tag:theconversation.com,2011:/uk/topics/extraterrestrial-life-1453/articlesExtraterrestrial life – 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>
<figcaption>
<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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<a href="https://images.theconversation.com/files/579676/original/file-20240304-28-76rhqs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="The Perseverance rover, dusty and dirty, parked in a patch of Martian soil." src="https://images.theconversation.com/files/579676/original/file-20240304-28-76rhqs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/579676/original/file-20240304-28-76rhqs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=551&fit=crop&dpr=1 600w, https://images.theconversation.com/files/579676/original/file-20240304-28-76rhqs.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=551&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/579676/original/file-20240304-28-76rhqs.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=551&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/579676/original/file-20240304-28-76rhqs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=692&fit=crop&dpr=1 754w, https://images.theconversation.com/files/579676/original/file-20240304-28-76rhqs.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=692&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/579676/original/file-20240304-28-76rhqs.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=692&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 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>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/YPNVVDphQVc?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<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/2168532024-02-05T13:30:30Z2024-02-05T13:30:30ZStudying lake deposits in Idaho could give scientists insight into ancient traces of life on Mars<figure><img src="https://images.theconversation.com/files/568753/original/file-20240110-30-i5trcc.JPG?ixlib=rb-1.1.0&rect=23%2C398%2C3128%2C1343&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Scientists have been studying the Clarkia site for nearly five decades.</span> <span class="attribution"><span class="source">Robert Patalano</span></span></figcaption></figure><p>Does life exist elsewhere in the universe? If so, how do scientists search for and identify it? Finding life beyond Earth is extremely difficult, partly because other planets are so far away and partly because we are not sure what to look for.</p>
<p>Yet, astrobiologists have learned a lot about <a href="https://science.nasa.gov/astrobiology/">how to find life</a> in extraterrestrial environments, mainly by studying how and when the early Earth became livable.</p>
<p>While research teams at NASA are <a href="https://mars.nasa.gov/mars2020/mission/overview/">directly combing</a> the surface of Mars for signs of life, our <a href="https://news.bryant.edu/there-life-red-planet-faculty-earns-funding-explore-theory-earth">interdisciplinary research group</a> is <a href="https://news.bryant.edu/mars-mind-bryant-students-earn-funding-nasa-ri-space-grant-consortium">using a site here on Earth</a> to approximate ancient environmental conditions on Mars. </p>
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<a href="https://images.theconversation.com/files/568752/original/file-20240110-18-1v7yda.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A rock face with several blocky layers of rock, in different stripes of color. The top layers are a darker clay, while the bottom layers are a lighter volcanic ash." src="https://images.theconversation.com/files/568752/original/file-20240110-18-1v7yda.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/568752/original/file-20240110-18-1v7yda.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/568752/original/file-20240110-18-1v7yda.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/568752/original/file-20240110-18-1v7yda.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/568752/original/file-20240110-18-1v7yda.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/568752/original/file-20240110-18-1v7yda.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/568752/original/file-20240110-18-1v7yda.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">A close-up view of the Clarkia site where you can see lacustrine clay and volcanic ash layers. This site represents Mars in our work.</span>
<span class="attribution"><span class="source">Taylor Vahey</span></span>
</figcaption>
</figure>
<p>Contained within northern Idaho’s <a href="https://doi.org/10.1130/G48901.1">Clarkia Middle Miocene Fossil Site</a> are sediments that preserve some of Earth’s most diverse biological marker molecules, or <a href="https://doi.org/10.1016/j.epsl.2008.07.012">biomarkers</a>. These are remains of past life that offer glimpses into Earth’s history.</p>
<h2>An ancient lake</h2>
<p>About 16 million years ago, a lava flow in what would one day become Clarkia, Idaho, dammed a local drainage system and created a deep lake in a <a href="https://archive.org/details/latecenozoichist0000unse/page/424/mode/2up">narrow, steep-sided valley</a>. Although the lake has since dried up, weathering, erosion and <a href="https://www.facebook.com/p/Fossil-Bowl-100063724775941/">human activity</a> have exposed sediments of the former lake bed.</p>
<p>For nearly five decades, research teams like ours – being led by <a href="https://www.radcliffe.harvard.edu/people/hong-yang">Dr. Hong Yang</a> and <a href="https://www.bryant.edu/academics/faculty/leng-qin">Dr. Qin Leng</a> – have used <a href="https://doi.org/10.7717/peerj.4880">fossil remains</a> and <a href="https://doi.org/10.1016/0146-6380(95)80001-8">biogeochemistry</a> to reconstruct past environments of the Clarkia Miocene Lake region. </p>
<p>The lake’s depth created the <a href="https://www.jstor.org/stable/1303276">perfect conditions</a> for protecting microbial, plant and animal remains that fell to the lake’s bottom. In fact, the sediments are so well preserved that some of the fossilized leaves still show their autumn colors from when they sank into the water millions of years ago.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/568751/original/file-20240110-15-2y3q3p.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A reddish brown long, thin leaf shown embedded on a piece of smooth sediment." src="https://images.theconversation.com/files/568751/original/file-20240110-15-2y3q3p.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/568751/original/file-20240110-15-2y3q3p.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/568751/original/file-20240110-15-2y3q3p.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/568751/original/file-20240110-15-2y3q3p.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/568751/original/file-20240110-15-2y3q3p.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/568751/original/file-20240110-15-2y3q3p.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/568751/original/file-20240110-15-2y3q3p.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">A fossil magnolia leaf showing fall (reddish) colors. This leaf likely fell off a tree in the fall once the trees paused photosynthesis for the winter and sank to the bottom of the lake, where it was buried. The leaf retained its fall coloring for 16 million years, though once being dug up and exposed to air, it quickly oxidized and lost its color.</span>
<span class="attribution"><span class="source">Robert Patalano</span></span>
</figcaption>
</figure>
<p>Today, ancient lake beds on Earth are becoming <a href="https://doi.org/10.1146/annurev-earth-053018-060332">important settings</a> for learning about habitable environments on other planets. </p>
<h2>Biological marker molecules</h2>
<p>Clarkia’s lake sediments <a href="https://doi.org/10.1016/0146-6380(94)90045-0">contain a suite</a> of ancient biomarkers. These compounds, or classes of compounds, can reveal how organisms and their <a href="https://doi.org/10.1016/j.quascirev.2011.07.009">environments functioned</a> in the past.</p>
<p>Since the discovery of the <a href="https://www.idahogeology.org/pub/Information_Circulars/IC-33.pdf">Clarkia fossil site in 1972</a>, multiple research teams have used various <a href="https://doi.org/10.1016/S0146-6380(02)00212-7">cutting-edge technologies to analyze</a> different biomarkers. </p>
<p>Some of those found at Clarkia <a href="https://doi.org/10.1073/pnas.90.6.2246">include lignin</a>, which is the structural support tissue of plants, <a href="https://doi.org/10.1016/S0146-6380(00)00107-8">lipids like fats and waxes</a>, and possibly <a href="https://doi.org/10.1038/344656a0">DNA and amino acids</a>.</p>
<p>Understanding the origins, history and environmental factors that have allowed these biosignatures to stay so well preserved at Clarkia may also allow our team to predict the potential of organic matter preservation in ancient lake deposits on Mars.</p>
<h2>Studying life signatures on Mars</h2>
<p>In 2021, the <a href="https://mars.nasa.gov/mars2020/">Mars Perseverance Rover</a> landed on top of lake deposits in Mars’ <a href="https://doi.org/10.1126/science.abl4051">Jezero Crater</a>. Jezero is a meteorite impact crater believed to have once been flooded with water and home to an ancient river delta. Microbial life may have lived in Jezero’s crater lake, and their biomarkers might be found in lake bed sediments today. Perseverance has been drilling into the crater’s surface to collect samples that could contain ancient signs of life, with the intent of <a href="https://mars.nasa.gov/msr/#Facts">returning the samples to Earth in 2033</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/547616/original/file-20230911-26-nc2bk5.jpg?ixlib=rb-1.1.0&rect=14%2C7%2C4977%2C2799&q=45&auto=format&w=1000&fit=clip"><img alt="An artist's rendition of the Perseverence rover, made of metal with six small wheels, a camera and a robotic arm." src="https://images.theconversation.com/files/547616/original/file-20230911-26-nc2bk5.jpg?ixlib=rb-1.1.0&rect=14%2C7%2C4977%2C2799&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/547616/original/file-20230911-26-nc2bk5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/547616/original/file-20230911-26-nc2bk5.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/547616/original/file-20230911-26-nc2bk5.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/547616/original/file-20230911-26-nc2bk5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/547616/original/file-20230911-26-nc2bk5.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/547616/original/file-20230911-26-nc2bk5.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">The Perseverance Rover is collecting samples to learn more about Mars’ environment.</span>
<span class="attribution"><a class="source" href="https://newsroom.ap.org/detail/MarsLanding/c835b14b3e6645d7a0cd46558745752b/photo?Query=mars%20rover&mediaType=photo&sortBy=&dateRange=Anytime&totalCount=530&currentItemNo=11&vs=true">NASA/JPL-Caltech via AP</a></span>
</figcaption>
</figure>
<p>Clarkia has many similarities to the Jezero Crater. Both Clarkia and Jezero Crater have ancient <a href="https://doi.org/10.1006/icar.2000.6530">lake deposits</a> derived from silica-rich, <a href="https://doi.org/10.1029/2017JE005478">basaltic rock</a> that formed under <a href="https://doi.org/10.1016/j.gloplacha.2022.103737">a climate with</a> higher temperatures, high humidity and a carbon dioxide-rich atmosphere. </p>
<p>At Clarkia, these conditions preserved microbial biomarkers in the ancient lake. Similar settings could have <a href="https://doi.org/10.1029/2012JE004115">formed lakes</a> on the surface of Mars. </p>
<p>The samples <a href="https://mars.nasa.gov/mars-rock-samples/#23">Perseverance is collecting</a> contain the geologic and climate history of the Jezero Crater landing site and may even contain preserved biomarkers of ancient life.</p>
<p>While Perseverance continues its mission, our group is <a href="https://agu.confex.com/agu/fm23/meetingapp.cgi/Paper/1367388">establishing criteria</a> for biomolecular authentication. That means we are developing ways to figure out whether ancient biomarkers from Earth, and hopefully Mars, are true echoes of life – rather than recent contamination or molecules from nonliving sources.</p>
<p>To do so, we are studying biomarkers from Clarkia’s fossil leaves and sediments and developing laboratory experiments using <a href="https://spaceresourcetech.com/collections/regolith-simulants">Martian simulants</a>. This material simulates the chemical and physical properties of Jezero Crater’s lake sediments.</p>
<p>By deciphering the sources, history and preservation of biomarkers connected with Clarkia’s ancient lake deposits, we hope to develop new strategies for studying the Perseverance Rover samples once they are back on Earth.</p><img src="https://counter.theconversation.com/content/216853/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Robert Patalano receives funding from the NASA Rhode Island Space Grant Program. </span></em></p>While NASA rovers on the surface of Mars look for hints of life, researchers back on Earth are studying ‘echoes of life’ from ancient basins – hoping that the two sites might be similar.Robert Patalano, Lecturer of Biological and Biomedical Sciences, Bryant UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2152192023-11-28T13:39:19Z2023-11-28T13:39:19ZUnwrapping Uranus and its icy secrets: What NASA would learn from a mission to a wild world<figure><img src="https://images.theconversation.com/files/556240/original/file-20231026-17-9wedv8.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C1720%2C1717&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Uranus is the coldest planet in the solar system.</span> <span class="attribution"><a class="source" href="https://science.nasa.gov/image-detail/amf-pia18182/">NASA/JPL</a></span></figcaption></figure><p>Uranus, the <a href="https://science.nasa.gov/uranus/">seventh planet from the Sun</a>, orbits in the outer solar system, about two billion miles (3.2 billion kilometers) from Earth. It is an enormous world – quadruple the diameter of Earth, with 15 times the mass and 63 times the volume. </p>
<p>Unvisited by spacecraft <a href="https://science.nasa.gov/mission/voyager-2/">for more than 35 years</a>, Uranus inhabits one of the least explored regions of <a href="https://science.nasa.gov/solar-system/">our solar system</a>. Although scientists have learned some things about it from telescopic observations and theoretical work since <a href="https://www.nasa.gov/history/35-years-ago-voyager-2-explores-uranus/">the Voyager 2 flyby in 1986</a>, the planet remains an enigma. </p>
<p>It’s easy to divide the solar system into two large groups: an inner zone with four rocky planets and an outer zone with four giant planets. But nature is, as usual, more complicated. Uranus and <a href="https://science.nasa.gov/neptune/">Neptune, the eighth planet from the Sun</a>, are vastly different from the others. Both are ice giants, composed largely of compounds such as water, ice, ammonia and methane; they are places where the average temperature is minus 320 to minus 350 degrees Fahrenheit (minus 212 Celsius). </p>
<p>Through <a href="https://theconversation.com/are-there-any-planets-outside-of-our-solar-system-164062">recent discoveries of exoplanets</a> – worlds outside our solar system that are trillions of miles away – astronomers have learned that ice giants are common throughout the galaxy. They challenge our understanding of planetary formation and evolution. Uranus, comparatively close to us, is our cornerstone for learning about them. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/m4NXbFOiOGk?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">All about Uranus, the unconventional planet.</span></figcaption>
</figure>
<h2>A new mission</h2>
<p>Many in the space community – <a href="https://www.michaelmsori.com/">like me</a> – are urging NASA to launch a robotic spacecraft to explore Uranus. Indeed, the <a href="https://nap.nationalacademies.org/catalog/26522/origins-worlds-and-life-a-decadal-strategy-for-planetary-science">2023 decadal survey of planetary scientists</a> ranked such a journey as the single highest priority for a new <a href="https://nap.nationalacademies.org/read/25146/chapter/11">NASA flagship mission</a>.</p>
<p>This time, the spacecraft would not simply fly by Uranus on its way somewhere else, as <a href="https://science.nasa.gov/mission/voyager-2/">Voyager 2 did</a>. Instead, the probe would spend years orbiting and studying the planet, its 27 moons and its 13 rings. </p>
<p>You may wonder, why send a spacecraft to Uranus and not Neptune. It’s a matter of orbital architecture. Because of the positions of both planets over the next two decades, a spacecraft from Earth will have an <a href="https://science.nasa.gov/learn/basics-of-space-flight/chapter4-1/">easier trajectory to follow</a> to reach Uranus than Neptune. Launched at the right time, the orbiter would arrive at Uranus in about 12 years.</p>
<p>Here are just a few of the basic questions a Uranus orbiter would help answer: What, exactly, is Uranus made of? Why is Uranus <a href="https://www.jpl.nasa.gov/edu/learn/video/dancing-uranus/#:%7E">tilted on its side</a>, with its poles pointed almost directly toward the Sun during summer – which is different from all the other planets in the solar system? What is generating Uranus’ <a href="https://svs.gsfc.nasa.gov/4666/">strange magnetic field</a>, shaped differently than Earth’s and misaligned with the direction the planet spins? How does atmospheric circulation work on an ice giant? What do the answers to all these questions tell us about how ice giants form? </p>
<p>Notwithstanding the progress scientists have made on these and other questions since the Voyager 2 flyby, there’s no substitute for direct, close-up and repeated observations from an orbiting spacecraft.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/558199/original/file-20231108-19-szzl9z.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="An illustration of the blue-green planet Uranus, as seen from the cratered surface of one of its moons." src="https://images.theconversation.com/files/558199/original/file-20231108-19-szzl9z.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/558199/original/file-20231108-19-szzl9z.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=333&fit=crop&dpr=1 600w, https://images.theconversation.com/files/558199/original/file-20231108-19-szzl9z.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=333&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/558199/original/file-20231108-19-szzl9z.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=333&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/558199/original/file-20231108-19-szzl9z.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=419&fit=crop&dpr=1 754w, https://images.theconversation.com/files/558199/original/file-20231108-19-szzl9z.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=419&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/558199/original/file-20231108-19-szzl9z.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=419&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 concept of Uranus, as seen from the surface of Ariel, one of its moons.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/illustration/uranus-seen-from-ariel-illustration-royalty-free-illustration/1088373686?phrase=Uranus&adppopup=true">Mark Garlick/Science Photo Laboratory via Getty Images</a></span>
</figcaption>
</figure>
<h2>The rings and those moons</h2>
<p>The rings around Uranus, probably made of dirty ice, are thinner and darker than those around Saturn. A Uranus orbiter would look for “ripples” in them, akin to waves on a lake. Finding them would let scientists use the rings <a href="https://www.youtube.com/watch?v=geNiqkgZDXA">as a giant seismometer</a> to help us learn about <a href="https://science.nasa.gov/uranus/facts/">the interior of Uranus</a>, one of its great secrets. </p>
<p>The moons, mostly named after literary characters from the writings of Shakespeare and Pope, are primarily made of frozen mixes of ice and rock. Five of the moons are particularly compelling. <a href="https://science.nasa.gov/uranus/moons/">Miranda, Ariel, Umbriel, Titania and Oberon</a> are all big enough to be spherical and treated as miniature worlds in their own right. </p>
<p>During its flyby, Voyager 2 <a href="https://doi.org/10.1126/science.233.4759.43">took low-resolution images</a> of the moons’ southern hemispheres. (Their northern hemispheres, still unseen, remain one of the major unexplored frontiers of our solar system.) Those images include photos of <a href="https://eos.org/features/cryovolcanisms-song-of-ice-and-fire">ice volcanoes on Ariel</a> – a tantalizing hint of past geological and tectonic activity and, possibly, subsurface water. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/558139/original/file-20231107-271094-y9msr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A black and white photo of a pockmarked moon of Uranus." src="https://images.theconversation.com/files/558139/original/file-20231107-271094-y9msr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/558139/original/file-20231107-271094-y9msr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=603&fit=crop&dpr=1 600w, https://images.theconversation.com/files/558139/original/file-20231107-271094-y9msr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=603&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/558139/original/file-20231107-271094-y9msr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=603&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/558139/original/file-20231107-271094-y9msr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=758&fit=crop&dpr=1 754w, https://images.theconversation.com/files/558139/original/file-20231107-271094-y9msr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=758&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/558139/original/file-20231107-271094-y9msr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=758&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 cratered world of varied landscapes, Miranda is a Uranus moon that might be an ocean world.</span>
<span class="attribution"><a class="source" href="https://photojournal.jpl.nasa.gov/catalog/PIA18185">NASA/JPL-Caltech</a></span>
</figcaption>
</figure>
<h2>The possibility of oceans and life</h2>
<p>Which leads to one of the most exciting parts of the mission: Many planetary scientists theorize that Ariel, and perhaps most or all of the other five moons, may be an <a href="https://www.nasa.gov/specials/ocean-worlds/">ocean world</a> harboring large, underground bodies of liquid water miles beneath the solid, icy surface. Finding out whether any of the moons have oceans is one of the major goals of the mission. </p>
<p>This is one reason why an orbiter would probably carry a <a href="https://svs.gsfc.nasa.gov/10682/">magnetometer</a> – to detect the electromagnetic interactions of an underground ocean as one of its moons <a href="https://doi.org/10.1029/2021GL094758">travels through Uranus’ magnetic field</a>. Instruments to measure the moons’ gravitational fields and cameras to study their surface geology would help, too.</p>
<p>Liquid water is an essential requirement for life as we know it. If oceans are detected, scientists will then want to look for other ingredients for life on the moons – <a href="https://astrobiology.nasa.gov/education/primer/">such as energy, nutrients and organic matter</a>. </p>
<h2>Not a done deal</h2>
<p>No launch date has been set for the mission, and there’s not yet an official go-ahead from NASA on its funding. The cost would probably be more than a billion dollars. </p>
<p>One critical factor to consider: The cosmos operates on its own timetable, and those spacecraft trajectories to Uranus will change over the years as the planets move along their orbits. Ideally, NASA would launch a mission in 2031 or 2032 to maximize trajectory convenience and minimize travel time. That time span is less than it may seem; it takes years of planning – and years more of constructing the spacecraft – to be ready for launch. That’s why the time is now to start the process and fund a mission to this fascinating world.</p><img src="https://counter.theconversation.com/content/215219/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Mike Sori receives funding from NASA. </span></em></p>Five of the Uranus moons might be ocean worlds − and if there’s water, there might be life.Mike Sori, Assistant Professor of Planetary Science, Purdue UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2160372023-10-20T15:24:19Z2023-10-20T15:24:19ZCarl Sagan detected life on Earth 30 years ago – here’s how his experiment is helping us search for alien species today<figure><img src="https://images.theconversation.com/files/554817/original/file-20231019-24-ktzu5b.jpeg?ixlib=rb-1.1.0&rect=0%2C88%2C494%2C415&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Earth and Moon as seen by the Galileo spacecraft from a distance of 6 million km away.</span> <span class="attribution"><span class="source">NASA</span></span></figcaption></figure><p>It’s been 30 years since a group of scientists led by <a href="https://science.nasa.gov/people/carl-sagan/">Carl Sagan</a> found <a href="https://www.nature.com/articles/365715a0">evidence</a> for life on Earth using data from instruments on board the Nasa <a href="https://science.nasa.gov/mission/galileo/">Galileo</a> robotic spacecraft. Yes, you read that correctly. Among his many pearls of wisdom, Sagan was famous for saying that science is more than a body of knowledge – it is a way of thinking.</p>
<p>In other words, how humans go about the business of discovering new knowledge is at least as important as the knowledge itself. In this vein, the study was an example of a “control experiment” – a critical part of the scientific method. This can involve asking whether a given study or method of analysis is capable of finding evidence for something we already know. </p>
<p>Suppose one were to fly past Earth in an alien spacecraft with the same instruments on board as Galileo had. If we knew nothing else about Earth, would we be able to unambiguously detect life here, using nothing but these instruments (which wouldn’t be optimised to find it)? If not, what would that say about our ability to detect life anywhere else? </p>
<p>Galileo launched in October 1989 on a six-year flight to Jupiter. However, Galileo had to first make several orbits of the inner Solar System, making close flybys of Earth and Venus, in order to pick up enough speed to reach Jupiter. </p>
<p>In the mid-2000s, scientists took samples of dirt from the Mars-like environment of Chile’s Atacama desert on Earth, which is <a href="https://new.nsf.gov/news/microbes-mars">known to contain</a> microbial life. They then used similar experiments as those used on the NASA Viking spacecraft (which aimed to detect life on Mars when they landed there in the <a href="https://www.nasa.gov/history/45-years-ago-viking-1-touches-down-on-mars/">1970s</a>) to see if life could be found in Atacama. </p>
<p>They failed – the implication being that had the Viking spacecraft landed on Earth in the Atacama Desert, and performed the same experiments as they did on Mars, they might well have <a href="https://www.space.com/3038-martian-life-evaded-detection-viking-landers.html">missed</a> signatures for life, even though it is known to be present. </p>
<h2>Galileo results</h2>
<p>Galileo was kitted out with a variety of instruments designed to study the atmosphere and space environment of Jupiter and its moons. These included imaging cameras, spectrometers (which break down light by wavelength) and a radio experiment.</p>
<p>Importantly, the authors of the study did not presume any characteristics of life on Earth <em>ab initio</em> (from the beginning), but attempted to derive their conclusions just from the data. The near infra-red mapping spectrometer (NIMS) instrument detected gaseous water distributed throughout the terrestrial atmosphere, ice at the poles and large expanses of liquid water “of oceanic dimensions”. It also recorded temperatures ranging from -30°C to +18°C. </p>
<figure class="align-center ">
<img alt="Image taken by the Galileo spacecraft at a distance of 2.4 million km." src="https://images.theconversation.com/files/554815/original/file-20231019-29-7ie95h.jpeg?ixlib=rb-1.1.0&rect=0%2C0%2C498%2C498&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/554815/original/file-20231019-29-7ie95h.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/554815/original/file-20231019-29-7ie95h.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/554815/original/file-20231019-29-7ie95h.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/554815/original/file-20231019-29-7ie95h.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/554815/original/file-20231019-29-7ie95h.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/554815/original/file-20231019-29-7ie95h.jpeg?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">
<figcaption>
<span class="caption">Can you see us? Galileo image.</span>
<span class="attribution"><span class="source">NASA</span></span>
</figcaption>
</figure>
<p>Evidence for life? Not yet. The study concluded that the detection of liquid water and a water weather system was a <a href="https://math.stackexchange.com/questions/1110111/necessary-but-not-sufficient-in-logic">necessary, but not sufficient</a> argument. </p>
<p>NIMS also detected high concentrations of oxygen and methane in the Earth’s atmosphere, as compared to other known planets. Both of these are highly reactive gases that would rapidly react with other chemicals and dissipate in a short period of time. The only way for such concentrations of these species to be upheld were if they were continuously replenished by some means – again suggesting, but not proving, life. Other instruments on the spacecraft detected the presence of an ozone layer, shielding the surface from damaging UV radiation from the Sun. </p>
<p>One might imagine that a simple look through the camera might be enough to spot life. But the images showed oceans, deserts, clouds, ice and darker regions in South America which, only with prior knowledge, we know of course to be rain forests. However, once combined with more spectrometry, a distinct absorption of red light was found to overlay the darker regions, which the study concluded was “strongly suggestive” of light being absorbed by photosynthetic plant life. No minerals were known to absorb light in exactly this fashion. </p>
<p>The highest resolution images taken, as dictated by the flyby geometry, were of the deserts of central Australia and the ice sheets of Antarctica. Hence none of the images taken showed cities or clear examples of agriculture. The spacecraft also flew by the planet at closest approach during the daytime, so lights from cities at night were not visible either. </p>
<p>Of greater interest though was Galileo’s <a href="https://pds-ppi.igpp.ucla.edu/data/GO-A-PWS-2-REFDR-GSAFULL-V1.0/DOCUMENT/PWS/PWS.PDF">plasma wave radio experiment</a>. The cosmos is full of natural radio emission, however most of it is broadband. That is to say, the emission from a given natural source occurs across many frequencies. Artificial radio sources, by contrast, are produced in a narrow band: an everyday example is the meticulous tuning of an analogue radio required to find a station amidst the static.</p>
<p>An example of natural radio emission from aurora in Saturn’s atmosphere can be heard below. The frequency changes rapidly – unlike a radio station.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/6nxLXvqLp50?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
</figure>
<p>Galileo detected consistent narrowband radio emission from Earth at fixed frequencies. The study concluded this could only have come from a technological civilisation, and would only be detectable within the last century. If our alien spacecraft had made the same flyby of Earth at any time in the few billion years prior to the 20th century then it would have seen no definitive evidence of a civilisation on Earth at all. </p>
<p>It is perhaps no surprise then that, as yet, no evidence for extra-terrestrial life has been found. Even a spacecraft flying within a few thousand kilometres of human civilisation on Earth is not guaranteed to detect it. Control experiments like this are therefore critical in informing the search for life elsewhere. </p>
<p>In the present era, humanity has now discovered over 5,000 planets around other stars, and we have even detected the presence of water <a href="https://www.nature.com/articles/s41550-019-0878-9">in the atmospheres</a> of some planets. Sagan’s experiment shows this is not enough by itself.</p>
