/1">laying the groundwork</a> for sample return with Perseverance, NASA is taking the next giant leap in its exploration of Mars. The rocks collected by Perseverance may be our only shot in the foreseeable future to search for signs of life with samples from another planet. This mission, therefore, is not just “go big or go home” – it is “go big <em>and</em> go home.”</p><img src="https://counter.theconversation.com/content/142705/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Briony Horgan receives funding from NASA to participate in the Mars 2020 Mission as a member of the Mastcam-Z team. </span></em></p><p class="fine-print"><em><span>Melissa Rice receives funding from NASA. </span></em></p>This summer, NASA’s Mars Perseverance rover is taking the next giant leap in our search for signs of life beyond Earth.Briony Horgan, Associate Professor of Planetary Science, Purdue UniversityMelissa Rice, Associate Professor of Planetary Science, Western Washington UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1301042020-06-16T11:53:17Z2020-06-16T11:53:17ZMeteorites from Mars contain clues about the red planet’s geology<figure><img src="https://images.theconversation.com/files/340422/original/file-20200608-176575-1vaxiqk.jpg?ixlib=rb-1.1.0&rect=0%2C6%2C1011%2C568&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Artist's rendition of NASA's 2020 Mars rover collecting rocks with its robotic arm.</span> <span class="attribution"><a class="source" href="https://mars.nasa.gov/mars2020/multimedia/images/?t=240">NASA</a></span></figcaption></figure><p>Despite the pandemic, NASA is on track to launch its Mars rover, Perseverance, this July from Cape Canaveral, Florida. Its central mission will be to search for evidence of previous life on Mars. </p>
<p>An exciting component of the rover will be a specialized drill that will collect rock and soil samples to be cached on the surface of Mars. If all goes according to plan, the cache will be retrieved by a future mission in 2031 and, for the first time, material from Mars will be brought back to Earth for analysis.</p>
<p>As someone who <a href="https://scholar.google.com/citations?hl=en&user=J5sY5JcAAAAJ">studies Martian geology</a>, I’m definitely looking forward to 2031 but am grateful I don’t have to wait 11 years to study rocks from Mars. Martian rock samples are already here on Earth in the form of meteorites.</p>
<h2>How rocks from Mars end up on Earth</h2>
<p>All Martian meteorites were formed millions of years ago, when asteroids and other space rocks collided into the surface of Mars with enough force to eject pieces of its crust into orbit. Sometimes these rock fragments, floating in outer space, enter Earth’s atmosphere, where gravity pulls them in.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/340423/original/file-20200608-176585-1ytg5id.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/340423/original/file-20200608-176585-1ytg5id.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/340423/original/file-20200608-176585-1ytg5id.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=800&fit=crop&dpr=1 600w, https://images.theconversation.com/files/340423/original/file-20200608-176585-1ytg5id.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=800&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/340423/original/file-20200608-176585-1ytg5id.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=800&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/340423/original/file-20200608-176585-1ytg5id.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1005&fit=crop&dpr=1 754w, https://images.theconversation.com/files/340423/original/file-20200608-176585-1ytg5id.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1005&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/340423/original/file-20200608-176585-1ytg5id.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1005&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Nicknamed ‘Black Beauty,’ this Martian meteorite was found in the Sahara Desert in 2011. It is believed to be the second oldest yet discovered.</span>
<span class="attribution"><a class="source" href="http://www.nasa.gov/images/content/716969main_black_beauty_full.jpg">NASA</a></span>
</figcaption>
</figure>
<p>Meteorites land everywhere on Earth, but are <a href="https://caslabs.case.edu/ansmet/faqs/">easiest to find in hot or cold deserts</a>, where the lack of vegetation and other rocks help them to stand out. Martian meteorites are rare: Only 261 pieces have been found on Earth, compared to the <a href="https://www.lpi.usra.edu/meteor/metbull.php">63,758 non-Martian meteorites currently cataloged</a>, most originating from the asteroid belt. </p>
<p>Martian meteorites have been <a href="https://doi.org/10.1002/essoar.10503123.1">recovered all over the world</a>, including Antarctica, northwest Africa, Chile, the United States, India, Nigeria, Mali, Mauritania, Brazil and Oman. Currently, scientists like me can obtain Martian meteorites for study in two ways: either from private dealers or from the Antarctic Search for Meteorites collection. </p>
<figure class="align-left zoomable">
<a href="https://images.theconversation.com/files/339558/original/file-20200603-130903-17z8a91.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/339558/original/file-20200603-130903-17z8a91.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/339558/original/file-20200603-130903-17z8a91.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=800&fit=crop&dpr=1 600w, https://images.theconversation.com/files/339558/original/file-20200603-130903-17z8a91.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=800&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/339558/original/file-20200603-130903-17z8a91.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=800&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/339558/original/file-20200603-130903-17z8a91.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1005&fit=crop&dpr=1 754w, https://images.theconversation.com/files/339558/original/file-20200603-130903-17z8a91.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1005&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/339558/original/file-20200603-130903-17z8a91.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1005&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Recovery of a meteorite in Antarctica by members of the Antarctic Search for Meteorites (ANSMET) expedition. A meteorite is picked up with sterile tongs and put into a clean Teflon bag.</span>
<span class="attribution"><a class="source" href="https://upload.wikimedia.org/wikipedia/commons/6/6a/Meteorite_Recovery_Antarctica_%28retouched%29.jpg">NASA</a></span>
</figcaption>
</figure>
<p>The ANSMET program is funded by both NASA and the National Science Foundation. Antarctica is a great place to spot meteorites due to the omnipresence of ice. Even better, meteorites tend to get trapped in moving ice floes which accumulate at the base of mountain ranges, <a href="https://caslabs.case.edu/ansmet/faqs/">where they often resurface</a>. </p>
<p>Every year since 1976, ANSMET has sent a team of eight volunteer planetary scientists and mountaineers to Antarctica in December and January to hunt for meteorites. The crew combs promising areas by lining up snowmobiles 100 feet apart and slowly creeping through the snow and ice looking for specimens in their path. </p>
<p>Scientists can also buy meteorites from trusted private dealers. Martian meteorites are expensive, however, usually running around US$1,000 a gram on average. The majority of Martian meteorites are found by nomads in the Saharan desert, mainly in Morocco. Locals have been trained to find meteorites by looking for the presence of a fusion crust on a rock, which is formed when the exterior of the meteor melts upon entering the Earth’s atmosphere. I’ve bought 15 samples from dealers who are well known in the meteorite community.</p>
<h2>Determining if a meteorite is from Mars</h2>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/340383/original/file-20200608-176550-1ociucb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/340383/original/file-20200608-176550-1ociucb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/340383/original/file-20200608-176550-1ociucb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=902&fit=crop&dpr=1 600w, https://images.theconversation.com/files/340383/original/file-20200608-176550-1ociucb.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=902&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/340383/original/file-20200608-176550-1ociucb.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=902&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/340383/original/file-20200608-176550-1ociucb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1134&fit=crop&dpr=1 754w, https://images.theconversation.com/files/340383/original/file-20200608-176550-1ociucb.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1134&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/340383/original/file-20200608-176550-1ociucb.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1134&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A thin section of a Martian meteorite under a microscope equipped with a polarizer to help distinguish the different minerals.</span>
<span class="attribution"><span class="source">Arya Udry</span>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>Initially, scientists analyzed the <a href="https://doi.org/10.1126/science.221.4611.651">gas pockets within the minerals of meteorites</a> and compared them to the known atmosphere on Mars, which was established by <a href="https://mars.nasa.gov/mars-exploration/missions/viking-1-2/">NASA’s Viking rovers in 1976</a>. When the gases match perfectly, scientists could conclude the meteorites came from Mars.</p>
<p>Starting in the 1990s, however, scientists like me began using cheaper and easier techniques to determine Martian provenance, such as <a href="https://doi.org/10.1111/j.1945-5100.1999.tb01371.x">oxygen isotopic compositions</a>, which are like atomic barcodes that are unique for each planet.</p>
<p>All told, the 261 known meteorites from Mars <a href="https://doi.org/10.1002/essoar.10503123.1">collectively weigh around 440 pounds</a>. Scientists study them using the same instruments and techniques we use to study Earth samples. My colleagues and I are interested in determining how and when these rocks were formed and how they are linked to each other. </p>
<h2>Mysterious Mars</h2>
<p>Unfortunately, my colleagues and I do not know where on the Martian surface the meteorites come from, but many are working to figure that out. We have been able to determine the different ages of the rocks themselves. We still do not know for sure if the core of Mars is liquid or not, but the meteorites inform us about how and when volcanoes were formed on the planet. </p>
<p>NASA’s Perseverance rover will be exploring an area called the Jezero crater. Igneous rocks, created by volcanic activity, are likely to be present, so it will be really interesting to study the history of the crater, which formed around 4 billion years ago. The Jezero crater also contains two large deltas, where we expect to find sediments that were once transported and deposited by rivers that existed long ago.</p>
<p>For scientists who study Martian geology, having diverse samples from a known field location will greatly boost our understanding of Mars’ core, the history of its climate and the potential life that once may have existed there.</p>
<p>[<em>You’re too busy to read everything. We get it. That’s why we’ve got a weekly newsletter.</em> <a href="https://theconversation.com/us/newsletters/weekly-highlights-61?utm_source=TCUS&utm_medium=inline-link&utm_campaign=newsletter-text&utm_content=weeklybusy">Sign up for good Sunday reading.</a> ]</p><img src="https://counter.theconversation.com/content/130104/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Arya Udry receives funding from NASA. </span></em></p>Martian meteorites allow scientists here on Earth to decode that planet’s geology, more than a decade before the first missions are scheduled to bring rocks back home from Mars.Arya Udry, Assistant Professor of Igneous Petrology, Planetary Science, University of Nevada, Las VegasLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1265682019-12-16T14:50:11Z2019-12-16T14:50:11ZSpotting alien life – how ‘microfossils’ can fool scientists<figure><img src="https://images.theconversation.com/files/307125/original/file-20191216-124022-8tpis0.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Mircobe-like features in a meteorite – later shown to probably be non-biological.</span> <span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/Allan_Hills_84001#/media/File:ALH84001_structures.jpg">NASA</a></span></figcaption></figure><p>Earth’s oldest fossils may be <a href="https://theconversation.com/how-we-discovered-the-worlds-oldest-fossils-73802">billions of years old</a> – although such claims are highly controversial. These kinds of discoveries usually start with finding what appear to be preserved outlines of microscopic lifeforms that look similar to microbe fossils found in much younger rocks. The rewards for exploring truly ancient life are high, because as well as providing a glimpse at some of the earliest life on Earth, these microfossils can also act as a model for what evidence we might find for life on other planets such as Mars. </p>
<p>But how do we know these really are fossils and not some other non-organic geological feature? In 1996, Nasa scientists claimed micro-structures in a meteorite could be the <a href="https://www.space.com/33690-allen-hills-mars-meteorite-alien-life-20-years.html">remains of extraterrestrial life</a>, but further investigation suggested the structures didn’t have biological origins after all.</p>
<p><a href="https://royalsocietypublishing.org/doi/10.1098/rspb.2019.2410">A recent study</a>, published in Royal Society B, has further examined this question by demonstrating how it is possible for some microfossil-like objects to form without any actual microbes. This study may lead to doubts about specific fossils. But ultimately it will help scientists focus their attention on the strongest and most likely case studies for the earliest evidence of life – on this planet or others.</p>
<p>Microbes don’t have easily fossilised hard parts like the bones or teeth of animals. Sometimes a geologist <a href="https://science.sciencemag.org/content/147/3658/563">may be lucky</a> and stumble across glassy silica deposits complete with entombed and immaculately preserved multi-billion-year-old microorganisms.</p>
<p>More commonly, we find some feature that at first glance could be a microfossil of a billion-year-old microscopic lifeform. But on closer inspection, we realise it is perhaps just be a “pseudofossil”, like a speck of microbe-shaped dirt or a lookalike mineral that grew in a crack in the rock. Just because it looks like a microbe doesn’t actually mean it’s a microbe.</p>
<p>To distinguish pseudofossils from real microfossils, geologists and astrobiologists look at the shape, structure and chemical composition of specimens. To know what we are looking for, we can compare these features to those from <a href="https://doi.org/10.1111/gbi.12292">modern fossilised microbes</a> in environments such as alkaline lakes, or from <a href="https://doi.org/10.1073/pnas.1405338111">uncontroversial well-preserved examples</a> from the older rock record. We can also conduct experiments to try to make microfossil-like objects without microbes and compare the results with purported ancient microfossil examples.</p>
<p>Sometimes microfossils are preserved as hair-like tubular filaments of organic carbon. Sometimes the organic carbon has long since disappeared and a microorganism-shaped hole in the rock is all that remains. And sometimes filaments of iron oxide have taken the shape of the organism. This last category includes some recent high-profile finds, including <a href="https://theconversation.com/how-we-discovered-the-worlds-oldest-fossils-73802">those from</a> 4-billion-year-old rocks in Canada.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/307124/original/file-20191216-124027-1uwzw3r.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/307124/original/file-20191216-124027-1uwzw3r.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=454&fit=crop&dpr=1 600w, https://images.theconversation.com/files/307124/original/file-20191216-124027-1uwzw3r.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=454&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/307124/original/file-20191216-124027-1uwzw3r.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=454&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/307124/original/file-20191216-124027-1uwzw3r.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=570&fit=crop&dpr=1 754w, https://images.theconversation.com/files/307124/original/file-20191216-124027-1uwzw3r.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=570&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/307124/original/file-20191216-124027-1uwzw3r.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=570&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">‘Chemical gardening’ can produce mineral features similar to those claimed to be microfossils.</span>
<span class="attribution"><a class="source" href="https://royalsocietypublishing.org/doi/10.1098/rspb.2019.2410">Sean McMahon/Royal Society</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>The new study shows that not all hollow tubular filaments made of iron oxide are biogenic microfossils. In an experimental process known as “chemical gardening”, researcher Sean McMahon created a pocket of acidic fluid enclosed within a membrane, sat in a highly alkaline carbonate or silicate solution. </p>
<p>As the outer solution flowed into the pocket, it would grow and eventually rupture, ejecting a jet of the internal fluid that is then rapidly enclosed by a new, tube-like membrane. This process ultimately created complex arrangements of hollow tubular filaments that can superficially resemble shapes of microbial lifeforms.</p>
<h2>Looking like a microbe isn’t enough</h2>
<p>This study is another reminder that extraordinary claims, such as finding Earth’s oldest fossils or life on Mars, must be supported by extraordinary evidence. Finding a microfossil-like shape is no longer enough without <a href="https://api.research-repository.uwa.edu.au/portalfiles/portal/16165129/SP448_1709_1..pdf">supporting evidence</a> that might include three-dimensional high-resolution microscopy, chemical analysis and a thorough consideration of the context and alternatives. </p>
<p>In his paper, McMahon indeed contends that the reported 4-billion-year-old iron oxide filaments are more likely to be the result of fluids chemically reacting with the ancient seafloor than Earth’s oldest fossil lifeforms. </p>
<p>But this research also doesn’t write off the possibility of true ancient iron oxide microfossils or their use as a model for evidence for life on other planets. It is notable that while the chemical experiments reproduced some microfossil-like shapes, they didn’t reproduce other shapes we could use to help identify microscopic life, such as septate (partitioned) filaments with cell walls.</p>
<p>Ultimately, finding the answers to these fundamental questions of when and where life existed requires a long journey, and we still don’t know if we are nearly there yet.</p><img src="https://counter.theconversation.com/content/126568/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Alexander Brasier does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>New research shows how rock features that look like fossilised microbes can form without life.Alexander Brasier, Senior Lecturer in Geology, University of AberdeenLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1228572019-09-05T05:01:59Z2019-09-05T05:01:59ZTiny specks in space could be the key to finding martian life<figure><img src="https://images.theconversation.com/files/291046/original/file-20190905-175705-19z1try.jpg?ixlib=rb-1.1.0&rect=30%2C17%2C2845%2C1780&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Much of Mars's surface is covered by fine-grained materials that hide the bedrock. The above bedrock is mostly exposed and it is in these areas that micrometeorites likely to accumulate.</span> <span class="attribution"><span class="source">NASA/JPL-Caltech/Univ. of Arizona</span></span></figcaption></figure><p>Next year, both NASA and the European Space Agency (ESA) will send new rovers to Mars to hunt for evidence of past life.</p>
<p>As previous missions have discovered, Mars had a <a href="https://doi.org/10.1146/annurev-earth-060115-012355">warmer and wetter past</a>, featuring conditions that could probably sustain life. Current satellites orbiting Mars also reveal there are many places where water was once present on the surface. </p>
<p>The difficulty in hunting for life lies not in finding where there was water, but in identifying where the essential nutrients for life coincided with water. </p>
<h2>Micrometeorites mean potential life</h2>
<p>For life to move into a new environment and survive, it needs essential nutrients such as carbon, hydrogen, nitrogen, oxygen, phosphorus, and sulfur (together known as <a href="https://en.wikipedia.org/wiki/CHON">CHNOPS</a>), plus other trace elements. It also needs to acquire energy from the environment. Some of Earth’s earliest life forms gained energy by oxidising minerals.</p>
<p>Mars’s crust is mostly made of intrusive and volcanic basalt (the same rock that forms from Hawaii’s lavas) which is not particularly nutrient-rich. However, meteorites and micrometeorites are known to continuously provide essential nutrients to the surfaces of planets. </p>
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<strong>
Read more:
<a href="https://theconversation.com/hope-springs-signs-of-life-could-be-waiting-for-us-on-mars-11800">Hope springs: signs of life could be waiting for us on Mars</a>
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<p><a href="https://doi.org/10.1029/2019JE006005">Our team investigated</a> how much cosmic dust (comet and asteroid dust) would survive atmospheric entry to Mars, and where it would accumulate on the surface as micrometeorites.</p>
<p>We <a href="https://doi.org/10.1111/maps.13360">modelled the heating and oxidation</a> effects of atmospheric entry to Mars and found most particles less than about 0.1-0.2mm in diameter would not melt, depending on their composition. In terms of materials accumulating on the martian surface, particles of this size are overwhelmingly more common than larger particles.</p>
