tag:theconversation.com,2011:/es/topics/space-51/articlesSpace – The Conversation2024-03-28T12:50:48Ztag:theconversation.com,2011:article/2257712024-03-28T12:50:48Z2024-03-28T12:50:48ZNASA’s mission to an ice-covered moon will contain a message between water worlds<figure><img src="https://images.theconversation.com/files/584594/original/file-20240326-30-7p4fl7.jpg?ixlib=rb-1.1.0&rect=7%2C8%2C1191%2C1212&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">An illustration of the Europa Clipper spacecraft, which will head to Jupiter's moon Europa. </span> <span class="attribution"><a class="source" href="https://europa.nasa.gov/resources/173/europa-clipper-journey-to-an-ocean-world-poster/">NASA/JPL-Caltech</a></span></figcaption></figure><p>NASA’s <a href="https://europa.nasa.gov/">Europa Clipper</a> spacecraft, <a href="https://theconversation.com/jupiters-moons-hide-giant-subsurface-oceans-two-missions-are-sending-spacecraft-to-see-if-these-moons-could-support-life-203207">headed to Jupiter’s ice-covered moon</a> Europa in October 2024, will carry <a href="https://europa.nasa.gov/spacecraft/vault-plate/">a laser-etched message</a> that celebrates humanity’s connection to water. The message pays homage to past NASA missions that carried similar messages. </p>
<p>As <a href="https://meti.org/en/board/douglas-vakoch">the president</a> of <a href="https://meti.org/mission">Messaging Extraterrestrial Intelligence, or METI, International</a>, I helped design the message on Clipper with two fellow members of our board of directors: linguists <a href="https://meti.org/en/board/sheri-wells-jensen">Sheri Wells-Jensen</a> and <a href="https://longnow.org/people/laura/">Laura Buszard-Welcher</a>. METI International is a scientific organization dedicated to transmitting powerful radio messages to extraterrestrial life.</p>
<p>We collected audio recordings in 103 languages, and we decided how to <a href="https://europa.nasa.gov/spacecraft/vault-plate/#otp_waveform_generator">convert these into waveforms</a> that show these sounds visually. Colleagues from NASA etched these waveforms into the metal plate that shields the spacecraft’s sensitive electronics from <a href="https://www.astronomy.com/science/what-is-the-source-of-jupiters-radiation/">Jupiter’s harsh radiation</a>. </p>
<p>I also designed another part of the message that visually depicts the wavelengths of water’s constituents, because water is so important to the search for intelligent life in the universe. </p>
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<figcaption><span class="caption">NASA’s design for the Clipper message heading to Jupiter’s moon Europa.</span></figcaption>
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<p>Etching messages into spacecraft isn’t a new practice, and Clipper’s message fits into a decades-old tradition started by <a href="https://www.britannica.com/biography/Carl-Sagan">astronomer Carl Sagan</a>.</p>
<p>In 1972 and 1973, two Pioneer spacecraft headed to Jupiter and Saturn carrying metal plaques engraved with scientific and pictorial messages. In 1977, two <a href="https://theconversation.com/what-the-voyager-space-probes-can-teach-humanity-about-immortality-and-legacy-as-they-sail-through-space-for-trillions-of-years-177513">Voyager spacecraft</a> headed to Jupiter, Saturn, Uranus and Nepture bearing <a href="https://theconversation.com/voyager-golden-records-40-years-later-real-audience-was-always-here-on-earth-79886">gold-plated copper phonograph records</a>. These records contained tutorials in mathematics and chemistry, as well as music, photos and sounds of Earth and greetings in 55 languages.</p>
<h2>Water words</h2>
<p>As water is essential for life on Earth, searching for its presence elsewhere has been key to many NASA missions. Astronomers <a href="https://science.nasa.gov/jupiter/moons/europa/">suspect that Europa</a>, where Clipper is headed, <a href="https://theconversation.com/jupiters-moons-hide-giant-subsurface-oceans-two-missions-are-sending-spacecraft-to-see-if-these-moons-could-support-life-203207">has an ocean underneath its icy surface</a>, making it a prime candidate for the search for life in the outer solar system.</p>
<p>Part of the Clipper message features the word for water in 103 languages. We started with audio files collected online, but we then needed to analyze those and find an output that could be engraved on a metal plate. I ended up going back to some of the techniques I used in some of my early psycholinguistic research, where I explored how <a href="https://doi.org/10.1121/1.408973">emotions are encoded in speech</a>.</p>
<p>The 103 spoken words we recorded represent a global snapshot of the diversity of Earth’s languages. The outward-facing side of the Clipper plate shows the words as waveforms that track the varying intensity of sound as each word is spoken. </p>
<p>Each person whom we recorded saying the word “water” for the waveform had a connection to water. For example, the lawyer who contributed the word for water in Uzbek – “suv” – organizes an annual music festival in Uzbekistan to raise awareness of the desertification of the Aral Sea. </p>
<p>The native speaker of the Catalan water word – “aigua” – hunts <a href="https://theconversation.com/nasas-tess-spacecraft-is-finding-hundreds-of-exoplanets-and-is-poised-to-find-thousands-more-122104">for exoplanets</a>, discovering potentially habitable planets that orbit other stars. </p>