<p>A strong case for life elsewhere will likely require a combination of mutually supporting evidence, such as light absorption by photosynthesis-like processes, narrowband radio emission, modest temperatures and weather and chemical traces in the atmosphere which are hard to explain by non-biological means. As we move into the era of instruments such as the <a href="https://webb.nasa.gov/">James Webb space telescope</a>, Sagan’s experiment remains as informative now as it was 30 years ago.</p><img src="https://counter.theconversation.com/content/216037/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Gareth Dorrian 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>Control experiments are critical in informing the search for alien life.Gareth Dorrian, Post Doctoral Research Fellow in Space Science, University of BirminghamLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2102762023-09-19T20:08:34Z2023-09-19T20:08:34ZChariots of the gods, ships in the sky: how unidentified aerial phenomena left their mark in ancient cultures<figure><img src="https://images.theconversation.com/files/544716/original/file-20230825-21-dja0ah.jpg?ixlib=rb-1.1.0&rect=7%2C7%2C1191%2C842&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Hanns Glaser, Celestial phenomenon over Nuremberg, April 1561.</span> <span class="attribution"><a class="source" href="https://uzb.swisscovery.slsp.ch/discovery/delivery/41SLSP_UZB:UZB/12464136840005508?lang=en">Zentralbibliothek Zürich</a></span></figcaption></figure><p>For thousands of years, people have been describing unexplainable gleaming objects in the sky.</p>
<p>Some aerial phenomena like comets, meteor showers, <a href="https://www.sciencedirect.com/topics/earth-and-planetary-sciences/bolide">bolides</a>, auroras or even earthquake lightning – all easily explained by today’s knowledge – were widely reported in the ancient world. </p>
<p>The US Congress is <a href="https://time.com/6298287/congress-ufo-hearing/">currently investigating</a> unidentified aerial phenomena (UAPs – what you <a href="https://www.smithsonianmag.com/air-space-magazine/ufos-uapswhatever-we-call-them-why-do-we-assume-mysterious-flying-objects-are-extraterrestrial-180978374/">might think of</a> as UFOs), in the wake of previously classified footage of UAPs being leaked and a former intelligence official alleging the US government possesses “off world” technologies. </p>
<p>Meanwhile, a recent NASA report concluded there is <a href="https://theconversation.com/nasa-report-finds-no-evidence-that-ufos-are-extraterrestrial-213528">no evidence</a> suggesting UAPs are of extraterrestrial origin.</p>
<p>Ancient writers saw these phenomena as signs of social unease and impending disaster. In this way, modern reactions to UAPs are similar to those of thousands of years ago. There is a long history of strange objects in the sky associated with political and military crises.</p>
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Read more:
<a href="https://theconversation.com/nasa-report-finds-no-evidence-that-ufos-are-extraterrestrial-213528">NASA report finds no evidence that UFOs are extraterrestrial</a>
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<hr>
<h2>Ancient signs of trouble</h2>
<p>In the Bible, the <a href="https://www.thetorah.com/article/ezekiels-vision-of-god-and-the-chariot">prophet Ezekiel</a> mentioned a divine chariot: it glowed like hot metal in a fire and Ezekiel could see four living beings in it. They <a href="https://www.biblegateway.com/passage/?search=Ezekiel%201%3A4-28&version=KJV">looked</a> human-like, though they had four faces and four wings.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/544705/original/file-20230825-2806-9j4ds9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/544705/original/file-20230825-2806-9j4ds9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/544705/original/file-20230825-2806-9j4ds9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=437&fit=crop&dpr=1 600w, https://images.theconversation.com/files/544705/original/file-20230825-2806-9j4ds9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=437&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/544705/original/file-20230825-2806-9j4ds9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=437&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/544705/original/file-20230825-2806-9j4ds9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=549&fit=crop&dpr=1 754w, https://images.theconversation.com/files/544705/original/file-20230825-2806-9j4ds9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=549&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/544705/original/file-20230825-2806-9j4ds9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=549&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 Battista Fontana, The Vision of Ezekiel, 1579.</span>
<span class="attribution"><a class="source" href="https://www.nga.gov/collection/art-object-page.162874.html">The National Gallery of Art</a></span>
</figcaption>
</figure>
<p>The <em>vimāna</em> – the flying chariots of the gods – also appear in ancient Indian epics, including the <a href="https://www.sacred-texts.com/hin/dutt/">Mahābhārata and the Rāmāyana</a>. </p>
<p>In Hindu myths, the gods were portrayed as riding these chariots to every corner of the universe.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/544708/original/file-20230825-22-hxy74b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/544708/original/file-20230825-22-hxy74b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/544708/original/file-20230825-22-hxy74b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=747&fit=crop&dpr=1 600w, https://images.theconversation.com/files/544708/original/file-20230825-22-hxy74b.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=747&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/544708/original/file-20230825-22-hxy74b.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=747&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/544708/original/file-20230825-22-hxy74b.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=939&fit=crop&dpr=1 754w, https://images.theconversation.com/files/544708/original/file-20230825-22-hxy74b.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=939&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/544708/original/file-20230825-22-hxy74b.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=939&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Krishna and Rukmini as Groom and Bride in a Celestial Chariot Driven by Ganesha, India, Rajasthan, Bundi, 1675-1700.</span>
<span class="attribution"><a class="source" href="https://collections.lacma.org/node/240545">Los Angeles County Museum of Art</a></span>
</figcaption>
</figure>
<p>Describing portents of the winter of 218 BC, the Roman historian <a href="https://www.perseus.tufts.edu/hopper/text?doc=Liv.%2021.62&lang=original">Livy said</a> a “spectacle of ships gleamed in the sky”. The Second Punic War had begun, and the enemy general Hannibal was on the verge of a series of victories. </p>
<p>Maybe these “ships” in the sky were odd cloud formations, but Livy’s choice of words suggests something “shining” or “gleaming” – qualities even today associated with UAPs. </p>
<p>Livy reports another appearance of ships in the sky in 173 BC, when a “great fleet” allegedly appeared. In the spring of 217 BC, with Hannibal still threatening Rome, Livy says “round shields were seen in the sky” over central Italy. </p>
<p>Livy doesn’t say if these objects gleamed like the “ships” seen the previous year, but the “shields” recall the appearance of “flying saucers”, the type of UAP that came to prominence at the height of the <a href="https://www.perseus.tufts.edu/hopper/text?doc=Liv.%2021.62&lang=original">Cold War</a>. </p>
<p>Another curious classical UAP is recorded by the Greek writer <a href="https://penelope.uchicago.edu/Thayer/E/Roman/Texts/Plutarch/Lives/Lucullus*.html">Plutarch in his Life of Lucullus</a>, a Roman general. Lucullus’ forces were about to fight King Mithridates VI of Pontus when a strange object appeared between the two armies:</p>
<blockquote>
<p>suddenly, the sky burst asunder, and a huge, flame-like body was seen to fall between the two armies. In shape, it was most like a wine-jar (<em>pithos</em>), and in colour, like molten silver. Both sides were astonished at the sight, and separated.</p>
</blockquote>
<p>That the object was described as a <em>pithos</em>, a vessel which has a specific shape, suggests something more than a flashing light. Some have <a href="http://www.perseus.tufts.edu/hopper/text?doc=Plut.+Luc.+8.6&fromdoc=Perseus%3Atext%3A2008.01.0046">interpreted this</a> as a meteor, but Plutarch’s focus on its shiny metallic nature does not match this possibility. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/544727/original/file-20230825-21-lhyfct.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A UFO shines down on Jesus" src="https://images.theconversation.com/files/544727/original/file-20230825-21-lhyfct.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/544727/original/file-20230825-21-lhyfct.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=786&fit=crop&dpr=1 600w, https://images.theconversation.com/files/544727/original/file-20230825-21-lhyfct.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=786&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/544727/original/file-20230825-21-lhyfct.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=786&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/544727/original/file-20230825-21-lhyfct.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=988&fit=crop&dpr=1 754w, https://images.theconversation.com/files/544727/original/file-20230825-21-lhyfct.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=988&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/544727/original/file-20230825-21-lhyfct.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=988&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Arent de Gelder (1645–1727), The Baptism of Christ.</span>
<span class="attribution"><a class="source" href="https://data.fitzmuseum.cam.ac.uk/id/object/1418">The Fitzwilliam Museum</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span>
</figcaption>
</figure>
<p>Whatever it was, both armies thought it was a bad omen and withdrew. </p>
<p>Roman-Jewish historian <a href="https://www.gutenberg.org/files/2850/2850-h/2850-h.htm">Josephus</a>, writing about war between Roman and Jewish forces, records an aerial battle between UAPs in AD 65. Before sunset, “chariots” were seen in the sky, accompanied by “armed battalions hurtling through the clouds”. </p>
<p>Josephus says numerous eyewitnesses saw it and believed it foretold the Roman victory that followed.</p>
<h2>From ancient to modern doomsdays</h2>
<p>Saint Paul referred to God’s “shield of faith” in his <a href="https://www.biblegateway.com/passage/?search=Ephesians%201&version=KJV">Letter to the Ephesians</a>, while “ships voyaging in the sky” were a common theme in medieval Ireland, symbolising the safety the “ship” of the Church <a href="https://journals.lib.unb.ca/index.php/MCR/article/view/17808/22180">afforded believers</a>. </p>
<p>Reports of unusual phenomena increased at the turn of <a href="https://www.jstor.org/stable/2887426">every millennium</a>, when Christian people feared or hoped for the Judgement Day predicted in the <a href="https://www.biblegateway.com/passage/?search=Revelation%201&version=KJV">Book of Revelation</a> in the Bible.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/548724/original/file-20230918-29-4f2kzo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/548724/original/file-20230918-29-4f2kzo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/548724/original/file-20230918-29-4f2kzo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=921&fit=crop&dpr=1 600w, https://images.theconversation.com/files/548724/original/file-20230918-29-4f2kzo.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=921&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/548724/original/file-20230918-29-4f2kzo.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=921&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/548724/original/file-20230918-29-4f2kzo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1157&fit=crop&dpr=1 754w, https://images.theconversation.com/files/548724/original/file-20230918-29-4f2kzo.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1157&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/548724/original/file-20230918-29-4f2kzo.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1157&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 King and His Retinue Confronting Ladies under a Celestial Battle, French, c. 1600.</span>
<span class="attribution"><a class="source" href="https://www.nga.gov/collection/art-object-page.62648.html">The National Gallery of Art</a></span>
</figcaption>
</figure>
<p><a href="https://academic.oup.com/book/27558/chapter-abstract/197560297?redirectedFrom=fulltext">Millennial ufology</a> is a fascinating development of recent Christian predictions of the end of the world, where the Messiah poses as a space traveller who returns to save us from Satanic aliens. </p>
<p>Millions of adults every year report experiences with UAPs: when interviewed about their experiences, some admit they are religious; others insist they are not. Importantly, ufology may well be a way of reconciling religion with science, <a href="https://www.jstor.org/stable/24458392">an approach many find appealing</a>. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/548729/original/file-20230918-27027-zzsqlo.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/548729/original/file-20230918-27027-zzsqlo.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/548729/original/file-20230918-27027-zzsqlo.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/548729/original/file-20230918-27027-zzsqlo.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/548729/original/file-20230918-27027-zzsqlo.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/548729/original/file-20230918-27027-zzsqlo.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=425&fit=crop&dpr=1 754w, https://images.theconversation.com/files/548729/original/file-20230918-27027-zzsqlo.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=425&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/548729/original/file-20230918-27027-zzsqlo.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=425&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 unclassified sketch of a UAP from the CIA.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:CIA_annotated_drawing_-_dark_grey_solid_looking_UFO.webp">National Archives/Wikimedia Commons</a></span>
</figcaption>
</figure>
<p>We will never know what the objects and lights described by ancient texts were, and whether they were real or the result of psychological stress. At the very least, significant ancient sightings of UAPs almost always speak to conditions of anxiety and imminent change. </p>
<p>UAPs – ancient and modern – confirm our need to project our crises to objects in the skies. </p>
<p>Ancient people did not have the <a href="https://thebulletin.org/2023/01/press-release-doomsday-clock-set-at-90-seconds-to-midnight/">Doomsday Clock</a> to warn them how close the end was, but they watched the skies carefully and found plenty of warning up there. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/is-there-evidence-aliens-have-visited-earth-heres-whats-come-out-of-us-congress-hearings-on-unidentified-aerial-phenomena-183443">Is there evidence aliens have visited Earth? Here's what's come out of US congress hearings on 'unidentified aerial phenomena'</a>
</strong>
</em>
</p>
<hr>
<img src="https://counter.theconversation.com/content/210276/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Eva Anagnostou-Laoutides receives funding from the Australian Research Council, Discovery Project: Crises of Leadership in the Eastern Roman Empire, 250-1000 CE.</span></em></p><p class="fine-print"><em><span>nothing to disclose </span></em></p><p class="fine-print"><em><span>Michael B. Charles 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>Modern reactions to unidentified aerial phenomena (UAPs – what you might think of as UFOs) are similar to those of thousands of years ago.Michael B. Charles, Associate Professor, Management Discipline, Faculty of Business, Arts and Law, Southern Cross UniversityEva Anagnostou-Laoutides, Associate Professor in Ancient History, Australian Research Council Future Fellow, Macquarie UniversityMarcus Harmes, Professor in Pathways Education, University of Southern QueenslandLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2136152023-09-19T15:08:14Z2023-09-19T15:08:14ZUFOs: how Nasa plans to get to the bottom of unexplained sightings<figure><img src="https://images.theconversation.com/files/548386/original/file-20230914-29-c7oo4l.jpg?ixlib=rb-1.1.0&rect=8%2C17%2C5982%2C3350&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-photo/ufo-concept-glowing-orbs-floating-above-1978082291">Raggedstone / Shutterstock</a></span></figcaption></figure><p>As reports continue flying in about what were traditionally called UFOs (unidentified flying objects), Nasa is taking the topic very seriously. In fact, following the publication of a report from an independent committee of experts in fields including astronomy and aviation safety, the agency has even appointed a new director of unidentified anomalous phenomena (UAP) research. </p>
<p>UAP is the term Nasa now uses for UFOs. <a href="https://science.nasa.gov/uap/">The committee was directed</a> to gather reports of UAPs and try to understand what these mysterious events really are, including answering the question of whether or not they could be extraterrestrial in origin. </p>
<p>The committee held a press conference <a href="https://theconversation.com/ufos-what-well-learn-from-the-nasa-panel-investigating-sightings-207328">back in May</a>, when it provided an update on its work up to that point. The study team outlined some of the common explanations for UAP sightings – which includes boats low on the horizon and high-flying balloons – as well as how many events remained truly unexplained. </p>
<p>Now, the committee has published the full report into what it has found, including recommendations for Nasa as its work continues. That report, which also contains Nasa’s response and plan as it moves forward, <a href="https://science.nasa.gov/science-pink/s3fs-public/atoms/files/UAP%20Independent%20Study%20Team%20-%20Final%20Report_0.pdf">can be read in full here</a>. I’ve also <a href="https://youtu.be/hUtH1r3o7VA">created a video</a> about the findings. </p>
<p>The report makes clear that, so far, the committee has absolutely no evidence that any of the reported UAP events have any involvement from aliens. But for the reports that are still unexplained by terrestrial phenomena or aircraft, the team doesn’t rule anything out. It makes it clear that an extraterrestrial origin is unlikely, but that it has no evidence at all for what these sightings are. </p>
<p>The rest of the report deals with how Nasa should respond to the findings, and what it plans to do to continue this research in future. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/ufos-what-well-learn-from-the-nasa-panel-investigating-sightings-207328">UFOs: what we'll learn from the Nasa panel investigating sightings</a>
</strong>
</em>
</p>
<hr>
<h2>Need for transparency</h2>
<p>The most substantial response has been the appointment of the director of UAP research – a brand new role. Initially, when announcing this, Nasa refused to name the person in the role. It hoped to shield the new UAP director from the kind of harassment that some members of the committee have received for their involvement in the research.</p>
<p>However, the space agency also pledged to be completely transparent about the work on UAPs and everything it finds. This philosophy seems to have prevailed, and Nasa later announced that the <a href="https://www.space.com/nasa-names-head-of-uap-research">new director would be Mark McInerney</a>, a previous Nasa liaison to the US Department of Defense. </p>
<figure class="align-center ">
<img alt="Representation of UFOs." src="https://images.theconversation.com/files/548382/original/file-20230914-17-54dkao.jpg?ixlib=rb-1.1.0&rect=940%2C407%2C2982%2C1754&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/548382/original/file-20230914-17-54dkao.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/548382/original/file-20230914-17-54dkao.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/548382/original/file-20230914-17-54dkao.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/548382/original/file-20230914-17-54dkao.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/548382/original/file-20230914-17-54dkao.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/548382/original/file-20230914-17-54dkao.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">A representation of UFOs.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/amazing-fantastic-background-extraterrestrial-aliens-spaceship-1461851036">IgorZH / Shutterstock</a></span>
</figcaption>
</figure>
<p>Nasa also put forward the idea of developing a smartphone app to aid with the future reporting of UAPs. While there are hundreds of sightings available for study by the committee, one persistent problem it has faced is <a href="https://www.nbcnews.com/science/ufos-and-aerial-phenomena/nasa-ufo-unidentified-aerial-phenomena-panel-hearing-rcna87034">poor data and images</a>.</p>
<p>Nasa hopes to combat this issue for future reports by using the billions of high-tech detectors around the world that most people carry everywhere. Smartphones can collect a lot of high quality information, starting with photos and videos, but they can also gather data on <a href="https://gizmodo.com/all-the-sensors-in-your-smartphone-and-how-they-work-1797121002">gravity, magnetic fields, locations and more</a>. If the general public were open to the idea, Nasa would like to one day allow people to report sightings directly from their phones to the agency. </p>
<p>Another interesting revelation in the report is the prominence that Nasa believes artificial intelligence (AI) and machine learning could have as this work continues. Looking for patterns in the UAP reports – such as geographical reporting hotspots – could hold the key to finally understanding the causes of some of the events that remain mysterious.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/hUtH1r3o7VA?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Chris Pattison explains the findings of the Nasa report on UAPs.</span></figcaption>
</figure>
<p>Pattern spotting is something that humans are very good at, but sometimes the common thread is so subtle and unexpected that people can’t spot it. Luckily, AI is getting better and more powerful, and pattern spotting is <a href="https://www.forbes.com/sites/cognitiveworld/2020/05/09/understanding-the-recognition-pattern-of-ai/">one of the things it excels at</a>. This raises the interesting possibility that AI could be essential in one day identifying the first evidence for extraterrestrial life visiting Earth. It’s not likely that we’ll identify aliens, but Nasa isn’t ruling it out. </p>
<p>The week that this report was released turned out to be a busy week for discussions about aliens. In Mexico, a journalist named Jaime Maussan <a href="https://www.theguardian.com/world/2023/sep/13/mexican-senate-hearing-ufos">presented alleged “mummified aliens”</a> to the country’s Congress that he claimed had been found in Peru. </p>
<p>He said the specimens contained non-human DNA, but this has <a href="https://www.bbc.co.uk/news/av/world-66853551">not yet been independently verified</a>. In fact, <a href="https://www.independent.co.uk/news/world/americas/aliens-mexico-congress-ufos-b2412522.html">much doubt</a> has been cast <a href="https://www.wired.com/story/mexico-congress-aliens-fake/">over the authenticity</a> of these corpses.</p>
<p>In both cases, the world must wait longer to get more concrete evidence. As more reports are collected by Nasa, it might be possible to get more clarity on what these strange objects are. And if independent testing of the Mexico specimens takes place, there might be a conclusion to this claim too.</p><img src="https://counter.theconversation.com/content/213615/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Christopher Pattison 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 space agency hopes to get to the bottom of the many sightings being reported.Christopher Pattison, Researcher at the Institute of Cosmology and Gravitation, University of PortsmouthLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2135282023-09-15T17:36:07Z2023-09-15T17:36:07ZNASA report finds no evidence that UFOs are extraterrestrial<figure><img src="https://images.theconversation.com/files/548453/original/file-20230915-27-9mccw0.jpg?ixlib=rb-1.1.0&rect=7%2C14%2C4690%2C2810&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">NASA's UAP study team and newly appointed director of UAP research represent growing efforts to study and declassify UFO-related data. </span> <span class="attribution"><a class="source" href="https://newsroom.ap.org/detail/f277d5676ab5460186317c9f8fd11427?ext=true">AP Photo/Terry Renn</a></span></figcaption></figure><p>NASA’s <a href="https://www.nasa.gov/feature/nasa-announces-unidentified-anomalous-phenomena-study-team-members/">independent study team</a> released its highly anticipated <a href="https://science.nasa.gov/science-pink/s3fs-public/atoms/files/UAP%20Independent%20Study%20Team%20-%20Final%20Report_0.pdf">report</a> on UFOs on Sept. 14, 2023. </p>
<p>In part to move beyond the <a href="https://www.politico.com/news/2022/05/17/pentagon-dod-ufos-00032929">stigma often attached to UFOs</a>, where military pilots fear ridicule or job sanctions if they report them, UFOs are now characterized by the U.S. government as UAPs, or unidentified anomalous phenomena.</p>
<p>Bottom line: The study team found no evidence that reported UAP observations are extraterrestrial.</p>
<p>I’m a <a href="https://www.as.arizona.edu/people/faculty/chris-impey">professor of astronomy</a> who has written extensively on <a href="https://www.cambridge.org/core/books/living-cosmos/11D69005D09D25581AE4E6684EC8A3C1">astrobiology</a> and the <a href="https://www.cambridge.org/core/books/talking-about-life/696F47F802931AE9021CA72083313579">scientists</a> who search for life in the universe. I have long been <a href="https://theconversation.com/im-an-astronomer-and-i-think-aliens-may-be-out-there-but-ufo-sightings-arent-persuasive-150498">skeptical of the claim</a> that UFOs represent visits by aliens to Earth.</p>
<h2>From sensationalism to science</h2>
<p>During a <a href="https://uk.sports.yahoo.com/video/nasa-announces-findings-ufo-report-160301583.html">press briefing</a>, NASA Administrator <a href="https://www.nasa.gov/feature/nasa-administrator-bill-nelson/">Bill Nelson</a> noted that NASA has scientific programs to search for <a href="https://mars.nasa.gov/msr/">traces of life on Mars</a> and the <a href="https://theconversation.com/to-search-for-alien-life-astronomers-will-look-for-clues-in-the-atmospheres-of-distant-planets-and-the-james-webb-space-telescope-just-proved-its-possible-to-do-so-184828">imprints of biology</a> in the atmospheres of exoplanets. He said he wanted to shift the UAP conversation from sensationalism to one of science.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1702321823692832843"}"></div></p>
<p>With this statement, Nelson was alluding to some of the more outlandish claims about UAPs and UFOs. At a <a href="https://theconversation.com/whistleblower-calls-for-government-transparency-as-congress-digs-for-the-truth-about-ufos-210435">congressional hearing in July</a>, former Pentagon intelligence officer <a href="https://www.space.com/us-hiding-evidence-alien-intelligence-ufo-whistleblower-claims">David Grusch testified</a> that the American government has been hiding evidence of crashed UAPs and alien biological specimens. <a href="https://www.politico.com/news/2023/07/28/pentagon-ufo-boss-congress-hearing-00108822">Sean Kirkpatrick</a>, head of the Pentagon office charged with investigating UAPs, has denied these claims.</p>
<p>And the same week NASA’s report came out, <a href="https://www.reuters.com/world/americas/mexican-congress-holds-hearing-ufos-featuring-purported-alien-bodies-2023-09-13/">Mexican lawmakers</a> were shown by journalist Jaime Maussan two tiny, 1,000-year-old bodies that he claimed were the remains of “non-human” beings. Scientists have called this <a href="https://www.livescience.com/62045-alien-mummies-explained.html">claim fraudulent</a> and say the mummies may have been looted from gravesites in Peru. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/ZAW1l5Q1e9c?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">A controversial journalist presented the Mexican government with 1,000-year-old bodies that he claimed were aliens.</span></figcaption>
</figure>
<h2>Conclusions from the report</h2>
<p>The NASA study team report sheds little light on whether some UAPs are extraterrestrial. In his comments, the chair of the study team, astronomer <a href="https://www.astro.princeton.edu/%7Edns/">David Spergel</a> stated that the team had seen “no evidence to suggest that UAPs are extraterrestrial in origin.” </p>
<p>Of the more than 800 unclassified sightings collected by the Department of Defense’s <a href="https://www.defense.gov/News/Releases/Release/Article/3100053/dod-announces-the-establishment-of-the-all-domain-anomaly-resolution-office/">All-domain Anomaly Resolution Office</a> and reported at the NASA panel’s <a href="https://interestingengineering.com/science/nasas-quest-for-unidentified-anomalies-among-ufos">first public meeting</a> back in May 2023, only “a small handful cannot be immediately identified as known human-made or natural phenomena,” according to <a href="https://science.nasa.gov/science-pink/s3fs-public/atoms/files/UAP%20Independent%20Study%20Team%20-%20Final%20Report_0.pdf">the report</a>. </p>
<p>Many of the <a href="https://www.nytimes.com/2022/10/28/us/politics/ufo-military-reports.html">recent sightings</a> can be attributed to weather balloons and airborne clutter. Historically, <a href="http://www.ianridpath.com/ufo/astroufo1.html">most UFOs are astronomical objects</a> such as meteors, <a href="https://cneos.jpl.nasa.gov/fireballs/intro.html">fireballs</a> and <a href="https://www.jsonline.com/story/news/local/2023/03/02/venus-and-jupiter-appeared-close-sparking-concern-of-ufos-or-aliens/69963097007/">the planet Venus</a>. </p>
<p>Some sightings represent <a href="https://www.nytimes.com/2022/10/28/us/politics/ufo-military-reports.html">surveillance operations</a> by foreign powers, which is why the U.S. military considers this <a href="https://theconversation.com/whistleblower-calls-for-government-transparency-as-congress-digs-for-the-truth-about-ufos-210435">a national security issue</a>.</p>
<p>The report does offer recommendations to NASA on how to move these investigations forward.</p>
<p>Most of the UAP data considered by the study team comes from U.S. military aircraft. Analysis of this data is “hampered by poor sensor calibration, the lack of multiple measurements, the lack of sensor metadata, and the lack of baseline data.” The ideal set of measurements would include optical imaging, infrared imaging, and radar data, but very few reports have all these.</p>
<p>The NASA study team described in the report the types of data that can shed more light on UAPs. The authors note the importance of reducing the stigma that can cause both military and commercial pilots to feel that they cannot freely report sightings. The stigma stems from decades of <a href="https://theconversation.com/are-we-alone-the-question-is-worthy-of-serious-scientific-study-98843">conspiracy theories tied to UFOs</a>. </p>
<p>The NASA study team suggests gathering sightings by commercial pilots using the Federal Aviation Administration and combining these with classified sightings not included in the report. Team members did not have security clearance, so they could look only at the subset of military sightings that were unclassified. At the moment, there is no anonymous nationwide UAP reporting mechanism for commercial pilots.</p>
<p>With access to these classified sightings and a structured mechanism for commercial pilots to report sightings, the <a href="https://www.aaro.mil/">All-domain Anomaly Resolution Office</a> – the military office charged with leading the analysis effort – could have the most data. </p>
<p><a href="https://www.nasa.gov/press-release/update-nasa-shares-uap-independent-study-report-names-director">NASA also announced</a> the appointment of a new director of research on UAPs. This position will oversee the creation of a database with resources to evaluate UAP sightings. </p>
<h2>Looking for a needle in a haystack</h2>
<p>Parts of the briefing resembled a primer on the scientific method. Using analogies, officials described the analysis process as looking for a needle in a haystack, or separating the wheat from the chaff. The officials said they needed a consistent and rigorous methodology for characterizing sightings, as a way of homing in on something truly anomalous.</p>