<p>On Earth, about 100 times as much cosmic dust in this size range accumulates on the surface, when compared to meteorites larger than 4mm. This is despite extensive melting and evaporation during atmospheric entry to Earth. </p>
<h2>Evidence closer to home</h2>
<p>As part of our research, we used an analogue site on the Nullarbor Plain in South Australia (which, like Mars, has wind-modified sediment sitting on cracked bedrock) to examine whether wind causes micrometeorites to accumulate at predictable locations. </p>
<p>We found more than 1,600 micrometeorites from a variety of sample sites.</p>
<figure class="align-right ">
<img alt="" src="https://images.theconversation.com/files/291022/original/file-20190904-175682-fzkd33.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/291022/original/file-20190904-175682-fzkd33.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=471&fit=crop&dpr=1 600w, https://images.theconversation.com/files/291022/original/file-20190904-175682-fzkd33.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=471&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/291022/original/file-20190904-175682-fzkd33.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=471&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/291022/original/file-20190904-175682-fzkd33.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=591&fit=crop&dpr=1 754w, https://images.theconversation.com/files/291022/original/file-20190904-175682-fzkd33.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=591&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/291022/original/file-20190904-175682-fzkd33.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=591&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Microscope image of a sectioned micrometeorite from the Nullarbor Plain, Australia. The bright sphere is iron-nickel metal, the grey minerals are iron oxides.</span>
<span class="attribution"><span class="source">Angus Rogers</span></span>
</figcaption>
</figure>
<p>Our observations show that because many micrometeorites are denser than normal sand grains, they are likely to accumulate in bedrock cracks and on gravel-rich surfaces where lighter particles have been blown away. Our samples typically contained several hundred micrometeorites per kilogram. </p>
<p>Several factors added together indicate that micrometeorites should be much more abundant on Mars than on Earth. And this is expected to be true for most of Mars’s 4.5-billion-year history. </p>
<h2>Even martians need nutrients</h2>
<p>Unmelted and partially melted micrometeorites supply complex carbon compounds to the martian surface, which are the building blocks of life. They also supply the only source of reduced phosphorus through the mineral <a href="https://www.mindat.org/min-3582.html">schreibersite</a>, which has been shown to react with simple hydroxyl compounds to <a href="https://www.nature.com/articles/srep17198">form the precursors for life</a>. </p>
<p>Micrometeorites also provide other reduced minerals like sulfides and iron-nickel metal that can be exploited as an energy source by primitive microbes. Therefore, they provide both the essential nutrients and an energy source that can allow existing microbes to migrate and persist. </p>
<h2>Mars 2020</h2>
<p>Many scientists believe life on Earth may have started around <a href="https://en.wikipedia.org/wiki/Hydrothermal_vent">undersea geothermal vents</a> or in volcanic hot springs like those at <a href="https://en.wikipedia.org/wiki/Geothermal_areas_of_Yellowstone">Yellowstone</a> or <a href="https://en.wikipedia.org/wiki/Waiotapu">Rotorua</a>. Beneath these, water circulates through the hot crust, dissolving nutrients from the rocks and carrying them upwards to the vents, where there are dramatic changes in temperature and chemistry. </p>
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<strong>
Read more:
<a href="https://theconversation.com/evidence-of-ancient-life-in-hot-springs-on-earth-could-point-to-fossil-life-on-mars-77388">Evidence of ancient life in hot springs on Earth could point to fossil life on Mars</a>
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<p>This creates a large range of niche environments, some of which have the ideal combination of water, temperate conditions and chemistry for life.</p>
<p>The expired Spirit rover found evidence of an <a href="https://www.nasa.gov/mission_pages/mer/mer-20070521.html">extinct volcanic spring on Mars</a> and more have been inferred from orbital observations. These volcanic springs were considered as a landing site for NASA’s Mars 2020 rover, but in the end Jezero Crater was chosen.</p>
<p>Jezero Crater has a combination of water-produced channels in a delta system that contains clay and carbonate minerals <a href="https://www.nature.com/articles/ngeo207">in sedimentary rocks</a>. These are ideal for <a href="https://www.nature.com/articles/srep05841">preserving</a> <a href="https://science.sciencemag.org/content/295/5555/657">geochemical signs</a> of life. Similarly, Oxia Planum has been chosen as the landing site for ESA’s ExoMars rover, which also contains clays in sedimentary deposits. </p>
<p>While neither Jezero Crater or Oxia Planum contain known volcanic springs, they are still water-rich environments where life may have existed on Mars. </p>
<p>Micrometeorites provide the nutrients that may have allowed life to migrate into and persist at these locations, and could even provide the ingredients for life to emerge away from Mars’s volcanic springs.</p>
<p>With plans in the works for 2020, we may soon be on the cusp of one of the greatest scientific breakthroughs of all time.</p><img src="https://counter.theconversation.com/content/122857/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Andrew Tomkins receives funding from the Australian Research Council. </span></em></p>It’s established Mars was once a planet with surface-level water. So with multiple MARS missions starting next year, the key to seeking out martian life may instead lie in the contents of its ‘dust’.Andrew Tomkins, Geologist, Monash UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1216022019-08-08T12:09:29Z2019-08-08T12:09:29ZTardigrades: we’re now polluting the moon with near indestructible little creatures<figure><img src="https://images.theconversation.com/files/287398/original/file-20190808-144868-10mhlpm.jpg?ixlib=rb-1.1.0&rect=0%2C157%2C3000%2C2070&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-illustration/tardigrade-water-bear-3d-rendered-illustration-535109380?src=cjaqEapOnY5_mpZ177xWvA-1-0">3DStock/Shutterstock</a></span></figcaption></figure><p>An Israeli spacecraft <a href="http://www.planetary.org/explore/space-topics/space-missions/beresheet.html">called Beresheet</a> almost made it to <a href="https://theconversation.com/uk/topics/moon-606">the moon</a> in April. It took a selfie with the lunar surface in the background, but then lost contact with Earth and presumably crashed onto the lunar surface. Now <a href="https://www.wired.com/story/a-crashed-israeli-lunar-lander-spilled-tardigrades-on-the-moon/">it’s been revealed</a> that the mission was carrying a cargo of dehydrated microscopic lifeforms known as tardigrades.</p>
<p>Beresheet was the first stage of a privately-funded initiative to <a href="https://www.archmission.org/">transfer living DNA to the moon</a>. The project is designed to act as Noah’s Ark Mark II, providing a repository from which plants and animals could be regenerated to repopulate the Earth should a catastrophe akin to a flood of biblical proportions overtake the planet.</p>
<p>Whether the project is far-sighted or foolish, what has roused interest is the fact that, as a result of the crash, the tardigrades may now be scattered across the lunar surface. They are hardy creatures and could probably survive on the moon for a long time. Is this a matter of concern? I believe so, but possibly not for the reasons you might think.</p>
<p>Tardigrades are <a href="https://www.livescience.com/57985-tardigrade-facts.html">odd little creatures</a>. Measuring up to about half a millimetre long, they have four pairs of stubby legs and a front-end that even the fondest parent couldn’t describe as beautiful. Striking, or distinctive, are my adjectives of choice. Moon-faced would be appropriate, given the context of the story – with a rounded, sucker-like structure in the centre that can project outwards, revealing a set of dangerous-looking sharp teeth. </p>
<p>They’re often called “water bears” but the images of tardigrades that I have seen remind me of a slightly over-inflated blimp, one of those large balloons that float overhead at carnivals. The legs stick out at a slight angle, as if they are too swollen to stand upright. And that is probably the clue as to why it is extremely unlikely that the creatures will survive indefinitely on the moon.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/287345/original/file-20190808-144868-1dp7qa3.jpg?ixlib=rb-1.1.0&rect=474%2C0%2C3610%2C2392&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/287345/original/file-20190808-144868-1dp7qa3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=200&fit=crop&dpr=1 600w, https://images.theconversation.com/files/287345/original/file-20190808-144868-1dp7qa3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=200&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/287345/original/file-20190808-144868-1dp7qa3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=200&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/287345/original/file-20190808-144868-1dp7qa3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=251&fit=crop&dpr=1 754w, https://images.theconversation.com/files/287345/original/file-20190808-144868-1dp7qa3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=251&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/287345/original/file-20190808-144868-1dp7qa3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=251&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">Tardigrades in space.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-illustration/tardigrade-vacuum-open-space-water-bear-726719797?src=cjaqEapOnY5_mpZ177xWvA-1-5">Dotted Yeti/Shutterstock</a></span>
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</figure>
<p>Tardigrades can survive extremes of temperature and pressure, including the frigid vacuum <a href="https://www.cell.com/current-biology/fulltext/S0960-9822(08)00805-1?_returnURL=https%3A%2F%2Flinkinghub.elsevier.com%2Fretrieve%2Fpii%2FS0960982208008051%3Fshowall%3Dtrue">of space</a>. They don’t seem to mind being <a href="https://journals.plos.org/plosone/article?id=10.1371/journal.pone.0064793">exposed to radiation</a> and are all-round tough little creatures. When dehydrated, they roll up into a <a href="https://www.cell.com/biophysj/fulltext/S0006-3495(16)33630-X">spore-like state</a> that slows down their metabolic rate by about a hundred-fold, enabling them to survive for potentially <a href="https://zslpublications.onlinelibrary.wiley.com/doi/abs/10.1017/S095283690200078X">over 100 years</a>. </p>
<p>But to live their life to the fullest requires water. It’s where they get their oxygen and food, typically colonising clumps of algae or burrowing into sediment to ingest nutrients from the fluid of other living creatures, even other tardigrades. So while the tardigrades will technically stay alive on the moon for some length of time in their rolled-up state, unless they are rescued, rehydrated and refuelled, they will eventually perish.</p>
<h2>Interplanetary pollution</h2>
<p>I’m not concerned about polluting the moon with organisms that might reanimate. My concern is about polluting the moon, full stop. There is already a fairly sizeable <a href="https://www.theatlantic.com/technology/archive/2012/12/the-trash-weve-left-on-the-moon/266465/">amount of debris</a> from redundant spacecraft and litter left behind by astronauts. As more missions are planned to the moon, eventually with human passengers and perhaps even settlements, we must learn to clean up as we go along. Otherwise, we are going to have the sort of crisis that we are seeing on Earth with the outcry about environmental damage <a href="https://theconversation.com/uk/topics/plastic-pollution-52714">from plastics</a>. </p>
<p>There is, though, another question to consider. What if the spacecraft had crashed as it approached Mars rather than the moon? The planet has had a poor record for successful landings, although it is much improved in the past decade. Would the tardigrades have survived atmospheric entry? Even though the atmosphere of Mars is thin, it still provides sufficient resistance to cause serious damage to the outer shell of an entry vehicle.</p>
<p>If they had survived, would they ultimately be any more successfully on Mars than on the moon? We know there is plenty of ice below the immediate surface across much of the planet. Would an impacting spacecraft transfer sufficient energy to melt a local region of ice? Could that meltwater survive without sublimating away or refreezing for long enough that the tardigrades rehydrate and wake up?</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/287348/original/file-20190808-144878-1qq5a3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/287348/original/file-20190808-144878-1qq5a3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=601&fit=crop&dpr=1 600w, https://images.theconversation.com/files/287348/original/file-20190808-144878-1qq5a3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=601&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/287348/original/file-20190808-144878-1qq5a3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=601&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/287348/original/file-20190808-144878-1qq5a3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=755&fit=crop&dpr=1 754w, https://images.theconversation.com/files/287348/original/file-20190808-144878-1qq5a3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=755&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/287348/original/file-20190808-144878-1qq5a3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=755&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The surface of Mars should be kept pristine.</span>
<span class="attribution"><a class="source" href="https://www.nasa.gov/multimedia/imagegallery/image_feature_645.html">NASA</a></span>
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</figure>
<p>I have no idea, but let’s speculate that the answer to the two questions is “yes”, and that following a crash, a flock (herd? shoal? pack?) of tardigrades reactivates. What happens next? As detailed above, tardigrades need water to survive, not just to rehydrate them. They live on fluids derived from other living beings. And, as far as we know, there are no <a href="https://theconversation.com/uk/topics/life-on-mars-6975">living beings on Mars</a>. </p>
<p>But we still keep sending spacecraft to look for life. Sending a cargo of tardigrades to Mars would be irresponsible, even if we don’t believe they would survive. Irresponsible because Mars has the potential for life. Restricted life, for sure, but we have no right to endanger that life. And we have a responsibility to maintain Mars as close to pristine as possible, exploring it with care.</p>
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Read more:
<a href="https://theconversation.com/to-the-moon-and-beyond-podcast-series-trailer-119250">To the moon and beyond podcast series – Trailer</a>
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<p>That is why space agencies take such stringent precautions about spacecraft construction. The rooms in which the craft are built are <a href="https://www.wired.com/story/inside-the-cleanroom-where-nasas-new-mars-lander-waits-to-launch/">cleaner and more sterile</a> than any operating theatre. They take every precaution to ensure that no terrestrial life is transferred to Mars.</p>
<p>NASA and ESA are currently planning a <a href="https://www.space.com/nasa-mars-sample-return-mission-2026.html">mission to return</a> samples from Mars to Earth. And precautions about the possibility of returning Martian life to Earth with the rocks are central to the design and build of the spacecraft.</p>
<p>Last week, we had an asteroid <a href="https://www.technologyreview.com/f/614027/a-huge-asteroid-flew-very-close-to-earth-last-week-how-did-we-miss-it/">passing close to the Earth</a>. Next week, maybe it will be killer bees. Or a plague of thieving magpies. But for now it is water bears on the moon. We should let them shrivel slowly into oblivion.</p><img src="https://counter.theconversation.com/content/121602/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Monica Grady is Professor of Planetary and Space Sciences at the Open University, and Research Fellow at the Natural History Museum, London. She receives funding from the STFC and the UK Space Agency. She is a Trustee of Lunar Mission One.</span></em></p>An Israeli spacecraft carrying tardigrades crashed into the moon. Whether they will survive is irrelevant.Monica Grady, Professor of Planetary and Space Sciences, The Open UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1156432019-04-25T20:12:59Z2019-04-25T20:12:59ZWhy the idea of alien life now seems inevitable and possibly imminent<figure><img src="https://images.theconversation.com/files/269753/original/file-20190417-139084-2drij5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Relative sizes of planets that are in a zone potentially compatible with life: Kepler-22b, Kepler-69c, Kepler-62e, Kepler-62f and Earth (named left to right; except for Earth, these are artists' renditions).</span> <span class="attribution"><a class="source" href="https://www.nasa.gov/mission_pages/kepler/multimedia/images/kepler-hz-2013-04.html">NASA</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span></figcaption></figure><p><em>This article is an edited extract from an essay, The search for ET, in The New Disruptors, the 64th edition of <a href="https://griffithreview.com/">Griffith Review</a>.</em></p>
<p><em>We’re publishing it as part of our occasional series Zoom Out, where authors explore key ideas in science and technology in the broader context of society and humanity.</em></p>
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<p>Extraterrestrial life, that familiar science-fiction trope, that kitschy fantasy, that CGI nightmare, has become a matter of serious discussion, a “risk factor”, a “scenario”. </p>
<p>How has ET gone from sci-fi fairytale to a serious scientific endeavour <a href="http://reports.weforum.org/global-risks-2013/section-five/x-factors/">modelled by macroeconomists</a>, <a href="https://www.aip.org/fyi/2017/congress-passes-bipartisan-nasa-authorization-legislation">funded by fiscal conservatives</a> and <a href="https://www.archbalt.org/vatican-sponsored-meeting-discusses-chances-of-extra-terrestrial-life">discussed by theologians</a>? </p>
<p>Because, following a string of remarkable discoveries over the past two decades, the idea of alien life is not as far-fetched as it used to seem. </p>
<p>Discovery now seems inevitable and possibly imminent. </p>
<h2>It’s just chemistry</h2>
<p>While life is a special kind of complex chemistry, the elements involved are nothing special: carbon, hydrogen, oxygen and so on are among the most abundant elements in the universe. Complex organic chemistry is surprisingly common. </p>
<p>Amino acids, just like those that make up every protein in our bodies, have been found in the <a href="https://onlinelibrary.wiley.com/doi/abs/10.1111/j.1945-5100.2009.tb01224.x">tails of comets</a>. There are other <a href="https://www.sciencemag.org/news/2018/06/nasa-rover-hits-organic-pay-dirt-mars">organic compounds in Martian soil</a>. </p>
<p>And 6,500 light years away a giant <a href="https://phys.org/news/2014-09-alcohol-clouds-space.html">cloud of space alcohol</a> floats among the stars. </p>
<p>Habitable planets seem to be common too. The first planet beyond our Solar System was discovered in 1995. Since then astronomers have catalogued thousands. </p>
<p>Based on this catalogue, astronomers from the University of California, Berkeley <a href="https://www.pnas.org/content/early/2013/10/31/1319909110/tab-article-info">worked out</a> there could be as many as 40 billion Earth-sized exoplanets in the so-called “habitable zone” around their star, where temperatures are mild enough for liquid water to exist on the surface. </p>
<p>There’s even a potentially <a href="https://www.nature.com/articles/nature19106">Earth-like world</a> orbiting our nearest neighbouring star, Proxima Centauri. At just four light years away, that system might be close enough for us to reach using current technology. With the <a href="https://breakthroughinitiatives.org/initiative/3">Breakthrough Starshot project</a> launched by Stephen Hawking in 2016, plans for this are already afoot.</p>
<h2>Life is robust</h2>
<p>It seems inevitable other life is out there, especially considering that life appeared on Earth so soon after the planet was formed. </p>
<p>The oldest fossils ever found here are <a href="https://www.pnas.org/content/115/1/53.short">3.5 billion years old</a>, while clues in our DNA suggest life could have started as far back as <a href="https://www.nature.com/articles/s41559-018-0644-x">4 billion years ago</a>, just when giant asteroids stopped crashing into the surface. </p>
<p>Our planet was inhabited as soon as it was habitable – and the definition of “habitable” has proven to be a rather flexible concept too. </p>
<p>Life survives in all manner of environments that seem hellish to us: </p>
<ul>
<li>floating on a lake of <a href="https://www.sciencedirect.com/science/article/pii/S0923250803001141">sulphuric acid</a></li>
<li>inside barrels of <a href="https://www.nature.com/articles/ismej2014125">nuclear waste</a></li>
<li>in water superheated to <a href="https://www.pnas.org/content/105/31/10949">122 degrees</a> </li>
<li>in the <a href="https://www.nature.com/articles/nature25014">wastelands of Antarctica</a></li>
<li>in rocks <a href="https://www.theguardian.com/science/2018/dec/10/tread-softly-because-you-tread-on-23bn-tonnes-of-micro-organisms">five kilometres below ground</a>. </li>
</ul>
<p>Tantalisingly, some of these conditions seem to be duplicated elsewhere in the Solar System.</p>
<h2>Snippets of promise</h2>
<p>Mars was once warm and wet, and was probably a fertile ground for life before the Earth. </p>