<h2>The Drake Equation</h2>
<p>Clipper’s message also pays homage to <a href="https://www.seti.org/frank-drake">astronomer Frank Drake</a>, the father of SETI – <a href="https://www.seti.org/">the Search for Extraterrestrial Intelligence</a> – by bearing <a href="https://www.seti.org/drake-equation-index">the Drake Equation</a>, his namesake formula. By drawing on scientific data, as well as some best guess hunches, the Drake Equation estimates the number of extraterrestrial civilizations in the galaxy currently sending messages into the cosmos. </p>
<p>By one <a href="https://www.britannica.com/science/Drake-equation">widely quoted estimate</a>, there are a tenth as many of these extraterrestrial civilizations as one’s average lifetime in years. If civilizations survive for a million years, for example, there should be about 100,000 in the galaxy. If they last only a century on average, scientists would estimate that about 10 exist.</p>
<p>Radio astronomers study the universe by examining the radiation that chemical elements in space give off. They spend much of their time mapping the distribution of the most abundant chemical in the universe – hydrogen.</p>
<p>Hydrogen emits radiation at a certain frequency called the <a href="http://www.setileague.org/askdr/hydrogen.htm">hydrogen line</a>, which radio telescopes can detect. During <a href="https://www.seti.org/project-ozma">Project Ozma</a>, the first modern-day SETI experiment, Drake looked for artificial signals at the same frequency, because he figured scientists on other worlds might recognize hydrogen as universally significant and broadcast signals at that frequency.</p>
<h2>The water hole</h2>
<p>As our team developed our water words message, I realized that the message would only make sense if it were discovered by someone already familiar with the contents inscribed on the plate. The Drake Equation would only make sense if someone already knew what each of the terms in the equation stood for. </p>
<p>The Europa Clipper will crash into Jupiter or one of its other moons, with <a href="https://www.space.com/europa-clipper-might-crash-into-ganymede">Ganymede or Callisto the leading candidates</a>. But if for some reason the mission changes and it survives that fate, then humans far in the future with a radically different cultural background and different language conventions may retrieve it millennia from now as an ancient artifact.</p>
<p>To ensure we had at least one part of the message that a distant future scientist might be able to understand, I also designed a pictorial representation of the same frequency that Drake used for Project Ozma: the hydrogen line. We engraved this on the Clipper plate, along with a frequency called the hydroxyl line.</p>
<p>When hydrogen (H+) and <a href="https://www.sciencedirect.com/topics/chemistry/hydroxyl">hydroxyl (OH-)</a> combine, they form water. Scientists call the range of frequencies between these lines the “<a href="http://www.setileague.org/general/waterhol.htm">water hole</a>.” The water hole represents the part of the radio spectrum where astronomers conducted the first SETI experiments.</p>
<p>We displayed the hydrogen and hydroxyl lines using their wavelengths in the Clipper message. The metal plate also has diagrams showing what hydrogen and hydroxyl look like at the atomic level. </p>
<p>We’re hoping that future chemists would recognize these chemical components as the ingredients of water. If they do, we will have succeeded in communicating at least a few core scientific concepts across time, space and language. </p>
<p>Waveforms let our team tie the messages on the two sides of the Clipper plate together. On the water words side, over a hundred words are depicted by their waveforms. On the other side, the wavelengths of hydrogen and hydroxyl – the constituents of water – are etched into the plate.</p>
<p>METI International funded the collection and curation of the water words, as well as my design of the hydrogen and hydroxyl lines, providing these to NASA at no cost.</p>
<p>While designing the message for the Europa Clipper, we got to reflect on the importance of water on Earth, and think about why astronomers feel so compelled to search for it beneath the icy crust of Jupiter’s moon Europa. The spacecraft is scheduled to enter Jupiter’s orbit in April 2030.</p><img src="https://counter.theconversation.com/content/225771/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Douglas Vakoch 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>Europa Clipper will contain a plaque that celebrates humanity’s relationship with water and a decades-old tradition of searching for life outside Earth.Douglas Vakoch, President, METI International; Professor Emeritus, California Institute of Integral StudiesLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2267292024-03-27T23:55:16Z2024-03-27T23:55:16ZA cosmic ‘speed camera’ just revealed the staggering speed of neutron star jets in a world first<figure><img src="https://images.theconversation.com/files/584904/original/file-20240327-26-ntaiw6.jpg?ixlib=rb-1.1.0&rect=1283%2C180%2C5431%2C3798&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Nuclear explosions on a neutron star feed its jets.