<p>Spergel said the study team’s goal was to characterize the hay – or the mundane phenomena – and subtract it to find the needle, or the potentially exciting discovery. He noted that artificial intelligence can help researchers comb through massive datasets to find rare, anomalous phenomena. AI is already being used this way in <a href="https://theconversation.com/ai-is-helping-astronomers-make-new-discoveries-and-learn-about-the-universe-faster-than-ever-before-204351">many areas of astronomy research</a>.</p>
<p>The speakers noted the importance of transparency. Transparency is important because UFOs have long been associated with <a href="https://www.nytimes.com/2021/06/24/us/politics/ufo-report-us-pentagon.html">conspiracy theories and government cover-ups</a>. Similarly, much of the discussion during the congressional <a href="https://www.cnn.com/2023/07/26/politics/ufo-house-hearing-congress/index.html">UAP hearing</a> in July focused on a need for transparency. All scientific data that NASA gathers is made public on various websites, and officials said they intend to do the same with the nonclassified UAP data. </p>
<p>At the <a href="https://uk.sports.yahoo.com/video/nasa-announces-findings-ufo-report-160301583.html">beginning of the briefing</a>, Nelson gave his opinion that there were perhaps a trillion instances of life beyond Earth. So, it’s plausible that there is intelligent life out there. But the report says that when it comes to UAPs, extraterrestrial life must be the hypothesis of last resort. It quotes Thomas Jefferson: “Extraordinary claims require extraordinary evidence.” That evidence does not yet exist.</p><img src="https://counter.theconversation.com/content/213528/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Chris Impey receives funding from the National Science Foundation.</span></em></p>Months after a military officer made sensational claims about unexplained objects in the skies, NASA released a report loosely outlining a scientific approach for analyzing UAP reports.Chris Impey, University Distinguished Professor of Astronomy, University of ArizonaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2133942023-09-13T13:57:15Z2023-09-13T13:57:15ZPossible hints of life found on distant planet – how excited should we be?<figure><img src="https://images.theconversation.com/files/547762/original/file-20230912-19-lzosd4.jpeg?ixlib=rb-1.1.0&rect=5%2C0%2C3811%2C2160&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The exoplanet K2-18b might host a water ocean.</span> <span class="attribution"><a class="source" href="https://www.nasa.gov/goddard/2023/webb-discovers-methane-carbon-dioxide-in-atmosphere-of-k2-18b">Credits: Illustration: NASA, CSA, ESA, J. Olmsted (STScI), Science: N. Madhusudhan (Cambridge University)</a></span></figcaption></figure><p>Data from the <a href="https://webb.nasa.gov/">James Webb Space Telescope</a> (JWST) has shown that an exoplanet around a star in the constellation Leo has some of the chemical markers that, on Earth, are associated with living organisms. But these are vague indications. So how likely is it that this exoplanet harbours alien life?</p>
<p>Exoplanets are worlds that orbit stars other than the Sun. The planet in question is named <a href="http://www.exoplanetkyoto.org/exohtml/K2-18.html">K2-18b</a>. It’s so named because it was the first planet found to orbit the red dwarf star K2-18. There is a K2-18c as well – the second planet to be discovered. The star itself is dimmer and cooler than the Sun, meaning that, to get the same level of light as we do on Earth, the planet would need to be much closer to its star than we are. </p>
<p>The system is roughly 124 light years away, which is close in astronomical terms. So what are conditions like on this exoplanet? This is a difficult question to answer. We have telescopes and techniques powerful enough to tell us what the star is like, and how far away the exoplanet is, but we can’t capture direct images of the planet. We can work out a few basics, however. </p>
<p>Working out how much light hits K2-18b is important for assessing the planet’s potential for life. K2-18b orbits closer to its star than Earth does: it’s at roughly 16% of the distance from Earth to the Sun. Another measurement we need is the star’s power output: the total amount of energy it radiates per second. K2-18’s power output is 2.3% that of the Sun. </p>
<p>Using geometry, we can work out that K2-18b receives about 1.22 kilowatts (kW) in solar power per square metre. <a href="https://www.sws.bom.gov.au/Educational/2/1/12">This is similar</a> to the 1.36 kW of incoming light we receive on Earth. Although there’s less energy coming from K2-18, it evens out because the planet is closer. So far, so good. However, the incoming light calculation doesn’t take into account clouds or how reflective the planet’s surface is.</p>
<figure class="align-center ">
<img alt="JWST" src="https://images.theconversation.com/files/548036/original/file-20230913-19-odwob3.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/548036/original/file-20230913-19-odwob3.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/548036/original/file-20230913-19-odwob3.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/548036/original/file-20230913-19-odwob3.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/548036/original/file-20230913-19-odwob3.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/548036/original/file-20230913-19-odwob3.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/548036/original/file-20230913-19-odwob3.jpeg?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">
<figcaption>
<span class="caption">Artist’s impression of the James Webb Space Telescope (JWST).</span>
<span class="attribution"><a class="source" href="https://www.nasa.gov/feature/ames/webb">NASA</a></span>
</figcaption>
</figure>
<p>When we consider life on other planets, a popular term to use is the <a href="https://exoplanets.nasa.gov/search-for-life/habitable-zone/">habitable zone</a>, which means that at an average surface temperature, water will be in a liquid state – as this condition is considered essential for life. In 2019, the Hubble Space Telescope determined that K2-18b showed signs of <a href="https://www.nature.com/articles/s41550-019-0878-9#change-history">water vapour</a>, suggesting that liquid water would be present on the surface. It is currently thought that there are large oceans on the planet.</p>
<p>This caused a ripple of excitement at the time, but without further evidence it was just an interesting result. Now we have reports that JWST has identified carbon dioxide, methane and – possibly – the compound dimethyl sulfide (DMS) <a href="https://www.nasa.gov/goddard/2023/webb-discovers-methane-carbon-dioxide-in-atmosphere-of-k2-18b">in the atmosphere</a>. The tentative detection of DMS is significant because it is only produced on Earth by <a href="https://www.sciencedirect.com/topics/agricultural-and-biological-sciences/dimethyl-sulfide">algae</a>. We currently know of no way it can be naturally produced without a life-form.</p>
<h2>Is there life on K2-18b?</h2>
<p>All these indications seem to suggest that K2-18b might be the place to go to find alien life. It is not quite as simple as that, though, as we have no idea how accurate the results are. The method used to determine what is in the atmosphere of an exoplanet involves light from a different source (usually a star or galaxy) passing through the edge of the atmosphere that is then observed by us. Any chemical compounds will <a href="https://webbtelescope.org/contents/media/images/01FEE26XVSM851DHPVCE1KB4S2">absorb light in specific wavelengths</a> which can then be identified. </p>
<p>Imagine it as looking at a light bulb through a glass tumbler. You can see through it perfectly when empty. If you fill it with water, you can still see through pretty well, but there are some optical effects and colouration, which are the equivalent of hydrogen and dust clouds in space. Now imagine you poured in red food dye – this might be the equivalent of the main chemical constituent in a planet’s atmosphere. </p>
<p>But most atmospheres are made up of many chemicals. The equivalent of looking for any one of them would be like pouring 50 – likely many more – coloured food dyes, in different amounts, into your tumbler and trying to identify how much of one particular colour is present. It is an incredibly difficult task with plenty of room for subjective assessment and errors. In addition, the light going through the atmosphere contains a signal of the star’s chemical constituents – further complicating the analysis.</p>
<figure class="align-center ">
<img alt="Atmospheric composition of K2-18 b." src="https://images.theconversation.com/files/547763/original/file-20230912-17-ds12z4.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/547763/original/file-20230912-17-ds12z4.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/547763/original/file-20230912-17-ds12z4.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/547763/original/file-20230912-17-ds12z4.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/547763/original/file-20230912-17-ds12z4.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/547763/original/file-20230912-17-ds12z4.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/547763/original/file-20230912-17-ds12z4.png?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 chemical composition of K2-18b’s atmosphere.</span>
<span class="attribution"><a class="source" href="https://www.nasa.gov/goddard/2023/webb-discovers-methane-carbon-dioxide-in-atmosphere-of-k2-18b">Credits: Illustration: NASA, CSA, ESA, R. Crawford (STScI), J. Olmsted (STScI), Science: N. Madhusudhan (Cambridge University)</a></span>
</figcaption>
</figure>
<p>Only a few years ago there was a surge of interest in <a href="https://www.nytimes.com/2020/09/14/science/venus-life-clouds.html">whether life existed on Venus</a>, as observations had indicated the presence of phosphine gas, which can be produced by microbes. </p>
<p>However, this finding was later successfully refuted by <a href="https://arxiv.org/pdf/2010.09761.pdf">several studies</a>. If there can be confusion about what is in the atmosphere of a planet that’s just next door, in astronomical terms, it’s easy to see why analysing a planet that’s many times further away is a difficult task.</p>
<h2>What can we take from this?</h2>
<p>The chances of life on exoplanet K2-18b are low but not impossible. These results will likely not change anybody’s opinions or beliefs about extraterrestrial life. Instead, they do demonstrate the advancing ability to look into worlds that are not our own and find more information. </p>
<figure class="align-center ">
<img alt="Rho Ophiuchi" src="https://images.theconversation.com/files/548021/original/file-20230913-21-su4cro.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/548021/original/file-20230913-21-su4cro.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=562&fit=crop&dpr=1 600w, https://images.theconversation.com/files/548021/original/file-20230913-21-su4cro.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=562&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/548021/original/file-20230913-21-su4cro.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=562&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/548021/original/file-20230913-21-su4cro.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=706&fit=crop&dpr=1 754w, https://images.theconversation.com/files/548021/original/file-20230913-21-su4cro.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=706&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/548021/original/file-20230913-21-su4cro.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=706&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">JWST image of Rho Ophiuchi, the closest star-forming region to Earth.</span>
<span class="attribution"><a class="source" href="https://webbtelescope.org/contents/media/images/2023/128/01H449193V5Q4Q6GFBKXAZ3S03?news=true">NASA, ESA, CSA, STScI, Klaus Pontoppidan (STScI)</a></span>
</figcaption>
</figure>
<p>The power of JWST is not only in producing incredible pictures, but in providing <a href="https://webbtelescope.org/contents/news-releases/2023/news-2023-103.html">more detailed</a> and accurate data on celestial objects themselves. Knowing which exoplanets host water and which do not could provide information on how the Earth formed. </p>
<p>Studying the atmospheres of gas giant exoplanets can inform the study of similar worlds in the Solar System, such as Jupiter and Saturn. And identifying levels of CO2 indicates how an extreme greenhouse effect might affect a planet. This is the real power of studying the composition of planetary atmospheres.</p><img src="https://counter.theconversation.com/content/213394/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Ian Whittaker 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 results are intriguing, but analysing the atmospheres of exoplanets is no easy task.Ian Whittaker, Senior Lecturer in Physics, Nottingham Trent UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2131042023-09-11T15:42:17Z2023-09-11T15:42:17ZHow to prove you’ve discovered alien life – new research<figure><img src="https://images.theconversation.com/files/547466/original/file-20230911-28-wkdmi6.jpeg?ixlib=rb-1.1.0&rect=0%2C0%2C498%2C498&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">In 2021, scientists thought they had discovered phosphine in the clouds of Venus.</span> <span class="attribution"><a class="source" href="https://photojournal.jpl.nasa.gov/catalog/PIA00270">NASA</a></span></figcaption></figure><p>In the past few decades, <a href="https://www.businessinsider.com/times-scientists-thought-they-discovered-extraterrestrial-alien-life-signs-2023-2?r=US&IR=T">several phenomena</a> have led to excited speculation in the scientific community that they might indeed be indications that there is extraterrestrial life. It will no doubt happen again. </p>
<p>Recently, two very different examples sparked excitement. In 2017, it was the mystery interstellar object <a href="https://theconversation.com/evidence-of-aliens-what-to-make-of-research-and-reporting-on-oumuamua-our-visitor-from-space-106711">‘Oumuamua</a>. And in 2021, it was the <a href="https://theconversation.com/venus-could-it-really-harbour-life-new-study-springs-a-surprise-145981">possible discovery of the gas phosphine</a> in the clouds of Venus.</p>
<p>In both cases, it seemed possible that the phenomenon indicated some kind of extraterrestrial biological source. Notably, physicist Avi Loeb from Harvard University <a href="https://theconversation.com/has-earth-been-visited-by-an-alien-spaceship-harvard-professor-avi-loeb-vs-everybody-else-155509">argued in favour</a> of the oddly shaped ‘Oumuamua being an alien spaceship. </p>
<p>And phosphine in the atmosphere of a rocky planet is <a href="https://www.liebertpub.com/doi/full/10.1089/ast.2018.1954">proposed to be</a> a strong signature for life, as it is continuously produced by microbes on Earth. </p>
<p>These are just two of the latest cases of a long list of examples of such initially promising phenomena. But although a few of the examples are still controversial, most have turned out to have other explanations (it wasn’t aliens).</p>
<p>So how can we be sure we’ve come to the right conclusion for something as subtle as the presence of a certain gas or a strange looking space rock? In our new paper <a href="https://www.liebertpub.com/doi/abs/10.1089/ast.2022.0084">published in the journal Astrobiology</a>, we have proposed a technique for reliably evaluating such evidence. </p>
<p>The word “possible” is strange, with a rather unfortunate degree of flexibility. There’s a sense in which it is possible that I’ll meet King Charles III today, but at the same time it is extraordinarily unlikely. </p>
<p>Many shouts of: “It might be aliens!” should be interpreted in this (strained) sense. By contrast, we often use the word “might” to express something that has high probability, as in “it might snow today.”</p>
<p>The concept of possibility incorporates these extremes, and everything in-between. Newspapers might capitalise on this flexibility with a cheeky headline that appears to indicate that something is a bit more exciting than it actually is. But the scientific world needs to express itself with rigour, transparently conveying the degree of confidence justified by the evidence.</p>
<p>Some would turn to <a href="https://theconversation.com/ufos-how-to-calculate-the-odds-that-an-alien-spaceship-has-been-spotted-162269">Bayes’ Theorem</a>, a common statistical formula, which gives the probability (Pr) of something, given some evidence. </p>
<p>One could, optimistically, input the available evidence into the Bayes formula, and achieve as output a number between 0 and 1 (where 0.5 is a 50:50 chance that a signal is produced by aliens). But the Bayesian approach doesn’t really help when it comes to extraterrestrial life. </p>
<figure class="align-center ">
<img alt="Image of the Bayesian formula." src="https://images.theconversation.com/files/404772/original/file-20210607-23-2oywyc.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/404772/original/file-20210607-23-2oywyc.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=79&fit=crop&dpr=1 600w, https://images.theconversation.com/files/404772/original/file-20210607-23-2oywyc.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=79&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/404772/original/file-20210607-23-2oywyc.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=79&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/404772/original/file-20210607-23-2oywyc.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=100&fit=crop&dpr=1 754w, https://images.theconversation.com/files/404772/original/file-20210607-23-2oywyc.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=100&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/404772/original/file-20210607-23-2oywyc.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=100&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The Bayesian formula for alien evidence, produced by Anders Sandberg, University of Oxford.</span>
<span class="attribution"><span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>For example, it requires an input for the prior probability that aliens exist. And intuitions about that vary dramatically (estimates for the number of inhabited planets in our galaxy <a href="https://www.forbes.com/sites/jamiecartereurope/2021/06/23/there-is-only-one-other-planet-in-our-galaxy-that-could-be-earth-like-say-scientists/">range from one to billions</a>). </p>
<p>It also requires a value for the probability of the phenomenon in question occurring naturally – not caused by aliens. For some kinds of “biosignatures” (such as a dinosaur skeleton) we know that the probability of it occurring without life is incredibly low. But for many others (say, a particular blend of gases) we don’t know much at all. </p>
<figure class="align-center ">
<img alt="Diagram of how much possibility space we have explored." src="https://images.theconversation.com/files/546969/original/file-20230907-20-2t155l.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/546969/original/file-20230907-20-2t155l.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=310&fit=crop&dpr=1 600w, https://images.theconversation.com/files/546969/original/file-20230907-20-2t155l.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=310&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/546969/original/file-20230907-20-2t155l.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=310&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/546969/original/file-20230907-20-2t155l.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=389&fit=crop&dpr=1 754w, https://images.theconversation.com/files/546969/original/file-20230907-20-2t155l.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=389&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/546969/original/file-20230907-20-2t155l.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=389&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">How much of the relevant possibility space have we explored?</span>
<span class="attribution"><span class="source">Peter Vickers</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>Here one meets with <a href="https://global.oup.com/academic/product/exceeding-our-grasp-9780195174083?cc=gb&lang=en&">the problem of “unconceived alternatives”</a>. Put simply: we may know too little about alternative sources of the phenomenon. Perhaps we just haven’t explored the space of possible causes of the relevant phenomenon very much. </p>
<p>After all, humans have only carried out a limited amount of rigorous research – we don’t know about every single process that could produce a certain gas in an atmosphere.</p>
<h2>New approaches</h2>
<p>In 2021, a Nasa-affiliated group <a href="https://www.nature.com/articles/s41586-021-03804-9.epdf?sharing_token=aMvAzNSKTDpeQ_Lx50lBO9RgN0jAjWel9jnR3ZoTv0OiHZ7kRMaxJS4ikXfsEfuhWNXQC4W7SsC52JCjUDnSSqLC5BhXbWxxUcFJQ3KnlmY6LAuQF02dgmfPAEQqFuQhHT7iq8uOqnhGqUWJGAFWKU9xwVrg8ofZtBSQm0hNMoQ%3D">published a paper</a> setting out the Confidence of Life Detection (CoLD) framework, designed to solve this problem.</p>
<p>It recommends seven steps to verifying a discovery, from ruling out contamination to getting follow-up observations of a predicted biological signal in the same region.</p>
<p>Unfortunately, the problem of unconceived alternatives remains a serious challenge. Level 4 in the framework requires that “all known non-biological sources of signal” are shown to be implausible. But this only starts to mean something when the relevant space of different possibilities has been thoroughly explored. </p>
<p>Our new paper, published by the group <a href="https://www.durham.ac.uk/research/institutes-and-centres/humanities-engaging-science-society/research/eurica-project-leverhulme/">Exploring Uncertainty and Risk in Contemporary Astrobiology</a> (EURiCA), has come up with another proposal.</p>
<p>Or, rather, it is an idea borrowed from another context. For many years, it has been imperative for the Intergovernmental Panel on Climate Change (IPCC) to be clear on how confident they are concerning a great many propositions about climate change. </p>
<p>In order to express their degree of confidence, <a href="https://www.ipcc.ch/site/assets/uploads/2017/08/AR5_Uncertainty_Guidance_Note.pdf">a framework has been in place</a> for more than 20 years now, which combines the quantity and quality of the evidence with the degree to which experts agree (the degree of consensus, if any). While this has been robustly challenged, it has stood the test of time in the face of extraordinary scrutiny and the highest possible stakes. </p>
<p>This same framework could be used in the context of discovering extraterrestrial life. A dedicated team of experts would make a judgement based not only on their assessment of the scientific evidence (X-axis in image above), but also the extent of agreement across the community (Y-axis). </p>
<p>So the worst assessment would have low agreement among experts and limited evidence while the best would have high agreement and robust evidence. </p>
<p>What of unconceived alternatives? The community of experts will only agree that purported evidence for life is “robust” if the relevant possibilities have been thoroughly explored. If they haven’t, there’s a good chance some other explanation will turn up in the long run. </p>
<p>Astrobiologists mustn’t limit their research to the study of the signatures of life. They must also carefully investigate the possible ways that non-biological processes might mimic those same signatures. </p>
<p>Only when we know that, might we finally be able to say, “This time, it really could be aliens.”</p><img src="https://counter.theconversation.com/content/213104/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Peter Vickers receives funding from Leverhulme Trust Research Project Grant (RPG-2021-274).</span></em></p><p class="fine-print"><em><span>Sean McMahon receives funding from Leverhulme Trust Research Project Grant (RPG-2021-274) and the Royal Society of Edinburgh grant #1918.</span></em></p>Alien hunters should learn from the Intergovernmental Panel on Climate Change (IPCC).Peter Vickers, Professor in Philosophy of Science, Durham UniversitySean McMahon, Chancellor's Fellow in Astrobiology, The University of EdinburghLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2109552023-08-04T12:30:01Z2023-08-04T12:30:01ZAre we alone in the universe? 4 essential reads on potential contact with aliens<figure><img src="https://images.theconversation.com/files/541095/original/file-20230803-27-wa23kr.jpg?ixlib=rb-1.1.0&rect=39%2C0%2C8694%2C5617&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">UFOs usually have non-extraterrestrial origins, but many have urged the government to be more transparent about UFO data. </span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/long-exposure-of-andromeda-galaxy-royalty-free-image/1455373371?phrase=space&adppopup=true">Westend61/Westend61 via Getty Images</a></span></figcaption></figure><p>The House subcommittee on National Security, the Border, and Foreign Affairs <a href="https://www.c-span.org/video/?529499-1/hearing-unidentified-aerial-phenomena">met in July 2023 to discuss</a> affairs so foreign that they may not even be of this world. During the meeting, several military officers testified that unidentified anomalous phenomena – the government’s name for UFOs – <a href="https://theconversation.com/whistleblower-calls-for-government-transparency-as-congress-digs-for-the-truth-about-ufos-210435">pose a threat</a> to national security. </p>
<p>Their testimony may have <a href="https://theconversation.com/whistleblower-calls-for-government-transparency-as-congress-digs-for-the-truth-about-ufos-210435">raised eyebrows in the chamber</a>, but there’s still no public physical evidence of extraterrestrial life. In fact, most UFO sightings <a href="https://theconversation.com/why-people-tend-to-believe-ufos-are-extraterrestrial-208403">have earthly explanations</a>, from tricks of the light to weather balloons. </p>
<p>Whether or not these testimonials hold any grains of truth, some scholars argue that simply by listening for signs of extraterrestrials, we’re already <a href="https://theconversation.com/first-contact-with-aliens-could-end-in-colonization-and-genocide-if-we-dont-learn-from-history-207793">engaging in the first phase of contact</a> with alien life. </p>
<p>These four articles from our archives dive into what went down during the subcommittee hearing, why perceived UFO sightings usually have human explanations, and how humanity can learn from history when it comes to engaging with extraterrestrials. </p>
<h2>1. Whistleblower allegations</h2>
<p>The most interesting testimony of the July 26 subcommittee hearing came from ex-Air Force Intelligence Officer David Grusch, who <a href="https://oversight.house.gov/wp-content/uploads/2023/07/Dave_G_HOC_Speech_FINAL_For_Trans.pdf">claimed that</a> the U.S. has nonhuman biological material recovered from a UFO crash site. The Pentagon has <a href="https://abcnews.go.com/Politics/house-oversight-plans-ufo-hearing-after-unconfirmed-claims/story?id=99899883">denied this claim</a>, and it has <a href="https://abcnews.go.com/Politics/house-oversight-plans-ufo-hearing-after-unconfirmed-claims/story?id=99899883">denied the existence of any program</a> designed to retrieve and reverse-engineer crashed UFOs. </p>
<p>All witnesses at the hearing advocated for more government transparency around reports of UFOs. Intelligence agencies and the Pentagon currently steward this data, most of which <a href="https://www.newsnationnow.com/space/ufo/pentagon-blocks-lawmakers-ufo-data-uap-hearing/">is not public</a>. While having access to more data may help understand what’s going on, as the University of Arizona’s <a href="https://scholar.google.com/citations?user=OrRLRQ4AAAAJ&hl=en">Chris Impey</a> put it, “the gold standard is physical evidence.”</p>
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Read more:
<a href="https://theconversation.com/whistleblower-calls-for-government-transparency-as-congress-digs-for-the-truth-about-ufos-210435">Whistleblower calls for government transparency as Congress digs for the truth about UFOs</a>
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<h2>2. Sociological explanations</h2>
<p>Again, while no physical evidence has been made public, anyone surfing the internet can see plenty of alleged UFO videos, photos and stories. <a href="https://scholar.google.com/citations?user=ZEQu09wAAAAJ&hl=en">Barry Markovsky</a>, from the University of South Carolina, is a sociologist of shared beliefs and misconceptions who explained why UFOs seem to <a href="https://theconversation.com/why-people-tend-to-believe-ufos-are-extraterrestrial-208403">captivate the public</a> every few years.</p>
<p>People want explanations <a href="https://thedecisionlab.com/biases/ambiguity-effect">for ambiguous situations</a>, and they’re easily influenced by others. Social media enables a concept called <a href="https://doi.org/10.31269/triplec.v3i2.21">bottom-up social diffusion</a>. Say one user posts a blurry video claiming it depicts a UFO. It’s easy for that user’s network to see and repost the video and so on, until it goes viral. Then, when organized institutions like news outlets or government sources publish UFO-related information, that’s called <a href="https://doi.org/10.31269/triplec.v3i2.21">top-down social diffusion</a>. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/536695/original/file-20230710-15-14kf6i.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Two circle-and-line graphics, the left showing several circles connected to one another with lines, while the right shows one circle at the top connecting several other circles" src="https://images.theconversation.com/files/536695/original/file-20230710-15-14kf6i.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/536695/original/file-20230710-15-14kf6i.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=284&fit=crop&dpr=1 600w, https://images.theconversation.com/files/536695/original/file-20230710-15-14kf6i.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=284&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/536695/original/file-20230710-15-14kf6i.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=284&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/536695/original/file-20230710-15-14kf6i.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=357&fit=crop&dpr=1 754w, https://images.theconversation.com/files/536695/original/file-20230710-15-14kf6i.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=357&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/536695/original/file-20230710-15-14kf6i.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=357&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 left image shows bottom-up diffusion, in which information spreads from person to person. The right shows top-down diffusion, in which information spreads from one authority.</span>
<span class="attribution"><span class="source">Barry Markovsky</span></span>
</figcaption>
</figure>
<p>“Diffusion processes can combine into self-reinforcing loops. Mass media spreads UFO content and piques worldwide interest in UFOs. More people aim their cameras at the skies, creating more opportunities to capture and share odd-looking content,” Markovsky wrote. “Poorly documented UFO pics and videos spread on social media, leading media outlets to grab and republish the most intriguing. Whistleblowers emerge periodically, fanning the flames with claims of secret evidence.”</p>
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Read more:
<a href="https://theconversation.com/why-people-tend-to-believe-ufos-are-extraterrestrial-208403">Why people tend to believe UFOs are extraterrestrial</a>
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<h2>3. Signature detection</h2>
<p>While UFOs might have traction on social media, it’s likely that the first trace of extraterrestrial life won’t come from a crashed alien spaceship. Instead, scientists could potentially <a href="https://theconversation.com/signatures-of-alien-technology-could-be-how-humanity-first-finds-extraterrestrial-life-191054">pick up signals</a> like radio waves or pollution from some distant galaxy that might indicate extraterrestrial technology. </p>
<p>The <a href="https://www.seti.org/">Search for Extraterrestrial Intelligence</a> is a group of scientists all working on the search for extraterrestrial life. Part of what they do is listen for these “<a href="https://doi.org/10.1017/S1473550419000284">technosignatures</a>”.</p>