<p>Today, Mars still has <a href="https://science.sciencemag.org/content/361/6401/490">liquid water underground</a>. One gas strongly associated with life on Earth, methane, has already been found in the Martian atmosphere, and at levels that mysteriously <a href="https://www.nasa.gov/press-release/nasa-finds-ancient-organic-material-mysterious-methane-on-mars">rise and fall with the seasons</a>. (However, the methane result is under debate, with one Mars orbiter recently <a href="https://www.nature.com/articles/s41561-019-0331-9">confirming the methane detection</a> and another <a href="https://www.nature.com/articles/s41586-019-1096-4">detecting nothing</a>.) </p>
<p>Martian bugs might turn up as soon as 2021 when the <a href="https://www.esa.int/Our_Activities/Human_and_Robotic_Exploration/Exploration/ExoMars/ESA_s_Mars_rover_has_a_name_Rosalind_Franklin">ExoMars rover Rosalind Franklin</a> will hunt for them with a <a href="http://exploration.esa.int/mars/60914-oxia-planum-favoured-for-exomars-surface-mission/">two-metre drill</a>. </p>
<p>Besides Earth and Mars, at least two other places in our Solar System might be inhabited. Jupiter’s moon Europa and Saturn’s moon Enceladus are both frozen ice worlds, but the gravity of their colossal planets is enough to churn up their insides, melting water to create <a href="https://www.nasa.gov/press-release/cassini-finds-global-ocean-in-saturns-moon-enceladus">vast subglacial seas</a>. </p>
<p>In 2017, specialists in sea ice from the University of Tasmania <a href="https://www.cambridge.org/core/journals/international-journal-of-astrobiology/article/sea-ice-extremophiles-and-life-on-extraterrestrial-ocean-worlds/C76FF80A75B755492331A3356CD1B824">concluded</a> that some Antarctic microbes could feasibly survive on these worlds. Both Europa and Enceladus have undersea hydrothermal vents, just like those on Earth where life may have originated. </p>
<p>When a NASA probe tasted the material geysered into space out of Enceladus last June it <a href="https://www.nature.com/articles/s41586-018-0246-4">found large organic molecules</a>. Possibly there was something living among the spray; the probe just didn’t have the right tools to detect it. </p>
<p>Russian billionaire Yuri Milner has been so enthused by this prospect, he wants to help <a href="https://earthsky.org/space/billionaire-yuri-milner-nasa-plan-life-search-enceladus">fund a return mission</a>.</p>
<h2>A second genesis?</h2>
<p>A discovery, if it came, could turn the world of biology upside down. </p>
<p>All life on Earth is related, descended ultimately from the first living cell to emerge some 4 billion years ago. </p>
<p>Bacteria, fungus, cacti and cockroaches are all our cousins and we all share the same basic molecular machinery: DNA that makes RNA, and RNA that makes protein. </p>
<p>A second sample of life, though, might represent a “second genesis” – totally unrelated to us. Perhaps it would use a different coding system in its DNA. Or it might not have DNA at all, but some other method of passing on genetic information. </p>
<p>By studying a second example of life, we could begin to figure out which parts of the machinery of life are universal, and which are just the particular accidents of our primordial soup. </p>
<p>Perhaps amino acids are always used as essential building blocks, perhaps not. </p>
<p>We might even be able to work out some universal laws of biology, the same way we have for physics – not to mention new angles on the question of the origin of life itself. </p>
<p>A second independent “tree of life” would mean that the rapid appearance of life on Earth was no fluke; life must abound in the universe. </p>
<p>It would greatly increase the chances that, somewhere among those billions of habitable planets in our galaxy, there could be something we could talk to.</p>
<h2>Perhaps life is infectious</h2>
<p>If, on the other hand, the discovered microbes were indeed related to us that would be a bombshell of a different kind: it would mean life is infectious. </p>
<p>When a large meteorite hits a planet, the impact can splash pulverised rock right out into space, and this rock can then fall onto other planets as meteorites. </p>
<p>Life from Earth has probably already been taken to other planets – perhaps even to the moons of Saturn and Jupiter. Microbes might well survive the trip. </p>
<p>In 1969, Apollo 12 astronauts retrieved an old probe that had sat on the Moon for three years in extreme cold and vacuum – there were <a href="https://lsda.jsc.nasa.gov/Experiment/exper/1651?">viable bacteria still inside</a>. </p>
<p>As Mars was probably habitable before Earth, it’s possible life originated there before hitchhiking on a space rock to here. Perhaps we’re all Martians.</p>
<p>Even if we never find other life in our Solar System, we might still detect it on any one of thousands of known exoplanets. </p>
<p>It is already possible to look at starlight filtered through an exoplanet and tell something about the composition of its atmosphere; an abundance of oxygen could be a telltale sign of life. </p>
<h2>A testable hypothesis</h2>
<p>The <a href="https://www.jwst.nasa.gov/">James Webb Space Telescope</a>, planned for a 2021 launch, will be able to take these measurements for some of the Earth-like worlds already discovered. </p>
<p>Just a few years later will come space-based telescopes that will take pictures of these planets directly. </p>
<p>Using a trick a bit like the sun visor in your car, planet-snapping telescopes will be paired with giant parasols called starshades that will fly in tandem <a href="https://science.nasa.gov/technology/technology-stories/starshade-enable-first-images-earth-sized-exoplanets">50,000 kilometres away</a> in just the right spot to block the blinding light of the star, allowing the faint speck of a planet to be captured. </p>
<p>The colour and the variability of that point of light could tell us the length of the planet’s day, whether it has seasons, whether it has clouds, whether it has oceans, possibly even the colour of its plants.</p>
<p>The ancient question “Are we alone?” has graduated from being a philosophical musing to a testable hypothesis. We should be prepared for an answer.</p><img src="https://counter.theconversation.com/content/115643/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Cathal D. O'Connell does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>The ancient question ‘Are we alone?’ has graduated from being a philosophical musing to a testable hypothesis. We should be prepared for an answer.Cathal D. O'Connell, Researcher and Centre Manager, BioFab3D (St Vincent's Hospital), The University of MelbourneLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1065412018-11-26T19:03:56Z2018-11-26T19:03:56ZOur long fascination with the journey to Mars<figure><img src="https://images.theconversation.com/files/247203/original/file-20181126-149317-1hdg0u9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Signs of life on Mars? These are the tracks of NASA's Curiosity rover exploring the Martian landscape.</span> <span class="attribution"><a class="source" href="https://solarsystem.nasa.gov/resources/464/curiositys-color-view-of-martian-dune-after-crossing-it/">NASA/JPL-Caltech/MSSS</a></span></figcaption></figure><p><em>This article is part of our occasional long read series <a href="https://theconversation.com/au/topics/zoom-out-51632">Zoom Out</a>, where authors explore key ideas in science and technology in the broader context of society and humanity.</em></p>
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<p>It’s touchdown again on <a href="https://solarsystem.nasa.gov/planets/mars/overview/">Mars</a>, thanks to NASA’s <a href="https://mars.nasa.gov/insight/">InSight</a> probe. This latest mission will continue our exploration of much that is still unknown about the planet.</p>
<p>As seen from Earth, the big red dot in the night sky has certainly caught the attention of humans since we started contemplating the universe. </p>
<p>The first observations with telescopes gave us a much clearer picture of Mars, with the poles covered in ice and different tones of red and black in the tropics.</p>
<p>NASA’s InSight (<a href="https://www.nasa.gov/mission_pages/insight/overview/index.html">Interior Exploration using Seismic Investigations, Geodesy and Heat Transport</a>) mission should tell us more about the interior of Mars and how the planet formed.</p>
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Read more:
<a href="https://theconversation.com/evidence-of-aliens-what-to-make-of-research-and-reporting-on-oumuamua-our-visitor-from-space-106711">Evidence of aliens? What to make of research and reporting on 'Oumuamua, our visitor from space</a>
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<hr>
<h2>Beware of Martians</h2>
<p>Perhaps the most curious account of Mars came from the Italian astronomer <a href="https://www.britannica.com/biography/Giovanni-Virginio-Schiaparelli">Giovanni Schiaparelli</a> in 1877. He observed a dense network of linear structures on the surface of Mars which he called “canali” in Italian, meaning “channels”. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/247190/original/file-20181126-149326-2q7lxx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/247190/original/file-20181126-149326-2q7lxx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/247190/original/file-20181126-149326-2q7lxx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=353&fit=crop&dpr=1 600w, https://images.theconversation.com/files/247190/original/file-20181126-149326-2q7lxx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=353&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/247190/original/file-20181126-149326-2q7lxx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=353&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/247190/original/file-20181126-149326-2q7lxx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=443&fit=crop&dpr=1 754w, https://images.theconversation.com/files/247190/original/file-20181126-149326-2q7lxx.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=443&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/247190/original/file-20181126-149326-2q7lxx.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=443&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Giovanni Schiaparelli’s map of Mars, compiled over the period 1877-1886.</span>
<span class="attribution"><a class="source" href="https://history.nasa.gov/SP-4212/p6.html">NASA/Flammarion, La Planète Mars</a></span>
</figcaption>
</figure>
<p>But the term was misinterpreted by some English-speakers as “canals”, which implied they were made by Martians.</p>
<p>Our love and fear relationship with Mars escalated to another level in 1938, when <a href="https://orsonwelles.indiana.edu/items/show/1972">Orson Welles broadcast</a> an all-too-real adaption of HG Wells’ classic The War of the Worlds.</p>
<p>The Halloween night broadcast of the invasion of Martians to Earth apparently lead some listeners in the United States to panic, as they took the fiction as a fact (a story told in the 1975 movie, <a href="https://www.imdb.com/title/tt0073454/">The Night That Panicked America</a>). How much panic is still <a href="https://www.telegraph.co.uk/radio/what-to-listen-to/the-war-of-the-worlds-panic-was-a-myth/">open to question</a>.</p>
<p>HG Wells’ <a href="https://www.britannica.com/topic/The-War-of-the-Worlds-novel-by-Wells">1898 novel</a> has inspired more than a few Hollywood movies, television series and a musical telling since then, including Steven Spielberg’s 2005 movie <a href="https://www.imdb.com/title/tt0407304">War of the Worlds</a>.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/rYGWG2_PB_Q?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">The chances of anything coming from Mars.</span></figcaption>
</figure>
<h2>Mars close up</h2>
<p>The first close-up images from Mars came in 1965 with the <a href="https://www.jpl.nasa.gov/missions/mariner-4/">Mariner 4</a> spacecraft flying by the planet, and then with <a href="https://www.jpl.nasa.gov/missions/mariner-9-mariner-i/">Mariner 9</a> entering orbit in 1971.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/247204/original/file-20181126-149341-d0j39m.gif?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/247204/original/file-20181126-149341-d0j39m.gif?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/247204/original/file-20181126-149341-d0j39m.gif?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=549&fit=crop&dpr=1 600w, https://images.theconversation.com/files/247204/original/file-20181126-149341-d0j39m.gif?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=549&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/247204/original/file-20181126-149341-d0j39m.gif?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=549&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/247204/original/file-20181126-149341-d0j39m.gif?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=690&fit=crop&dpr=1 754w, https://images.theconversation.com/files/247204/original/file-20181126-149341-d0j39m.gif?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=690&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/247204/original/file-20181126-149341-d0j39m.gif?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=690&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Mariner 4 takes the first close-up image ever taken of Mars.</span>
<span class="attribution"><a class="source" href="https://nssdc.gsfc.nasa.gov/imgcat/html/object_page/m04_01d.html">NASA</a></span>
</figcaption>
</figure>
<p>Both spacecraft showed Mars as a cold, barren, desert-like world. Before these missions we had only seen Mars through telescopes, and the question of whether the planet was habitable (or inhabited) was still open.</p>
<p>I still remember when I was a child watching a TV program showing images of the <a href="https://www.nasa.gov/mission_pages/viking">Viking mission</a> which landed <a href="https://www2.jpl.nasa.gov/missions/past/viking.html">two probes on Mars</a> in 1976.</p>
<p>Instead of talking about our first successful spacecraft to land on Mars and sending us images and scientific data from the surface of another planet, the program talked for a long time about a feature that looked like a face of a man on the surface of Mars, and structures that resembled pyramids. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/247170/original/file-20181126-149335-1bssgtt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/247170/original/file-20181126-149335-1bssgtt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/247170/original/file-20181126-149335-1bssgtt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=443&fit=crop&dpr=1 600w, https://images.theconversation.com/files/247170/original/file-20181126-149335-1bssgtt.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=443&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/247170/original/file-20181126-149335-1bssgtt.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=443&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/247170/original/file-20181126-149335-1bssgtt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=556&fit=crop&dpr=1 754w, https://images.theconversation.com/files/247170/original/file-20181126-149335-1bssgtt.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=556&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/247170/original/file-20181126-149335-1bssgtt.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=556&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">NASA’s Viking 1 Orbiter spacecraft photographed this region in the northern latitudes of Mars on July 25, 1976 while searching for a landing site for the Viking 2 Lander. The eroded rock resembles a human face near the centre of the image.</span>
<span class="attribution"><a class="source" href="https://www.jpl.nasa.gov/spaceimages/details.php?id=PIA01141">NASA/JPL</a></span>
</figcaption>
</figure>
<p>Those images certainly affected me, and were key in my fascination for Mars and space in general. </p>
<p>The legacy of the Viking landers was mostly their first geochemical characterisation from the surface, and a detailed atmospheric composition analysis from Mars. </p>
<p>Viking results were fantastic in many ways, but disappointing too as they indicated a dry planet, full of primary rocks that would have transformed into minerals if water was present.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/247195/original/file-20181126-149323-10ojcfs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/247195/original/file-20181126-149323-10ojcfs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/247195/original/file-20181126-149323-10ojcfs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=617&fit=crop&dpr=1 600w, https://images.theconversation.com/files/247195/original/file-20181126-149323-10ojcfs.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=617&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/247195/original/file-20181126-149323-10ojcfs.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=617&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/247195/original/file-20181126-149323-10ojcfs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=775&fit=crop&dpr=1 754w, https://images.theconversation.com/files/247195/original/file-20181126-149323-10ojcfs.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=775&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/247195/original/file-20181126-149323-10ojcfs.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=775&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">This colour image of the Martian surface was taken by Viking Lander 1, looking southwest, about 15 minutes before sunset.</span>
<span class="attribution"><a class="source" href="https://www.nasa.gov/image-feature/sunset-at-the-viking-lander-1-site">NASA/JPL</a></span>
</figcaption>
</figure>
<p>Pictures from the surface showed no signs of life – no signs of little bushes, a bit of moss on some rocks, or a green man smiling to the cameras. </p>
<p>In a way we lost our interest for Mars until it attacked us with meteorites.</p>
<h2>Rocks from Mars</h2>
<p>Rocks from planets and the Moon, and meteors, hold chemical hints of where they came from. So it’s possible to tell if a meteorite is from our Moon, from Mars, or from elsewhere. </p>
<p>A meteorite found in Antarctica (dubbed <a href="https://www.britannica.com/topic/ALH84001">ALH84001</a>) is one that scientists affirm came from Mars. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/247184/original/file-20181126-149338-50z6es.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/247184/original/file-20181126-149338-50z6es.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/247184/original/file-20181126-149338-50z6es.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=471&fit=crop&dpr=1 600w, https://images.theconversation.com/files/247184/original/file-20181126-149338-50z6es.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=471&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/247184/original/file-20181126-149338-50z6es.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=471&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/247184/original/file-20181126-149338-50z6es.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=592&fit=crop&dpr=1 754w, https://images.theconversation.com/files/247184/original/file-20181126-149338-50z6es.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=592&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/247184/original/file-20181126-149338-50z6es.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=592&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A 4.5 billion-year-old rock, labeled meteorite ALH84001, identified from Mars.</span>
<span class="attribution"><a class="source" href="https://www.nasa.gov/mission_pages/mars/multimedia/pia00289.html">NASA/JSC/Stanford University</a></span>
</figcaption>
</figure>
<p>Martian meteorites can be found on Earth because a big meteorite probably fell on Mars, and in the process ended up ejecting pieces of the surface into space. </p>
<p>Some were big enough to enter our atmosphere and be found later. ALH84001 is made mostly of carbonate: a mineral that needs water to be formed. Therefore, indirectly we can conclude that Mars was once wet. </p>
<p>To make it even more interesting, this Martian postcard has some miniscule structures that look like some bacteria found on Earth.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/199135/original/file-20171214-27575-1xga58h.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/199135/original/file-20171214-27575-1xga58h.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/199135/original/file-20171214-27575-1xga58h.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=410&fit=crop&dpr=1 600w, https://images.theconversation.com/files/199135/original/file-20171214-27575-1xga58h.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=410&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/199135/original/file-20171214-27575-1xga58h.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=410&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/199135/original/file-20171214-27575-1xga58h.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=516&fit=crop&dpr=1 754w, https://images.theconversation.com/files/199135/original/file-20171214-27575-1xga58h.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=516&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/199135/original/file-20171214-27575-1xga58h.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=516&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">This high-resolution scanning electron microscope image shows an unusual tube-like structural form that is less than 1/100th the width of a human hair in size found in meteorite ALH84001.</span>
<span class="attribution"><a class="source" href="https://spaceflight.nasa.gov/gallery/images/exploration/marsexploration/html/s96_12609.html">NASA</a></span>
</figcaption>
</figure>
<p>Scientists are still debating whether those structures are Martian fossils or not. But the discovery and analysis of ALH84001 brought us back to Mars. Now it was time for us to counterattack.</p>
<h2>Rover missions to Mars</h2>
<p>NASA then announced the first rover mission to Mars called <a href="https://www.nasa.gov/mission_pages/mars-pathfinder">Pathfinder</a>. The microwave oven sized rover it carried, called Sojourner, landed on Mars in 1997. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/9HGRReKUzfU?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Take a look around on Mars.</span></figcaption>
</figure>