<p>As two astronomers who work on the Search for Extraterrestrial Intelligence, Penn State’s <a href="https://sites.psu.edu/macyhuston/">Macy Huston</a> and <a href="https://sites.psu.edu/astrowright/">Jason Wright</a> wrote about how humans often <a href="https://www.doi.org/10.1126/science.199.4327.377">unintentionally broadcast signals</a> like radio waves into space. In theory, extraterrestrial civilizations could be doing the same thing – and if scientists can pick up on these signals, they might have their first hints at alien life. </p>
<p>“However, this approach assumes that extraterrestrial civilizations <a href="https://www.universetoday.com/149513/beyond-fermis-paradox-xvii-what-is-the-seti-paradox-hypothesis/">want to communicate</a> with other technologically advanced life,” Huston and Wright explained. “Humans very rarely send targeted signals into space, and some scholars argue that intelligent species may <a href="https://theconversation.com/blasting-out-earths-location-with-the-hope-of-reaching-aliens-is-a-controversial-idea-two-teams-of-scientists-are-doing-it-anyway-182036">purposefully avoid broadcasting</a> out their locations. This search for signals that no one may be sending is called <a href="https://doi.org/10.48550/arXiv.physics/0611283">the SETI Paradox</a>.” </p>
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Read more:
<a href="https://theconversation.com/signatures-of-alien-technology-could-be-how-humanity-first-finds-extraterrestrial-life-191054">Signatures of alien technology could be how humanity first finds extraterrestrial life</a>
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<h2>4. Ethical considerations</h2>
<p>While the Search for Extraterrestrial Intelligence hasn’t yet detected any extraterrestrial technosignatures, a <a href="https://escholarship.org/uc/item/2sq6f3b0">working group of interdisciplinary scholars</a> in Indigenous studies argued that the act of listening for these signals may already count as engaging in first contact with extraterrestrial life.</p>
<p>The Indigenous studies working group argued that first contact may not be just one event – rather, you can think of it as a <a href="https://doi.org/10.1177/2514848619862191">long phase</a> that begins with listening and planning. Listening can be an act of surveillance, and with that comes ethical considerations. </p>
<p>But research groups like the Search for Extraterrestrial Intelligence don’t often include perspectives from the humanities, even though there are many histories of first contact between groups of people here on Earth to draw from. </p>
<p>James Cook’s 1768 voyage to Oceania, for example, was planned as scientific exploration. But its <a href="https://doi.org/10.17953/aicrj.45.1.lempert">legacy of genocide</a> still affects the Indigenous people of Australia and New Zealand today. </p>
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<iframe width="440" height="260" src="https://www.youtube.com/embed/5gZwLGrJQrM?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">This BBC video describes the modern ramifications of Captain James Cook’s colonial legacy in New Zealand.</span></figcaption>
</figure>
<p>“The initial domino of a public ET message, or recovered bodies or ships, could initiate <a href="https://doi.org/10.1098/rsta.2010.0236">cascading events</a>, including military actions, corporate resource mining and perhaps even geopolitical reorganizing,” wrote <a href="https://www.wacd.ucla.edu/people/faculty/david-shorter">David Shorter</a>, <a href="https://www.bowdoin.edu/profiles/faculty/wlempert/index.html">William Lempert</a> and <a href="https://kimtallbear.com/">Kim Tallbear</a>. “No one can know for sure <a href="https://theconversation.com/is-your-religion-ready-to-meet-et-32541">how engagement with extraterrestrials would go</a>, though it’s better to consider cautionary tales from Earth’s own history sooner rather than later.”</p>
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Read more:
<a href="https://theconversation.com/first-contact-with-aliens-could-end-in-colonization-and-genocide-if-we-dont-learn-from-history-207793">First contact with aliens could end in colonization and genocide if we don't learn from history</a>
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<p><em>Editor’s note: This story is a roundup of articles from The Conversation’s archives.</em></p><img src="https://counter.theconversation.com/content/210955/count.gif" alt="The Conversation" width="1" height="1" />
Whistleblower allegations that the government possesses UFOs may not be backed up by public physical evidence, but some argue that listening for extraterrestrial life is the first phase of contact.Mary Magnuson, Assistant Science EditorLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2104352023-07-27T18:18:33Z2023-07-27T18:18:33ZWhistleblower calls for government transparency as Congress digs for the truth about UFOs<figure><img src="https://images.theconversation.com/files/539676/original/file-20230727-29-h44roy.jpg?ixlib=rb-1.1.0&rect=44%2C35%2C5845%2C3884&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A congressional subcommittee on unidentified anomalous phenomena met to hear testimony from military officers. </span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/the-u-s-capitol-building-royalty-free-image/1409850965?phrase=congress">Sarah Silbiger/Bloomberg via Getty Images</a></span></figcaption></figure><p>A <a href="https://oversight.house.gov/subcommittee/national-security/">congressional subcommittee</a> <a href="https://www.c-span.org/video/?529499-1/hearing-unidentified-anomalous-phenomena-uap">met on July 26, 2023, to hear testimony</a> from several military officers who allege the government is concealing evidence of UFOs. By holding a <a href="https://oversight.house.gov/hearing/unidentified-anomalous-phenomena-implications-on-national-security-public-safety-and-government-transparency/">hearing</a> on UFOs – <a href="https://www.latimes.com/politics/story/2023-07-24/congress-ufos-hearing-uap">now called</a> “unidentified anomalous phenomena” by government agencies – the subcommittee sought to understand whether these UAPs pose a threat to national security.</p>
<p>I’m an <a href="https://scholar.google.com/citations?user=OrRLRQ4AAAAJ&hl=en">astronomer</a> who studies and has written about <a href="https://wwnorton.com/books/9780393343861">cosmology</a>, <a href="https://wwnorton.com/books/9780393357509">black holes</a>, <a href="https://www.penguinrandomhouse.com/books/718149/worlds-without-end-by-chris-impey/">exoplanets</a> and <a href="https://www.cambridge.org/core/books/living-cosmos/11D69005D09D25581AE4E6684EC8A3C1">life in the universe</a>. I’m also on the <a href="http://meti.org/en/advisors">advisory council</a> for an international group that strategizes how to communicate with an extraterrestrial civilization should the need ever arise.</p>
<p>While the hearings brought attention to UAPs and could lead to more reporting from people who work in the military and aviation, the testimonies did not produce evidence to fundamentally change the understanding of UAPs.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/539775/original/file-20230727-15-yzt55u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A close-up shot of a blue striped suit and pink tie with a rectangular pin that has a UFO on it and the words 'I still want to believe'" src="https://images.theconversation.com/files/539775/original/file-20230727-15-yzt55u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/539775/original/file-20230727-15-yzt55u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/539775/original/file-20230727-15-yzt55u.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/539775/original/file-20230727-15-yzt55u.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/539775/original/file-20230727-15-yzt55u.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/539775/original/file-20230727-15-yzt55u.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/539775/original/file-20230727-15-yzt55u.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 audience member at the hearing wears an ‘X-Files’ UFO pin.</span>
<span class="attribution"><span class="source">AP Photo/Nathan Howard</span></span>
</figcaption>
</figure>
<h2>UFO oversight so far</h2>
<p>The House subcommittee hearing follows a flurry of activity over the past few years. Public interest in UAPs surged in 2017 after three Navy videos were leaked and <a href="https://www.nytimes.com/2017/12/16/us/politics/pentagon-program-ufo-harry-reid.html">The New York Times reported</a> on a shadowy UAP program run by the Pentagon. In <a href="https://theconversation.com/us-intelligence-report-on-ufos-no-aliens-but-government-transparency-and-desire-for-better-data-might-bring-science-to-the-ufo-world-163059">June 2021</a>, the Office of the Director of National Intelligence released a <a href="https://www.dni.gov/files/ODNI/documents/assessments/Prelimary-Assessment-UAP-20210625.pdf">report</a> on the phenomena. In November 2021, the Pentagon <a href="https://www.defense.gov/News/Releases/Release/Article/2853121/dod-announces-the-establishment-of-the-airborne-object-identification-and-manag/">formed a new group</a> to coordinate efforts to detect and identify objects in restricted airspace.</p>
<p>Then in May 2022, a House Intelligence subcommittee held the first congressional hearing in over half a century on military reports of UAPs. Little new light was shed on the true nature of the sightings, but the <a href="https://www.independent.co.uk/tech/ufo-senate-hearing-congress-live-pentagon-b2080711.html">officials tried to clarify the situation</a> by ruling things out.</p>
<p>While <a href="https://www.youtube.com/watch?v=FYfxwBQL69A&t=4s">officials noted</a> 18 occasions in which aerial objects had moved at considerable speed without visible means of propulsion, nobody had found unexplained wreckage or records of the military having either received communications from or having fired shots at UAPs. As such, the subcommittee decided that there was not yet enough evidence to claim UAPs are extraterrestrial.</p>
<p>Most recently, <a href="https://www.nasa.gov/feature/nasa-to-set-up-independent-study-on-unidentified-aerial-phenomena/">NASA convened</a> a panel in June 2022, which held its first public hearing in May this year. The panel will help NASA advise intelligence agencies and the Department of Defense on how to evaluate mysterious sightings. The panel is considering <a href="https://www.cnn.com/2023/05/31/world/nasa-uap-study-public-meeting-scn/index.html">800 sightings</a> accumulated over 27 years, with <a href="https://www.cnn.com/2023/05/31/world/nasa-uap-study-public-meeting-scn/index.html">50 to 100 new reports</a> coming in each month. Sean Kirkpatrick from the Department of Defense said that <a href="https://www.cnn.com/2023/05/31/world/nasa-uap-study-public-meeting-scn/index.html">only 2% to 5% of these are anomalous</a>, and the meeting drew no firm conclusions.</p>
<p>Which brings us to this week’s hearing. Congress is <a href="https://oversight.house.gov/release/national-security-subcommittee-to-hold-hearing-on-unidentified-anomalous-phenomena">getting frustrated</a> with the lack of transparency over UAP sightings. So the subcommittee is using its <a href="https://oversight.house.gov/about/">overall charge</a> of oversight and accountability to get some answers.</p>
<h2>Eyebrow-raising testimony</h2>
<p>Three witnesses, all ex-military officers, gave <a href="https://oversight.house.gov/hearing/unidentified-anomalous-phenomena-implications-on-national-security-public-safety-and-government-transparency/">sworn testimony</a> to the subcommittee. </p>
<p>David Fravor was a commander in the U.S. Navy in 2004, stationed on the USS Nimitz, when he and another pilot <a href="https://www.cbsnews.com/news/navy-ufo-sighting-60-minutes-2021-05-16/">saw an object behaving inexplicably</a>. Video of the encounter was released by the Department of Defense in 2017 and publicized by <a href="https://www.nytimes.com/2017/12/16/us/politics/unidentified-flying-object-navy.html">The New York Times</a>. </p>
<p><a href="https://oversight.house.gov/wp-content/uploads/2023/07/David-Fravor-Statement-for-House-Oversight-Committee.pdf">Fravor testified</a> that the technology he witnessed was far superior to anything human beings have. He described objects with no visible means of propulsion carrying out sudden maneuvers that no known technology could achieve.</p>
<p>“What concerns me is that there is no oversight from our elected officials on anything associated with our government possessing or working on craft that we believe are not of this world,” Fravor said. </p>
<p>The second witness, Ryan Graves, was an F-18 pilot for over a decade. While stationed at Virginia Beach in 2014, he says, UAP sightings were so frequent among his crew that they became part of daily briefs. <a href="https://oversight.house.gov/wp-content/uploads/2023/07/Ryan-HOC-Testimony.pdf">He recounted</a> a situation in which two jets had to take evasive action as they encountered a UAP. The description was striking – a dark gray cube inside a clear sphere – quite different from the classic “<a href="https://www.theguardian.com/lifeandstyle/2020/oct/13/is-the-flying-saucer-the-best-shape-for-a-spaceship">flying saucer</a>.”</p>
<p>Graves founded <a href="https://www.safeaerospace.org/">Americans for Safe Aerospace</a> to create a center of support and education for aircrew affected by UAP encounters. He testified that the group has 5,000 members and has taken information from 30 witnesses. Most are commercial pilots at major airlines. He alleged that all UAP videos since 2021 are classified by the Pentagon as secret or higher. Graves also said that only 5% of UAP sightings by military and commercial pilots are reported by the pilots that spot them. </p>
<p>“If everyone could see the sensor and video data that I have, there is no doubt that UAP would be a top priority for our defense, intelligence and scientific communities,” Graves said. </p>
<p>The real bombshell came from David Grusch, an Air Force intelligence officer who retired with the rank of major. His high level of security clearance meant he saw reports that were unknown to the public. He sought whistleblower protection after claiming that the U.S. government was <a href="https://thedebrief.org/intelligence-officials-say-u-s-has-retrieved-non-human-craft/">operating with secrecy</a> and above congressional oversight with regards to UAP – even claiming that crashed UAPs had yielded biological material of nonhuman origin. The <a href="https://abcnews.go.com/Politics/house-oversight-plans-ufo-hearing-after-unconfirmed-claims/story?id=99899883">Pentagon has denied</a> this claim. He also said he’d suffered retaliation after reporting this information to his superiors and to multiple inspectors general.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/0w5T2skzNI4?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Grusch testifies that the U.S. government has recovered ‘nonhuman biologics.’</span></figcaption>
</figure>
<p>“I was informed, in the course of my official duties, of a multidecade UAP crash-retrieval and reverse-engineering program to which I was denied access,” Grusch said in <a href="https://oversight.house.gov/wp-content/uploads/2023/07/Dave_G_HOC_Speech_FINAL_For_Trans.pdf">his opening statement</a> to the subcommittee. The Pentagon has <a href="https://abcnews.go.com/Politics/house-oversight-plans-ufo-hearing-after-unconfirmed-claims/story?id=99899883">denied the existence of such a program</a> now or in the past. </p>
<h2>Calls for transparency</h2>
<p>While none of this testimony brought forward viable evidence of a broad government conspiracy, most UAP data is <a href="https://www.newsnationnow.com/space/ufo/pentagon-blocks-lawmakers-ufo-data-uap-hearing/">not made public</a> and is held by intelligence agencies or the Pentagon. Lawmakers from both parties called for more government transparency. When questioned, all three witnesses said that UAPs represented a clear threat to national security. </p>
<p>If these testimonies are truthful, UAPs of advanced technology – whether they originate from a foreign adversary or not – that make routine incursions into U.S. airspace are a cause for concern.</p>
<p>For now, the subcommittee will continue its work. A tangible outcome will probably be an <a href="https://oversight.house.gov/whistle/">anonymous reporting mechanism</a> to overcome the stigma commercial and military pilots feel when they witness a UAP. The push for government transparency will likely intensify, and subcommittee members hope to have a classified briefing to evaluate the claims made by Grusch.</p>
<p>As a scientist, I’m trained to be skeptical, and I know that <a href="http://www.ianridpath.com/ufo/astroufo1.html">most UFO sightings</a> <a href="https://theconversation.com/why-people-tend-to-believe-ufos-are-extraterrestrial-208403">have mundane explanations</a>. Visual evidence is also notoriously difficult to interpret, and even the dramatic Navy videos have been <a href="https://www.leonarddavid.com/debunking-navy-ufo-videos/">debunked</a>. More and better data will help resolve the issue, but the gold standard is physical evidence. If Grusch’s claims of crashed UAPs are ever verified, that will be the first UAP hearing with a truly dramatic outcome.</p>
<p><em>This article was updated on August 2, 2023 to correct the date of the Congressional hearing.</em></p><img src="https://counter.theconversation.com/content/210435/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Chris Impey receives funding from the National Science Foundation. </span></em></p>All who testified before a congressional subcommittee claimed that UFOs pose a threat to national security, though there’s still no public evidence that UFOs are extraterrestrial.Chris Impey, University Distinguished Professor of Astronomy, University of ArizonaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2077932023-07-19T12:23:49Z2023-07-19T12:23:49ZFirst contact with aliens could end in colonization and genocide if we don’t learn from history<figure><img src="https://images.theconversation.com/files/536178/original/file-20230706-15-uc6ukv.jpg?ixlib=rb-1.1.0&rect=44%2C0%2C4928%2C3260&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">SETI has been listening for markers that may indicate alien life -- but is doing so ethical?</span> <span class="attribution"><a class="source" href="https://unsplash.com/photos/4TpL_oVkUcQ">Donald Giannati via Unsplash</a></span></figcaption></figure><p>We’re only halfway through 2023, and it feels already like the year of alien contact. </p>
<p>In February, President Joe Biden <a href="https://www.whitehouse.gov/briefing-room/speeches-remarks/2023/02/16/remarks-by-president-biden-on-the-united-states-response-to-recent-aerial-objects/">gave orders</a> to shoot down three unidentified aerial phenomena – NASA’s title for UFOs. Then, the alleged <a href="https://www.cnn.com/videos/business/2021/05/19/ufo-navy-video-jeremy-corbell-orig-jm.cnn">leaked footage</a> from a Navy pilot of a UFO, and then news of a <a href="https://www.theguardian.com/world/2023/jun/06/whistleblower-ufo-alien-tech-spacecraft">whistleblower’s report</a> on a possible U.S. government cover-up about UFO research. Most recently, an independent analysis <a href="https://douglasjohnson.ghost.io/senate-intelligence-bill-gives-holders-of-non-earth-origin-six-months/">published in June</a> suggests that UFOs might have been collected by a clandestine agency of the U.S. government.</p>
<p>If any actual evidence of extraterrestrial life emerges, whether from whistleblower testimony or an admission of a cover-up, humans would face a historic paradigm shift. </p>
<p>As members of an Indigenous studies working group who were asked to lend our disciplinary expertise to a workshop affiliated with the <a href="https://seti.berkeley.edu/">Berkeley SETI Research Center</a>, we have studied centuries of culture contacts and their outcomes from around the globe. Our collaborative preparations for the workshop drew from transdisciplinary research in Australia, New Zealand, Africa and across the Americas. </p>
<p>In its final form, our <a href="https://escholarship.org/uc/item/2sq6f3b0">group statement</a> illustrated the need for diverse perspectives on the ethics of listening for alien life and a broadening of <a href="https://doi.org/10.17953/aicrj.45.1.shorter">what defines “intelligence” and “life.”</a> Based on our findings, we consider first contact less as an event and more as a long process that has already begun. </p>
<h2>Who’s in charge of first contact</h2>
<p>The question of who is “in charge” of preparing for contact with alien life immediately comes to mind. The communities – and their interpretive lenses – most likely to engage in any contact scenario would be military, corporate and scientific. </p>
<p>By giving Americans the legal right to profit from space tourism and planetary resource extraction, the <a href="https://www.govinfo.gov/app/details/COMPS-15975">Commercial Space Launch Competitiveness Act of 2015</a> could mean that corporations will be the first to find signs of extraterrestrial societies. Otherwise, while detecting unidentified aerial phenomena is usually a military matter, and NASA takes the lead on <a href="https://theconversation.com/blasting-out-earths-location-with-the-hope-of-reaching-aliens-is-a-controversial-idea-two-teams-of-scientists-are-doing-it-anyway-182036">sending messages from Earth</a>, most activities around extraterrestrial communications and evidence fall to a program called <a href="https://www.seti.org/">SETI, or the search for extraterrestrial intelligence</a>. </p>
<p>SETI is a collection of scientists with a <a href="https://www.sciencedirect.com/topics/earth-and-planetary-sciences/project-seti">variety of research endeavors</a>, including Breakthrough Listen, which listens for “<a href="https://iopscience.iop.org/article/10.3847/1538-3881/abf649">technosignatures</a>,” or markers, like pollutants, <a href="https://theconversation.com/signatures-of-alien-technology-could-be-how-humanity-first-finds-extraterrestrial-life-191054">of a designed technology</a>. </p>
<p>SETI investigators are <a href="https://www.seti.org/become-pi-or-affiliate">virtually always STEM</a> – science, technology, engineering and math – scholars. Few in the social science and humanities fields have been afforded opportunities to contribute to concepts of and preparations for contact.</p>
<p>In a promising act of disciplinary inclusion, the <a href="https://seti.berkeley.edu/listen/">Berkeley SETI Research Center</a> in 2018 invited working groups – including our <a href="https://doi.org/10.17953/aicrj.45.1.atalay_etal">Indigenous studies working group</a> – from outside STEM fields to craft perspective papers for SETI scientists to consider.</p>
<h2>Ethics of listening</h2>
<p>Neither Breakthough Listen nor SETI’s site features a current <a href="https://doi.org/10.1002/9781119711186.ch13">statement of ethics</a> beyond a <a href="https://doi.org/10.1098/rsta.2010.0311">commitment to transparency</a>. Our working group was <a href="https://bis-space.com/shop/product/do-no-harm-cultural-imperialism-and-the-ethics-of-active-seti/">not the first</a> to raise this issue. And while the <a href="https://www.seti.org/event/seti-live-ethics-outer-space">SETI Institute</a> and <a href="https://www.pseti.psu.edu/seminar/">certain research centers</a> have included ethics in their event programming, it seems relevant to ask who NASA and SETI answer to, and what ethical guidelines they’re following for a potential first contact scenario. </p>
<p><a href="https://seti.wp.st-andrews.ac.uk/">SETI’s Post-Detection Hub</a> – another rare exception to SETI’s STEM-centrism – seems the most likely to develop a range of contact scenarios. The possible circumstances imagined include finding ET artifacts, detecting signals from thousands of light years away, dealing with linguistic incompatibility, finding microbial organisms in space or on other planets, and biological contamination of either their or our species. Whether the U.S. government or heads of military would heed these scenarios is another matter. </p>
<p>SETI-affiliated scholars <a href="https://youtu.be/1Op7AN0MeNw?t=1237">tend to reassure critics</a> that the intentions of those listening for technosignatures are benevolent, since “what harm could come from simply listening?” The chair emeritus of SETI Research, Jill Tarter, <a href="https://www.jstor.org/stable/j.ctt1814k0q">defended listening</a> because any ET civilization would perceive our listening techniques as immature or elementary. </p>
<p>But our working group drew upon the history of colonial contacts <a href="https://doi.org/10.17953/aicrj.45.1.shorter">to show the dangers</a> of thinking that whole civilizations are comparatively advanced or intelligent. For example, when Christopher Columbus and other European explorers came to the Americas, those relationships were shaped by <a href="https://doi.org/10.1163/9789004421882_011">the preconceived notion</a> that the “Indians” were less advanced due to <a href="https://www.nebraskapress.unl.edu/nebraska-paperback/9780803253445/">their lack of writing</a>. This led to decades of <a href="https://www.harpercollins.com/products/the-other-slavery-andres-resendez?variant=39936147849250">Indigenous servitude</a> in the Americas. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/537513/original/file-20230714-23-b71osm.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A black and white engraving of a group of armed and armored men standing on the shore speaking to many naked men. Large ships sail in the background." src="https://images.theconversation.com/files/537513/original/file-20230714-23-b71osm.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/537513/original/file-20230714-23-b71osm.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=480&fit=crop&dpr=1 600w, https://images.theconversation.com/files/537513/original/file-20230714-23-b71osm.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=480&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/537513/original/file-20230714-23-b71osm.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=480&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/537513/original/file-20230714-23-b71osm.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=603&fit=crop&dpr=1 754w, https://images.theconversation.com/files/537513/original/file-20230714-23-b71osm.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=603&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/537513/original/file-20230714-23-b71osm.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=603&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 16th century engraving shows Christopher Columbus landing in the Americas, where he and his explorers deemed the Indigenous people there as ‘primitive,’ as they had no writing system.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Columbus_landing_on_Hispaniola.JPG">Theodor de Bry/Wikimedia Commons</a></span>
</figcaption>
</figure>
<p>The working group statement also suggested that the act of listening is itself already within a “<a href="https://doi.org/10.1177/2514848619862191">phase of contact</a>.” Like colonialism itself, contact might best be thought of as a series of events that starts with planning, rather than a singular event. Seen this way, isn’t listening potentially without permission just another form of surveillance? To listen intently but indiscriminately seemed to our working group like a <a href="https://doi.org/10.17953/aicrj.45.1.shorter_tallbear">type of eavesdropping</a>. </p>
<p>It seems contradictory that we begin our relations with aliens by listening in without their permission while actively working to stop other countries from <a href="https://www.youtube.com/watch?v=QI_rUsLT5Iw&ab_channel=WION">listening to certain U.S. communications</a>. If humans are initially perceived as disrespectful or careless, ET contact could more likely lead to <a href="https://theconversation.com/how-could-we-build-an-invisibility-cloak-to-hide-earth-from-an-alien-civilization-57092">their colonization of us</a>.</p>
<h2>Histories of contact</h2>
<p>Throughout histories of Western colonization, even in those few cases when contactees were intended to be protected, contact has led to brutal violence, pandemics, enslavement and genocide. </p>
<p>James Cook’s 1768 voyage on the HMS Endeavor was initiated by the <a href="https://doi.org/10.1098/rsnr.1969.0003">Royal Society</a>. This prestigious British academic society charged him with calculating the solar distance between the Earth and the Sun by measuring the visible movement of Venus across the Sun from Tahiti. The society strictly forbade him from any colonial engagements. </p>
<p>Though he achieved his scientific goals, Cook also <a href="https://doi.org/10.1017/S1743921305001262">received orders</a> from the Crown to map and claim as much territory as possible on the return voyage. Cook’s actions put into motion wide-scale colonization and Indigenous dispossession across Oceania, including the <a href="https://doi.org/10.17953/aicrj.45.1.lempert">violent conquests of Australia and New Zealand</a>. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/537303/original/file-20230713-17-55wdsd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A painting showing five men, two dogs, and a statue of a woman standing in a clearing near the ocean shore. The center man, James Cook, is holding his hat out." src="https://images.theconversation.com/files/537303/original/file-20230713-17-55wdsd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/537303/original/file-20230713-17-55wdsd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=431&fit=crop&dpr=1 600w, https://images.theconversation.com/files/537303/original/file-20230713-17-55wdsd.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=431&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/537303/original/file-20230713-17-55wdsd.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=431&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/537303/original/file-20230713-17-55wdsd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=542&fit=crop&dpr=1 754w, https://images.theconversation.com/files/537303/original/file-20230713-17-55wdsd.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=542&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/537303/original/file-20230713-17-55wdsd.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=542&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 1768 voyage of British captain James Cook, center, put into motion wide-scale colonization and Indigenous dispossession across Oceania.</span>
<span class="attribution"><a class="source" href="https://nla.gov.au/nla.obj-135646842/view">John Hamilton Mortimer via the National Library of Australia</a></span>
</figcaption>
</figure>
<p>The Royal Society gave Cook a “<a href="https://bigthink.com/thinking/star-trek-prime-directive/">prime directive</a>” of doing no harm and to only conduct research that would broadly benefit humanity. However, explorers are rarely independent from their funders, and their explorations reflect the political contexts of their time. </p>
<p>As scholars attuned to both research ethics and histories of colonialism, we wrote about Cook in our working group statement to showcase why SETI might want to explicitly disentangle their intentions <a href="https://www.govinfo.gov/app/details/COMPS-15975">from those of corporations, the military and the government</a>. </p>
<p>Although separated by vast time and space, both Cook’s voyage and SETI share key qualities, including their appeal to celestial science in the service of all humanity. They also share a mismatch between their ethical protocols and the likely long-term impacts of their success.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/5gZwLGrJQrM?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">This BBC video describes the modern ramifications of Captain James Cook’s colonial legacy in New Zealand.</span></figcaption>
</figure>
<p>The initial domino of a public ET message, or recovered bodies or ships, could initiate <a href="https://doi.org/10.1098/rsta.2010.0236">cascading events</a>, including military actions, corporate resource mining and perhaps even geopolitical reorganizing. The history of imperialism and colonialism on Earth illustrates that <a href="https://doi.org/10.1080/14623520601056240">not everyone benefits from colonization</a>. No one can know for sure <a href="https://theconversation.com/is-your-religion-ready-to-meet-et-32541">how engagement with extraterrestrials would go</a>, though it’s better to consider cautionary tales from Earth’s own history sooner rather than later.</p>