<p>The rover produced results quite similar to those found by Viking, pointing to a very dry past and present on Mars. What followed was a considerable effort to get more images of the Martian surface from orbiters, and select the place to land with future payloads.</p>
<p>After debating more than 174 potential landing sites, scientists and engineers involved with Mars research discussed and they to two places to land on Mars with two large rovers: <a href="https://www.nasa.gov/mission_pages/mer/index.html">Spirit and Opportunity</a>. </p>
<p>After seven months of interplanetary travel, the rovers landed in January 2004. The initial results obtained by Spirit were similar to those from Viking and Mars Pathfinder. </p>
<p>The first groundbreaking results came from Opportunity with the discovery of <a href="http://science.sciencemag.org/content/306/5702/1740">jarosite and hematite</a>: two minerals that need water and acidic conditions to be formed. </p>
<p>After working way beyond their manufacture warranty (three months), the twin rovers transformed our knowledge about the past of Mars.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/247206/original/file-20181126-149335-1t1fh3t.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/247206/original/file-20181126-149335-1t1fh3t.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/247206/original/file-20181126-149335-1t1fh3t.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=739&fit=crop&dpr=1 600w, https://images.theconversation.com/files/247206/original/file-20181126-149335-1t1fh3t.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=739&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/247206/original/file-20181126-149335-1t1fh3t.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=739&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/247206/original/file-20181126-149335-1t1fh3t.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=929&fit=crop&dpr=1 754w, https://images.theconversation.com/files/247206/original/file-20181126-149335-1t1fh3t.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=929&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/247206/original/file-20181126-149335-1t1fh3t.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=929&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">NASA’s Mars rover Opportunity catches its own late-afternoon shadow in this dramatically lit view eastward across Endeavour Crater on Mars.</span>
<span class="attribution"><a class="source" href="https://www.nasa.gov/multimedia/imagegallery/image_feature_2255.html">NASA/JPL-Caltech/Cornell/Arizona State Univ.</a></span>
</figcaption>
</figure>
<p>Before we landed there was the question of whether Mars was once wet. Now we know that there were once oceans on Mars as salty as the Dead Sea, plus there were hot springs and fresh water streams.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/discovered-a-huge-liquid-water-lake-beneath-the-southern-pole-of-mars-100523">Discovered: a huge liquid water lake beneath the southern pole of Mars</a>
</strong>
</em>
</p>
<hr>
<p>Water on Mars was not only present, but it was there in different forms. Mars had perfect conditions for long enough for life to form and evolve. At least we can say Mars was habitable. </p>
<p>Spirit was active for six years and Opportunity, after 15 years, is still officially going on. </p>
<p>During this time a lander called Phoenix landed in the Green Valley of Castitas Borealis on the Martian northern hemisphere, near the north pole. The key discovery from Phoenix was the presence of minute concentrations of <a href="https://www.nature.com/news/2008/080806/full/news.2008.1016.html">perchlorate</a>, a powerful bacterial killer salt.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/247205/original/file-20181126-149323-10pf5mw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/247205/original/file-20181126-149323-10pf5mw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/247205/original/file-20181126-149323-10pf5mw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/247205/original/file-20181126-149323-10pf5mw.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/247205/original/file-20181126-149323-10pf5mw.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/247205/original/file-20181126-149323-10pf5mw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/247205/original/file-20181126-149323-10pf5mw.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/247205/original/file-20181126-149323-10pf5mw.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A thin layer of water frost is visible on the ground around NASA’s Phoenix Mars Lander.</span>
<span class="attribution"><a class="source" href="https://www.nasa.gov/multimedia/imagegallery/image_feature_1160.html">NASA/JPL-Caltech/University of Arizona/Texas A&M University</a></span>
</figcaption>
</figure>
<p>Despite the impact these missions have in our understanding about Mars, there were a number of instruments we would love to use and could not fit in a rover. </p>
<p>The idea of having a fully equipped Martian laboratory fuelled scientists to propose a new mission: Mars Science Laboratory with a much larger rover. It’s equipped with laser beams able to analyse rocks at distance, rock grinders and analysers able to provide a more detailed characterisation of Mars rocks, soil and atmosphere. </p>
<p>Perchlorates were also <a href="http://science.sciencemag.org/content/340/6129/138.2">found by the Curiosity rover</a>, from the Mars Science Laboratory mission, and also <a href="https://doi.org/10.1016/j.icarus.2013.11.012">on a Martian meteorite called EETA79001</a> which suggest a global distribution of these bacterial-killer salts.</p>
<h2>A new InSight to Mars</h2>
<p>The past 50 years were full of discoveries about Mars’s surface, but little is known about its subsoil or inner core. This is where the InSight mission that is about to land on Mars comes in to play. </p>
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<iframe width="440" height="260" src="https://www.youtube.com/embed/LKLITDmm4NA?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Inside Mars.</span></figcaption>
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<p>It’s supported by NASA’s Deep Space Network, including our station in Canberra which is managed on NASA’s behalf by CSIRO. InSight’s team hopes to learn how the deep interior of Mars was formed, and how similar they would be to other rocky worlds such as Venus, Mercury, our Moon, Earth, or those exoplanets from other solar systems. </p>
<p>This is the first mission that is designed to investigate deep inside of Mars. Insight has a seismometer and temperature probe as part of its payload.</p>
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Read more:
<a href="https://theconversation.com/curious-kids-what-are-some-of-the-challenges-to-mars-travel-105030">Curious Kids: What are some of the challenges to Mars travel?</a>
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<p>The future will be dominated by sample return missions: those spacecraft able to land on Mars and bring samples back to Earth (similar to what Russians did on the Moon) and by our effort to have astronauts exploring Mars on their own feet. </p>
<p>We don’t yet have the technology required to make that happen. An idea of the challenge ahead is captured by the CSIRO <a href="https://www.csiro.au/en/do-business/futures/reports/space-roadmap">Space Industry Roadmap</a>, which outlines some of the key technologies needed for future exploration and the unique contributions that Australian companies and universities could offer in that pursuit</p>
<p>The quest for understanding the evolution of our Solar System continues and I am still confronted by a large number of questions without an answer. Hopefully InSight will provide some of those answers but there is still much to learn about what lies above us on Mars, the fourth planet out from the Sun.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/247207/original/file-20181126-149311-17gaydj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/247207/original/file-20181126-149311-17gaydj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/247207/original/file-20181126-149311-17gaydj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=337&fit=crop&dpr=1 600w, https://images.theconversation.com/files/247207/original/file-20181126-149311-17gaydj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=337&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/247207/original/file-20181126-149311-17gaydj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=337&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/247207/original/file-20181126-149311-17gaydj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/247207/original/file-20181126-149311-17gaydj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/247207/original/file-20181126-149311-17gaydj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">This artist’s concept depicts NASA’s InSight lander after it has deployed its instruments on the Martian surface.</span>
<span class="attribution"><a class="source" href="https://www.nasa.gov/feature/jpl/nasas-insight-will-study-mars-while-standing-still">NASA/JPL-Caltech</a></span>
</figcaption>
</figure><img src="https://counter.theconversation.com/content/106541/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Paulo de Souza does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Mars has long captured our imagination, from claims of canals to Martian attacks and now our latest NASA exploration to look inside the red planet.Paulo de Souza, Science Leader – Cybernetics, CSIROLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1030532018-11-06T11:41:10Z2018-11-06T11:41:10ZColonizing Mars means contaminating Mars – and never knowing for sure if it had its own native life<figure><img src="https://images.theconversation.com/files/242763/original/file-20181029-76411-ioau9b.jpg?ixlib=rb-1.1.0&rect=814%2C0%2C3775%2C2574&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Once people get there, Mars will be contaminated with Earth life.</span> <span class="attribution"><a class="source" href="https://www.nasa.gov/multimedia/imagegallery/image_feature_261.html">NASA/Pat Rawlings, SAIC</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span></figcaption></figure><p>The closest place in the universe where extraterrestrial life might exist is Mars, and human beings are poised to attempt to colonize this planetary neighbor within the next decade. Before that happens, we need to recognize that a very real possibility exists that the first human steps on the Martian surface will lead to a collision between terrestrial life and biota native to Mars.</p>
<p>If the red planet is sterile, a human presence there would create no moral or ethical dilemmas on this front. But if life does exist on Mars, human explorers could easily lead to the extinction of Martian life. <a href="https://scholar.google.com/citations?user=KOrEwdkAAAAJ&hl=en&oi=ao">As an astronomer</a> who explores these questions in my book “<a href="https://press.princeton.edu/titles/11233.html">Life on Mars: What to Know Before We Go</a>,” I contend that we Earthlings need to understand this scenario and debate the possible outcomes of colonizing our neighboring planet in advance. Maybe missions that would carry humans to Mars need a timeout.</p>
<h2>Where life could be</h2>
<p>Life, scientists suggest, has some basic requirements. It could exist anywhere in the universe that has liquid water, a source of heat and energy, and copious amounts of a few essential elements, such as carbon, hydrogen, oxygen, nitrogen and potassium.</p>
<p>Mars qualifies, as do at least two other places in our solar system. Both <a href="https://solarsystem.nasa.gov/moons/jupiter-moons/europa/in-depth/">Europa</a>, one of Jupiter’s large moons, and <a href="https://solarsystem.nasa.gov/moons/saturn-moons/enceladus/in-depth/">Enceladus</a>, one of Saturn’s large moons, appear to possess these prerequisites for hosting native biology.</p>
<p>I suggest that how scientists planned the exploratory missions to these two moons provides valuable background when considering how to explore Mars without risk of contamination.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/242558/original/file-20181026-7050-3k87rh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/242558/original/file-20181026-7050-3k87rh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/242558/original/file-20181026-7050-3k87rh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=685&fit=crop&dpr=1 600w, https://images.theconversation.com/files/242558/original/file-20181026-7050-3k87rh.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=685&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/242558/original/file-20181026-7050-3k87rh.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=685&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/242558/original/file-20181026-7050-3k87rh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=860&fit=crop&dpr=1 754w, https://images.theconversation.com/files/242558/original/file-20181026-7050-3k87rh.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=860&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/242558/original/file-20181026-7050-3k87rh.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=860&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">Cassini shot this false-color image of jets erupting from the southern hemisphere of Enceladus on Nov. 27, 2005.</span>
<span class="attribution"><a class="source" href="https://www.nasa.gov/mission_pages/cassini/media/saturn_sponge.html">NASA/JPL/Space Science Institute</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
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<p>Below their thick layers of surface ice, both Europa and Enceladus have global oceans in which 4.5 billion years of churning of the primordial soup may have enabled life to develop and take root. NASA spacecraft have even imaged spectacular geysers ejecting plumes of water out into space from these subsurface oceans.</p>
<p>To find out if either moon has life, planetary scientists are actively developing the <a href="https://europa.nasa.gov/">Europa Clipper mission</a> for a 2020s launch. They also hope to plan future missions that will target Enceladus.</p>
<h2>Taking care to not contaminate</h2>
<p>Since the start of the space age, scientists have taken the threat of biological contamination of other worlds seriously. As early as 1959, NASA held meetings <a href="https://www.nasa.gov/connect/ebooks/when_biospheres_collide_detail.html">to debate the necessity of sterilizing spacecraft</a> that might be sent to other worlds. Since then, all planetary exploration missions have adhered to sterilization standards that balance their scientific goals with limitations of not damaging sensitive equipment, which could potentially lead to mission failures. Today, NASA protocols exist for the <a href="https://sma.nasa.gov/sma-disciplines/planetary-protection">protection of all solar system bodies</a>, including Mars.</p>
<p>Since avoiding the biological contamination of Europa and Enceladus is an extremely well-understood, high-priority requirement of all missions to the Jovian and Saturnian environments, their moons remain uncontaminated.</p>
<p>NASA’s <a href="https://solarsystem.nasa.gov/missions/galileo/overview/">Galileo mission explored Jupiter</a> and its moons from 1995 until 2003. Given Galileo’s orbit, the possibility existed that the spacecraft, once out of rocket propellant and subject to the whims of gravitational tugs from Jupiter and its many moons, could someday crash into and thereby contaminate Europa. </p>
<p>Such a collision might not occur until many millions of years from now. Nevertheless, though the risk was small, it was also real. NASA paid close attention to guidance from the <a href="https://www.nap.edu/initiative/committee-on-planetary-and-lunar-exploration">National Academies’ Committee on Planetary and Lunar Exploration</a>, which noted serious national and international objections to the possible accidental disposal of the Galileo spacecraft on Europa.</p>
<p>To completely eliminate any such risk, on Sept. 21, 2003, NASA used the last bit of fuel on the spacecraft to send it plunging into Jupiter’s atmosphere. At a speed of 30 miles per second, <a href="https://www.nasa.gov/vision/universe/solarsystem/galileo_final.html">Galileo vaporized within seconds</a>.</p>
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<figcaption><span class="caption">Cassini’s ‘Grand Finale’ ended with the spacecraft burning up in Saturn’s atmosphere.</span></figcaption>
</figure>
<p>Fourteen years later, NASA repeated this protect-the-moon scenario. The <a href="https://solarsystem.nasa.gov/missions/cassini/overview/">Cassini mission orbited and studied Saturn</a> and its moons from 2004 until 2017. On Sept. 15, 2017, when fuel had run low, on instructions from NASA Cassini’s operators deliberately <a href="https://saturn.jpl.nasa.gov/mission/about-the-mission/summary/">plunged the spacecraft into Saturn’s atmosphere</a>, where it disintegrated.</p>
<h2>But what about Mars?</h2>
<p>Mars is the target of <a href="https://mars.nasa.gov/#missions">seven active missions</a>, including two rovers, <a href="https://mars.nasa.gov/programmissions/missions/present/2003/">Opportunity</a> and <a href="https://mars.nasa.gov/msl/mission/mars-rover-curiosity-mission-updates/">Curiosity</a>. In addition, on Nov. 26 NASA’s <a href="https://mars.nasa.gov/insight/">InSight mission</a> is scheduled to land on Mars, where it will make measurements of Mars’ interior structure. Next, with planned 2020 launches, both ESA’s <a href="http://exploration.esa.int/mars/48088-mission-overview/">ExoMars rover</a> and NASA’s <a href="https://mars.nasa.gov/mars2020/">Mars 2020 rover</a> are designed to search for evidence of life on Mars.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/242772/original/file-20181029-76413-otea1r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/242772/original/file-20181029-76413-otea1r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/242772/original/file-20181029-76413-otea1r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=430&fit=crop&dpr=1 600w, https://images.theconversation.com/files/242772/original/file-20181029-76413-otea1r.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=430&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/242772/original/file-20181029-76413-otea1r.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=430&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/242772/original/file-20181029-76413-otea1r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=540&fit=crop&dpr=1 754w, https://images.theconversation.com/files/242772/original/file-20181029-76413-otea1r.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=540&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/242772/original/file-20181029-76413-otea1r.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=540&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The Curiosity rover was tested under clean conditions on Earth before launch to prevent microbial stowaways.</span>
<span class="attribution"><a class="source" href="https://www.nasa.gov/mission_pages/msl/msl20100913.html">NASA/JPL-Caltech</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>The good news is that robotic rovers pose little risk of contamination to Mars, since all spacecraft designed to land on Mars are subject to <a href="https://www.nasa.gov/missions/solarsystem/mer_clean.html">strict sterilization procedures before launch</a>. This has been the case since NASA imposed “rigorous sterilization procedures” for the <a href="https://mars.nasa.gov/programmissions/missions/past/viking/">Viking Lander Capsules</a> in the 1970s, since they would directly contact the Martian surface. These rovers likely have an extremely low number of microbial stowaways.</p>
<p>Any terrestrial biota that do manage to hitch rides on the outside of those rovers would have a very hard time surviving the half-year journey from Earth to Mars. The vacuum of space combined with exposure to harsh X-rays, ultraviolet light and cosmic rays would <a href="https://www.nasa.gov/connect/ebooks/when_biospheres_collide_detail.html">almost certainly sterilize the outsides of any spacecraft</a> sent to Mars.</p>
<p>Any bacteria that sneaked rides inside one of the rovers might arrive at Mars alive. But if any escaped, the <a href="https://www.space.com/16903-mars-atmosphere-climate-weather.html">thin Martian atmosphere</a> would offer virtually no protection from high energy, sterilizing radiation from space. Those bacteria would likely be killed immediately. Because of this harsh environment, life on Mars, if it currently exists, almost certainly must be hiding beneath the planet’s surface. Since no rovers have explored caves or dug deep holes, we have not yet had the opportunity to come face-to-drill-bit with any possible Martian microbes.</p>
<p>Given that the exploration of Mars has so far been limited to unmanned vehicles, the planet likely remains free from terrestrial contamination.</p>
<p>But when Earth sends astronauts to Mars, they’ll travel with life support and energy supply systems, habitats, 3D printers, food and tools. None of these materials can be sterilized in the same ways systems associated with robotic spacecraft can. Human colonists will produce waste, try to grow food and use machines to extract water from the ground and atmosphere. Simply by living on Mars, human colonists will contaminate Mars.</p>
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<iframe width="440" height="260" src="https://www.youtube.com/embed/_dafbHGxNOE?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
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<h2>Can’t turn back the clock after contamination</h2>
<p>Space researchers have developed a careful approach to robotic exploration of Mars and a hands-off attitude toward Europa and Enceladus. Why, then, are we collectively willing to overlook the risk to Martian life of human exploration and colonization of the red planet?</p>
<p>Contaminating Mars isn’t an unforeseen consequence. A quarter century ago, a National Research Council report entitled <a href="https://doi.org/10.17226/12305">“Biological Contamination of Mars: Issues and Recommendations”</a> asserted that missions carrying humans to Mars will inevitably contaminate the planet. </p>
<p>I believe it’s critical that every attempt be made to obtain evidence of any past or present life on Mars well in advance of future missions to Mars that include humans. What we discover could influence our collective decision whether to send colonists there at all.</p>