<p><em>This article has been updated to correct the date of James Cook’s voyage.</em></p><img src="https://counter.theconversation.com/content/207793/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>David Delgado Shorter has received funding from the National Science Foundation, the University of California, and the California Community Foundation. </span></em></p><p class="fine-print"><em><span>William Lempert has received funding from Bowdoin College, the Wenner-Gren Foundation for Anthropological Research, the Fulbright IIE US Scholar Program, the Lois Roth Endowment, the Andrew W. Mellon Foundation, and the American Council of Learned Societies.</span></em></p><p class="fine-print"><em><span>Kim TallBear 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>Three Indigenous studies scholars draw from colonial histories and explain why listening for alien life can have ethical ramifications.David Delgado Shorter, Professor of World Arts and Cultures/Dance, University of California, Los AngelesKim TallBear, Professor of Native Studies, University of AlbertaWilliam Lempert, Assistant Professor of Anthropology, Bowdoin CollegeLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2077142023-06-14T23:03:46Z2023-06-14T23:03:46ZFor the first time, astronomers have found life-supporting molecules called phosphates on Enceladus<figure><img src="https://images.theconversation.com/files/531898/original/file-20230614-22-z3g0a3.png?ixlib=rb-1.1.0&rect=742%2C233%2C3155%2C1760&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">NASA/JPL/Space Science Institute</span></span></figcaption></figure><p>The search for habitable conditions beyond Earth has just become more interesting with the discovery of biologically available phosphorus from one of Saturn’s moons. Phosphorus is the most elusive of the six crucial elements needed for life.</p>
<p>In research <a href="https://doi.org/10.1038/s41586-023-05987-9">published today in Nature</a>, data from the Cassini spacecraft were used to find phosphorus compounds called phosphates in <a href="https://solarsystem.nasa.gov/news/13021/put-a-ring-on-it/">Saturn’s E ring</a> – one of the fainter outer rings of the planet.</p>
<p>These compounds likely came from the ice volcano (cryovolcano) plumes from the <a href="https://theconversation.com/waterworld-cassini-spots-the-motion-of-enceladuss-ocean-25069">sub-surface liquid water ocean</a> on Saturn’s moon Enceladus.</p>
<h2>A famous moon</h2>
<p>Enceladus seemed like a typical moon of Saturn until the Cassini spacecraft came to take a closer look. <a href="https://theconversation.com/a-look-back-at-cassinis-incredible-mission-to-saturn-before-its-final-plunge-into-the-planet-83226">Arriving at Saturn in 2005</a>, Cassini has been making <a href="https://solarsystem.nasa.gov/news/12892/cassini-10-years-at-saturn-top-10-discoveries/">discovery after discovery</a> that have catapulted Enceladus to one of the top places to look for life beyond Earth.</p>
<p>In particular, we learned Enceladus has a liquid water ocean beneath its icy surface, heated by gravitational tidal forcing – the kind of forcing that produces ocean tides on Earth.</p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/531895/original/file-20230614-19-jl252o.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/531895/original/file-20230614-19-jl252o.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/531895/original/file-20230614-19-jl252o.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=640&fit=crop&dpr=1 600w, https://images.theconversation.com/files/531895/original/file-20230614-19-jl252o.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=640&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/531895/original/file-20230614-19-jl252o.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=640&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/531895/original/file-20230614-19-jl252o.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=805&fit=crop&dpr=1 754w, https://images.theconversation.com/files/531895/original/file-20230614-19-jl252o.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=805&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/531895/original/file-20230614-19-jl252o.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=805&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 process of organic compounds making their way onto ice grains emitted in plumes from Saturn’s moon Enceladus, where they were detected by NASA’s Cassini spacecraft.</span>
<span class="attribution"><span class="source">NASA/JPL-Caltech</span></span>
</figcaption>
</figure>
<p>This environment is tantalisingly similar to the <a href="https://theconversation.com/origins-of-life-new-evidence-first-cells-could-have-formed-at-the-bottom-of-the-ocean-126228">hydrothermal vents thought by some</a> to be the place where life may have originated on Earth. Such vents certainly host life on Earth today.</p>
<p>Most life on Earth ultimately relies on photosynthesis – generating energy from sunlight. Meanwhile, the ultimate energy source for any life on Enceladus would be the gravity of Saturn producing tides far stronger than the Moon produces on Earth, allowing a liquid water ocean despite the very cold -200°C ice crust surface.</p>
<h2>Easy sampling</h2>
<p>The Enceladus plumes have been called a “gimme” for efforts to sample the oceans of alien worlds. One wouldn’t need to land to collect a sample, nor to then launch to return it for analysis.</p>
<p>An obvious approach to sampling an ice volcano is to simply fly through it. However, this is difficult because the speed at which a space probe would encounter the plume would likely kill most organics.</p>
<p>Instead, the easiest approach is to examine the accumulation of ejected material from Enceladus in Saturn’s E ring, which is what the team did in this latest study. </p>
<p>Using this approach, researchers have previously discovered <a href="https://academic.oup.com/mnras/article/489/4/5231/5573821">complex organic molecules</a> <a href="https://www.nature.com/articles/s41586-018-0246-4">coming from Enceladus</a>. These findings confirmed that the watery environment on Enceladus supports complex chemistry involving nitrogen and oxygen.</p>
<p>However, until now we didn’t know about the availability of phosphorus on Enceladus; in many environments this element is locked in rocks.</p>
<h2>A crucial element</h2>
<p>The discovery of phosphates in Saturn’s E ring suggests phosphates could be available within the oceans of Enceladus at a concentration 100 times higher than in Earth’s oceans.</p>
<p>Phosphorus is crucial for life as we know it, partly because it is a key building block of DNA and RNA, molecules essential to all life on Earth. Phosphate is also vital for a number of other metabolic processes in all life. </p>
<p>Many of the essential components necessary for the emergence of life as we know it have thus been discovered on Enceladus. This puts it at or near the top of lists of places to search for life beyond Earth in our Solar System. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/humans-are-still-hunting-for-aliens-heres-how-astronomers-are-looking-for-life-beyond-earth-197621">Humans are still hunting for aliens. Here's how astronomers are looking for life beyond Earth</a>
</strong>
</em>
</p>
<hr>
<p>Nevertheless, this discovery is only the start of the story. For phosphate to form bonds with carbon – this type of bond is found in the backbone of DNA – we need specialised chemistry that’s very dependent on the environment.</p>
<p>We’ll need further study of the chemistry in and under the crust of Enceladus. But a future detection of organic phosphate compounds would be particularly interesting for the potential for life in the moon’s oceans.</p>
<h2>No ‘smoking gun’</h2>
<p>This research is reminiscent of the reported detection of <a href="https://theconversation.com/the-detection-of-phosphine-in-venus-clouds-is-a-big-deal-heres-how-we-can-find-out-if-its-a-sign-of-life-146185">phosphine on Venus</a> in September 2020, which was <a href="https://www.universetoday.com/158983/sofia-fails-to-find-phosphine-in-the-atmosphere-of-venus-but-the-debate-continues/">cast into doubt by later evidence</a>.</p>
<p>However, the detection method is quite different. On Venus the presence of phosphine was proposed by observing the atmosphere from Earth. The phosphates in this study were detected using an instrument orbiting Saturn called a mass spectrometer, which measured the mass of individual compounds found in the ice of the E ring.</p>
<p>To verify the analysis, the authors created a water solution on Earth very similar to the predicted Enceladus ocean.</p>
<p>That said, both detection methods carry a risk of misidentification, where a different molecule that’s not phosphine is actually responsible for the result. </p>
<p>It would be great to have a “smoking gun” for life beyond Earth, but realistically it will instead be a trickle of evidence that grows as we discover more about these environments. </p>
<p>The study published today is one more piece of evidence supporting the fact that Enceladus may be a great location in our search for extraterrestrial life. </p>
<hr>
<p><em>Acknowledgements: We thank Prof Steve Benner from The Foundation For Applied Molecular Evolution for his insight and contributions to this article.</em></p><img src="https://counter.theconversation.com/content/207714/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>The authors do not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and have disclosed no relevant affiliations beyond their academic appointment.</span></em></p>Phosphorus is the most elusive element crucial for life as we know it – and we now have the first evidence there’s some available in the oceans of Enceladus.Laura McKemmish, Lecturer, UNSW SydneyAlbert Fahrenbach, Senior Lecturer, UNSW SydneyMartin Van Kranendonk, Professor and Director of the Australian Centre for Astrobiology, UNSW SydneyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2003042023-03-10T18:01:48Z2023-03-10T18:01:48ZA brief history of the UK’s Winchcombe meteorite<figure><img src="https://images.theconversation.com/files/512936/original/file-20230301-22-2u3bf5.jpg?ixlib=rb-1.1.0&rect=7%2C0%2C2432%2C1964&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">There was little time for water from the Earth's atmosphere to contaminate the meteorite after it fell.</span> <span class="attribution"><span class="source">Trustees of the Natural History Museum</span>, <span class="license">Author provided</span></span></figcaption></figure><p>On 28 February 2021, for the first time in 30 years, a meteorite <a href="https://www.theguardian.com/uk-news/2021/mar/01/meteorites-from-fireball-that-lit-up-sky-could-have-fallen-to-earth">fell in the UK</a> and was <a href="https://theconversation.com/meteorite-hunters-how-we-found-the-first-bit-of-uk-space-rock-in-over-30-years-157157">later recovered</a> by scientists. Today, there’s an international effort to study this space rock and learn more about its place in the early solar system.</p>
<p>This meteorite is named after <a href="https://en.wikipedia.org/wiki/Winchcombe">Winchcombe</a>, the town in Gloucestershire where several fragments were recovered – including a piece that landed on <a href="https://www.gloucestershirelive.co.uk/news/cheltenham-news/winchcombe-meteorite-how-tracked-down-5103696">the driveway of a family home.</a> </p>
<p><a href="https://www.amnh.org/exhibitions/permanent/meteorites/meteorites/what-is-a-meteorite">The meteorite</a> formed 4.5 billion years ago in the distant outer solar system, beyond the orbit of Jupiter. We refer to such objects as primitive because they contain some of the earliest solid material to form in our cosmic neighbourhood, <a href="https://theconversation.com/a-pristine-chunk-of-space-rock-found-within-hours-of-hitting-earth-can-tell-us-about-the-birth-of-the-solar-system-194725">offering insights into a time</a> when our solar system was in its infancy.</p>
<p>Over time, much of this solid material merged to form larger objects, which eventually led to the emergence of planets. Some of the early building blocks that avoided being consumed in this process of planetary assembly are present today as <a href="https://solarsystem.nasa.gov/asteroids-comets-and-meteors/asteroids/in-depth/#many_shapes_and_sizes_otp">asteroids</a> or even smaller objects. <a href="https://theconversation.com/a-pristine-chunk-of-space-rock-found-within-hours-of-hitting-earth-can-tell-us-about-the-birth-of-the-solar-system-194725">The Winchcombe meteorite</a> is just such a celestial body.</p>
<p>Some of these free-roaming planetary building blocks may have been responsible for delivering water to the early Earth. Therefore, Winchcombe can provide a glimpse <a href="https://www.science.org/doi/10.1126/sciadv.abq3925">into the activity of water</a> on solid bodies in the ancient solar system.</p>
<h2>Path through space</h2>
<p>Winchcombe is a rare type of meteorite <a href="https://onlinelibrary.wiley.com/doi/10.1111/maps.13918">known as a CM chondrite</a>. <a href="https://en.wikipedia.org/wiki/CM_chondrite">These meteorites are characterised</a> by high concentrations of water and organic matter (molecules with chains of carbon atoms), both of which are essential ingredients for the emergence of life. </p>
<p><a href="https://www.science.org/doi/10.1126/sciadv.abq3925">We know the path through space</a> that the Winchcombe object took – its orbit – before it fell to Earth. It is one of only five primitive, water-bearing chondrites for which scientists have this information. Knowing its orbit means we can pinpoint where in the solar system it came from. </p>
<figure class="align-center ">
<img alt="Fireball generated by the Winchcombe meteorite entering the atmosphere." src="https://images.theconversation.com/files/514468/original/file-20230309-16-suqhy6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/514468/original/file-20230309-16-suqhy6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=494&fit=crop&dpr=1 600w, https://images.theconversation.com/files/514468/original/file-20230309-16-suqhy6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=494&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/514468/original/file-20230309-16-suqhy6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=494&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/514468/original/file-20230309-16-suqhy6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=621&fit=crop&dpr=1 754w, https://images.theconversation.com/files/514468/original/file-20230309-16-suqhy6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=621&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/514468/original/file-20230309-16-suqhy6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=621&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The meteorite appeared as a yellow-green fireball over Gloucestershire.</span>
<span class="attribution"><span class="source">UKFN / Dr Martin Suttle</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>The pieces of this meteorite <a href="https://academic.oup.com/astrogeo/article/63/1/1.21/6507492">were recovered very rapidly</a> – within 12 hours of arriving on Earth. This means there was little time for water from Earth’s atmosphere to react with and contaminate the meteorite. Taken together with the meteorite’s rarity, primitive characteristics and distant origin, its swift recovery makes the object an ideal candidate for studying the role of asteroids in the early solar system.</p>
<p>The meteorite was probably once part of a larger asteroid. But looking at pieces of the Winchcombe object under the microscope, it quickly became clear that <a href="https://onlinelibrary.wiley.com/doi/full/10.1111/maps.13938">it is not one rock but many</a> –- a complex mix of fragments loosely held together. This structure is the result of collisions between larger asteroids in space. </p>
<p>The debris field created by the collision subsequently merged to form a new population of smaller second-generation asteroids referred to as rubble-pile objects because of their loose, blocky configuration. Winchcombe came from one of these rubble-pile bodies – fragmented remains of the diverse rocky objects that existed in the age before planets.</p>
<h2>Space mud</h2>
<p>Each rock fragment that makes up the Winchcombe meteorite records a distinct history, revealing, for example, differences in the amount of water it interacted with, and implying that the parent asteroid had a complex structure. </p>
<p>These observations point to either variable amounts of water on that parent body, which condensed as ice as the asteroid grew, or the uneven flow of water through the asteroid. When space rocks come into <a href="http://advances.sciencemag.org/content/3/7/e1602514">contact with liquid water</a> they begin to change, forming an unusual form of dark black, fine-grained “space mud”. </p>
<p>Researchers from across the world jump at the chance to study these minerals because they hold, inside their crystal structure, molecules of
the original water that flowed on these asteroids. </p>
<figure class="align-center ">
<img alt="Winchombe meteorite" src="https://images.theconversation.com/files/514467/original/file-20230309-672-u0roc3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/514467/original/file-20230309-672-u0roc3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=332&fit=crop&dpr=1 600w, https://images.theconversation.com/files/514467/original/file-20230309-672-u0roc3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=332&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/514467/original/file-20230309-672-u0roc3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=332&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/514467/original/file-20230309-672-u0roc3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=417&fit=crop&dpr=1 754w, https://images.theconversation.com/files/514467/original/file-20230309-672-u0roc3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=417&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/514467/original/file-20230309-672-u0roc3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=417&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The space rock contains some of the very earliest material to form in the solar system.</span>
<span class="attribution"><span class="source">Mira Ihasz SpireGlobal</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>A group of scientists accurately measured the different isotopes (or chemical forms) of the hydrogen present in Winchcombe. Along with oxygen, hydrogen is one of the two chemical elements in water. The scientists’ findings demonstrated that water contained within the meteorite is very similar to the water on Earth. </p>
<p>This strengthens a theory that asteroids played a critical role in delivering water to the early Earth and thereby generating the oceans we see today.</p>
<h2>Catastrophic collision</h2>
<p>At some point, chemical reactions between water and rock were halted by the <a href="https://onlinelibrary.wiley.com/doi/full/10.1111/maps.13938">catastrophic collision with another asteroid</a>. This event shattered the meteorite’s parent body. Most of the rock fragments in the Winchcombe meteorite are very small, less than 1mm in size. This pattern of small pieces is evidence of the high-energy collision but also the signature of a weak asteroid. </p>
<p>As our understanding of planetary building blocks grows, we are increasingly recognising that the types of planetary bodies represented by the Winchcombe meteorite no longer exist in their original form. </p>
<figure class="align-center ">
<img alt="Winchcombe meteorite under Scanning Electron Microscope." src="https://images.theconversation.com/files/514512/original/file-20230309-16-5wv0zt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/514512/original/file-20230309-16-5wv0zt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=297&fit=crop&dpr=1 600w, https://images.theconversation.com/files/514512/original/file-20230309-16-5wv0zt.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=297&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/514512/original/file-20230309-16-5wv0zt.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=297&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/514512/original/file-20230309-16-5wv0zt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=373&fit=crop&dpr=1 754w, https://images.theconversation.com/files/514512/original/file-20230309-16-5wv0zt.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=373&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/514512/original/file-20230309-16-5wv0zt.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=373&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The fragmented nature of the Winchcombe meteorite was visible with a powerful microscope.</span>
<span class="attribution"><span class="source">Martin Suttle</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Most, if not all, small asteroids (those measuring less than 10km in diameter) are likely to be <a href="https://en.wikipedia.org/wiki/Rubble_pile">rubble-pile bodies</a>. Winchcombe is a relic from that time and a testament to the fate of most asteroids. We can summarise their history in a few simple words: hot and wet, then smashed to rubble. </p>
<p>Studying Winchcombe has also helped us to understand how these types of meteorites break-up in the atmosphere and, therefore, why they are rarely found as large rocks.</p>
<p>Research on Winchcombe continues and there are many more science questions that we hope to answer. One particularly interesting study relates to the type and amount of organic matter within Winchcombe and whether organic matter delivered by meteorites played a role in the supply of nutrients – food, essentially – for the emerging life on Earth.</p><img src="https://counter.theconversation.com/content/200304/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Dr Martin D. Suttle has received funding from UKRI Science and Technology Facilities Council (STFC). </span></em></p>In 2021, searchers recovered a meteorite that fell over the UK just hours earlier. Scientists have now reconstructed its story.Martin D. Suttle, Lecturer in Planetary Science, The Open UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1976212023-03-03T00:13:56Z2023-03-03T00:13:56ZHumans are still hunting for aliens. Here’s how astronomers are looking for life beyond Earth<figure><img src="https://images.theconversation.com/files/508029/original/file-20230203-12-uvmpl6.jpg?ixlib=rb-1.1.0&rect=302%2C315%2C4072%2C2733&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">zhengzaishuru/Shutterstock</span></span></figcaption></figure><p>We have long been fascinated with the idea of alien life. The earliest written record presenting the idea of “aliens” is seen in the satiric work of Assyrian writer <a href="https://blogs.scientificamerican.com/life-unbounded/the-first-alien/">Lucian of Samosata</a> dated to 200 AD.</p>
<p>In one novel, Lucian <a href="https://www.yorku.ca/inpar/lucian_true_tale.pdf">writes of a journey to the Moon</a> and the bizarre life he imagines living there – everything from three-headed vultures to fleas the size of elephants.</p>
<p>Now, 2,000 years later, we still write stories of epic adventures beyond Earth to meet otherworldly beings (<a href="https://www.britannica.com/topic/The-Hitchhikers-Guide-to-the-Galaxy-novel-by-Adams">Hitchhiker’s Guide</a>, anyone?). Stories like these entertain and inspire, and we are forever trying to find out if science fiction will become science fact.</p>
<h2>Not all alien life is the same</h2>
<p>When looking for life beyond Earth, we are faced with two possibilities. We might find basic microbial life hiding somewhere in our Solar System; or we will identify signals from intelligent life somewhere far away.</p>
<p>Unlike in <a href="https://www.britannica.com/topic/Star-Wars-film-series">Star Wars</a>, we’re not talking far, far away in another galaxy, but rather around other nearby stars. It is this second possibility which really excites me, and should excite you too. A detection of intelligent life would fundamentally change how we see ourselves in the Universe. </p>
<p>In the last 80 years, programs dedicated to the search for extraterrestrial intelligence (SETI) have worked tirelessly searching for cosmic “hellos” in the form of radio signals.</p>
<p>The reason we think any intelligent life would communicate via radio waves is due to the waves’ ability to travel vast distances through space, rarely interacting with the dust and gas in between stars. If anything out there is trying to communicate, it’s a pretty fair bet they would do it through radio waves. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/505679/original/file-20230121-18-zi7kes.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/505679/original/file-20230121-18-zi7kes.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/505679/original/file-20230121-18-zi7kes.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=134&fit=crop&dpr=1 600w, https://images.theconversation.com/files/505679/original/file-20230121-18-zi7kes.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=134&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/505679/original/file-20230121-18-zi7kes.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=134&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/505679/original/file-20230121-18-zi7kes.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=169&fit=crop&dpr=1 754w, https://images.theconversation.com/files/505679/original/file-20230121-18-zi7kes.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=169&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/505679/original/file-20230121-18-zi7kes.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=169&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 three radio facilities used in the Breakthrough Listen Initiative. Left to Right: 100m Robert C. Byrd Green Bank Telescope, 64m Murriyang (Parkes) Radio Telescope, 64-antenna MeerKAT array.</span>
<span class="attribution"><span class="source">NRAO, CSIRO, MeerKAT</span></span>
</figcaption>
</figure>
<h2>Listening to the stars</h2>
<p>One of the most exciting searches to date is <a href="https://breakthroughinitiatives.org/initiative/1">Breakthrough Listen</a>, the largest scientific research program dedicated to looking for evidence of intelligent life beyond Earth.</p>
<p>This is one of many projects funded by US-based Israeli entrepreneurs Julia and Yuri Milner, with some serious dollars attached. Over a ten-year period a total amount of <a href="https://breakthroughinitiatives.org/initiative/1">US$100 million</a> will be invested in this effort, and they have a mighty big task at hand. </p>
<p>Breakthrough Listen is currently targeting the closest one million stars in the hope of identifying any unnatural, alien-made radio signals. Using telescopes around the globe, from the 64-metre Murriyang Dish (Parkes) here in Australia, to the 64-antenna MeerKAT array in South Africa, the search is one of epic proportions. But it isn’t the only one. </p>
<p>Hiding away in the Cascade Mountains north of San Francisco sits the <a href="https://www.seti.org/ata">Allen Telescope Array</a>, the first radio telescope built from the ground up specifically for SETI use.</p>
<p>This unique facility is another exciting project, able to search for signals every day of the year. This project is currently upgrading the hardware and software on the original dish, including the ability to target several stars at once. This is a part of the non-profit research organisation, the SETI Institute.</p>
<h2>Space lasers!</h2>
<p>The SETI Institute is also looking for signals that would be best explained as “space lasers”.</p>
<p>Some astronomers hypothesise that intelligent beings might use massive lasers to communicate or even to propel spacecraft. This is because even here on Earth we’re investigating <a href="https://www.nasa.gov/feature/goddard/2022/the-future-of-laser-communications/">laser communication</a> and laser-propelled <a href="https://www.insidescience.org/news/new-light-sail-design-would-use-laser-beam-ride-space">light sails</a>.</p>
<p>To search for these mysterious flashes in the night sky, we need speciality instruments in locations around the globe, which are currently being developed and deployed. This is a research area I’m excited to watch progress and eagerly await results. </p>
<p>As of writing this article, sadly no alien laser signals have been found yet.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/do-aliens-exist-we-asked-five-experts-161811">Do aliens exist? We asked five experts</a>
</strong>
</em>
</p>
<hr>
<h2>Out there, somewhere</h2>
<p>It’s always interesting to ponder who or what might be living out in the Universe, but there is one problem we must overcome to meet or communicate with aliens. It’s the speed of light.</p>
<p>Everything we rely on to communicate via space requires light, and it can only travel so fast. This is where my optimism for finding intelligent life begins to fade. The Universe is big – <em>really</em> big.</p>
<p>To put it in perspective, humans started using radio waves to communicate across large distances in 1901. That <a href="https://ethw.org/Milestones:Reception_of_Transatlantic_Radio_Signals,_1901">first transatlantic signal</a> has only travelled 122 light years, reaching just 0.0000015% of the stars in our Milky Way.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/505680/original/file-20230121-16-884k8k.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="An image of a spiral galaxy with a box on the lower right corner centred on a tiny blue dot" src="https://images.theconversation.com/files/505680/original/file-20230121-16-884k8k.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/505680/original/file-20230121-16-884k8k.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/505680/original/file-20230121-16-884k8k.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/505680/original/file-20230121-16-884k8k.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/505680/original/file-20230121-16-884k8k.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/505680/original/file-20230121-16-884k8k.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/505680/original/file-20230121-16-884k8k.jpeg?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 little blue dot in the centre of the square is the current extent of human broadcasts just in our own galaxy.</span>
<span class="attribution"><a class="source" href="https://www.planetary.org/space-images/extent-of-human-radio-broadcasts">Adam Grossman/Nick Risinger</a></span>
</figcaption>
</figure>
<p>Did your optimism just fade too? That is okay, because here is the wonderful thing… we don’t have to find life to know it is out there, somewhere.</p>
<p>When we consider the <a href="https://theconversation.com/how-many-stars-are-there-in-space-165370">trillions of galaxies</a>, septillion of stars, and likely many more planets just in the observable Universe, it feels near impossible that we are alone.</p>
<p>We can’t fully constrain the parameters we need to estimate how many other lifeforms might be out there, as famously proposed by Frank Drake, but using our best estimates and <a href="https://www.cambridge.org/core/journals/international-journal-of-astrobiology/article/numerical-testbed-for-hypotheses-of-extraterrestrial-life-and-intelligence/0C97E7803EEB69323C3728F02BA31AFA">simulations</a> the current best answer to this is tens of thousands of possible civilisations out there. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/frank-drake-has-passed-away-but-his-equation-for-alien-intelligence-is-more-important-than-ever-189935">Frank Drake has passed away but his equation for alien intelligence is more important than ever</a>
</strong>
</em>
</p>
<hr>
<p>The Universe <a href="https://theconversation.com/is-space-infinite-we-asked-5-experts-165742">might even be infinite</a>, but that is too much for my brain to comprehend on a weekday.</p>
<h2>Don’t forget the tiny aliens</h2>
<p>So, despite keenly listening for signals, we might not find intelligent life in our lifetimes. But there is hope for aliens yet.</p>
<p>The ones hiding in plain sight, on the planetary bodies of our Solar System. In the coming decades we’ll explore the moons of Jupiter and Saturn like never before, with missions hunting to find traces of basic life.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/505682/original/file-20230121-23485-sxmcy9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/505682/original/file-20230121-23485-sxmcy9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/505682/original/file-20230121-23485-sxmcy9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/505682/original/file-20230121-23485-sxmcy9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/505682/original/file-20230121-23485-sxmcy9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/505682/original/file-20230121-23485-sxmcy9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/505682/original/file-20230121-23485-sxmcy9.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">
<figcaption>
<span class="caption">Jupiter and the icy moon Europa. Concept art of the Europa Clipper mission currently under development.</span>
<span class="attribution"><span class="source">NASA/JPL</span></span>
</figcaption>
</figure>