<p>Even if we ignore or don’t care about the risks a human presence would pose to Martian life, the issue of bringing Martian life back to Earth has serious societal, legal and international implications that deserve discussion before it’s too late. What risks might Martian life pose to our environment or our health? And does any one country or group have the right to risk back contamination if those Martian lifeforms could attack the DNA molecule and thereby put all of life on Earth at risk?</p>
<p>But players both public – NASA, United Arab Emirates’ <a href="https://government.ae/en/more/uae-future/2030-2117">Mars 2117 project</a> – and private – <a href="https://www.spacex.com/mars">SpaceX</a>, <a href="https://www.mars-one.com">Mars One</a>, <a href="https://www.blueorigin.com">Blue Origin</a> – already plan to transport colonists to build cities on Mars. And these missions will contaminate Mars. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/242775/original/file-20181029-76399-1ozr59w.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/242775/original/file-20181029-76399-1ozr59w.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/242775/original/file-20181029-76399-1ozr59w.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=312&fit=crop&dpr=1 600w, https://images.theconversation.com/files/242775/original/file-20181029-76399-1ozr59w.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=312&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/242775/original/file-20181029-76399-1ozr59w.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=312&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/242775/original/file-20181029-76399-1ozr59w.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=392&fit=crop&dpr=1 754w, https://images.theconversation.com/files/242775/original/file-20181029-76399-1ozr59w.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=392&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/242775/original/file-20181029-76399-1ozr59w.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=392&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Scientists hypothesize that dark narrow streaks were formed by briny liquid water – necessary for life – flowing down the walls of a crater on Mars.</span>
<span class="attribution"><a class="source" href="https://mars.nasa.gov/resources/7488/dark-recurring-streaks-on-walls-of-garni-crater/">NASA/JPL-Caltech/Univ. of Arizona</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p><a href="https://doi.org/10.1126/science.1165243">Some scientists believe they</a> <a href="https://doi.org/10.1126/science.aaq0131">have already uncovered</a> <a href="https://www.nasa.gov/press-release/nasa-finds-ancient-organic-material-mysterious-methane-on-mars">strong evidence for life on Mars</a>, both past and present. If life already exists on Mars, then Mars, for now at least, belongs to the Martians. Mars is their planet, and Martian life would be threatened by a human presence there.</p>
<p>Does humanity have an inalienable right to colonize Mars simply because we will soon be able to do so? We have the technology to use robots to determine whether Mars is inhabited. Do ethics demand that we use those tools to answer definitively whether Mars is inhabited or sterile before we put human footprints on the Martian surface?</p><img src="https://counter.theconversation.com/content/103053/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>David Weintraub does not work for, consult, own shares in or receive funding from any company or organization that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>NASA’s InSight Mars lander touches down Nov. 26, part of a careful robotic approach to exploring the red planet. But human exploration of Mars will inevitably introduce Earth life. Are you OK with that?David Weintraub, Professor of Astronomy, Vanderbilt UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1009642018-08-02T10:11:37Z2018-08-02T10:11:37ZSorry Elon Musk, but it’s now clear that colonising Mars is unlikely – and a bad idea<figure><img src="https://images.theconversation.com/files/230364/original/file-20180802-136670-1tq8zjh.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Pie in the sky? Mars Ice Home concept.</span> <span class="attribution"><span class="source">NASA/Clouds AO/SEArch </span></span></figcaption></figure><p>Space X and Tesla founder Elon Musk has a vision for colonising Mars, based on a big rocket, nuclear explosions and an infrastructure to transport millions of people there. This was seen as <a href="https://theconversation.com/elon-musk-releases-details-of-plan-to-colonise-mars-heres-what-a-planetary-expert-thinks-79733">highly ambitious but technically challenging</a> in several ways. Planetary protection rules and the difficulties of terraforming (making the planet hospitable by, for example, warming it up) and dealing with the harsh radiation were quoted as severe obstacles.</p>
<p>Undeterred, Musk took a first step towards his aim in February this year with <a href="https://theconversation.com/falcon-heavy-spacex-stages-an-amazing-launch-but-what-about-the-environmental-impact-91423">the launch of a Tesla roadster</a> car into an orbit travelling beyond Mars on the first Falcon Heavy rocket. This dramatically illustrated the increasing launch capability for future missions made available by partnerships between commercial and government agencies. </p>
<p>But six months later, the plans have started to look more like fantasy. We have since learned that there could be life beneath Mars’ surface and that it may be impossible to terraform its surface.</p>
<p>The possibility that there currently could be life on the red planet was raised last week as scientists <a href="https://theconversation.com/discovered-a-huge-liquid-water-lake-beneath-the-southern-pole-of-mars-100523">reported the discovery</a> of a salt water lake beneath Mars’ surface. The lake would be 1.5km below the south polar cap and at least 20km in diameter. This was found from analysis of subsurface radar data from the <a href="http://sci.esa.int/mars-express/">Mars Express spacecraft</a>. The water is thought to be briny, with the likely magnesium, calcium, and sodium perchlorate salts acting as an antifreeze down to temperatures of perhaps 200K (-73.15°C).</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/230369/original/file-20180802-136649-2i8mzy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/230369/original/file-20180802-136649-2i8mzy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=438&fit=crop&dpr=1 600w, https://images.theconversation.com/files/230369/original/file-20180802-136649-2i8mzy.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=438&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/230369/original/file-20180802-136649-2i8mzy.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=438&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/230369/original/file-20180802-136649-2i8mzy.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=551&fit=crop&dpr=1 754w, https://images.theconversation.com/files/230369/original/file-20180802-136649-2i8mzy.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=551&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/230369/original/file-20180802-136649-2i8mzy.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=551&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">Mars’ south polar cap, hiding the lake.</span>
<span class="attribution"><span class="source">NASA/JPL/MSSS</span></span>
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</figure>
<p>This is exciting as it is the first definitive detection of liquid water on Mars, and it is possible that there may be further deep lakes elsewhere on the planet. This means there is a real possibility of current life on Mars.</p>
<p>We already knew life could have existed on Mars in the past. There are several pieces of evidence indicating that Mars was habitable 3.8-4 billion years ago. Data from recent missions – including <a href="https://mars.nasa.gov/programmissions/missions/past/globalsurveyor/">Mars Global Surveyor</a>, <a href="https://mars.nasa.gov/odyssey/">Odyssey</a>, <a href="https://mars.nasa.gov/mer/mission/status_opportunityAll.html">Opportunity</a>, <a href="https://www.space.com/17963-mars-curiosity.html">Curiosity</a> and Mars Express – have provided mounting evidence that water was present on the surface in streams and lakes with reasonable acidity and that the right chemistry for life to evolve existed there around the time that life was evolving on Earth. </p>
<p>But Mars lost its magnetic field, which would have protected life from harsh radiation from space, 3.8 billion years ago. This also meant its <a href="https://theconversation.com/how-did-mars-lose-its-habitable-climate-the-answer-is-blowing-in-the-solar-wind-50258">atmosphere started leaking into space</a>, making it increasingly inhospitable. So living organisms may not have survived.</p>
<p>But while the new discovery may fuel aspiring colonisers’ dreams that the water in the subsurface lake might be usable to sustain a human presence, the reality is very different.</p>
<p>The risk of contamination means we shouldn’t send humans there until we know for sure whether there is naturally evolved life – something that could take years to decades. We will need to drill under the surface and to analyse samples, either in-situ or from material returned to Earth, and find <a href="https://theconversation.com/exoplanets-how-we-used-chemistry-to-identify-the-worlds-most-likely-to-host-life-100897">suitable biomarkers</a> to be sure.</p>
<h2>Terraforming plans crushed?</h2>
<p>Perhaps even more damning, the long-suggested idea of terraforming Mars is now firmly locked in the realm of science fiction. Musk has previously indicated that he wants to terraform the planet to make it more Earth-like, so you can “<a href="https://www.cbsnews.com/news/elon-musk-on-mars-its-a-fixer-upper-of-a-planet/">eventually walk around outside without anything on</a>.” This would most easily be done by producing an atmosphere made of heat-trapping greenhouse gases locked in the planet’s ice in order to raise its temperature and pressure. Musk has suggested that we could <a href="http://www.iflscience.com/space/elon-musk-says-we-could-terraform-mars-dropping-thermonuclear-bombs-it/">drop thermonuclear bombs </a> on the ice at its poles in order to heat it up to release the carbon dioxide.</p>
<p>But according to a new study, <a href="https://www.newscientist.com/article/2175414-terraforming-mars-might-be-impossible-due-to-a-lack-of-carbon-dioxide/">published in Nature Astronomy</a>, Mars has lost so much of its potential greenhouse gases to space over billions of years that there is now no possibility of transforming the remaining atmosphere into a breathable one with available technology. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/230370/original/file-20180802-136646-atzfoi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/230370/original/file-20180802-136646-atzfoi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=280&fit=crop&dpr=1 600w, https://images.theconversation.com/files/230370/original/file-20180802-136646-atzfoi.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=280&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/230370/original/file-20180802-136646-atzfoi.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=280&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/230370/original/file-20180802-136646-atzfoi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=352&fit=crop&dpr=1 754w, https://images.theconversation.com/files/230370/original/file-20180802-136646-atzfoi.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=352&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/230370/original/file-20180802-136646-atzfoi.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=352&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">An Earth-like Mars?</span>
<span class="attribution"><span class="source">Steve Jurvetson/Flickr</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
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<p>The study is based on measurements of the recent escape rate of gases to space measured over the last 15 years by Mars Express and the last four years by <a href="https://mars.nasa.gov/maven/">MAVEN</a>. This can tell us how much effective greenhouse gases, carbon dioxide and water are available at Mars. The measurements, combined with knowledge of the inventories of carbon dioxide and water on Mars from recent space missions, show that greenhouses gases locked in the ice caps are not enough to provide the necessary heating.</p>
<p>More may be available deep within the planet but extracting that is well beyond today’s technology. Also, the atmosphere is still being lost due to the lack of a magnetic field, so that would need to be somehow slowed to maintain any changes achieved by terraforming. This means that potential explorers would need to use heavy, airtight walls, roofs or buildings to provide the right atmosphere and the required screening from cosmic radiation.</p>
<p>While Musk may be disappointed by these new results, most Mars scientists are breathing a sigh of relief. There may be present or past life on Mars, and we can now focus on finding it.</p>
<p>We will be searching for signs of life with the <a href="https://theconversation.com/decades-of-attempts-show-how-hard-it-is-to-land-on-mars-heres-how-we-plan-to-succeed-in-2021-69734">ESA-Russian ExoMars 2020 rover</a>, and the NASA <a href="https://mars.nasa.gov/mars2020/">Mars 2020 mission</a> will gather samples for eventual return to Earthbound laboratories by around 2030. The results of all this may tell us if there was, is or could be life elsewhere. In our solar system, the best targets are Mars, <a href="https://theconversation.com/nasa-saturn-moon-enceladus-is-able-to-host-life-its-time-for-a-new-mission-76102">Saturn’s moon Enceladus</a> and <a href="https://theconversation.com/saturns-moon-titan-may-harbour-simple-life-forms-and-reveal-how-organisms-first-formed-on-earth-81527">Titan</a>, and <a href="https://theconversation.com/signs-of-water-plumes-boost-chances-of-finding-life-on-jupiters-moon-europa-96507">Jupiter’s moons Europa</a>. And these just hint of the potential for life on the many planets beyond our own solar system.</p>
<p>Mars is bright in our skies this week, the brightest since 2003. The red planet is never far from our thoughts, whether as a potential cradle for life beyond Earth or as a target for humans in the future. We live in exciting times when it comes to space exploration. So let’s not spoil one of the largest and most fundamental experiments for humankind by letting dreams of colonisation go too far – at least until we know whether there is life.</p><img src="https://counter.theconversation.com/content/100964/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Andrew Coates receives funding from STFC and UKSA. </span></em></p>Elon Musk may be disappointed by recent studies threatening his plans to go to Mars, but planetary scientists are breathing a sigh of relief.Andrew Coates, Professor of Physics, Deputy Director (Solar System) at the Mullard Space Science Laboratory, UCLLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/999432018-07-26T05:39:42Z2018-07-26T05:39:42ZHow to grow crops on Mars if we are to live on the red planet<figure><img src="https://images.theconversation.com/files/229365/original/file-20180726-106502-1nt78ux.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">We can create the right kind of food plants to survive on Mars.</span> <span class="attribution"><span class="source">Shutterstock/SergeyDV</span></span></figcaption></figure><p>Preparations are <a href="https://www.nasa.gov/content/journey-to-mars-overview">already underway</a> for <a href="https://theconversation.com/the-new-space-race-why-we-need-a-human-mission-to-mars-73757">missions</a> that will land humans on Mars in a decade or so. But what would people eat if these missions eventually lead to the permanent colonisation of the red planet?</p>
<p>Once (if) humans do make it to Mars, a major challenge for any colony will be to generate a stable supply of food. The enormous costs of launching and resupplying resources from Earth will make that impractical.</p>
<p>Humans on Mars will need to move away from complete reliance on shipped cargo, and achieve a high level of self-sufficient and sustainable agriculture.</p>
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Read more:
<a href="https://theconversation.com/discovered-a-huge-liquid-water-lake-beneath-the-southern-pole-of-mars-100523">Discovered: a huge liquid water lake beneath the southern pole of Mars</a>
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<p>The <a href="http://science.sciencemag.org/content/early/2018/07/24/science.aar7268">recent discovery</a> of liquid water on Mars – which adds new information to the question of whether we will find life on the planet – does raise the possibility of using such supplies to help grow food.</p>
<p>But water is only one of many things we will need if we’re to grow enough food on Mars.</p>
<h2>What sort of food?</h2>
<p>Previous work has suggested the use of <a href="http://rsif.royalsocietypublishing.org/content/12/102/20140715">microbes</a> as a source of food on Mars. The use of <a href="https://www.nasa.gov/feature/lunar-martian-greenhouses-designed-to-mimic-those-on-earth">hydroponic greenhouses</a> and controlled environmental systems, similar to <a href="https://www.nasa.gov/mission_pages/station/research/10-074.html">one being tested</a> onboard the International Space Station to grow crops, is another option.</p>
<p><a href="https://doi.org/10.3390/genes9070348">This month</a>, in the journal Genes, we provide a new perspective based on the use of advanced synthetic biology to improve the potential performance of plant life on Mars.</p>
<p>Synthetic biology is a fast-growing field. It combines principles from engineering, DNA science, and computer science (among many other disciplines) to impart new and improved functions to living organisms.</p>
<p>Not only can we read DNA, but we can also design biological systems, test them, and even engineer whole organisms. <a href="http://syntheticyeast.org/sc2-0/introduction/">Yeast</a> is just one example of an industrial workhorse microbe whose whole genome is currently being re-engineered by an international consortium.</p>
<p>The technology has progressed so far that precision genetic engineering and automation can now be merged into automated robotic facilities, known as biofoundries.</p>
<p>These biofoundries can test millions of DNA designs in parallel to find the organisms with the qualities that we are looking for.</p>
<h2>Mars: Earth-like but not Earth</h2>
<p>Although Mars is the most Earth-like of our neighbouring planets, Mars and Earth differ in many ways.</p>
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Read more:
<a href="https://theconversation.com/dear-diary-the-sun-never-set-on-the-arctic-mars-simulation-84597">Dear diary: the Sun never set on the Arctic Mars simulation</a>
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<p>The gravity on Mars is around a third of that on Earth. Mars receives about half of the sunlight we get on Earth, but much higher levels of harmful ultraviolet (UV) and cosmic rays. The surface temperature of Mars is about -60°C and it has a thin atmosphere primarily made of carbon dioxide.</p>
<p>Unlike Earth’s soil, which is humid and rich in nutrients and microorganisms that support plant growth, Mars is covered with <a href="https://www.britannica.com/science/regolith">regolith</a>. This is an arid material that contains <a href="https://www.space.com/37402-mars-life-soil-toxic-perchlorates-radiation.html">perchlorate chemicals</a> that are toxic to humans.</p>
<p>Also – despite the latest sub-surface lake find – water on Mars mostly exists in the form of ice, and the low atmospheric pressure of the planet makes liquid water boil at around 5°C.</p>
<p>Plants on Earth have evolved for hundreds of millions of years and are adapted to terrestrial conditions, but they will not grow well on Mars. </p>
<p>This means that substantial resources that would be scarce and priceless for humans on Mars, like liquid water and energy, would need to be allocated to achieve efficient farming by artificially creating optimal plant growth conditions.</p>
<h2>Adapting plants to Mars</h2>
<p>A more rational alternative is to use synthetic biology to develop crops specifically for Mars. This formidable challenge can be tackled and fast-tracked by building a plant-focused Mars biofoundry. </p>
<p>Such an automated facility would be capable of expediting the engineering of biological designs and testing of their performance under simulated Martian conditions.</p>
<p>With adequate funding and active international collaboration, such an advanced facility could improve many of the traits required for making crops thrive on Mars within a decade. </p>
<p>This includes improving <a href="https://www.britannica.com/science/photosynthesis">photosynthesis</a> and photoprotection (to help protect plants from sunlight and UV rays), as well as drought and cold tolerance in plants, and engineering high-yield functional crops. We also need to modify microbes to detoxify and improve the Martian soil quality.</p>
<p>These are all challenges that are within the capability of modern synthetic biology.</p>
<h2>Benefits for Earth</h2>
<p>Developing the next generation of crops required for sustaining humans on Mars would also have great benefits for people on Earth.</p>
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Read more:
<a href="https://theconversation.com/before-we-colonise-mars-lets-look-to-our-problems-on-earth-87770">Before we colonise Mars, let's look to our problems on Earth</a>
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<p>The growing global population is <a href="https://theconversation.com/the-future-of-food-growing-more-with-the-same-land-35559">increasing the demand for food</a>. To meet this demand we must increase agricultural productivity, but we have to do so without negatively impacting our environment.</p>
<p>The best way to achieve these goals would be to improve the crops that are already widely used. Setting up facilities such as the proposed Mars Biofoundry would bring immense benefit to the turnaround time of plant research with implications for food security and environmental protection.</p>