<p>Mars will continue to be explored – eventually by humans – which could allow us to uncover and retrieve samples from new and unexplored regions.</p>
<p>Even if our future aliens are only tiny microbes, it would still be nice to know we have company in this Universe.</p>
<hr>
<p><em>Correction: this article has been amended to clarify that Julia and Yuri Milner are no longer Russian citizens.</em></p><img src="https://counter.theconversation.com/content/197621/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Sara Webb 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>To date, we have not heard from any aliens. Nor have we seen any – but here are the fascinating projects working to change that.Sara Webb, Postdoctoral Research Fellow, Centre for Astrophysics and Supercomputing, Swinburne University of TechnologyLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1986942023-02-01T12:08:35Z2023-02-01T12:08:35ZSeti: alien hunters get a boost as AI helps identify promising signals from space<figure><img src="https://images.theconversation.com/files/507097/original/file-20230130-12-qfen8v.jpg?ixlib=rb-1.1.0&rect=672%2C272%2C2956%2C1999&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The new study analysed data gathered at the Green Bank Observatory in West Virginia.</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/green-bank-west-virginia-october-15-762059119">Shutterstock</a></span></figcaption></figure><p>An international team of researchers looking for signs of intelligent life in space have used artificial intelligence (AI) to reveal eight promising radio signals in data collected at a US observatory.</p>
<p>The results of their research, <a href="https://www.nature.com/articles/s41550-022-01872-z">published in Nature Astronomy</a> are remarkable. The team hasn’t yet carried out an exhaustive analysis, but the paper suggests the signals have many of the characteristics we would expect if they were artificially generated. In other words, they are the kinds of signals we might pick up from an extraterrestrial civilisation broadcasting into space.</p>
<p>A cursory review of the new paper suggest these are indeed promising signals. They’re much more compelling than what is perhaps the most famous Seti candidate, <a href="https://astronomy.com/news/2020/09/the-wow-signal-an-alien-missed-connectio">the “Wow!” signal</a>, radio emission bearing the hallmarks of an extraterrestrial origin that was collected by an Ohio telescope in 1977.</p>
<p>Realistically, it’s most likely that these eight new signals were generated by human technology. But the real story here is the effectiveness of AI and <a href="https://en.wikipedia.org/wiki/Deep_learning">the techniques used by the team to</a> dig out rare and interesting signals previously buried in the noise of human-generated <a href="https://public.nrao.edu/telescopes/radio-frequency-interference/">radio frequency interference,</a> such as mobile phones and GPS.</p>
<p>Astronomers working in the field of <a href="https://www.seti.org/primer-seti-seti-institute">Seti (the search for extraterrestrial intelligence)</a> must filter out interference produced by radio communications here on Earth.</p>
<p>In this case, Peter Ma from the University of Toronto and his colleagues unleashed a set of algorithms on a mountain of data collected by the <a href="https://greenbankobservatory.org">Green Bank Telescope in West Virginia</a>, US. The data was gathered through a Seti initiative called <a href="https://seti.berkeley.edu/listen/">Breakthrough Listen</a>, established in 2015 by the investor Yuri Milner and his wife Julia. </p>
<p>Here are the characteristics astronomers look for in signals that could be artificially-generated: firstly they are <a href="https://en.wikipedia.org/wiki/Narrowband">narrow-band</a>, which means that where the radio transmission is confined to only a few frequency channels. They also disappear as the telescope is moved to another direction in the sky, and they exhibit <a href="https://en.wikipedia.org/wiki/Doppler_effect">“Doppler drifting”</a>, where the frequency of the signal changes in a predictable way with time. We would expect Doppler drifting because both the transmitter — on a distant planet, for example — and the receiver, on Earth, are moving.</p>
<figure class="align-center ">
<img alt="Artist's impression of exoplanets" src="https://images.theconversation.com/files/507060/original/file-20230130-22-kadncw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/507060/original/file-20230130-22-kadncw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=449&fit=crop&dpr=1 600w, https://images.theconversation.com/files/507060/original/file-20230130-22-kadncw.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=449&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/507060/original/file-20230130-22-kadncw.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=449&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/507060/original/file-20230130-22-kadncw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=565&fit=crop&dpr=1 754w, https://images.theconversation.com/files/507060/original/file-20230130-22-kadncw.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=565&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/507060/original/file-20230130-22-kadncw.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=565&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Any artificial signals from deep space need to be distinguished from radio interference here on Earth.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/planets-deep-space-cosmos-nebula-stars-2057080619">Shutterstock</a></span>
</figcaption>
</figure>
<h2>Buried in the noise</h2>
<p>The Breakthrough Listen project’s <a href="https://seti.berkeley.edu/blc1/">first candidate signal</a>, called BLC1, was first announced in 2020. But it was <a href="https://www.nature.com/articles/s41550-021-01508-8">later traced</a> to transmissions associated with cheap electronic devices on this planet. The application of AI techniques to the Breakthrough Listen observing programme, however, is a potential game changer for the field. Even seasoned Seti researchers are beginning to think that we might be on the cusp of a momentous scientific breakthrough.</p>
<p>This may explain renewed interest by groups around the world that are planning for Seti success. For example, a <a href="https://seti.wp.st-andrews.ac.uk">Seti post-detection hub</a> has been set up at the University of St Andrews in Scotland. This will study how humans should react if we discover we are not alone in the Universe.</p>
<p>The International Academy of Astronautics (IAA) <a href="https://iaaseti.org/en/">Seti permanent committee</a> oversees the <a href="https://iaaseti.org/en/protocols/">Seti post-detection protocols</a>, which outline what steps scientists should take in the event of detecting a genuine signal. The IAA has opted to update the text of the protocols sometime later this year.</p>
<p>But the new study highlights a problem with previous signals of interest. When the team took another look at the stars associated with the eight narrow-band transmissions, they could no longer detect the signals. </p>
<p>It would not be surprising if many, and perhaps the vast majority of bona-fide Seti signals, were isolated events. After all, what are the chances that we point our telescopes in exactly the right direction, at the right time and with the right frequency on multiple occasions?</p>
<h2>Missing ingredients</h2>
<p>As I <a href="https://theconversation.com/seti-new-signal-excites-alien-hunters-heres-how-we-could-find-out-if-its-real-152498">argued here</a> a few years ago, Seti surveys would greatly benefit from employing multiple radio telescopes, operating in a manner that’s known as a <a href="https://public.nrao.edu/ask/how-does-a-radio-interferometer-work/">classical interferometer network</a>. </p>
<p>These telescope arrays (groups of several antennas observing together) generate huge amounts of data. With AI onboard, the challenge is perhaps more manageable than previously thought. </p>
<p>Breakthrough Listen is already using telescope arrays such as <a href="https://www.sarao.ac.za/science/meerkat/about-meerkat/">MeerKAT in South Africa</a> for Seti searches. In Europe, researchers have been experimenting with <a href="https://www.evlbi.org">arrays that span the globe</a>.</p>
<p>This European approach would help us isolate signals from human-made interference, give us multiple independent detections of individual events, and permit us to localise signals to individual stars and possibly orbiting planets. </p>
<p>Among the future projects is the <a href="https://www.skao.int/en">Square Kilometre Array</a>, an international project to build the two largest telescope arrays in the world, which will be based in Australia and South Africa. Another upcoming project is the <a href="https://ngvla.nrao.edu">next generation VLA (ngVLA)</a>, a series of linked telescope facilities that will be spread across the United States. These radio telescope arrays will be even more sensitive than current instruments.</p>
<p>It’s my belief — and indeed hope — that somewhere out there intelligent beings are waiting to be discovered. The AI revolution might be the missing ingredient that previous endeavours have lacked. In particular, AI algorithms will eventually evolve into powerful tools that no longer suffer from <a href="https://www.nist.gov/news-events/news/2022/03/theres-more-ai-bias-biased-data-nist-report-highlights">human biases</a>. </p>
<p>Lord Martin Rees, chairman of the Breakthrough Listen advisory board and the astronomer royal, has proposed that if we do find aliens they are likely to be <a href="https://theconversation.com/seti-why-extraterrestrial-intelligence-is-more-likely-to-be-artificial-than-biological-169966">intelligent machines</a> operating in the depths of space, unconstrained by the biological limitations placed on humans. </p>
<p>If we ever do find a bona-fide signal, it could just be that it’s mediated by machines on Earth and in space.</p><img src="https://counter.theconversation.com/content/198694/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Michael Garrett is on the advisory board of the Breakthrough Listen initiative and the Seti Institute.</span></em></p>Can artificial intelligence transform the search for alien intelligence?Michael Garrett, Sir Bernard Lovell chair of Astrophysics and Director of Jodrell Bank Centre for Astrophysics, University of ManchesterLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1987542023-01-30T19:12:02Z2023-01-30T19:12:02ZAI is helping us search for intelligent alien life – and we’ve found 8 strange new signals<figure><img src="https://images.theconversation.com/files/506973/original/file-20230130-19-jtv92r.png?ixlib=rb-1.1.0&rect=6%2C13%2C1477%2C974&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Midjourney</span>, <span class="license">Author provided</span></span></figcaption></figure><p>Some 540 million years ago, diverse life forms suddenly began to emerge from the muddy ocean floors of planet Earth. This period is known as the Cambrian Explosion, and these aquatic critters are our ancient ancestors. </p>
<p>All complex life on Earth evolved from these underwater creatures. Scientists believe all it took was an ever-so-slight increase in ocean oxygen levels above a certain threshold.</p>
<p>We may now be in the midst of a Cambrian Explosion for artificial intelligence (AI). In the past few years, a burst of incredibly capable AI programs like <a href="https://www.midjourney.com">Midjourney</a>, <a href="https://openai.com/dall-e-2/">DALL-E 2</a> and <a href="https://openai.com/blog/chatgpt/">ChatGPT</a> have showcased the rapid progress we’ve made in machine learning. </p>
<p>AI is now used in virtually all areas of science to help researchers with routine classification tasks. It’s also helping our team of radio astronomers broaden the search for extraterrestrial life, and results so far have been promising.</p>
<h2>Discovering alien signals with AI</h2>
<p>As scientists searching for evidence of intelligent life beyond Earth, we have <a href="https://www.nature.com/articles/s41550-022-01872-z">built an AI system</a> that beats classical algorithms in signal detection tasks. Our AI was trained to search through data from radio telescopes for signals that couldn’t be generated by natural astrophysical processes. </p>
<p>When we fed our AI a previously studied dataset, it discovered eight signals of interest the classic algorithm missed. To be clear, these signals are probably not from extraterrestrial intelligence, and are more likely rare cases of radio interference. </p>
<p>Nonetheless, our findings – <a href="https://www.nature.com/articles/s41550-022-01872-z">published today</a> in Nature Astronomy – highlight how AI techniques are sure to play a continued role in the search for extraterrestrial intelligence.</p>
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<img alt="An AI-generated image signifying an AI entity searching for extraterrestrial life in space." src="https://images.theconversation.com/files/506972/original/file-20230130-217-ye6duz.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/506972/original/file-20230130-217-ye6duz.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/506972/original/file-20230130-217-ye6duz.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/506972/original/file-20230130-217-ye6duz.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/506972/original/file-20230130-217-ye6duz.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/506972/original/file-20230130-217-ye6duz.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/506972/original/file-20230130-217-ye6duz.png?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">
<figcaption>
<span class="caption">AI-based systems are being increasingly used to classify signals found in massive amounts of radio data, helping speed-up the search for alien life.</span>
<span class="attribution"><span class="source">Generated by DALL-E 2</span>, <span class="license">Author provided</span></span>
</figcaption>
</figure>
<h2>Not so intelligent</h2>
<p>AI algorithms do not “understand” or “think”. They do excel at pattern recognition, and have proven exceedingly useful for tasks such as classification – but they don’t have the ability to problem solve. They only do the specific tasks they were trained to do.</p>
<p>So although the idea of an AI detecting extraterrestrial intelligence sounds like the plot of an exciting science fiction novel, both terms are flawed: AI programs are not intelligent, and searches for extraterrestrial intelligence can’t find direct evidence of intelligence.</p>
<p>Instead, radio astronomers look for radio “technosignatures”. These hypothesised signals would indicate the presence of technology and, by proxy, the existence of a society with the capability to harness technology for communication.</p>
<p>For our research, we created an algorithm that uses AI methods to classify signals as being either radio interference, or a genuine technosignature candidate. And our algorithm is performing better than we’d hoped.</p>
<h2>What our AI algorithm does</h2>
<p>Technosignature searches have been likened to looking for a needle in a cosmic haystack. Radio telescopes produce huge volumes of data, and in it are huge amounts of interference from sources such as phones, WiFi and satellites. </p>
<p>Search algorithms need to be able to sift out real technosignatures from “false positives”, and do so quickly. Our AI classifier delivers on these requirements. </p>
<p>It was devised by Peter Ma, a University of Toronto student and the lead author on our paper. To create a set of training data, Peter inserted simulated signals into real data, and then used this dataset to train an AI algorithm called an autoencoder. As the autoencoder processed the data, it “learned” to identify salient features in the data.</p>
<p>In a second step, these features were fed to an algorithm called a random forest classifier. This classifier creates decision trees to decide if a signal is noteworthy, or just radio interference – essentially separating the technosignature “needles” from the haystack.</p>
<p>After training our AI algorithm, we fed it more than 150 terabytes of data (480 observing hours) from the Green Bank Telescope in West Virginia. It identified 20,515 signals of interest, which we then had to manually inspect. Of these, eight signals had the characteristics of technosignatures, and couldn’t be attributed to radio interference.</p>
<h2>Eight signals, no re-detections</h2>
<p>To try and verify these signals, we went back to the telescope to re-observe all eight signals of interest. Unfortunately, we were not able to re-detect any of them in our follow-up observations.</p>
<p>We’ve been in similar situations before. In 2020 <a href="https://theconversation.com/a-mysterious-signal-looked-like-a-sign-of-alien-technology-but-it-turned-out-to-be-radio-interference-170548">we detected</a> a signal that turned out to be pernicious radio interference. While we will monitor these eight new candidates, the most likely explanation is they were unusual manifestations of radio interference: not aliens.</p>
<p>Sadly the issue of radio interference isn’t going anywhere. But we will be better equipped to deal with it as new technologies emerge.</p>
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<em>
<strong>
Read more:
<a href="https://theconversation.com/a-mysterious-signal-looked-like-a-sign-of-alien-technology-but-it-turned-out-to-be-radio-interference-170548">A mysterious signal looked like a sign of alien technology — but it turned out to be radio interference</a>
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</p>
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<h2>Narrowing the search</h2>
<p>Our team recently deployed a <a href="https://breakthroughinitiatives.org/news/38">powerful signal processor</a> on the MeerKAT telescope in South Africa. MeerKAT uses a technique called interferometry to combine its 64 dishes to act as a single telescope. This technique is better able to pinpoint where in the sky a signal comes from, which will drastically reduce false positives from radio interference.</p>
<p>If astronomers do manage to detect a technosignature that can’t be explained away as interference, it would strongly suggest humans aren’t the sole creators of technology within the Galaxy. This would be one of the most profound discoveries imaginable.</p>
<p>At the same time, if we detect nothing, that doesn’t necessarily mean we’re the only technologically-capable “intelligent” species around. A non-detection could also mean we haven’t looked for the right type of signals, or our telescopes aren’t yet sensitive enough to detect faint transmissions from distant exoplanets. </p>
<p>We may need to cross a sensitivity threshold before a Cambrian Explosion of discoveries can be made. Alternatively, if we really are alone, we should reflect on the unique beauty and fragility of life here on Earth.</p>
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<em>
<strong>
Read more:
<a href="https://theconversation.com/we-asked-astronomers-are-we-alone-in-the-universe-the-answer-was-surprisingly-consistent-132088">We asked astronomers: are we alone in the Universe? The answer was surprisingly consistent</a>
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</em>
</p>
<hr>
<img src="https://counter.theconversation.com/content/198754/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Danny Price is a senior postdoctoral researcher at the International Centre for Radio Astronomy Research (ICRAR) at Curtin University. He is a member of the Breakthrough Listen initiative to search for intelligent life beyond Earth.</span></em></p>AI’s ability to identify ‘technosignatures’ missed by classical algorithms is an exciting step forward for radio astronomers.Danny C Price, Senior research fellow, Curtin UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1952242022-11-24T20:14:01Z2022-11-24T20:14:01ZJames Webb space telescope uncovers chemical secrets of distant world – paving the way for studying Earth-like planets<figure><img src="https://images.theconversation.com/files/497034/original/file-20221123-22-xg8b05.jpg?ixlib=rb-1.1.0&rect=5%2C5%2C3822%2C2144&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Artist impression of WASP b and its star</span> <span class="attribution"><a class="source" href="https://www.esa.int/ESA_Multimedia/Images/2022/08/Artist_impression_of_WASP-39_b_and_its_star">NASA, ESA, CSA, and J. Olmsted (STScI)</a></span></figcaption></figure><p>Since the first planet orbiting a star other than the Sun was discovered in 1995, we have realised that planets and planetary systems are more diverse than we ever imagined. Such distant worlds – exoplanets – give us the opportunity to study how planets behave in different situations. And learning about their atmospheres is a crucial piece of the puzzle.</p>
<p>Nasa’s <a href="https://webb.nasa.gov/">James Webb space telescope</a> (JWST) is the largest telescope in space. Launched on Christmas Day 2021, it is the perfect tool for investigating these worlds. Now my colleagues and I have used the telescope for the first time to unveil the chemical make-up of an exoplanet. And <a href="https://www.mpg.de/19521589/Alderson_ERS_WASP39b_JWST_NIRSpec.pdf">the data</a>, <a href="https://arxiv.org/abs/2211.10488">released</a> <a href="https://arxiv.org/abs/2211.10489">in preprint</a> <a href="https://arxiv.org/abs/2211.10493">form</a> (meaning it has yet to be published in a peer-reviewed journal), <a href="https://exoplanets.nasa.gov/news/1715/nasas-webb-reveals-an-exoplanet-atmosphere-as-never-seen-before/">suggests some surprising results</a>.</p>
<p>Many exoplanets are too close to their parent stars for even this powerful telescope to distinguish them. But we can use the trick of watching as the planet passes in front of (transits) its star. During transit, the planet blocks a small fraction of the starlight, and an even tinier fraction of the starlight is filtered through the outer layers of the planet’s atmosphere. </p>
<p>Gases within the atmosphere absorb some of the light – leaving fingerprints on the starlight in the form of a reduction in brightness at certain colours, or wavelengths. JWST is particularly suited to exoplanet atmosphere studies because it is an infrared telescope. Most of the gases that are in an atmosphere – such as water vapour and carbon dioxide – absorb infrared rather than visible light.</p>
<figure class="align-center ">
<img alt="The image shows a graph with wavelength on the horizontal axis, increasing left to right, and the amount of light blocked on the vertical axis, increasing towards the top. The data resemble a bumpy line." src="https://images.theconversation.com/files/497079/original/file-20221123-12-ba99xt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/497079/original/file-20221123-12-ba99xt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=368&fit=crop&dpr=1 600w, https://images.theconversation.com/files/497079/original/file-20221123-12-ba99xt.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=368&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/497079/original/file-20221123-12-ba99xt.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=368&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/497079/original/file-20221123-12-ba99xt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=463&fit=crop&dpr=1 754w, https://images.theconversation.com/files/497079/original/file-20221123-12-ba99xt.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=463&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/497079/original/file-20221123-12-ba99xt.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=463&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">One of four separate measurements. Each bump corresponds to a different absorbing gas in the atmosphere.</span>
<span class="attribution"><span class="source">NASA, ESA, CSA, Joseph Olmsted (STScI)</span></span>
</figcaption>
</figure>
<p>I am part of an international team of exoplanet scientists that has been using JWST to study a roughly Jupiter-sized planet called <a href="https://exoplanets.nasa.gov/exoplanet-catalog/5673/wasp-39-b/">WASP-39b</a>. Unlike Jupiter, however, this world takes only a few days to orbit its star, so it is being cooked – reaching temperatures exceeding 827°C. This gives us the perfect opportunity to explore how a planetary atmosphere behaves in extreme temperature conditions. </p>
<p>We used JWST to recover the most complete spectrum yet of this fascinating planet. In fact, our work represents the first chemical inventory of the planet’s atmosphere.</p>
<p>We already knew that most of this large planet’s atmosphere had to be a mixture of hydrogen and helium – the lightest and most abundant gases in the universe. And the Hubble telescope has previously detected water vapour, sodium and potassium there.</p>
<p>Now, we’ve been able to confirm our detection and produce a measurement of the amount of water vapour. The data also suggests there are other gases including <a href="https://scied.ucar.edu/learning-zone/how-climate-works/carbon-dioxide">carbon dioxide</a>, <a href="https://www.gov.uk/government/publications/carbon-monoxide-properties-incident-management-and-toxicology/carbon-monoxide-general-information">carbon monoxide</a>, and unexpectedly, <a href="https://www.epa.gov/so2-pollution/sulfur-dioxide-basics">sulphur dioxide</a>.</p>
<p>Having measurements of how much of each of these gases is present in the atmosphere means we can estimate the relative amounts of the elements that make up the gases – hydrogen, oxygen, carbon and sulphur. Planets are formed in a disc of dust and gas around a young star, and we expect different amounts of these elements to be available to a baby planet at different distances from the star. </p>
<p>WASP-39b appears to have a relatively low amount of carbon relative to oxygen, indicating it probably formed at a greater distance from the star where it could have easily absorbed water ice from the disc (boosting its oxygen), compared with its current very close orbit. If this planet has migrated, it could help us develop our theories about planet formation, and would support the idea that the giant planets in our Solar System also did a fair bit of moving and shaking early on.</p>
<h2>A sulphurous key</h2>
<p>The amount of sulphur we detected relative to oxygen is quite high for WASP-39b. We’d expect sulphur in a young planetary system to be more concentrated in bits of rock and rubble than as an atmospheric gas. So this indicates that WASP-39b might have undergone an unusual amount of collisions with sulphur-containing chunks of rock. Some of that sulphur would be released as gas.</p>
<p>In a planet’s atmosphere, different chemicals react with each other at different rates depending on how hot it is. Usually, these settle into an equilibrium state, with the total amounts of each gas remaining stable as the reactions balance each other. We managed to predict what gases we would see in WASP-39b’s atmosphere for a range of starting points. But none of them came up with sulphur dioxide, instead expecting any sulphur to be locked up in a different gas, hydrogen sulphide.</p>
<figure class="align-left zoomable">
<a href="https://images.theconversation.com/files/497115/original/file-20221123-18-j3raez.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A diagram showing the chemical process that converts hydrogen sulphide to sulphur dioxide." src="https://images.theconversation.com/files/497115/original/file-20221123-18-j3raez.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/497115/original/file-20221123-18-j3raez.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/497115/original/file-20221123-18-j3raez.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/497115/original/file-20221123-18-j3raez.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/497115/original/file-20221123-18-j3raez.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/497115/original/file-20221123-18-j3raez.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/497115/original/file-20221123-18-j3raez.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>
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<span class="caption">Photochemistry on WASP-39b.</span>
<span class="attribution"><span class="source">NASA/JPL-Caltech/Robert Hurt; Center for Astrophysics-Harvard & Smithsonian/Melissa Weiss</span></span>
</figcaption>
</figure>
<p>The missing piece of the chemical jigsaw puzzle was a process called <a href="https://arxiv.org/abs/2211.10490">photochemistry</a>. This is when the rates of certain chemical reactions are driven by energy from photons – packets of light – coming from the star, rather than by the temperature of the atmosphere. Because WASP-39b is so hot, and reactions generally speed up at higher temperatures, we didn’t expect photochemistry to be quite as important as it has turned out to be. </p>
<p>The data suggests that water vapour in the atmosphere is split apart by light into oxygen and hydrogen. These products would then react with the gas hydrogen sulphide, eventually stripping away the hydrogen and replacing it with oxygen to form sulphur dioxide.</p>
<h2>What’s next for JWST?</h2>
<p>Photochemistry is even more important on cooler planets that may be habitable – the ozone layer on our own planet is formed via a photochemical process. JWST will be observing the rocky worlds in the <a href="https://theconversation.com/solar-system-with-seven-earth-like-planets-found-around-nearby-star-heres-what-they-could-be-like-73394">Trappist-1 system</a> during its first year of operation. Some of these measurements have already been made – and all of these planets have temperatures more similar to Earth’s. </p>
<p>Some may even have the right temperature to have liquid water on the surface, and potentially life. Having a good understanding of how photochemistry influences atmospheric composition is going to be critical for interpreting the Webb telescope observations of the Trappist-1 system. This is especially important since an apparent chemical imbalance in an atmosphere might hint at the presence of life, so we need to be aware of other possible explanations for this. </p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/four-ways-to-spot-hints-of-alien-life-using-the-james-webb-space-telescope-192445">Four ways to spot hints of alien life using the James Webb Space Telescope</a>
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<p>The WASP-39b chemical inventory has shown us just how powerful a tool JWST is. We’re at the start of a very exciting era in exoplanet science, so stay tuned.</p><img src="https://counter.theconversation.com/content/195224/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Joanna Barstow receives funding from the Science and Technology Facilities Council. She is a Councillor and Trustee for the Royal Astronomical Society. </span></em></p>The James Webb space telescope is making the headlines again – this time completing its first chemical inventory of a distant, exotic world.Joanna Barstow, Ernest Rutherford Fellow, The Open UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1915342022-09-29T16:12:59Z2022-09-29T16:12:59ZVenus: the trouble with sending people there<figure><img src="https://images.theconversation.com/files/487253/original/file-20220929-25-a6bvkz.jpeg?ixlib=rb-1.1.0&rect=0%2C0%2C4096%2C4071&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">NASA/JPL</span></span></figcaption></figure><p>Venus, often called <a href="https://www.esa.int/ESA_Multimedia/Images/2019/05/Earth_s_evil_twin">Earth’s “evil twin” planet</a>, formed closer to the Sun and has since evolved quite differently from our own planet. It has a <a href="https://www.space.com/venus-runaway-greenhouse-effect-earth-next.html">“runaway” greenhouse effect</a> (meaning heat is completely trapped), a thick carbon-dioxide-rich atmosphere, no magnetic field and a surface hot enough to melt lead. </p>
<p>Several uncrewed scientific missions will study how and why that happened in the next decade. But now some scientists <a href="https://www.theguardian.com/science/2022/sep/25/target-venus-not-mars-for-first-crewed-mission-to-another-planet-experts-say">want to send a crewed mission</a> there as well for a flyby. Is that a good idea?</p>
<p>With a slightly smaller diameter than Earth, Venus orbits closer to the Sun. This means that any water on the surface would have evaporated shortly after its formation, starting its greenhouse effect. Early and sustained volcanic eruptions created lava plains and increased the carbon dioxide in the atmosphere – starting the runaway greenhouse effect, which increased the temperature from just a little higher than Earth’s to its current high value of 475°C. </p>
<p>While the Venus year is shorter than ours (225 days), its rotation is very slow (243 days) and “retrograde” – the other way round to Earth. The slow rotation is related to a lack of magnetic field, resulting in a continuing loss of atmosphere.