<p>So ultimately, the main beneficiary of efforts to develop crops for Mars would be Earth.</p><img src="https://counter.theconversation.com/content/99943/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Briardo Llorente receives funding from the CSIRO Synthetic Biology Future Science Platform and Macquarie University. </span></em></p>If humans are to live on Mars they will need a stable supply of food. Earth plants are not suited to the Mars climate but we can engineer plants that are.Briardo Llorente, CSIRO Synthetic Biology Future Science Fellow, Macquarie UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1005232018-07-25T14:02:02Z2018-07-25T14:02:02ZDiscovered: a huge liquid water lake beneath the southern pole of Mars<figure><img src="https://images.theconversation.com/files/229230/original/file-20180725-194134-1xuput9.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C1690%2C1105&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Mars' south polar cap, as seen from Mars Global Surveyor. Buried beneath, we now know, is a lake of liquid water.</span> <span class="attribution"><a class="source" href="https://photojournal.jpl.nasa.gov/catalog/PIA02393">NASA/JPL/MSSS</a></span></figcaption></figure><p>We now know that there is permanent liquid water on Mars, according to a <a href="http://dx.doi.org/10.1126/science.aar7268">paper published today</a> in the journal Science.</p>
<p>This finding comes from research using the <a href="http://sci.esa.int/mars-express/">Mars Express</a> spacecraft, which has been orbiting the red planet since December 25 2003. </p>
<p>One of the suite of instruments carried by Mars Express is MARSIS (the <a href="https://mars.jpl.nasa.gov/express/mission/sc_science_marsis01.html">Mars Advanced Radar for Subsurface and Ionosphere Sounding</a>), which allows researchers to use radar to study features beneath the planet’s surface.</p>
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<a href="https://theconversation.com/there-is-water-on-mars-but-what-does-this-mean-for-life-48310">There is water on Mars, but what does this mean for life?</a>
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<p>Using observations spanning a period of four years, a team of researchers from Italy found evidence of a large lake of salty water, buried 1.5 kilometres beneath Mars’ southern polar cap. That lake is at least 20 kilometres across and seems to be a permanent feature.</p>
<h2>More than droplets</h2>
<p>The reason people are excited about this discovery is because everywhere you find liquid water on Earth, you find life. NASA has long espoused a philosophy of “<a href="https://www.nasa.gov/vision/earth/everydaylife/jamestown-water-fs.html">follow the water</a>” in its program of <a href="https://astrobiology.nasa.gov/">astrobiological research</a> – trying to answer the question “are we alone?”</p>
<p>Over the past two decades, we have seen mission after mission travel to Mars. Some, like Mars Express, are orbiters. Others (such as the incredible <a href="https://www.jpl.nasa.gov/missions/mars-exploration-rover-spirit-mer/">Spirit</a> and <a href="https://www.jpl.nasa.gov/missions/mars-exploration-rover-opportunity-mer/">Opportunity</a>) are rovers. A unifying theme across those missions has been their attempts to see whether Mars once had the right conditions for life to exist and thrive.</p>
<p>Through them we have found <a href="https://theconversation.com/the-lost-ocean-of-mars-38739">abundant evidence that Mars was once warm and wet</a>. We also have evidence that <a href="https://theconversation.com/there-is-water-on-mars-but-what-does-this-mean-for-life-48310">liquid water can still be found on the surface of Mars</a> from time to time. </p>
<p>But, until today, the evidence of modern water all pointed towards fleeting moments - <a href="https://www.space.com/6394-phoenix-mars-lander-liquid-water-scientists.html">droplets condensing on the Mars Phoenix lander</a>, or evidence of <a href="https://theconversation.com/nasa-streaks-of-salt-on-mars-mean-flowing-water-and-raise-new-hopes-of-finding-life-48182">brief outflows of salty water in Martian valleys</a>.</p>
<p>Compared with today’s discovery, those earlier findings are a drop in the ocean.</p>
<h2>Mars has a lake</h2>
<p>The latest observations reveal something remarkable: a salty lake buried deep beneath the ice, which seems to be a permanent feature rather than a transient phenomenon.</p>
<p>The comparison that springs to mind are the myriad lakes buried under the ice of Antarctica. So far <a href="http://rsta.royalsocietypublishing.org/content/374/2059/20140306">more than 400</a> such lakes have been found <a href="https://theconversation.com/what-lies-beneath-antarcticas-ice-lakes-life-and-the-grandest-of-canyons-61748">beneath the surface of the frozen continent</a>. </p>
<p>Perhaps the most famous is <a href="http://www.sciencemag.org/news/2013/07/what-s-really-going-lake-vostok">Lake Vostok</a> – one of the world’s largest lakes, buried and hidden away. But the one to which I want to draw your attention is Lake Whillans.</p>
<p>Lake Whillans is buried some 800 metres below the ice in West Antarctica. In 2013, a team of researchers <a href="https://www.bbc.com/news/science-environment-21231380">succeeded in drilling down into the lake</a> and recovering samples. What did they find? That it was <a href="https://theconversation.com/what-lies-beneath-antarcticas-ice-lakes-life-and-the-grandest-of-canyons-61748">teeming with microbial life</a>. </p>
<p>In other words, the best Earth-based analogues for the newly discovered Martian lake are not just habitable, they are <em>inhabited</em>. Where there’s water, there’s life.</p>
<h2>Is there life on Mars?</h2>
<p>Finding this new lake, buried beneath Mars’ south pole, is another exciting step on our journey of discovery of the red planet. Could there be life there, beneath the ice?</p>
<p>The short answer is that we still don’t know. But it seems like the ideal place to look. What we <em>do</em> know is:</p>
<ul>
<li><p>Mars was once warm and wet, potentially with oceans, lakes and rivers.</p></li>
<li><p>On Earth, where you find water, you find life.</p></li>
<li><p>The transition from warm, wet Mars to the cold and barren Mars we see today occurred over millions of years.</p></li>
<li><p>Life adapts to changing environments, so long as that change is not too fast or dramatic.</p></li>
</ul>
<p>So what do you get if you put all that together? Well, this is where things get speculative. </p>
<p>But let’s imagine that in the far distant past Mars had life. Perhaps the life originated there, or <a href="https://cosmosmagazine.com/biology/over-our-heads-a-brief-history-of-panspermia">maybe it was delivered from Earth, hitching a ride on a meteorite</a>.</p>
<p>Once life is established, it is amazingly hard to get rid of. Over millions of years, Mars cooled and its water became locked in permafrost. Its atmosphere thinned and it became <a href="http://www.midnightplanets.com/">the red planet we see today</a>.</p>
<p>But maybe, just maybe, that life would have been able to follow the water - to move underground, where it might have found a niche in a dark salty lake, buried beneath the ice of Mars’ southern polar cap.</p>
<h2>That’s all well and good, but what next?</h2>
<p>That’s all speculation, but it shows the kind of thought processes that have driven our ongoing exploration of Mars for the past couple of decades. </p>
<p>Now that we know for sure that there is a reservoir of liquid water just beneath the planet’s surface, astronomers around the globe will be thinking of ways to get down to that water to see what’s there.</p>
<p>That is easier said than done. Landing on Mars is challenging at the best of times, and the great majority of missions to date have landed within about 30 degrees latitude of Mars’ equator. The two exceptions are the <a href="https://www.jpl.nasa.gov/missions/viking-2/">Viking 2</a> and <a href="https://www.nasa.gov/mission_pages/phoenix/main/index.html">Phoenix</a> landers, both of which landed in Mars’ northern lowlands. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/229229/original/file-20180725-194128-r72ht1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/229229/original/file-20180725-194128-r72ht1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/229229/original/file-20180725-194128-r72ht1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=345&fit=crop&dpr=1 600w, https://images.theconversation.com/files/229229/original/file-20180725-194128-r72ht1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=345&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/229229/original/file-20180725-194128-r72ht1.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=345&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/229229/original/file-20180725-194128-r72ht1.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=433&fit=crop&dpr=1 754w, https://images.theconversation.com/files/229229/original/file-20180725-194128-r72ht1.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=433&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/229229/original/file-20180725-194128-r72ht1.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=433&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The locations on Mars’ surface visited by landers to date. It is far easier to land near Mars’ equator than its poles.</span>
<span class="attribution"><span class="source">NASA/JPL-Caltech</span></span>
</figcaption>
</figure>
<p>In addition, landing on Mars’ southern hemisphere is harder still. The north is the lowlands and the atmosphere there is markedly thicker, and the surface smoother (as befits, potentially, <a href="http://planetary-mechanics.com/2017/09/17/the-lowlands-of-mars/">the floor of an ancient ocean</a>).</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/before-we-colonise-mars-lets-look-to-our-problems-on-earth-87770">Before we colonise Mars, let's look to our problems on Earth</a>
</strong>
</em>
</p>
<hr>
<p>To the south, you have less atmosphere to slow your descent and a rougher surface to make your landing harder.</p>
<p>But, while tricky, it is not impossible. And now we have a huge motivation to try. </p>
<p>It would not surprise me if, within a decade, we see missions being designed to visit Mars’ south pole and drill down to this great lake, to see what lurks within.</p><img src="https://counter.theconversation.com/content/100523/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jonti Horner does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Researchers have found evidence of a large lake of salty water, buried 1.5 kilometres beneath the southern polar ice cap on Mars. So what does that mean for life on the red planet?Jonti Horner, Professor (Astrophysics), University of Southern QueenslandLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/877702017-12-27T20:46:49Z2017-12-27T20:46:49ZBefore we colonise Mars, let’s look to our problems on Earth<figure><img src="https://images.theconversation.com/files/199343/original/file-20171215-16456-1ar4m9m.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Mars NASA JPL Caltech cd f d o</span> </figcaption></figure><p>Everyone wants to go to Mars, or so it seems. </p>
<p>Elon Musk, NASA with Lockheed Martin, and now Boeing are all looking towards the red planet, with heady predictions of missions during the 2020s. </p>
<p>But at what cost? And could we even survive any long-term colonisation on Mars? Given the problems we face here on Earth it’s important to ask whether we should be better tasked with looking after the only planet we know (so far) that can harbour life.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/revealed-today-elon-musks-new-space-vision-took-us-from-earth-to-mars-and-back-home-again-84837">Revealed today, Elon Musk's new space vision took us from Earth to Mars, and back home again</a>
</strong>
</em>
</p>
<hr>
<h2>The race to Mars</h2>
<p>Boeing says it wants <a href="http://fortune.com/2017/12/07/boeing-dennis-muilenburg-elon-musk-mars/">to be involved in the first mission to send humans</a> to the red planet. The company’s chief executive Dennis Muilenburg told a US TV host in December 2017:</p>
<blockquote>
<p>I firmly believe the first person that sets foot on Mars will get there on a Boeing rocket. </p>
</blockquote>
<p>A key rival is Musk, the billionaire founder of SpaceX, which is already <a href="http://www.spacex.com/missions">launching rockets</a>. At the 68th Annual International Aeronautics Congress, in Adelaide in September 2017, Musk spoke of <a href="http://www.news.com.au/national/south-australia/elon-musk-to-detail-his-mission-to-mars-at-international-astronautical-congress-in-adelaide-on-friday/news-story/53708c3d16e4070a66aab3d0b8b7477a">airline-like connections</a> between Earth and Mars, with cargo missions to begin by 2022. </p>
<p>Lockheed Martin says it <a href="https://www.scientificamerican.com/article/lockheed-martin-reveals-plans-for-sending-humans-to-mars/">plans to send humans to Mars</a> in the next decade. </p>
<p>Even the famous theoretical physicist Stephen Hawking <a href="http://news.bbc.co.uk/today/hi/today/newsid_9672000/9672233.stm">has argued</a> that it is “essential that we colonise space” although he doesn’t see it happening that soon:</p>
<blockquote>
<p>I believe that we will eventually establish self-sustaining colonies on Mars and other bodies in the Solar system although probably not within the next 100 years.</p>
</blockquote>
<h2>Exploring other planets</h2>
<p>Scientific exploration of Solar system planets constitutes one of the most exciting achievements the human race is realising.</p>
<p>But by contrast, the idea of colonising Mars or other planets or moons is misleading. It yields an impression in many people’s mind that an alternative exists to Earth, a unique (so far) haven of life in the Solar system, currently suffering from <a href="https://theconversation.com/au/topics/global-warming-2768">global warming</a>, <a href="https://theconversation.com/contributions-to-sea-level-rise-have-increased-by-half-since-1993-largely-because-of-greenlands-ice-79175">rising oceans</a>, <a href="https://theconversation.com/not-just-heat-even-our-spring-frosts-can-bear-the-fingerprint-of-climate-change-89029">extreme weather events</a>, <a href="https://theconversation.com/earths-sixth-mass-extinction-has-begun-new-study-confirms-43432">mass extinction of species</a> and <a href="https://theconversation.com/why-we-signed-the-open-letter-from-scientists-supporting-a-total-ban-on-nuclear-weapons-75209">growing risk of nuclear wars</a>.</p>
<p>Microbial life <a href="https://www.smithsonianmag.com/science-nature/life-on-mars-78138144/">may exist on Mars</a> or <a href="https://www2.jpl.nasa.gov/snc/nasa1.html">may have existed in the past</a>. <a href="https://www.nasa.gov/mission_pages/mars/overview/index.html">According to NASA</a>:</p>
<blockquote>
<p>Among our discoveries about Mars, one stands out above all others: the possible presence of liquid water, either in its ancient past or preserved in the subsurface today. Water is key because almost everywhere we find water on Earth, we find life. If Mars once had liquid water, or still does today, it’s compelling to ask whether any microscopic life forms could have developed on its surface.</p>
</blockquote>
<p>But doubts have been raised recently with regard to the distinction between water and <a href="https://www.nasa.gov/feature/jpl/recurring-martian-streaks-flowing-sand-not-water">sand flow on Mars</a>.</p>
<h2>No atmosphere for life</h2>
<p>At present there is no evidence of a liveable atmosphere under which plants or other organisms would survive on Mars. </p>
<p>Its <a href="https://nssdc.gsfc.nasa.gov/planetary/factsheet/marsfact.html">thin atmosphere</a> is less than 1% of Earth’s, consisting of 96% carbon dioxide, 1.9% nitrogen, 1.9% argon and trace amounts of oxygen and carbon monoxide. It provides little protection from the Sun’s radiation, nor does it allow retention of heat at the surface.</p>
<p>Suggestions as to whether <a href="https://www.space.com/33690-allen-hills-mars-meteorite-alien-life-20-years.html">biological-like textures</a> in a Martian meteorite (<a href="https://www.lpi.usra.edu/lpi/meteorites/The_Meteorite.shtml">ALH84001</a>) signify ancient fossils have not been confirmed.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/199135/original/file-20171214-27575-1xga58h.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/199135/original/file-20171214-27575-1xga58h.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/199135/original/file-20171214-27575-1xga58h.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=410&fit=crop&dpr=1 600w, https://images.theconversation.com/files/199135/original/file-20171214-27575-1xga58h.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=410&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/199135/original/file-20171214-27575-1xga58h.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=410&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/199135/original/file-20171214-27575-1xga58h.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=516&fit=crop&dpr=1 754w, https://images.theconversation.com/files/199135/original/file-20171214-27575-1xga58h.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=516&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/199135/original/file-20171214-27575-1xga58h.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=516&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">This high-resolution scanning electron microscope image shows an unusual tube-like structural form that is less than 1/100th the width of a human hair in size found in meteorite ALH84001, a meteorite believed to be of Martian origin.</span>
<span class="attribution"><a class="source" href="https://spaceflight.nasa.gov/gallery/images/exploration/marsexploration/html/s96_12609.html">NASA</a></span>
</figcaption>
</figure>
<p>In July 2017 <a href="https://www.nature.com/articles/s41598-017-04910-3">researchers reported</a> that the surface of Mars may be more toxic to microorganisms than previously thought.</p>
<h2>A Mars colony warning</h2>
<p>There is <a href="https://www.vox.com/science-and-health/2016/9/30/13099898/mars-death-risk-illustrated">no lack of warnings</a> regarding the colonisation of Mars.</p>
<p>If a colony was established it would take continuous efforts and major expense to keep it supplied, including likely rescue missions. Furthermore, the long-term isolation of the colonists may take its toll.</p>
<p>When the <a href="http://www.mars-one.com/">Mars One</a> project announced in 2013 that it was looking to recruit four people to send on a mission to colonise Mars, Chris Chambers, a professor of cognitive neuroscience at Cardiff University, <a href="https://www.theguardian.com/science/head-quarters/2013/sep/09/neuroscience-psychology">warned of the psychological risks</a> the colonists would face.</p>
<p>Yet dreams stay alive. According to NASA’s <a href="https://mars.nasa.gov/programmissions/overview/">mission statement</a>:</p>
<blockquote>
<p>Even if Mars is devoid of past or present life, however, there’s still much excitement on the horizon. We ourselves might become “life on Mars”, should humans choose to travel there one day.</p>
</blockquote>
<h2>Earth calling Mars</h2>
<p>Space colonisation dreams are not entirely devoid of economic interests. The international space industry is <a href="http://www.abc.net.au/news/2017-09-24/what-australians-need-to-know-about-space/8979036">said to be worth</a> in the order of some US$400 billion a year, and <a href="https://www.cnbc.com/2017/10/31/the-space-industry-will-be-worth-nearly-3-trillion-in-30-years-bank-of-america-predicts.html">predicted to grow</a> to nearly US$3 trillion over the next three decades. </p>
<p>Space travel and colonisation ideas are mostly promoted by engineers and entrepreneurs who stand to gain from these schemes, but far less so by biologists and medical scientists who understand the terrestrial origin and physiological limitations of the human body.</p>
<p>There can be little doubt that, given modern and future computer and space technologies, space stations could be constructed on Mars, where a few privileged humans may be able to live for periods of time.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/the-new-space-race-why-we-need-a-human-mission-to-mars-73757">The new space race: why we need a human mission to Mars</a>
</strong>
</em>
</p>
<hr>
<p>Should humans colonise a life-bearing planet, we should ask whether organisms would fare any better than <a href="http://www.biologicaldiversity.org/programs/biodiversity/elements_of_biodiversity/extinction_crisis/">species extinguished on Earth</a>. </p>
<p>The ethical polarity between those dreaming of conquering space and those hoping to defend Earth from global heating and a nuclear calamity could not be greater. </p>
<p>The billions and trillions of dollars required to develop and maintain colonies in space could approach the <a href="https://www.sipri.org/research/armament-and-disarmament/arms-transfers-and-military-spending/military-expenditure">estimated US$1.69 trillion military spending globally</a> in 2016.</p>
<p>As a scientist who examines how a changing climate influences human evolution, I argue that funds on this scale would be better directed at the defence of the lives of <a href="https://www.census.gov/popclock/">more than 7 billion humans</a> on Earth, as well as protection of animals and of nature more broadly.</p><img src="https://counter.theconversation.com/content/87770/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Andrew Glikson does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>The race may be on to send humans to live on Mars, but is it worth the effort – and the spend – when we have our own problems to deal with on Earth.Andrew Glikson, Earth and paleo-climate scientist, Australian National UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/885072017-12-06T18:05:29Z2017-12-06T18:05:29ZResearch on clay formation could have implications for how to search for life on Mars<figure><img src="https://images.theconversation.com/files/197926/original/file-20171206-907-1gkmwrm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The Wdowiak Ridge on Mars as seen by NASA's Mars Exploration Rover Opportunity. </span> <span class="attribution"><span class="source">NASA/JPL-Caltech/Cornell Univ./Arizona State Univ.</span></span></figcaption></figure><p>Today Mars has only a thin atmosphere, and its surface is very dry with the possible exception of some localised and temporary <a href="https://theconversation.com/nasa-streaks-of-salt-on-mars-mean-flowing-water-and-raise-new-hopes-of-finding-life-48182">water seeps</a>. However, ancient eroded valley networks that were discovered by orbiting spacecraft in the early days of exploration prove that water flowed across the surface in the remote past.</p>