Venus’ atmosphere “super-rotates” faster than the planet itself. Images from many missions show V-shaped patterns of clouds, composed of sulphuric acid droplets. </p>
<p>Despite the harsh conditions, some scientists have speculated that Venus’ clouds might at some altitudes harbour habitable conditions. Recent measurements apparently <a href="https://theconversation.com/venus-could-it-really-harbour-life-new-study-springs-a-surprise-145981">showing phosphine</a> – a potential sign of life as it is continuously produced by microbes on Earth – in Venus’ clouds have been strongly debated. Clearly, we need more measurements and exploration to work out where it comes from.</p>
<h2>Future missions</h2>
<p>What we know about Venus so far has been gathered from several past probes. In 1970-82, for example, the Soviet <a href="https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1970-060A">Venera 7-14 probes</a> were able to land on Venus’ harsh surface, survive for up to two hours and send back images and data. But there are remaining questions about how Venus evolved so differently from Earth, which are also relevant for understanding which planets orbiting other stars may harbour life.</p>
<p>The next decade promises to be a bonanza for Venus scientists. In 2021, Nasa <a href="https://theconversation.com/nasa-has-announced-two-missions-to-venus-by-2030-heres-why-thats-exciting-162133">selected two missions</a>, <a href="https://www.jpl.nasa.gov/missions/veritas">Veritas</a> and <a href="https://ntrs.nasa.gov/api/citations/20170002022/downloads/20170002022.pdf">DaVinci+,</a> due for launch in 2028-30. The European Space Agency <a href="https://www.esa.int/Science_Exploration/Space_Science/ESA_selects_revolutionary_Venus_mission_EnVision">selected EnVision</a> for launch in the early 2030s. These are complementary, uncrewed missions which will give us deeper understanding of Venus’ environment and evolution.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/487252/original/file-20220929-1555-oz5asc.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Image of craters on Venus seen by Venus Nasa's Magellan probe." src="https://images.theconversation.com/files/487252/original/file-20220929-1555-oz5asc.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/487252/original/file-20220929-1555-oz5asc.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=480&fit=crop&dpr=1 600w, https://images.theconversation.com/files/487252/original/file-20220929-1555-oz5asc.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=480&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/487252/original/file-20220929-1555-oz5asc.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=480&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/487252/original/file-20220929-1555-oz5asc.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=603&fit=crop&dpr=1 754w, https://images.theconversation.com/files/487252/original/file-20220929-1555-oz5asc.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=603&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/487252/original/file-20220929-1555-oz5asc.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=603&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Craters on Venus seen by Venus Nasa’s Magellan probe.</span>
<span class="attribution"><span class="source">NASA/JPL</span></span>
</figcaption>
</figure>
<p>Veritas will map Venus’ surface to determine the geological history, rock composition and the importance of early water. DaVinci+ includes an orbiter and a small probe that will descend through the atmosphere and measure its composition, study the planet’s formation and evolution and determine whether it ever had an ocean. EnVision will study the planet’s surface, subsurface and atmospheric trace gases. It will use radar to map the surface with better resolution than ever before.</p>
<p>India also plans an uncrewed mission, <a href="https://www.space.com/india-venus-orbiter-shukrayaan-2024-launch">Shukrayaan-1</a>, and Russia has proposed <a href="https://www.esa.int/About_Us/ESA_Permanent_Mission_in_Russia/Venera-D">Venera-D</a>.</p>
<h2>Do we need crewed flybys?</h2>
<p>The idea of a crewed flyby of Venus <a href="http://spaceflighthistory.blogspot.com/2017/05/apollo-ends-at-venus-1967-proposal-for.html">was suggested in the late 1960s</a>, and involved using an Apollo capsule to fly people around the planet. But this idea ended when Apollo finished. Now, the Artemis project to fly around the Moon, and other ideas of crewed missions, have led to the idea being floated again, most recently in <a href="https://www.sciencedirect.com/science/article/pii/S0094576520307554">journal papers</a> and at a recent meeting of the <a href="https://www.iafastro.org/">International Astronautical Federation</a>, an advocacy organisation, in September 2022. </p>
<p>The idea would be to fly a crewed spacecraft around Venus and return to Earth. This would allow scientists to test deep-space techniques such as how to operate a crewed mission with significant time delays when communicating with Earth. It could therefore prepare us for a more complex, crewed mission to Mars. However, the crew wouldn’t do any landing or actual atmosphere investigation at Venus – the conditions are way too harsh.</p>
<p>The researchers who back this idea argue that you could also use Venus’ gravity to alter the spacecraft’s course for Mars, which could save time and energy compared with going directly from Earth to Mars. That’s because the latter option would require the orbits of the two planets to be aligned, meaning you’d have to wait for the right moment both on the way there and back. However, as a crewed mission to Mars would be highly complex, going directly from Earth to Mars would keep designs simpler.</p>
<p>Sending humans to a planet that may harbour living organisms also won’t make it easier to find them. It is risky – we may end up contaminating the atmosphere before we discover any life. The best way to look for biochemical signs of life is with uncrewed probes. There would also be significant thermal challenges and higher radiation from solar flares due to closer proximity to the Sun.</p>
<p>And, unfortunately, with a flyby mission like this, only a few hours of data would be possible on the inbound and outbound trajectories. It would be a highly expensive venture, which would no doubt produce some amazing imagery and useful additional data. However, this would add little to the detailed and much longer bespoke studies currently planned. I, therefore, believe the likelihood of a crewed mission to Venus is very unlikely. </p>
<p>There have also been conceptual, more far-fetched studies – including sending <a href="https://theconversation.com/nasa-wants-to-send-humans-to-venus-heres-why-thats-a-brilliant-idea-104961">crewed airships to hover in Venus’ atmosphere</a>, rather than just flying by. This is a nice idea, which may achieve more science than a flyby, but it remains a distant and unrealistic concept for now. </p>
<p>For the moment, we only carry out crewed exploration in low-Earth orbit. The Artemis project, however, aims to fly people around the Moon and build a station, called Gateway, in lunar orbit. This is being designed to do science, enable crewed landings on the Moon and crucially to test deep space techniques such as refuelling and operating in a remote environment that could in the long run help get us to Mars without doing training at Venus.</p><img src="https://counter.theconversation.com/content/191534/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Andrew Coates receives funding from UKSA and STFC (UK). </span></em></p>Some scientists are keen to send humans to Venus on a flyby.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/1899352022-09-05T13:47:40Z2022-09-05T13:47:40ZFrank Drake has passed away but his equation for alien intelligence is more important than ever<figure><img src="https://images.theconversation.com/files/482721/original/file-20220905-26-uhmq7a.jpg?ixlib=rb-1.1.0&rect=14%2C0%2C1977%2C1130&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The spiral galaxy M74 imaged by the NASA/ESA JWST.</span> <span class="attribution"><a class="source" href="https://www.flickr.com/photos/nasawebbtelescope/52324826014/in/album-72177720301006030/">ESA/Webb, NASA & CSA, J. Lee and the PHANGS-JWST Team.</a>, <a class="license" href="http://creativecommons.org/licenses/by-nc-nd/4.0/">CC BY-NC-ND</a></span></figcaption></figure><p>How many intelligent civilisations should there be in our galaxy right now? In 1961, the US astrophysicist Frank Drake, who passed away on September 2 at the age of 92, came up with an <a href="https://theconversation.com/where-is-everybody-doing-the-maths-on-extraterrestrial-life-3390">equation to estimate this</a>. The Drake equation, dating from a stage in his career when he was “too naive to be nervous” (as he later put it), has become famous and bears his name.</p>
<p>This places Drake in the company of towering physicists with equations named after them including James Clerk Maxwell and Erwin Schrödinger. Unlike those, Drake’s equation does not encapsulate a law of nature. Instead it combines some poorly known probabilities into an informed estimate. </p>
<p>Whatever reasonable values you feed into the equation (see image below) it is hard to avoid the conclusion that we shouldn’t be alone in the galaxy. Drake remained a proponent and a supporter of the search for extraterrestrial life throughout his days, but has his equation really taught us anything?</p>
<figure class="align-center ">
<img alt="N = R∗ ⋅ fp ⋅ ne ⋅ fl ⋅ fi ⋅ fc ⋅ L" src="https://images.theconversation.com/files/482606/original/file-20220903-13447-vjbyw6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/482606/original/file-20220903-13447-vjbyw6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=242&fit=crop&dpr=1 600w, https://images.theconversation.com/files/482606/original/file-20220903-13447-vjbyw6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=242&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/482606/original/file-20220903-13447-vjbyw6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=242&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/482606/original/file-20220903-13447-vjbyw6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=304&fit=crop&dpr=1 754w, https://images.theconversation.com/files/482606/original/file-20220903-13447-vjbyw6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=304&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/482606/original/file-20220903-13447-vjbyw6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=304&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The expanded Drake equation.</span>
<span class="attribution"><span class="license">Author provided</span></span>
</figcaption>
</figure>
<p>Drake’s equation may look complicated, but its principles are really rather simple. It states that, in a galaxy as old as ours, the number of civilisations that are detectable by virtue of them broadcasting their presence must equate to the rate at which they arise, multiplied by their average lifetime.</p>
<p>Putting a value on the rate at which civilisations occur might seem to be guesswork, but Drake realised that it can be broken down into more tractable components.</p>
<p>He stated that the total rate is equal to the rate at which suitable stars are formed, multiplied by the fraction of those stars that have planets. This is then multiplied by the number of planets that are capable of bearing life per system, times the fraction of those planets where life gets started, multiplied by the fraction of those where life becomes intelligent, times the fraction of those that broadcast their presence.</p>
<h2>Tricky values</h2>
<figure class="align-right ">
<img alt="Frank Drake." src="https://images.theconversation.com/files/482781/original/file-20220905-2133-j7iuee.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/482781/original/file-20220905-2133-j7iuee.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=775&fit=crop&dpr=1 600w, https://images.theconversation.com/files/482781/original/file-20220905-2133-j7iuee.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=775&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/482781/original/file-20220905-2133-j7iuee.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=775&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/482781/original/file-20220905-2133-j7iuee.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=973&fit=crop&dpr=1 754w, https://images.theconversation.com/files/482781/original/file-20220905-2133-j7iuee.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=973&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/482781/original/file-20220905-2133-j7iuee.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=973&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Frank Drake.</span>
<span class="attribution"><span class="source">wikipedia</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>When Drake first formulated his equation, the only term that was known with any confidence was the rate of star formation – about 30 per year. </p>
<p>As for the next term, back in the 1960s, we had no evidence that any other stars have planets, and one in ten may have seemed like an optimistic guess. However, observational discoveries of exoplanets (planets orbiting other stars) that began in the 1990s and <a href="https://theconversation.com/more-than-1-000-new-exoplanets-discovered-but-still-no-earth-twin-59274">have blossomed this century</a> now makes us confident that most stars have planets. </p>
<p>Common sense suggests that most systems of multiple planets would include one at the right distance from its star to be capable of supporting life. Earth is that planet in our solar system. In addition, Mars may have been suitable for abundant life in the past – and it <a href="https://theconversation.com/mars-mounting-evidence-for-subglacial-lakes-but-could-they-really-host-life-146732">could still be clinging on</a>. </p>
<p>Today we also realise that planets don’t need to be warm enough for liquid water to exist at the surface to support life. It can occur <a href="https://theconversation.com/nasa-considers-sending-swimming-robots-to-habitable-ocean-worlds-of-the-solar-system-186228">in the internal ocean of an ice-covered body</a>, supported by heat generated either by radioctivity or tides rather than sunlight. </p>
<p>There are several likely candidates among the moons of Jupiter and Saturn, for example. In fact, when we add moons as being capable of hosting life, the average number of habitable bodies per planetary system could easily exceed one. </p>
<p>The values of the terms towards the right hand side of the equation, however, remain more open to challenge. Some would hold that, given a few million years to play with, life will get started anywhere that is suitable.</p>
<p>That would be mean that the fraction of suitable bodies where life actually gets going is pretty much equal to one. Others say that we have as yet no proof of life starting anywhere other than Earth, and that the origin of life could actually be an exceedingly rare event.</p>
<p>Will life, once started, eventually evolve intelligence? It probably has to get past the microbial stage and become multicellular first. </p>
<p>There is evidence that <a href="https://www.nature.com/scitable/content/multicellularity-evolved-from-multiple-independent-origins-14458921/">multicellular life started more than once</a> on Earth, so becoming multicellular may not be a barrier. Others, however, point out that on Earth the <a href="https://theconversation.com/evolution-tells-us-we-might-be-the-only-intelligent-life-in-the-universe-124706">“right kind” of multicellular life</a>, which continued to evolve, appeared only once and could be rare on the galactic scale. </p>
<p>Intelligence may confer a competitive advantage over other species, meaning its evolution could be rather likely. But we don’t know for sure. </p>
<p>And will intelligent life develop technology to the stage where it (accidentally or deliberately) broadcasts its existence across space? Perhaps for surface-dwellers such as ourselves, but it might be rare for inhabitants of internal oceans of frozen worlds with no atmosphere.</p>
<h2>How long do civilisations last?</h2>
<p>What about the average lifetime of a detectable civilisation, <em>L</em>? Our TV transmissions began to make Earth detectable from afar in the 1950s, giving a minimum value for <em>L</em> of about 70 years in our own case. </p>
<p>In general though, <em>L</em> may be limited by the collapse of civilisation (what are the odds of our own lasting a further 100 years?) or by the near total demise of radio broadcasting in favour of the internet, or by a <a href="https://theconversation.com/blasting-out-earths-location-with-the-hope-of-reaching-aliens-is-a-controversial-idea-two-teams-of-scientists-are-doing-it-anyway-182036">deliberate choice to “go quiet”</a> for fear of hostile galactic inhabitants.</p>
<p>Play with the numbers yourself - it’s fun! You’ll find that if <em>L</em> is more than 1,000 years, <em>N</em> (the number of detectable civilisations) is likely to be greater than a hundred. In <a href="https://www.youtube.com/watch?v=_RcMrb9ve_k">an interview recorded in 2010</a>, Drake said his best guess at <em>N</em> was about 10,000.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/_RcMrb9ve_k?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
</figure>
<p>We are learning more about exoplanets every year, and are entering an era when <a href="https://theconversation.com/to-search-for-alien-life-astronomers-will-look-for-clues-in-the-atmospheres-of-distant-planets-and-the-james-webb-space-telescope-just-proved-its-possible-to-do-so-184828">measuring their atmospheric composition</a> to reveal evidence of life is becoming increasingly feasible. Within the next decade or two, we can hope for a much more soundly based estimate of the fraction of Earth-like planets where life gets started. </p>
<p>This won’t tell us about life in the internal oceans, but we can hope for insights into that from missions to the icy moons of <a href="https://theconversation.com/europa-there-may-be-life-on-jupiters-moon-and-two-new-missions-will-pave-the-way-for-finding-it-122551">Jupiter</a>, <a href="https://theconversation.com/nasa-saturn-moon-enceladus-is-able-to-host-life-its-time-for-a-new-mission-76102">Saturn</a> and <a href="https://theconversation.com/jupiter-saturn-uranus-neptune-why-our-next-visit-to-the-giant-planets-will-be-so-important-and-just-as-difficult-175918">Uranus</a>. And we could, of course, detect actual signals from extraterrestrial intelligence.</p>
<p>Either way, Frank Drake’s equation, which has stimulated so many lines of research, will continue to give us a thought-provoking sense of perspective. For that we should be grateful.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/seti-why-extraterrestrial-intelligence-is-more-likely-to-be-artificial-than-biological-169966">Seti: why extraterrestrial intelligence is more likely to be artificial than biological</a>
</strong>
</em>
</p>
<hr>
<img src="https://counter.theconversation.com/content/189935/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 from 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>Research on exoplanets over the next couple of decades could help us more accurately estimate how many intelligent alien civilisations there are in our galaxy.David Rothery, Professor of Planetary Geosciences, The Open UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1862282022-07-04T13:13:01Z2022-07-04T13:13:01ZNasa considers sending swimming robots to habitable ‘ocean worlds’ of the Solar System<figure><img src="https://images.theconversation.com/files/472142/original/file-20220702-5543-5lvwti.jpg?ixlib=rb-1.1.0&rect=541%2C0%2C1355%2C576&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Realistic colour view of Jupiter's moon Europa.</span> <span class="attribution"><a class="source" href="https://photojournal.jpl.nasa.gov/jpeg/PIA19048.jpg">NASA/JPL-Caltech/SETI Institute</a></span></figcaption></figure><p>Nasa has recently <a href="https://www.jpl.nasa.gov/news/swarm-of-tiny-swimming-robots-could-look-for-life-on-distant-worlds">announced US$600,000 (£495,000) in funding for a study</a> into the feasibility of sending swarms of miniature swimming robots (known as independent micro-swimmers) to explore oceans beneath the icy shells of our Solar System’s many “ocean worlds”. But don’t imagine metal humanoids swimming frog-like underwater. They will probably be simple, triangular wedges.</p>
<p><a href="https://theconversation.com/life-inside-pluto-hot-birth-may-have-created-internal-ocean-on-dwarf-planet-140976">Pluto</a> is one example of a likely ocean world. But the worlds with oceans nearest to the surface, making them the most accessible, are <a href="https://theconversation.com/new-water-plumes-from-jupiters-moon-europa-raise-hopes-of-detecting-microbial-life-66019">Europa</a>, a moon of Jupiter, and <a href="https://theconversation.com/the-chemistry-that-could-feed-life-within-saturns-moon-enceladus-study-gives-clue-ahead-of-flyby-49683">Enceladus</a>, a moon of Saturn.</p>
<figure class="align-center ">
<img alt="Impression showing the cross-section of Europa." src="https://images.theconversation.com/files/139258/original/image-20160926-31840-4e1ocg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/139258/original/image-20160926-31840-4e1ocg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=405&fit=crop&dpr=1 600w, https://images.theconversation.com/files/139258/original/image-20160926-31840-4e1ocg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=405&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/139258/original/image-20160926-31840-4e1ocg.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=405&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/139258/original/image-20160926-31840-4e1ocg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=508&fit=crop&dpr=1 754w, https://images.theconversation.com/files/139258/original/image-20160926-31840-4e1ocg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=508&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/139258/original/image-20160926-31840-4e1ocg.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=508&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Cross-section through the outer zone of Europa’s south polar region showing plumes, the fractured ice shell, the liquid water ocean (cloudy at the base near hydrothermal plumes) and the rocky interior.</span>
<span class="attribution"><a class="source" href="http://www.nasa.gov/topics/solarsystem/features/pia16826.html">Nasa/JPL</a></span>
</figcaption>
</figure>
<h2>Life inside ocean worlds</h2>
<p>These oceans are of interest to scientists not just because they contain so much liquid water (Europa’s ocean probably has about <a href="https://solarsystem.nasa.gov/moons/jupiter-moons/europa/in-depth/">twice as much water</a> as the whole of Earth’s oceans), but because chemical interactions between rock and the ocean water could support life. In fact, the environment in these oceans may be very similar to that on Earth <a href="https://theconversation.com/origins-of-life-new-evidence-first-cells-could-have-formed-at-the-bottom-of-the-ocean-126228">at the time life began</a>.</p>
<p>These are environments where water that has seeped into the rock of the ocean floor becomes hot and chemically enriched – water that is then expelled back into the ocean. Microbes can feed off this chemical energy, and can in turn be eaten by larger organisms. No sunlight or atmosphere is actually needed. Many warm, rocky structures of this sort, known as “hydrothermal vents”, have been documented on Earth’s ocean floors since they <a href="https://www.nhm.ac.uk/discover/survival-at-hydrothermal-vents.html">were discovered in 1977</a>. In these locations, the local food web is indeed supported by chemosynthesis (energy from chemical reactions) rather than photosynthesis (energy from sunlight).</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/472087/original/file-20220701-11-vo5zyy.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Image of a vent on the Earth’s ocean floor." src="https://images.theconversation.com/files/472087/original/file-20220701-11-vo5zyy.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/472087/original/file-20220701-11-vo5zyy.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/472087/original/file-20220701-11-vo5zyy.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/472087/original/file-20220701-11-vo5zyy.JPG?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/472087/original/file-20220701-11-vo5zyy.JPG?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/472087/original/file-20220701-11-vo5zyy.JPG?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/472087/original/file-20220701-11-vo5zyy.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">A vent on the floor of the northeast Pacific. A bed of tube worms feeding on chemosynthetic microbes covers the base.</span>
<span class="attribution"><span class="source">NOAA/PMEL</span></span>
</figcaption>
</figure>
<p>In most of our Solar System’s ocean worlds, the energy that heats their rocky interiors and prevents the oceans from freezing all the way to the base comes principally from tides. This is in contrast to the largely radioactive heating of the Earth’s interior. But the chemistry of the water-rock interactions is similar.</p>
<p>Enceladus’s ocean has already been sampled <a href="https://theconversation.com/nasa-saturn-moon-enceladus-is-able-to-host-life-its-time-for-a-new-mission-76102">by flying the Cassini spacecraft through plumes</a> of ice crystals that erupt through cracks in the ice. And there are hopes that Nasa’s <a href="https://europa.nasa.gov/">Europa Clipper mission</a> may find similar plumes to sample when it begins a series of close Europa flybys in 2030. However, getting inside the ocean to go exploring would potentially be much more informative than merely sniffing at a freeze-dried sample.</p>
<figure class="align-center ">
<img alt="Artist’s impression of swimming robotic devices." src="https://images.theconversation.com/files/472141/original/file-20220702-24-5c4qf4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/472141/original/file-20220702-24-5c4qf4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=911&fit=crop&dpr=1 600w, https://images.theconversation.com/files/472141/original/file-20220702-24-5c4qf4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=911&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/472141/original/file-20220702-24-5c4qf4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=911&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/472141/original/file-20220702-24-5c4qf4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1145&fit=crop&dpr=1 754w, https://images.theconversation.com/files/472141/original/file-20220702-24-5c4qf4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1145&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/472141/original/file-20220702-24-5c4qf4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1145&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A lander of Europa uses a probe to melt a hole through the ice, which then releases a swarm of swimming robots. Conceptual impression, not to scale.</span>
<span class="attribution"><span class="source">Nasa/JPL-Caltech</span></span>
</figcaption>
</figure>
<h2>In the Swim</h2>
<p>This is where the <a href="https://www.jpl.nasa.gov/news/swarm-of-tiny-swimming-robots-could-look-for-life-on-distant-worlds">sensing with independent micro-swimmers (Swim)</a> concept comes. The idea is to land on Europa or Enceladus (which would be neither cheap nor easy) at a place where the ice is relatively thin (not yet located) and use a radioactively heated probe to melt a 25cm-wide hole through to the ocean – located hundreds or thousands of metres below.</p>
<p>Once there, it would release up to about four dozen 12cm long, wedge-shaped micro-swimmers to go exploring. Their endurance would be much less than that of the 3.6m long autonomous underwater vehicle famously named <a href="https://noc.ac.uk/education/educational-resources/boaty-mcboatface">Boaty McBoatface</a>, with a range of 2,000km that has already achieved a cruise of more than 100km below the Antarctic ice.</p>
<figure class="align-center ">
<img alt="Artist’s impression of swimming robotic devices, deployed from a probe that has penetrated the ice crust of a moon." src="https://images.theconversation.com/files/472081/original/file-20220701-20-fpy5b5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/472081/original/file-20220701-20-fpy5b5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=345&fit=crop&dpr=1 600w, https://images.theconversation.com/files/472081/original/file-20220701-20-fpy5b5.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=345&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/472081/original/file-20220701-20-fpy5b5.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=345&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/472081/original/file-20220701-20-fpy5b5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=434&fit=crop&dpr=1 754w, https://images.theconversation.com/files/472081/original/file-20220701-20-fpy5b5.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=434&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/472081/original/file-20220701-20-fpy5b5.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=434&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Independent micro-swimmers, deployed from a probe that has penetrated the ice crust of a moon. Not to scale.</span>
<span class="attribution"><span class="source">Nasa/JPL</span></span>
</figcaption>
</figure>
<p>At this stage, Swim is merely one of five “phase 2 studies” into a range of “advanced concepts” funded in the 2022 round of Nasa’s <a href="https://www.nasa.gov/directorates/spacetech/niac/index.html">Innovative Advanced Concepts (NIAC) programme</a>. So there are still long odds against Swim becoming a reality, and no complete mission has been scoped out or funded.</p>
<p>The micro-swimmers would communicate with the probe acoustically (through sound waves), and the probe would send its data via cable to the lander on the surface. The study will trial prototypes in a test tank with all subsystems integrated. </p>
<p>Each micro-swimmer could explore maybe only tens of metres away from the probe, limited by their battery power and the range of their acoustic data link, but by acting as a flock they could map changes (in time or location) in temperature and salinity. They may even be able to measure changes in the <a href="https://www.geo-ocean.fr/en/Science-pour-tous/Nos-salles-d-etudes/Systemes-hydrothermaux/Hydrothermalism/Plumes">cloudiness of the water</a>, which could indicate the direction towards the nearest hydrothermal vent.</p>
<p>Power limitations of the micro-swimmers may mean that none could carry cameras (these would need their own light source) or sensors that could specifically sniff out organic molecules, though. But at this stage, nothing is ruled out.</p>
<p>I think finding signs of hydrothermal vents is a long shot, however. The ocean floor would, after all, be many kilometres below the micro-swimmer’s release point. But, to be fair, pinpointing vents is not explicitly suggested in the Swim proposal. To locate and examine the vents themselves, we probably do need Boaty McBoatface in space. That said, Swim would be a good start.</p><img src="https://counter.theconversation.com/content/186228/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 from 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>There may be life on Jupiter’s moon Europa or Saturn moon’s Enceladus.David Rothery, Professor of Planetary Geosciences, The Open UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1851652022-06-16T04:37:39Z2022-06-16T04:37:39ZDid a giant radio telescope in China just discover aliens? Not so FAST…<blockquote>
<p>“Extraordinary claims require extraordinary evidence.”<br>
– <cite>Carl Sagan (Cosmos, 1980)</cite></p>
</blockquote>
<p>This phrase is the <a href="https://en.wikipedia.org/wiki/Sagan_standard">standard</a> that astronomers will be applying to a curious signal captured with China’s “Sky Eye” telescope that <em>might</em> be a transmission from alien technology. </p>
<p>An article reporting the signal was posted on the website of China’s state-backed Science and Technology Daily newspaper, <a href="https://www.bloomberg.com/news/articles/2022-06-15/china-says-it-may-have-detected-signals-from-alien-civilizations">but was later removed.</a> So have astronomers finally found evidence of intelligent found life beyond Earth? And is it being hushed up?</p>
<p>We should be intrigued, but not too excited (yet). An interesting signal has to go through a lot of tests to check whether it truly carries the signature of extraterrestrial technology or is just the result of an unexpected source of terrestrial interference. </p>
<p>And as for the deletion: media releases are normally timed for simultaneous release with peer-reviewed results – which are not yet available – so it was likely just released a bit early by mistake. </p>
<h2>An eye on the sky</h2>
<p>Sky Eye, which is offically known as the <a href="https://en.wikipedia.org/wiki/Five-hundred-meter_Aperture_Spherical_Telescope">Five-hundred-meter Aperture Spherical Telescope (FAST)</a>, is the the largest and most sensitive single-dish radio telescope in the world. A engineering marvel, its gargantuan structure is built inside a natural basin in the mountains of <a href="https://goo.gl/maps/wd25oAxVWSV9Ddnf8">Guizhou, China</a>. </p>
<p>The telescope is so huge it can’t be physically tilted, but it can be pointed in a direction by thousands of actuators that deform the telescope’s reflective surface. By deforming the surface, the location of the telescope’s focal point changes, and the telescope can look at a different part of the sky.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/china-completes-worlds-largest-radio-telescope-raising-hopes-of-finding-new-worlds-and-alien-life-62237">China completes world's largest radio telescope – raising hopes of finding new worlds and alien life</a>
</strong>
</em>
</p>
<hr>
<p>FAST detects radiation at radio wavelengths (up to 10 cm) and is used for astronomical research in a wide range of areas. One area is the search for extraterrestrial intelligence, or SETI. </p>
<p>SETI observations are mainly done in “piggy-back” mode, which means they are taken while the telescope is also running its primary science programs. In this way, large swaths of the sky can be scanned for signs of alien technology – or “technosignatures” – without getting in the way of other science operations. For special targets like nearby exoplanets, dedicated SETI observations are still carried out.</p>
<h2>The hunt for alien technology</h2>
<p>Technosignature searches have been ongoing since the 1960s, when the American astronomer <a href="https://en.wikipedia.org/wiki/Frank_Drake">Frank Drake</a> pointed the <a href="https://public.nrao.edu/telescopes/tatel/">26-metre Tatel telescope</a> toward two nearby Sun-like stars and scanned them for signs of technology. </p>
<p>Over the years, technosignature searches have become far more rigorous and sensitive. The systems in place at FAST are also able to process billions of times more of the radio spectrum than Drake’s experiment. </p>
<p>Despite these advances, we haven’t yet found any evidence of life beyond Earth.</p>
<p>FAST sifts through enormous amounts of data. The telescope feeds 38 billion samples a second into a cluster of high-performance computers, which then produces exquisitely detailed charts of incoming radio signals. These charts are then searched for signals that look like technosignatures. </p>
<p>With such a large collecting area, FAST can pick up incredibly faint signals. It is about 20 times more sensitive than Australia’s Murriyang telescope at the Parkes Radio Observatory. FAST could easily detect a transmitter on a nearby exoplanet with a similar output power to radar systems we have here on Earth. </p>
<h2>The trouble with sensitivity</h2>
<p>The trouble with being so sensitive is that you can uncover radio interference that would otherwise be too faint to detect. We SETI researchers have had this problem before. </p>
<p>Last year, using Murriyang, we detected an extremely interesting signal we called <a href="https://theconversation.com/a-mysterious-signal-looked-like-a-sign-of-alien-technology-but-it-turned-out-to-be-radio-interference-170548">BLC1</a>. </p>
<p>However, it turned out to be very strange interference (not aliens). To uncover its true nature, we had to develop a <a href="https://seti.berkeley.edu/blc1/flowchart.html">new verification framework</a>. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/469059/original/file-20220615-3512-8jqevi.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Technosignature verification flowchart" src="https://images.theconversation.com/files/469059/original/file-20220615-3512-8jqevi.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/469059/original/file-20220615-3512-8jqevi.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/469059/original/file-20220615-3512-8jqevi.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/469059/original/file-20220615-3512-8jqevi.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/469059/original/file-20220615-3512-8jqevi.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/469059/original/file-20220615-3512-8jqevi.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/469059/original/file-20220615-3512-8jqevi.png?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">A flowchart for verifying candidate technosignatures, developed for BLC1.</span>
<span class="attribution"><span class="source">Sofia Sheikh (SETI Institute)</span></span>
</figcaption>
</figure>
<p>With BLC1, it took about a year from when it was initially reported to when peer-reviewed analysis was published. Similarly, we may need to wait a while for the FAST signal to be analysed in depth. </p>
<p>Professor Zhang Tongjie, chief scientist for the China Extraterrestrial Civilization Research Group, acknowledged this in the Science & Technology Daily report: </p>
<blockquote>
<p>The possibility that the suspicious signal is some kind of radio interference is also very high, and it needs to be further confirmed and ruled out. This may be a long process.</p>
</blockquote>
<p>And we may need to get used to a gap between finding candidate signals and verifying them. FAST and other telescopes are likely to find many more signals of interest. </p>
<p>Most of these will turn out to be interference, but some may be new astrophysical phenomena, and some may be <em>bona fide</em> technosignatures.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/a-mysterious-signal-looked-like-a-sign-of-alien-technology-but-it-turned-out-to-be-radio-interference-170548">A mysterious signal looked like a sign of alien technology — but it turned out to be radio interference</a>
</strong>
</em>
</p>
<hr>
<h2>Stay intrigued</h2>
<p>Will FAST’s extraordinary signals meet the burden of extraordinary evidence? Until their work is reviewed and published, it’s still too early to say, but it’s encouraging that their SETI search algorithms are finding curious signals. </p>
<p>Between FAST, the <a href="https://breakthroughinitiatives.org/initiative/1">Breakthrough Listen</a> initiative, and the SETI Institute’s <a href="https://www.seti.org/press-release/cosmic-all-antennas-very-large-array-ready-stream-data-technosignature-research">COSMIC</a> program, the SETI field is seeing a lot of interest and activity. And it’s not just radio waves: searches are also underway using <a href="https://oirlab.ucsd.edu/PANOSETI.html">optical and infrared light</a>. </p>