<p>The branching nature of the oldest valleys, which have many tributaries, shows that the water was most likely supplied by rainfall. This means the surface was very likely habitable for life back then. </p>
<p>When clay minerals were detected from orbit and subsequently <a href="https://theconversation.com/wrestling-some-science-off-of-mars-how-clays-became-sexy-12969">confirmed by surface rovers</a>, it was taken as further evidence that Mars once had a wet surface environment, hospitable to life. This is because when most rocky minerals weather away under humid conditions they rot to form various kinds of clay. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/197435/original/file-20171203-5420-ban7sr.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/197435/original/file-20171203-5420-ban7sr.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=342&fit=crop&dpr=1 600w, https://images.theconversation.com/files/197435/original/file-20171203-5420-ban7sr.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=342&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/197435/original/file-20171203-5420-ban7sr.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=342&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/197435/original/file-20171203-5420-ban7sr.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=430&fit=crop&dpr=1 754w, https://images.theconversation.com/files/197435/original/file-20171203-5420-ban7sr.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=430&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/197435/original/file-20171203-5420-ban7sr.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=430&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Branching tributaries with ancient valleys seen in a 120km wide region of Mars.</span>
<span class="attribution"><span class="source">GoogleEarth (ESA/DLR/FU Berlin)</span></span>
</figcaption>
</figure>
<p>Clay minerals cannot form unless there is water available – it is an essential ingredient in their microscopic crystalline structure. Clays are found virtually nowhere on the red planet except in Mars’s most ancient terrains, dating back to an epoch about 3.7-4.1 billion years ago, called the Noachian.</p>
<p>Understanding these martian clays is difficult, because they can be seen only sparsely across the surface. Some of the detected clays are in bedrock that has been exposed by erosion, others have been washed downstream from such sources by the Noachian rivers.</p>
<p>On Earth, clay forms by weathering of mineral grains chemically attacked by water. Most scientists believe that a similar process took place on Mars during its wet, Noachian period. However, some researchers <a href="https://www.nasa.gov/mission_pages/MRO/news/mro20111102.html">have suggested</a> that most of the detected clay was not formed in this way at all. They argue instead it formed prior to that, while warm water was circulating through the bedrock in response to nearby volcanic and intrusive activity. </p>
<h2>Heat and steam from the magma ocean</h2>
<p>Now a new study by a group from Brown University, Rhode Island, <a href="http://nature.com/articles/doi:10.1038/nature24657">published in Nature</a>, further challenges the idea that clay on Mars formed just like that on Earth. The team has done experiments suggesting that the origin of most of Mars’s clays was <em>even earlier</em>. They considered the likely conditions on the hot, infant Mars, 4.5 billion years ago. At that time, the primordial magma ocean that once covered the planet was still cooling, and the first crystals had floated to the surface to grow Mars’s original “primary crust”. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/197328/original/file-20171201-17360-11u9vvg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/197328/original/file-20171201-17360-11u9vvg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=187&fit=crop&dpr=1 600w, https://images.theconversation.com/files/197328/original/file-20171201-17360-11u9vvg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=187&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/197328/original/file-20171201-17360-11u9vvg.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=187&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/197328/original/file-20171201-17360-11u9vvg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=235&fit=crop&dpr=1 754w, https://images.theconversation.com/files/197328/original/file-20171201-17360-11u9vvg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=235&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/197328/original/file-20171201-17360-11u9vvg.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=235&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Artist’s impression of very early Mars, with a steamy carbon dioxide-rich atmosphere above the surface of a cooling magma ocean.</span>
<span class="attribution"><a class="source" href="https://sservi.nasa.gov/articles/early-formation-of-the-moon/">David A Rothery</a>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>At this time, Mars very likely had a hot and steamy atmosphere, which was still degassing from inside the planet and had not yet had a chance to escape to space. Conditions would have been perfect to make clays by chemical reactions between the atmosphere and the minerals within the warm and porous top of the crust.</p>
<p>The team suggests that such clay formation would have pervaded a layer up to 10km thick. This, they say, was subsequently buried by material spread across the surface by asteroid impacts and by lava from volcanic eruptions. Surface traces of clay are rare today, because they depend on the buried layer having been re-exposed by later, smaller, impacts or erosional processes that have acted locally to strip away the cover.</p>
<h2>Not like Earth?</h2>
<p>The evidence for flowing water in the Noachian is robust, and has not been undermined. However, if the new study is right, Mars may not have experienced a prolonged period when the surface conditions were right for clays to be made by weathering under humid, Earth-like, conditions. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/197344/original/file-20171201-17360-y3rigg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/197344/original/file-20171201-17360-y3rigg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=481&fit=crop&dpr=1 600w, https://images.theconversation.com/files/197344/original/file-20171201-17360-y3rigg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=481&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/197344/original/file-20171201-17360-y3rigg.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=481&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/197344/original/file-20171201-17360-y3rigg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=604&fit=crop&dpr=1 754w, https://images.theconversation.com/files/197344/original/file-20171201-17360-y3rigg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=604&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/197344/original/file-20171201-17360-y3rigg.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=604&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">20km wide image showing the Jezero crater, a candidate landing site for NASA’s Mars 2020 mission. Areas of clay minerals appear green.</span>
<span class="attribution"><span class="source">NASA/JPL-Caltech/MSSS/JHU-APL</span></span>
</figcaption>
</figure>
<p>The next Mars landers, NASA’s <a href="https://mars.nasa.gov/mars2020/mission/overview/">Mars 2020</a> and ESA’s <a href="http://exploration.esa.int/mars/48088-mission-overview/">ExoMars 2020</a>, are both targeted at <a href="http://exploration.esa.int/mars/53845-landing-site/">sites</a> where <a href="https://mars.nasa.gov/mars2020/mission/timeline/prelaunch/landing-site-selection/">clays have been detected</a>. That’s precisely because these may mark sites where Earth-like habitable conditions formerly prevailed, and may have once hosted microbial life just like Earth. </p>
<p>On the balance of probabilities, these are still good places to look for traces of ancient microbial life. The new research suggests ancient life is unlikely to be found where the clays initially formed by chemical reactions with the atmosphere – it doesn’t rule out habitability at the sites where clays have been deposited. Yet, one link in the chain of logic may just have have been at least partially severed.</p><img src="https://counter.theconversation.com/content/88507/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>David Rothery is author of Planet Mercury - from Pale Pink Dot to Dynamic World (Springer, 2015), Moons: A Very Short Introduction (Oxford University Press, 2015) and Planets: A Very Short Introduction (Oxford University Press, 2010). He has received funding from the UK Space Agency and the Science & Technology Facilities Council for work related to Mercury and the European Space Agency's Mercury orbiter BepiColombo. He is co-leader of the European Space Agency's Mercury Surface and Composition Working Group, and a Co-Investigator on MIXS (Mercury Imaging X-ray Spectrometer). He is Educator on the Open University/FutureLearn Moons MOOC and chair of the Open University's Planetary Science and the Search for Life course.</span></em></p>Clay on early Mars could have formed under hot and steamy conditions, challenging the idea that it was created just like that on Earth.David Rothery, Professor of Planetary Geosciences, The Open UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/847422017-09-29T02:35:41Z2017-09-29T02:35:41ZWorries about spreading Earth microbes shouldn’t slow search for life on Mars<figure><img src="https://images.theconversation.com/files/188019/original/file-20170928-2939-1iwisqx.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The Viking landers in the 1970s were the last to look directly for life on Mars.</span> <span class="attribution"><a class="source" href="https://images.nasa.gov/#/details-PIA00382.html">NASA/JPL</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span></figcaption></figure><p>There may be no bigger question than whether we are alone in our solar system. As our spacecraft find new clues about the presence of liquid water now or in the past on Mars, the possibility of some kind of life there looks more likely. On Earth, water means life, and that’s why the exploration of Mars is guided by the idea of following the water.</p>
<p>But the search for life on Mars is paired with plenty of strong warnings about how we must sterilize our spacecraft to avoid contaminating our neighbor planet. How will we know what’s native Martian if we unintentionally seed the place with Earth organisms? A popular analogy points out that Europeans unknowingly brought smallpox to the New World, and they took home syphilis. Similarly, it is argued, our robotic explorations could contaminate Mars with terrestrial microorganisms.</p>
<p>As an astrobiologist who researches the environments of early Mars, I suggest these arguments are misleading. The current danger of contamination via unmanned robots is actually quite low. But contamination <a href="https://doi.org/10.1089/ast.2017.1703">will become unavoidable once astronauts get there</a>. <a href="https://www.nasa.gov/content/journey-to-mars-overview">NASA</a>, other agencies and the <a href="http://www.spacex.com/mars">private sector</a> hope to send <a href="https://www.nytimes.com/2017/09/28/science/elon-musk-mars.html">human missions to Mars by the 2030s</a>.</p>
<p>Space agencies have long prioritized preventing contamination over our hunt for life on Mars. Now is the time to reassess and update this strategy – before human beings get there and inevitably introduce Earth organisms despite our best efforts.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/188026/original/file-20170928-1449-h7tdl9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/188026/original/file-20170928-1449-h7tdl9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/188026/original/file-20170928-1449-h7tdl9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=449&fit=crop&dpr=1 600w, https://images.theconversation.com/files/188026/original/file-20170928-1449-h7tdl9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=449&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/188026/original/file-20170928-1449-h7tdl9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=449&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/188026/original/file-20170928-1449-h7tdl9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=564&fit=crop&dpr=1 754w, https://images.theconversation.com/files/188026/original/file-20170928-1449-h7tdl9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=564&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/188026/original/file-20170928-1449-h7tdl9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=564&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Microbiologists frequently collect swab samples from the floor of clean rooms during spacecraft assembly.</span>
<span class="attribution"><a class="source" href="https://images.nasa.gov/#/details-PIA17368.html">NASA/JPL-Caltech</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<h2>What planetary protection protocols do</h2>
<p>Arguments calling for extra caution have permeated Mars exploration strategies and led to the creation of specific guiding policies, known as <a href="https://planetaryprotection.nasa.gov/">planetary protection</a> protocols. </p>
<p>Strict cleaning procedures are required on our spacecraft before they’re allowed to sample regions on Mars which could be a habitat for microorganisms, either native to Mars or brought there from Earth. These areas are labeled by the planetary protection offices as “<a href="https://www.nap.edu/catalog/21816/review-of-the-mepag-report-on-mars-special-regions">Special Regions</a>.”</p>
<p>The worry is that, otherwise, terrestrial invaders could jeopardize potential Mars life. They also could confound future researchers trying to distinguish between any indigenous Martian life forms and life that arrived as contamination from Earth via today’s spacecraft. </p>
<p>The sad consequence of these policies is that the multi-billion-dollar Mars spacecraft programs run by <a href="https://mars.nasa.gov/programmissions/overview/">space</a> <a href="http://exploration.esa.int/mars/44997-the-red-planet/">agencies</a> in the West have not proactively looked for life on the planet since the late 1970s.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/188014/original/file-20170928-1438-4xut2s.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/188014/original/file-20170928-1438-4xut2s.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/188014/original/file-20170928-1438-4xut2s.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=403&fit=crop&dpr=1 600w, https://images.theconversation.com/files/188014/original/file-20170928-1438-4xut2s.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=403&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/188014/original/file-20170928-1438-4xut2s.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=403&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/188014/original/file-20170928-1438-4xut2s.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=506&fit=crop&dpr=1 754w, https://images.theconversation.com/files/188014/original/file-20170928-1438-4xut2s.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=506&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/188014/original/file-20170928-1438-4xut2s.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=506&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Dr. Carl Sagan poses with a model of the Viking lander in Death Valley, California.</span>
<span class="attribution"><a class="source" href="https://www.nasa.gov/sites/default/files/images/151106main_image_feature_599_ys_full.jpg">NASA</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>That’s when NASA’s Viking landers made the only attempt ever to find life on Mars (or on any planet outside Earth, for that matter). They carried out specific biological experiments looking for evidence of microbial life. Since then, that incipient biological exploration has shifted to less ambitious geological surveys that try to demonstrate only that Mars was “<a href="https://mars.nasa.gov/msl/mission/science/objectives/">habitable</a>” in the past, meaning it had conditions that could likely support life.</p>
<p>Even worse, if a dedicated life-seeking spacecraft ever does get to Mars, planetary protection policies will allow it to search for life everywhere on the Martian surface, except in the very places we suspect life may exist: the Special Regions. The concern is that exploration could contaminate them with terrestrial microorganisms.</p>
<h2>Can Earth life make it on Mars?</h2>
<p>Consider again the Europeans who first journeyed to the New World and back. Yes, smallpox and syphilis traveled with them, between human populations, living inside warm bodies in temperate latitudes. But that situation is irrelevant to Mars exploration. Any analogy addressing possible biological exchange between Earth and Mars must consider the absolute contrast in the planets’ environments.</p>
<p>A more accurate analogy would be bringing 12 Asian tropical parrots to the Venezuelan rainforest. In 10 years we may very likely have an invasion of Asian parrots in South America. But if we bring the same 12 Asian parrots to Antarctica, in 10 hours we’ll have 12 dead parrots.</p>
<p>We’d assume that any indigenous life on Mars should be much better adapted to Martian stresses than Earth life is, and therefore would outcompete any possible terrestrial newcomers. Microorganisms on Earth have evolved to thrive in challenging environments like salt crusts in the Atacama desert or hydrothermal vents on the deep ocean floor. In the same way, we can imagine any potential Martian biosphere would have experienced enormous evolutionary pressure during billions of years to become expert in inhabiting <a href="http://online.liebertpub.com/doi/abs/10.1089/ast.2015.1380">Mars’ today environments</a>. The microorganisms hitchhiking on our spacecraft wouldn’t stand much of a chance against super-specialized Martians in their own territory.</p>
<p>So if Earth life cannot survive and, most importantly, reproduce on Mars, concerns going forward about our spacecraft contaminating Mars with terrestrial organisms are unwarranted. This would be the parrots-in-Antarctica scenario.</p>
<p>On the other hand, perhaps Earth microorganisms can, in fact, survive and create active microbial ecosystems on present-day Mars – the parrots-in-South America scenario. We can then presume that terrestrial microorganisms are already there, carried by any one of the dozens of spacecraft sent from Earth in the last decades, or by the natural exchange of rocks pulled out from one planet by a meteoritic impact and transported to the other. </p>
<p>In this case, protection protocols are overly cautious since contamination is already a fact.</p>
<h2>Technological reasons the protocols don’t make sense</h2>
<p>Another argument to soften planetary protection protocols hinges on the fact that current sterilization methods don’t actually “sterilize” our spacecraft, a feat engineers still don’t know how to accomplish definitively.</p>
<p>The cleaning procedures we use on our robots rely on pretty much the same stresses prevailing on the Martian surface: oxidizing chemicals and radiation. They end up killing only those microorganisms with no chance of surviving on Mars anyway. So current cleaning protocols are essentially conducting an artificial selection experiment, with the result that we carry to Mars only the most hardy microorganisms. This should put into question the whole cleaning procedure.</p>
<p>Further, technology has advanced enough that distinguishing between Earthlings and Martians is no longer a problem. If Martian life is biochemically similar to Earth life, we could sequence genomes of any organisms located. If they don’t match anything we know is on Earth, we can surmise it’s native to Mars. Then we could add Mars’ creatures to the tree of DNA-based life we already know, probably somewhere on its lower branches. And if it is different, we would be able to identify such differences based on its building blocks.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/188023/original/file-20170928-22252-1wes7l6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/188023/original/file-20170928-22252-1wes7l6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/188023/original/file-20170928-22252-1wes7l6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=473&fit=crop&dpr=1 600w, https://images.theconversation.com/files/188023/original/file-20170928-22252-1wes7l6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=473&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/188023/original/file-20170928-22252-1wes7l6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=473&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/188023/original/file-20170928-22252-1wes7l6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=594&fit=crop&dpr=1 754w, https://images.theconversation.com/files/188023/original/file-20170928-22252-1wes7l6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=594&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/188023/original/file-20170928-22252-1wes7l6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=594&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Bacterial species <em>Tersicoccus phoenicis</em> is found in only two places: clean rooms in Florida and South America where spacecraft are assembled for launch.</span>
<span class="attribution"><a class="source" href="https://images.nasa.gov/#/details-PIA17369.html">NASA/JPL-Caltech</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>Mars explorers have yet another technique to help differentiate between Earth and Mars life. The microbes <a href="https://doi.org/10.1089/ast.2012.0906">we know persist in clean spacecraft assembly rooms</a> provide an excellent control with which to monitor potential contamination. Any microorganism found in a Martian sample identical or highly similar to those present in the clean rooms would very likely indicate contamination – not indigenous life on Mars.</p>
<h2>The window is closing</h2>