<p>As for right now: stay intrigued, but don’t get too excited.</p><img src="https://counter.theconversation.com/content/185165/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Danny C Price is Australian Project Scientist for the Breakthrough Listen initiative.</span></em></p>Have astronomers finally found evidence of intelligent found life beyond Earth?Danny C Price, Senior research fellow, Curtin UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1835622022-05-25T10:57:30Z2022-05-25T10:57:30ZA ‘doorway’ on Mars? How we see things in space that aren’t there<figure><img src="https://images.theconversation.com/files/464594/original/file-20220521-19-9cg9h2.jpeg?ixlib=rb-1.1.0&rect=65%2C34%2C1808%2C642&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A panorama stitched together from about 100 individual Curiosity images. The 'door' is circled, and is tiny and hard to see at this scale.</span> <span class="attribution"><a class="source" href="https://mars.nasa.gov/resources/26754/door-shaped-fracture-spotted-by-curiosity-at-east-cliffs/">NASA/JPL-Caltech/MSSS</a></span></figcaption></figure><p>Enthusiasts lit up social media recently with images of what appeared to be a “doorway” into a hillside on Mars. Was it, some wondered, evidence that the red planet could be, or have been, inhabited by aliens? The “door” was imaged by Nasa’s Curiosity rover on May 7 on the slopes of Mount Sharp, the central massif within Gale crater, where it landed in 2012. Described on one website as a “<a href="https://thinis.net/pharaonic-tomb-door-on-mars/">pharaonic tomb door</a>”, because of its resemblance to some ancient Egyptian remains, it is in fact only about one foot high.</p>
<p>It is hard to spot on the panoramic image mosaic of the hillside above, but it leaps out at the eye if you see the individual frame where it occurs, seen below. It does look like a doorway until you realise how small it is. And if you boost the contrast in the dark parts of the image, the picture just about reveals a solid rock face at the back of the shadowed interior. So as a gateway into the hollow hills of Mars, it doesn’t lead very far.</p>
<figure class="align-center ">
<img alt="Image of the 'door' in black and white." src="https://images.theconversation.com/files/464596/original/file-20220521-14810-plryu4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/464596/original/file-20220521-14810-plryu4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=535&fit=crop&dpr=1 600w, https://images.theconversation.com/files/464596/original/file-20220521-14810-plryu4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=535&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/464596/original/file-20220521-14810-plryu4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=535&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/464596/original/file-20220521-14810-plryu4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=672&fit=crop&dpr=1 754w, https://images.theconversation.com/files/464596/original/file-20220521-14810-plryu4.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=672&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/464596/original/file-20220521-14810-plryu4.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=672&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Raw Curiosity camera image centred on the ‘door’.</span>
<span class="attribution"><span class="source">Nasa/JPL-Caltech/MSSS</span></span>
</figcaption>
</figure>
<h2>What the “door” really is</h2>
<p>Nobody with even a little geological experience is likely to mistake the feature as a “door”. A geologist would note the thin and slightly sloping repeated layers of sandstone making up the whole of the rock face, and would immediately expect that they were looking at the eroded remains of hardened sand dunes. These once covered the stream and lake sediments that <a href="https://theconversation.com/rover-detects-ancient-organic-material-on-mars-and-it-could-be-trace-of-past-life-97755">Curiosity examined earlier</a> in its gradual climb up through the layers of sedimentary rock making up Mount Sharp.</p>
<p>A geologist would also spot the steep and fairly straight cracks running up the rock face, and recognise these as “joints”. These are fractures that typically open up when the weight of overlying rock layers is removed by erosion. There is a particularly obvious joint in the left of the “door” image, but several others can be made out – including one that forms the smooth wall that lines up with the left side of the “door” itself. There’s another joint that forms the right side of the feature.</p>
<figure class="align-center ">
<img alt="Black and white detail of the 'door' with red lines added to show joints." src="https://images.theconversation.com/files/464597/original/file-20220521-16-to6nmg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/464597/original/file-20220521-16-to6nmg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=536&fit=crop&dpr=1 600w, https://images.theconversation.com/files/464597/original/file-20220521-16-to6nmg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=536&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/464597/original/file-20220521-16-to6nmg.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=536&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/464597/original/file-20220521-16-to6nmg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=673&fit=crop&dpr=1 754w, https://images.theconversation.com/files/464597/original/file-20220521-16-to6nmg.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=673&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/464597/original/file-20220521-16-to6nmg.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=673&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The raw image with red lines added to show some of the joints.</span>
<span class="attribution"><span class="source">Nasa/JPL-Caltech/MSSS</span></span>
</figcaption>
</figure>
<p>The whole hillside has been eroded back. The “doorway” is simply a place where the wind has been able to scour out the poorly consolidated sand and dust from the rock face a little more effectively, in an area bounded by the joints on either side. The base of an overlying bed of sandstone is the “door lintel”, and the sloping top of a bed of sandstone forms the gentle ramp that leads up to the door.</p>
<h2>Artefacts on Mars</h2>
<p>It doesn’t take much searching on the internet to find images taken by Mars rovers that show rock formations that resemble other familiar objects, even though all are implausibly out of place. We should not be surprised that some of the innumerable rocks on Mars have weird shapes, because many have been sandblasted by wind erosion for billions of years. </p>
<figure class="align-center ">
<img alt="Image of a long stone among several others looks superficially like a thigh bone." src="https://images.theconversation.com/files/464759/original/file-20220523-18-k5bah8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/464759/original/file-20220523-18-k5bah8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=536&fit=crop&dpr=1 600w, https://images.theconversation.com/files/464759/original/file-20220523-18-k5bah8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=536&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/464759/original/file-20220523-18-k5bah8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=536&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/464759/original/file-20220523-18-k5bah8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=673&fit=crop&dpr=1 754w, https://images.theconversation.com/files/464759/original/file-20220523-18-k5bah8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=673&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/464759/original/file-20220523-18-k5bah8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=673&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A bunch of stones scoured out by the wind on Mars. One in the middle looks like a thigh-bone from this angle.</span>
<span class="attribution"><span class="source">Nasa/JPL-Caltech/MSSS</span></span>
</figcaption>
</figure>
<p>Apart from “doors” and bits of “hardware” ranging from wrecked “spaceships” and a <a href="https://www.republicworld.com/technology-news/science/ufo-specialist-detects-ancient-alien-jet-engine-remains-on-mars.html">“jet engine”</a> to individual items of “cutlery”, images have also captured “pyramids”, numerous <a href="https://www.news.com.au/technology/science/archaeology/mars-female-warrior-statue-represents-everything-crazy-about-the-ancient-alien-crowd/news-story/de94bf2c89c04bb6b00cba0db966440e">“humanoid heads”</a>, “dinosaurs”, various “bones”, and even a <a href="https://gizmodo.com/the-weirdest-images-ever-taken-on-mars-1843445035">“squirrel”</a>. Only a few of these strange objects are real, and those are all junk that humans put there. The others lose their visual distinctiveness if seen at closer range or from a different perspective. </p>
<figure class="align-center ">
<img alt="Image of wreckage, deliberately crashed on Mars, seen from above." src="https://images.theconversation.com/files/464760/original/file-20220523-29403-smhn9r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/464760/original/file-20220523-29403-smhn9r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=430&fit=crop&dpr=1 600w, https://images.theconversation.com/files/464760/original/file-20220523-29403-smhn9r.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=430&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/464760/original/file-20220523-29403-smhn9r.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=430&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/464760/original/file-20220523-29403-smhn9r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=541&fit=crop&dpr=1 754w, https://images.theconversation.com/files/464760/original/file-20220523-29403-smhn9r.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=541&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/464760/original/file-20220523-29403-smhn9r.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=541&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">A genuine alien artefact on Mars: the backshell of the Perseverance lander, jettisoned prior to landing.</span>
<span class="attribution"><span class="source">Nasa/JPL-Caltech</span></span>
</figcaption>
</figure>
<h2>Weirdness beyond Mars</h2>
<p>“Seeing” the familiar even when it isn’t there is a phenomenon called <a href="https://mars.nasa.gov/multimedia/space-oddities/">pareidolia</a>. This denotes what happens when you see faces in the random pattern of your wallpaper, or peering out from the <a href="https://www.mirror.co.uk/news/weird-news/woman-stitches-after-finding-face-27038975">grain of wooden flooring</a>, or in the clouds. The latter, for example, is what’s causing Jupiter to look angry in the image below. </p>
<figure class="align-center ">
<img alt="Image of a part of Jupiter, where the clouds look like an angry face." src="https://images.theconversation.com/files/464771/original/file-20220523-18-do8uey.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/464771/original/file-20220523-18-do8uey.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/464771/original/file-20220523-18-do8uey.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/464771/original/file-20220523-18-do8uey.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/464771/original/file-20220523-18-do8uey.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/464771/original/file-20220523-18-do8uey.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/464771/original/file-20220523-18-do8uey.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">
<figcaption>
<span class="caption">Jupiter looking angry, imaged by Nasa’s JunoCam on 19 May 2017.</span>
<span class="attribution"><span class="source">Nasa/JPL-Caltech/SwRI/MSSS/Jason Major</span></span>
</figcaption>
</figure>
<p>Seemingly mysterious objects don’t occur solely on Mars. In December 2021, <a href="https://theconversation.com/china-lands-on-the-far-side-of-moon-here-is-the-science-behind-the-mission-108566">China’s Chang'e 4 rover </a> – still doing great things on the on the lunar far side more than three years after landing – spotted a <a href="https://www.space.com/china-yutu-2-moon-rover-cube-shaped-object-photos">“hut shaped” object</a> 80 metres away. It duly trundled towards it, and revealed it to be just a boulder, presumably ejected from a nearby impact crater. Some say it looks like a crouching rabbit, but I doubt anyone is claiming that it was sculpted by aliens.</p>
<figure class="align-center ">
<img alt="Distant view by the Chang'e 4 rover showing the 'hut' like rock 80 m away, plus a close up view when it got there." src="https://images.theconversation.com/files/464787/original/file-20220523-43418-k5lek2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/464787/original/file-20220523-43418-k5lek2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=374&fit=crop&dpr=1 600w, https://images.theconversation.com/files/464787/original/file-20220523-43418-k5lek2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=374&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/464787/original/file-20220523-43418-k5lek2.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=374&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/464787/original/file-20220523-43418-k5lek2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=470&fit=crop&dpr=1 754w, https://images.theconversation.com/files/464787/original/file-20220523-43418-k5lek2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=470&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/464787/original/file-20220523-43418-k5lek2.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=470&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Distant view by the Chang'e 4 rover showing the hut-like rock 80m away, plus a close up view when it got there.</span>
<span class="attribution"><span class="source">CNSA/CLEP</span></span>
</figcaption>
</figure>
<p>One of the most famous, and largest, examples of pareidolia is the Horsehead Nebula. This is a vast cosmic cloud of gas and dust, within which whole stellar systems are forming. An image collected in the right part of the spectrum and with an appropriate exposure time shows a shape that most people would recognise as a horse’s head. Shift wavelengths (which we can do) or look at it from a different direction (which we can’t) and the recognisable shape will vanish.</p>
<figure class="align-center ">
<img alt="Image of a dark nebula in the shape of a horse's head" src="https://images.theconversation.com/files/464845/original/file-20220523-30932-px0mdh.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/464845/original/file-20220523-30932-px0mdh.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=616&fit=crop&dpr=1 600w, https://images.theconversation.com/files/464845/original/file-20220523-30932-px0mdh.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=616&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/464845/original/file-20220523-30932-px0mdh.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=616&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/464845/original/file-20220523-30932-px0mdh.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=775&fit=crop&dpr=1 754w, https://images.theconversation.com/files/464845/original/file-20220523-30932-px0mdh.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=775&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/464845/original/file-20220523-30932-px0mdh.jpeg?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">
<figcaption>
<span class="caption">The Horsehead nebula in Orion, imaged in the visible part of the spectrum.</span>
<span class="attribution"><span class="source">ESO</span></span>
</figcaption>
</figure>
<p>Back on Earth, climbers high on <a href="https://www.stridingedge.net/walks/8308/">Great Gable</a>, a mountain in Cumbria, UK, often look out for Cat Rock, otherwise known as Sphinx Rock. Seen from below this looks like a sitting cat, and seen side-on it resembles the profile of the Sphinx’s head. So far as I know, everyone accepts this as fluke and no one claims it as evidence that aliens have left landscape clues to their visits to Earth. It beats me why people persist in making such claims for flukey rock formations on Mars.</p>
<p>Ultimately, although you can generally believe your eyes, you should be cautious in believing your brain’s interpretation of what your eyes see.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/perseverance-mars-rover-how-to-prove-whether-theres-life-on-the-red-planet-154982">Perseverance Mars rover: how to prove whether there’s life on the red planet</a>
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</p>
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<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/mushrooms-on-mars-five-unproven-claims-that-alien-life-exists-161366">Mushrooms on Mars? Five unproven claims that alien life exists</a>
</strong>
</em>
</p>
<hr>
<img src="https://counter.theconversation.com/content/183562/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 from 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>We should not be surprised that some of the innumerable rocks on Mars have weird shapes, because many have been sand-blasted by wind erosion for billions of years.David Rothery, Professor of Planetary Geosciences, The Open UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1834462022-05-23T03:33:48Z2022-05-23T03:33:48ZDid NASA find a mysterious doorway on Mars? No, but that’s no reason to stop looking<figure><img src="https://images.theconversation.com/files/464681/original/file-20220522-20-amoytm.jpg?ixlib=rb-1.1.0&rect=0%2C7%2C1326%2C1174&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://mars.nasa.gov/raw_images/1064629/">NASA/JPL-Caltech/MSSS</a></span></figcaption></figure><p>For the past ten years, <a href="https://mars.nasa.gov/msl/home/">NASA’s Curiosity rover</a> has been trundling around the surface of Mars, taking photos in its quest to understand the history and geology of the red planet and perhaps even find signs of life. </p>
<p>Last week it took a photo which appeared to show a doorway carved into the rock. It’s the sort of thing that on Earth might indicate an underground bunker, such as an air-raid shelter. </p>
<h2>Seeing is not always believing</h2>
<p>At first sight, the picture is totally convincing. At second sight, maybe not. The passage seems to go in only a short way before the steeply descending roof meets the floor. </p>
<p>And then those killjoys at NASA tell us its only about 45 cm high. Still, who said Martians had to be the same height as us? But <em>then</em> <a href="https://mars.nasa.gov/resources/26754/door-shaped-fracture-spotted-by-curiosity-at-east-cliffs/">geologists point out</a> several straight-line fractures can be seen in this site, and the “doorway” is where they happen to intersect. </p>
<p>Such a pity. It would have been so exciting if it had been a real doorway. Instead it joins the <a href="https://en.wikipedia.org/wiki/Cydonia_(Mars)#%22Face_on_Mars%22">face on Mars</a>, the <a href="https://mars.nasa.gov/resources/7457/spooner-or-later/?site=msl">spoon on Mars</a>, the <a href="https://www.nytimes.com/2022/01/07/science/moon-cube-china-rover.html">cube on the Moon</a>, and all the other things seen in photos from space that turn out not to be as exciting as we thought. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/464683/original/file-20220522-56160-gdlrix.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/464683/original/file-20220522-56160-gdlrix.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/464683/original/file-20220522-56160-gdlrix.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=174&fit=crop&dpr=1 600w, https://images.theconversation.com/files/464683/original/file-20220522-56160-gdlrix.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=174&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/464683/original/file-20220522-56160-gdlrix.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=174&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/464683/original/file-20220522-56160-gdlrix.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=218&fit=crop&dpr=1 754w, https://images.theconversation.com/files/464683/original/file-20220522-56160-gdlrix.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=218&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/464683/original/file-20220522-56160-gdlrix.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=218&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 face on Mars, the spoon on Mars, and the cube on the Moon. On closer examination, each turned out to be a natural geological formation.</span>
<span class="attribution"><span class="source">NASA, NASA, CNSA</span></span>
</figcaption>
</figure>
<h2>Faces in the clouds</h2>
<p>Worse, the “doorway” joins the even longer list of wacky images like the <a href="https://www.theage.com.au/national/victoria/flaky-bidders-battle-over-corny-piece-of-australiana-20110909-1k0ka.html">cornflake that looks like Australia</a>, the <a href="https://en.wikipedia.org/wiki/Cats_That_Look_Like_Hitler">cats that look like Hitler</a>, and so on. And who hasn’t seen a face in the clouds?</p>
<p>The sad fact is that when presented with an unclear or unfamiliar image, humans try to turn it into a familiar-looking object. Scientists call our tendency to do this “<a href="https://en.wikipedia.org/wiki/Pareidolia">pareidolia</a>”. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/holy-grilled-cheese-sandwich-what-is-pareidolia-14170">Holy grilled cheese sandwich! What is pareidolia?</a>
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<p>It’s easy to understand why it happens. We <a href="https://newsroom.unsw.edu.au/news/science-tech/why-brain-programmed-see-faces-everyday-objects">likely evolved this tendency</a> because spotting important things like predators or faces, even when the light is poor or they are partly obscured, gave us an advantage. And getting false positives – seeing a predator where there is none – is better than not seeing a predator who then eats you.</p>
<h2>No signs of life</h2>
<p>Reasonable explanations won’t deter the <a href="https://www.telegraph.co.uk/news/2022/05/12/doorway-mars-leads-fresh-conspiracy-theories-scientists-quickly/">conspiracy theorists</a> who say the doorway really is evidence of life on Mars, and maintain that scientists are engaged in some sort of cover-up. </p>
<p>If I were trying to do a cover-up, I wouldn’t be releasing the photos! So a conspiracy doesn’t seem very likely.</p>
<p>But there’s also a lesson here for serious searchers for alien life. As astronomer <a href="https://en.wikipedia.org/wiki/Carl_Sagan">Carl Sagan</a> said, extraordinary claims require extraordinary evidence. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/the-search-for-et-has-been-going-on-for-years-so-what-do-we-know-so-far-44966">The search for ET has been going on for years: so what do we know so far?</a>
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<p>Following this maxim, scientists seeking evidence of extra-terrestrial life demand much stronger evidence, than, say, someone looking for a geological formation. And despite decades of searching for evidence of life on Mars, we have found nothing. </p>
<p>It is still possible there may once have been life on Mars. We may yet find some fossilised relics of ancient cellular life. But suddenly finding an artefact such as a doorway, or a spoon, seems unlikely. </p>
<h2>The bigger picture</h2>
<p>There’s a similar story with the broader <a href="https://en.wikipedia.org/wiki/Search_for_extraterrestrial_intelligence">search for extra-terrestrial intelligence (SETI)</a>. For years, SETI scientists have been searching the skies for signals from other civilisations, but so far we have found nothing. But nearly all our searches have been on the nearest few stars, and so in a sense the search has barely started. </p>
<p>Meanwhile, we continue to be bombarded with photos purporting to show UFOs (Unidentified Flying Objects) or <a href="https://theconversation.com/is-there-evidence-aliens-have-visited-earth-heres-whats-come-out-of-us-congress-hearings-on-unidentified-aerial-phenomena-183443">UAP (Unidentified Aerial Phenomena)</a>. </p>
<p>The vast majority of these photos are probably fakes, or mistaken photos of familiar objects such as weather balloons. But as scientists, we must keep an open mind. In among the rubbish, perhaps there may be one or two photos or videos that really could stretch our current knowledge. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/is-there-evidence-aliens-have-visited-earth-heres-whats-come-out-of-us-congress-hearings-on-unidentified-aerial-phenomena-183443">Is there evidence aliens have visited Earth? Here's what's come out of US congress hearings on 'unidentified aerial phenomena'</a>
</strong>
</em>
</p>
<hr>
<p>The problem is that if someone presents me with a photo purporting to show a flying saucer, I know that the odds overwhelmingly favour it being a fake, and so I’m likely to dismiss it rather than wasting my time examining it carefully. But supposing I’m wrong?</p>
<p>Similarly, when we see a doorway, or a face, or a spoon, on Mars, it’s all too easy to dismiss it out of hand. But we must remain alert to the possibility that one day we might find archaeological evidence of past life on Mars. </p>
<p>Admittedly, this seems very unlikely. But not impossible. It would be a terrible loss if, among all our careful searching through the data, we missed the thing we had been searching for because it was too easily dismissed as a trick of the light.</p><img src="https://counter.theconversation.com/content/183446/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Ray Norris 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>A photo of ‘doorway’ on Mars shows how ready our minds are to see significance and signs of life in the natural world.Ray Norris, Professor, School of Science, Western Sydney UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1788442022-04-04T12:28:37Z2022-04-04T12:28:37ZWhat is a dwarf planet?<figure><img src="https://images.theconversation.com/files/452922/original/file-20220317-13-1u6oyiu.jpg?ixlib=rb-1.1.0&rect=0%2C3%2C1039%2C713&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Pluto, the largest of the dwarf planets. This image was taken by NASA's New Horizons spacecraft.</span> <span class="attribution"><a class="source" href="https://solarsystem.nasa.gov/resources/699/pluto-dazzles-in-false-color/">NASA/JHUAPL/SwRI</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">
<figcaption>
<span class="caption"></span>
</figcaption>
</figure>
<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>
<hr>
<blockquote>
<p><strong>What is a dwarf planet? – Myranda, age 8, Knoxville, Tennessee</strong></p>
</blockquote>
<hr>
<p>The word “planet” came from the ancient Greek words that mean “wandering star.” That makes sense, because for thousands of years, people have watched planets change position in the night sky – unlike stars, which appear fixed and unmoving to the naked eye. </p>
<p>That’s how the ancients discovered five of the planets: <a href="https://solarsystem.nasa.gov/planets/mercury/overview/">Mercury</a>, <a href="https://solarsystem.nasa.gov/planets/venus/overview/">Venus</a>, <a href="https://solarsystem.nasa.gov/news/1679/mars-resources/?">Mars</a>, <a href="https://solarsystem.nasa.gov/planets/jupiter/overview/">Jupiter</a> and <a href="https://solarsystem.nasa.gov/planets/saturn/overview/">Saturn</a>. Astronomers using telescopes found <a href="https://solarsystem.nasa.gov/planets/uranus/overview/">Uranus</a> in 1781, <a href="https://solarsystem.nasa.gov/planets/neptune/overview/">Neptune</a> in 1846, and <a href="https://solarsystem.nasa.gov/planets/dwarf-planets/pluto/overview/">Pluto</a> in 1930. </p>
<figure class="align-center ">
<img alt="Artist's impression of the dwarf planet Eris, a white and pale gray sphere." src="https://images.theconversation.com/files/454273/original/file-20220324-13-18yzsb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/454273/original/file-20220324-13-18yzsb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/454273/original/file-20220324-13-18yzsb.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/454273/original/file-20220324-13-18yzsb.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/454273/original/file-20220324-13-18yzsb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/454273/original/file-20220324-13-18yzsb.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/454273/original/file-20220324-13-18yzsb.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">
<figcaption>
<span class="caption">Artist’s impression of the dwarf planet Eris.</span>
<span class="attribution"><a class="source" href="https://www.eso.org/public/images/eso1142a/">ESO/L.Calçada and Nick Risinger</a></span>
</figcaption>
</figure>
<h2>Solar system leftovers</h2>
<p><a href="https://dornsife.usc.edu/cf/faculty-and-staff/faculty.cfm?pid=1063926">I’m a space scientist</a> with a passion for astronomy and the exploration of the Solar System. I received my Ph.D. in physics in 1994, about the time astronomers began to find more and more objects beyond Neptune, in the <a href="https://spaceplace.nasa.gov/kuiper-belt/en/">Kuiper belt</a>. That’s a place in space that holds the “leftovers” of the solar system – particularly small icy bodies. </p>
<p>Three of those icy bodies – <a href="https://solarsystem.nasa.gov/planets/dwarf-planets/eris/in-depth/">Eris</a>, <a href="https://solarsystem.nasa.gov/planets/dwarf-planets/haumea/in-depth/">Haumea</a> and <a href="https://solarsystem.nasa.gov/planets/dwarf-planets/makemake/in-depth/">Makemake</a> – were discovered in the early to mid 2000s. They seemed large enough to be planets; all of them are roughly the same size as Pluto.</p>
<p>Astronomers then surmised that there were likely many more of these icy bodies in the Kuiper belt. They began to wonder: How many planets might we end up identifying in our solar system? Twenty? Thirty? A hundred? More?</p>
<figure class="align-center ">
<img alt="An artist's illustration of the dwarf planet Haumea, an oval shaped world surrounded by its ring." src="https://images.theconversation.com/files/454305/original/file-20220325-27-j10f5i.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/454305/original/file-20220325-27-j10f5i.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=480&fit=crop&dpr=1 600w, https://images.theconversation.com/files/454305/original/file-20220325-27-j10f5i.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=480&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/454305/original/file-20220325-27-j10f5i.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=480&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/454305/original/file-20220325-27-j10f5i.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=603&fit=crop&dpr=1 754w, https://images.theconversation.com/files/454305/original/file-20220325-27-j10f5i.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=603&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/454305/original/file-20220325-27-j10f5i.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=603&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">An artist’s illustration of the dwarf planet Haumea, surrounded by its ring.</span>
<span class="attribution"><a class="source" href="https://science.nasa.gov/haumea-outer-solar-system">Instituto de Asrofísica de Andalucía</a></span>
</figcaption>
</figure>
<h2>Dwarf planet defined</h2>
<p>In 2006, and after much debate, the <a href="https://www.iau.org/">International Astronomical Union</a> came up with a new definition for a planet. And for the first time, the term “dwarf planet” was used.</p>
<p>Here’s what the IAU said: A planet has to orbit the Sun directly. It also must be large enough to have a round, or spherical, physical shape. </p>
<p>And the planet must “<a href="https://solarsystem.nasa.gov/planets/in-depth/">clear its neighborhood</a>.” That means, aside from any moons it might have, the planet can’t share its orbit with other objects of comparable size.</p>
<p>An object that satisfies only the first two criteria – but not the last – is now called a dwarf planet. </p>
<figure class="align-center ">
<img alt="Artist's illustration of Makemake, a dwarf planet in the Kuiper Belt. Nearby is its moon, MK 2. Off in the distance: the Sun." src="https://images.theconversation.com/files/454461/original/file-20220325-25-1th3ksp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/454461/original/file-20220325-25-1th3ksp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/454461/original/file-20220325-25-1th3ksp.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/454461/original/file-20220325-25-1th3ksp.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/454461/original/file-20220325-25-1th3ksp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/454461/original/file-20220325-25-1th3ksp.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/454461/original/file-20220325-25-1th3ksp.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">
<figcaption>
<span class="caption">Artist’s illustration of Makemake, a dwarf planet in the Kuiper belt. Nearby is its moon, MK 2. Off in the distance: the Sun.</span>
<span class="attribution"><a class="source" href="https://www.nasa.gov/sites/default/files/thumbnails/image/makemakemoon100mile.jpg">NASA/ESA/A. Parker/Southwest Research Institute</a></span>
</figcaption>
</figure>
<h2>Pluto is demoted</h2>
<p>That’s why Pluto <a href="https://www.kidsnews.com.au/space/pluto-lost-its-spot-in-our-solar-system-but-still-holds-a-place-in-many-hearts/news-story/4b4f0862a47b089ea5850d9522f211ca">lost its status as a planet</a> and is now classified as a dwarf planet. It failed the final item on the checklist – other icy Kuiper belt bodies are within its orbital path. The decision, a controversial one to be sure, is <a href="https://www.sciencenewsforstudents.org/article/pluto-dwarf-planet-definition-iau-astronomy">debated by scientists to this very day</a>. </p>
<p>At the same time Pluto got demoted, another solar system object was promoted. <a href="https://solarsystem.nasa.gov/planets/dwarf-planets/ceres/overview/">Ceres</a>, once considered an asteroid, is now classified as a dwarf planet. It’s nowhere near the Kuiper belt; instead, Ceres is in <a href="https://solarsystem.nasa.gov/asteroids-comets-and-meteors/asteroids/overview/?">the main asteroid belt</a>, orbiting between Mars and Jupiter.</p>
<p>Add them up – Pluto, Ceres, Eris, Haumea and Makemake – and that brings the number of dwarf planets in our solar system to five. But that list is sure to grow. Already, hundreds of candidates, nearly all in the Kuiper belt, potentially satisfy the criteria to be a dwarf planet. </p>
<figure class="align-center ">
<img alt="A photo of the dwarf planet Ceres. To the human eye, it appears a sandy brown color and is pockmarked with craters." src="https://images.theconversation.com/files/454567/original/file-20220328-13-1wwgmnd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/454567/original/file-20220328-13-1wwgmnd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/454567/original/file-20220328-13-1wwgmnd.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/454567/original/file-20220328-13-1wwgmnd.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/454567/original/file-20220328-13-1wwgmnd.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/454567/original/file-20220328-13-1wwgmnd.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/454567/original/file-20220328-13-1wwgmnd.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">
<figcaption>
<span class="caption">This photograph of Ceres, a dwarf planet in the main asteroid belt, was taken by NASA’s Dawn spacecraft.</span>
<span class="attribution"><a class="source" href="https://solarsystem.nasa.gov/resources/622/ceres-in-color/?category=planets/dwarf-planets_ceres">NASA/JPL-Caltech/UCLA/MPS/DLR/IDA</a></span>
</figcaption>
</figure>
<h2>About the dwarf planets</h2>
<p>Dwarf planets are nothing like Earth. </p>
<p>As their name implies, they are much smaller. Pluto and Eris, the largest of the dwarfs, have less than one-fifth the diameter of the Earth. </p>
<p><a href="https://spaceplace.nasa.gov/planets-weight/en/#:%7E:text=Mass%20stays%20the%20same%20regardless,mass%20is%20the%20same%20everywhere!">They have less mass, too</a>. For example, Earth has <a href="https://theplanets.org/ceres/">about 6,400 times more mass</a> than Ceres. That’s like comparing two <a href="https://en.wikipedia.org/wiki/Orca">killer whales</a> to a <a href="https://en.wikipedia.org/wiki/Guinea_pig">guinea pig</a>.</p>
<p>And dwarf planets are cold. <a href="https://solarsystem.nasa.gov/planets/dwarf-planets/pluto/in-depth/#:%7E:text=On%20average%2C%20Pluto's%20temperature%20is,orbits%20in%20our%20solar%20system.">Pluto’s average temperature</a> is around minus 400 degrees Fahrenheit (minus 240 Celsius).</p>
<figure class="align-center ">
<img alt="A photograph of Pluto and one of its five moons, Charon." src="https://images.theconversation.com/files/454578/original/file-20220328-25-rfa5po.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/454578/original/file-20220328-25-rfa5po.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/454578/original/file-20220328-25-rfa5po.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/454578/original/file-20220328-25-rfa5po.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/454578/original/file-20220328-25-rfa5po.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/454578/original/file-20220328-25-rfa5po.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/454578/original/file-20220328-25-rfa5po.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">A photograph of Pluto and one of its five moons, Charon. Except for Ceres, all the dwarf planets have at least one moon. Charon is nearly half Pluto’s size.</span>
<span class="attribution"><a class="source" href="https://solarsystem.nasa.gov/resources/853/pluto-and-charon/?category=planets/dwarf-planets_pluto">NASA/Johns Hopkins University Applied Physics Laboratory/Southwest Research Institute</a></span>
</figcaption>
</figure>
<h2>Could life exist on a dwarf planet?</h2>
<p>Three things are needed for life: liquid water, an energy source and organic molecules – that is, molecules containing carbon. </p>
<p>More than 100 miles (161 kilometers) below Pluto’s surface, an enormous ocean of liquid water may exist; this might also be true for other Kuiper belt worlds. <a href="https://astronomy.com/news/2020/08/ceres-an-ocean-world-in-the-asteroid-belt">Ceres also has subsurface water</a>, remnants of what might have been an ancient global ocean. </p>
<p>Organic molecules, in abundance <a href="https://www.extremetech.com/extreme/271914-organic-molecules-on-ceres-are-more-abundant-than-previously-thought">everywhere in our solar system</a>, have been found on Ceres and Pluto. </p>
<p>But the one missing ingredient for all the dwarf planets is a source of energy. </p>
<p>Sunlight won’t work, particularly for the Kuiper belt dwarfs; they are simply too far away from the Sun. To reach the belt, the light must travel <a href="https://imagine.gsfc.nasa.gov/features/cosmic/solar_system_info.html">more than 2.7 billion miles</a> (4.4 billion km). By the time the sunshine arrives at these distant worlds, it’s <a href="https://solarsystem.nasa.gov/solar-system/kuiper-belt/in-depth/">too weak to significantly heat</a> any of them.</p>
<p>And all the dwarf planets are too small to hold the inner heat that remains from the <a href="https://kids.britannica.com/kids/article/solar-system/353789#:%7E:text=The%20solar%20system%20was%20formed%20about%204.7%20billion%20years%20ago,that%20it%20got%20very%20hot.">solar system’s formation</a>. </p>
<p>Yet scientists have discovered life on Earth in the most hostile places imaginable – near the bottom of the ocean, miles deep in the soil and even inside an active volcano. When it comes to life in our solar system, never say never. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/nJiw2NxqoBU?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Take a tour of the dwarf planet Ceres.</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/178844/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Vahe Peroomian has received funding in the past from the National Science Foundation and from the National Aeronautics and Space Administration.</span></em></p>The dwarf planets in our Solar System are cold, dark, far away and full of surprises.Vahe Peroomian, Professor of Physics and Astronomy, USC Dornsife College of Letters, Arts and SciencesLicensed as Creative Commons – attribution, no derivatives.