<p>On top of all these reasons, it’s pointless to split hairs about current planetary protection guidelines as applied to today’s unmanned robots since human explorers are on the horizon. <a href="https://doi.org/10.1016/j.actaastro.2009.08.015">People would inevitably bring microbial hitchhikers with them</a>, because we cannot sterilize humans. Contamination risks between robotic and manned missions are simply not comparable. </p>
<p>Whether the microbes that fly with humans will be able to last on Mars is a separate question – though their survival is probably assured if they stay within a spacesuit or a human habitat engineered to preserve life. But no matter what, they’ll definitely be introduced to the Martian environment. Continuing to delay the astrobiological exploration of Mars now because we don’t want to contaminate the planet with microorganisms hiding in our spacecrafts isn’t logical considering astronauts (and their microbial stowaways) may arrive within two or three decades.</p>
<p>Prior to landing humans on Mars or bringing samples back to Earth, it makes sense to determine whether there is indigenous Martian life. What might robots or astronauts encounter there – and import to Earth? More knowledge now will increase the safety of Earth’s biosphere. After all, we still don’t know if returning samples could endanger humanity and the terrestrial biosphere. Perhaps reverse contamination should be our big concern.</p>
<p>The main goal of Mars exploration should be to try to find life on Mars and address the question of whether it is a separate genesis or shares a common ancestor with life on Earth. In the end, if Mars is lifeless, maybe we are alone in the universe; but if there is or was life on Mars, then there’s a zoo out there.</p><img src="https://counter.theconversation.com/content/84742/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Alberto G. Fairén receives funding from the European Research Council.</span></em></p>Planetary protection protocols try to make sure we don’t seed places like Mars with life from our planet. An astrobiologist argues they’re misguided – especially with human astronauts on the horizon.Alberto G. Fairén, Research Scientist at Centro de Astrobiología, Spain, and Visiting Scientist in Astronomy, Cornell UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/845972017-09-28T19:03:52Z2017-09-28T19:03:52ZDear diary: the Sun never set on the Arctic Mars simulation<figure><img src="https://images.theconversation.com/files/187935/original/file-20170928-3485-mcnipt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Anastasiya (left) and myself working on the Haughton crater rim.</span> <span class="attribution"><span class="source">Mars Society</span>, <span class="license">Author provided</span></span></figcaption></figure><p><em>Jonathan Clarke has just returned from another <a href="https://theconversation.com/dear-diary-another-day-in-the-life-on-mars-75929">mission</a> to simulate life on Mars. This time he was on Devon Island in the Canadian Arctic, where the sun never sets in the northern summer.</em></p>
<p><em>It’s all part of a project to see what some of the challenges are, should humans one day decide to live on Mars. He’s detailed some of the events as they happened across 52 days of his most recent experience.</em></p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/187679/original/file-20170926-3108-1xyhvm8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/187679/original/file-20170926-3108-1xyhvm8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/187679/original/file-20170926-3108-1xyhvm8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/187679/original/file-20170926-3108-1xyhvm8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/187679/original/file-20170926-3108-1xyhvm8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/187679/original/file-20170926-3108-1xyhvm8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/187679/original/file-20170926-3108-1xyhvm8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/187679/original/file-20170926-3108-1xyhvm8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=503&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">The crew outside station. (Left to right) Yusuke Murakami (Japan), Paul Knightly (USA), Anastasiya Stepanova (Russia), Anushree Srivastava (India), Alexandre Mangeot (France), and Jonathan Clarke (Australia).</span>
<span class="attribution"><span class="source">Mars Society</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<h2>Day 16, Sol 1 (A Sol is a Martian day)</h2>
<p>Can’t believe it, after more than two weeks of waiting we are finally here at Devon Island. It looks very alien, very Mars-like in appearance: stark, a visual symphony in brown, orange and grey.</p>
<p>We landed about 2.5km from the Flashline Mars Arctic Research Station (FMARS) habitat, gleaming white on the distant ridge in the evening sunshine. We forded two creeks and climbed the rocky ridge to get there.</p>
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<p>
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Read more:
<a href="https://theconversation.com/the-new-space-race-why-we-need-a-human-mission-to-mars-73757">The new space race: why we need a human mission to Mars</a>
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<p>The habitat was in better condition than we had feared, but there was still some mould and it smelled a bit musty. We opened everything up, and settled into the least grotty rooms and mattresses.</p>
<p>There was lots and lots of junk, lots of tidying to do. I went back with the quad bike and trailer to ferry our stuff back to the habitat while the others began to make the station operational.</p>
<p>Felt odd and exposed by myself in the Arctic. No bears though; maybe carrying a shotgun kept them away. Then went down to the creek with some jerrycans and collected water. By the time we were ready for bed it was 1am. Still bright daylight of course.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/187674/original/file-20170926-10403-rmb44u.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/187674/original/file-20170926-10403-rmb44u.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/187674/original/file-20170926-10403-rmb44u.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/187674/original/file-20170926-10403-rmb44u.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/187674/original/file-20170926-10403-rmb44u.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/187674/original/file-20170926-10403-rmb44u.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/187674/original/file-20170926-10403-rmb44u.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/187674/original/file-20170926-10403-rmb44u.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Unloading the the gear from the aircraft.</span>
<span class="attribution"><span class="source">Jonathan Clarke</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<h2>Sol 6</h2>
<p>Today is July 20, an appropriate day for us to start the main part of our mission, because 41 years ago <a href="https://www.jpl.nasa.gov/missions/viking-1/">Viking 1</a> performed the first successful robotic landing on Mars.</p>
<p>The FMARS habitat is very similar to the <a href="https://theconversation.com/dear-diary-another-day-in-the-life-on-mars-75929">unit in Utah I stayed in previously</a>. It’s a two storey cylinder with two decks; eight metres in diameter and eight metres high. The upper deck has our cabins, galley and wardroom, the lower deck airlocks, lab, workshop, toilets, and shower. There is a small generator that provides us with power.</p>
<p>Going into simulation mode means we will be only going outside while wearing our simulated space suits, with a few exceptions. These include heavy engineering tasks – water management, rubbish burning and so on – and of course shotgun duty, where every outside team is accompanied by an armed lookout. A very non-Martian threat here is the possibility of polar bears.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/187689/original/file-20170926-28228-13v89xx.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/187689/original/file-20170926-28228-13v89xx.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/187689/original/file-20170926-28228-13v89xx.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/187689/original/file-20170926-28228-13v89xx.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/187689/original/file-20170926-28228-13v89xx.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/187689/original/file-20170926-28228-13v89xx.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/187689/original/file-20170926-28228-13v89xx.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/187689/original/file-20170926-28228-13v89xx.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Shotgun duty.</span>
<span class="attribution"><span class="source">Jonathan Clarke</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Nearby is Haughton crater. An asteroid impact 39 million years ago blasted this crater 22km across and hundreds of metres deep. Even though reduced by erosion, it’s still 14km from rim to rim.</p>
<p>Haughton crater is actually similar in size to Endeavour crater on Mars, currently being explored by the <a href="https://mars.jpl.nasa.gov/mer/home/index.html">Mars Opportunity Rover mission</a>.</p>
<p>The FMARS habitat is perched on the northwest rim of the crater, and affords us a spectacular view of the crater with its complex geology, meltwater steams and residual snow patches. From here we can proceed on foot, or quad bike to study the geology and biology of the area, much as we would on Mars.</p>
<p>Anushree and Paul did the first extravehicular activity (EVA) outside the FMARS this afternoon. They went to the snow melt zone below the habitat, with Alex riding shotgun. Paul was checking his environmental monitoring stations he had put in a few days ago. </p>
<p>I spent the day planning future work, setting up spreadsheets, planning excursions. All plans are tentative of course, being so dependent on weather and other factors. This will be less of an issue on Mars of course, as all but the most intense dust storms and solar radiation events will have little impact on day-to-day activities. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/187692/original/file-20170926-19342-llk625.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/187692/original/file-20170926-19342-llk625.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/187692/original/file-20170926-19342-llk625.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/187692/original/file-20170926-19342-llk625.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/187692/original/file-20170926-19342-llk625.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/187692/original/file-20170926-19342-llk625.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/187692/original/file-20170926-19342-llk625.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/187692/original/file-20170926-19342-llk625.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Yusuke (left) and Paul (right) carrying out photographic surveys on polygons in Haughton crater.</span>
<span class="attribution"><span class="source">Jonathan Clarke</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<h2>Sol 13</h2>
<p>When I got up it was foggy and the cloud was low on the ridge, although the crater was more clear. The cloud lifted during the morning, which was good. There was no wind; also good. </p>
<p>Went out on EVA 6 with Anastasiya, and Yusuke as shotgun. Worked southwest along the crater rim from the habitat, and then down across the crater wall looking at some mounds. Lots of issues with helmet fogging though. </p>
<p>On the ridge I was sampling different limestone lithologies. On the crater floor it was a bit boggy in places, so we had to walk on the stones to avoid sinking. This usually worked, although there were some close calls in places. This is not something we will expect on Mars.</p>
<p>In the afternoon I worked on photos, EVA notes and field science, and emails for the family and friends. While we don’t have a specific time delay built into communications, contact with the outside world (except in an emergency) is certainly asynchronous. </p>
<p>The Sun came out this afternoon (hello stranger) but all too briefly. The cloud closed in again soon after. The habitat is now completely fog-bound. A bit like living on Mars during a particularly dense dust storm. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/187687/original/file-20170926-25765-18se4u8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/187687/original/file-20170926-25765-18se4u8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/187687/original/file-20170926-25765-18se4u8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=689&fit=crop&dpr=1 600w, https://images.theconversation.com/files/187687/original/file-20170926-25765-18se4u8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=689&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/187687/original/file-20170926-25765-18se4u8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=689&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/187687/original/file-20170926-25765-18se4u8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=865&fit=crop&dpr=1 754w, https://images.theconversation.com/files/187687/original/file-20170926-25765-18se4u8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=865&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/187687/original/file-20170926-25765-18se4u8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=865&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Anushree looking at samples in the lab.</span>
<span class="attribution"><span class="source">Mars Society</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<h2>Sol 21</h2>
<p>Woke up to a great silence. Looking out the windows (after wiping all the condensation off them) I saw the reason: we were still enveloped in thick fog. Visibility was down to less than 200m, far worse than we would like to have on Mars, even with the worst dust storms. </p>
<p>It stayed like this most of the day. The ground is also very wet, pools of water everywhere, saturated by the recent rain. The depth of soil above the permafrost here is so thin that it does not take much rain to saturate it.</p>
<p>So no EVA again today, which was frustrating. We have lost three EVA days because of bad weather so far. The ground was too wet for trenching, the visibility too poor for driving, and even for 3D imaging, which is the simplest field task. </p>
<p>So we spent the day working inside. Cleaning, rigging lights (or trying to), sorting old food and equipment, writing up notes, doing psychology tests for the <a href="http://www.istc.int/en/institute/9799">Institute for Biomedical Problems</a> in Moscow, and planning for the day when we will be able to do a proper EVA. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/187681/original/file-20170926-25765-1ky6gp0.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/187681/original/file-20170926-25765-1ky6gp0.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/187681/original/file-20170926-25765-1ky6gp0.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/187681/original/file-20170926-25765-1ky6gp0.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/187681/original/file-20170926-25765-1ky6gp0.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/187681/original/file-20170926-25765-1ky6gp0.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/187681/original/file-20170926-25765-1ky6gp0.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/187681/original/file-20170926-25765-1ky6gp0.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Breakfast in the wardroom. Clockwise: Paul, Anastasiya, Alex, Yusuke and Aushree.</span>
<span class="attribution"><span class="source">Jonathan Clarke</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Days like this are a good opportunity to consider the differences between life here and last year at MDRS in Utah. One of the biggest differences is the very limited power situation. We ran the generator for only eight to nine hours a day, so having more than three things on at once (two hot plates and a heater for example) trips the safety switches either in the station or on the generator. </p>
<p>Hopefully on Mars our equipment will be more reliable, with more abundant power, and resets more easily achieved.</p>
<p>At the FMARS though, it is often chilly, damp and even dark on days like this. We also have even more limited internet resources, so the sense of isolation is much greater. </p>
<p>Then of course there is the humidity, condensation, leaks and constant battle with mould that ensues. This can sometimes be a problem on <a href="https://science.nasa.gov/science-news/science-at-nasa/2007/11may_locad3">space stations</a>, so we are not alone in battling this problem.</p>
<p>Sanitation is also somewhat primitive; we pee into a funnel that runs into an outside drum, and we poo into plastic bags that are then incinerated. On Mars solid waste would most likely be incinerated as well (despite what was shown in <a href="http://www.imdb.com/title/tt3659388/">The Martian</a> film), but <a href="https://www.nasa.gov/mission_pages/station/behindscenes/waterrecycler.html">urine would be recycled</a>, as is already done on the International Space Station. </p>
<p>The rest of the crew availed themselves of the shower this evening (after a few of us washed yesterday), so we are all clean and human looking again. Due to the cooler temperatures and higher humidity we don’t get as grotty as we did in Utah. </p>
<h2>Day 48, Sol 32</h2>
<p>We are now out of simulation mode, in preparation for our leaving. In the morning we received email confirmation that the first flight out was midday. I was on the first flight, with the samples and the trash.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/187695/original/file-20170926-10403-e8uwfz.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/187695/original/file-20170926-10403-e8uwfz.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/187695/original/file-20170926-10403-e8uwfz.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/187695/original/file-20170926-10403-e8uwfz.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/187695/original/file-20170926-10403-e8uwfz.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/187695/original/file-20170926-10403-e8uwfz.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/187695/original/file-20170926-10403-e8uwfz.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/187695/original/file-20170926-10403-e8uwfz.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Leaving Devon Island.</span>
<span class="attribution"><span class="source">Jonathan Clarke</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Mixed feelings on leaving – sad to leave Devon Island, the end of an experience I will mostly likely never repeat, satisfaction at a job well done by all of us.</p>
<h2>Day 49 and after</h2>
<p>It’s sad to leave the Arctic, but the changing weather and the start of sunsets tell us it’s time to go.</p>
<p>As we fly out separately there are sad farewells to the rest of the crew. It’s the breaking of the fellowship, and these people over the past year have become like family. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/dear-diary-another-day-in-the-life-on-mars-75929">Dear diary: another day in the life on Mars</a>
</strong>
</em>
</p>
<hr>
<p>As I fly south, it’s strange to see fields again after two months of desolate landscape. I become aware of how humanity has transformed the surface of the Earth, for better and for worse. Maybe that’s one reason some of us want to go to Mars: to find a new world, apply the lessons of the old and perhaps avoid some of the mistakes.</p>
<p>Speaking of lessons, what have I learned about Mars missions, and indeed myself? We have completed our mission despite delays, bad weather, and various other problems, and are a closer and better knit team than when we have started. </p>
<p>Our success has shown, through an operationally realistic analogue mission, that a crew of six can, over 30 days, perform work that on Mars would cover more ground, study more sites and find out more than all the unmanned Mars missions to date.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/187666/original/file-20170926-32444-vvwisv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/187666/original/file-20170926-32444-vvwisv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/187666/original/file-20170926-32444-vvwisv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=454&fit=crop&dpr=1 600w, https://images.theconversation.com/files/187666/original/file-20170926-32444-vvwisv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=454&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/187666/original/file-20170926-32444-vvwisv.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=454&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/187666/original/file-20170926-32444-vvwisv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=570&fit=crop&dpr=1 754w, https://images.theconversation.com/files/187666/original/file-20170926-32444-vvwisv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=570&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/187666/original/file-20170926-32444-vvwisv.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=570&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">A twin otter aircraft flying over the Flashline Mars Arctic Research Station on Devon Island.</span>
<span class="attribution"><span class="source">Mars Society</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure><img src="https://counter.theconversation.com/content/84597/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jonathan Clarke is president of Mars Society Australia (MSA), which has been supported by grants from organisations including CSIRO, Australian Geographic, the WA Royalties for Regions, Tata Motors, Starchaser industries and the Pilbara Development Commission The MSA has also previously partnered with Saber Astronautics and Arkaroola Village in field projects in Arkaroola, South Australia. Jonathan works part time for Swinburne University and is affiliated with the Australian Centre for Astrobiology at UNSW University. The Mars 160 expedition was organised and funded by the Mars Society in the United States.</span></em></p>Will humans ever live on Mars? Whoever it is to get there first will benefit from the experiences of those who stayed in simulated Martian missions here on Earth.Jonathan Clarke, Associate member of the Australian Centre for Astrobiology, UNSW SydneyLicensed as Creative Commons – attribution, no derivatives.