</span> <span class="attribution"><span class="source">Danielle Futselaar and Nathalie Degenaar, Anton Pannekoek Institute, University of Amsterdam</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>How fast can a neutron star drive powerful jets into space? The answer, it turns out, is about one-third the speed of light, as our team has just revealed in a <a href="https://www.nature.com/articles/s41586-024-07133-5">new study</a> published in Nature.</p>
<p>Energetic cosmic beams known as <a href="https://www.britannica.com/science/radio-jet">jets</a> are seen throughout our universe. They are launched when material – mainly dust and gas – falls in towards any dense central object, such as a neutron star (an extremely dense remnant of a once-massive star) or a <a href="https://science.nasa.gov/universe/black-holes/">black hole</a>. </p>
<p>The jets carry away some of the gravitational energy released by the infalling gas, recycling it back into the surroundings on far larger scales.</p>
<p>The most powerful jets in the universe come from the biggest black holes at the centres of galaxies. The energy output of these jets can affect the evolution of an entire galaxy, or even a galaxy cluster. This makes jets a critical, yet intriguing, component of our universe.</p>
<p>Although jets are common, we still don’t fully understand how they are launched. Measuring the jets from a neutron star has now given us valuable information.</p>
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Read more:
<a href="https://theconversation.com/the-brightest-object-in-the-universe-is-a-black-hole-that-eats-a-star-a-day-222612">The brightest object in the universe is a black hole that eats a star a day</a>
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<h2>Jets from stellar corpses</h2>
<p>Jets from black holes tend to be bright, and have been well studied. However, the jets from neutron stars are typically much fainter, and much less is known about them.</p>
<p>This presents a problem, since we can learn a lot by comparing the jets launched by different celestial objects. <a href="https://imagine.gsfc.nasa.gov/science/objects/neutron_stars1.html">Neutron stars</a> are extremely dense stellar corpses – cosmic cinders the size of a city, yet containing the mass of a star. We can think of them as enormous atomic nuclei, each about 20 kilometres across.</p>
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<p>In contrast to black holes, neutron stars have both a solid surface and a magnetic field, and gas falling onto them releases less gravitational energy. All of these properties will have an effect on how their jets are launched, making studies of neutron star jets particularly valuable.</p>
<p>One key clue to how jets are launched comes from their speeds. If we can determine how jet speeds vary with the mass or spin of the neutron star, that would provide a powerful test of theoretical predictions. But it is extremely challenging to measure jet speeds accurately enough for such a test.</p>
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Read more:
<a href="https://theconversation.com/unexpected-find-from-a-neutron-star-forces-a-rethink-on-radio-jets-103843">Unexpected find from a neutron star forces a rethink on radio jets</a>
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<h2>A cosmic speed camera</h2>
<p>When we measure speeds on Earth, we time an object between two points. This could be a 100-metre sprinter running down the track, or a point-to-point speed camera tracking a car.</p>
<p>Our team, led by Thomas Russell from the <a href="http://www.inaf.it/en">Italian National Institute of Astrophysics</a> in Palermo, conducted a new experiment to do this for neutron star jets.</p>
<p>What has made this measurement so difficult in the past is that jets are steady flows. This means there is no single starting point for our timer. But we were able to identify a short-lived signal at X-ray wavelengths that we could use as our “starting gun”.</p>
<p>Being so dense, neutron stars can “steal” matter from a nearby orbiting companion star. While some of that gas is launched outwards as jets, most of it ends up falling onto the neutron star. As the material piles up, it gets hotter and denser.</p>
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<p>When enough material has built up, it triggers a thermonuclear explosion. A runaway nuclear fusion reaction occurs and rapidly spreads to engulf the entire star. The fusion lasts for a few seconds to minutes, causing a short-lived <a href="https://www.nasa.gov/universe/nasas-nicer-catches-record-setting-x-ray-burst/">burst of X-rays</a>.</p>
<h2>One step closer to solving a mystery</h2>
<p>We thought this thermonuclear explosion would disrupt the neutron star’s jets. So, we used CSIRO’s <a href="https://www.csiro.au/en/about/facilities-collections/atnf/australia-telescope-compact-array">Australia Telescope Compact Array</a> to stare at the jets for three days at radio wavelengths to try and catch the disruption. At the same time, we used the European Space Agency’s <a href="https://www.esa.int/Science_Exploration/Space_Science/Integral_overview">Integral</a> telescope to look at the X-rays from the system.</p>
<p>To our surprise, we found the jets got brighter after every pulse of X-rays. Instead of disrupting the jets, the thermonuclear explosions seemed to power them up. And this pattern was repeated ten times in one neutron star system, and then again in a second system.</p>
<p>We can explain this surprising result if the X-ray pulse causes gas swirling around the neutron star to fall inwards more quickly. This, in turn, provides more energy and material to divert into the jets.</p>
<p>Most importantly, however, we can use the X-ray burst to indicate the launch time of the jets. We timed how long they took to move outwards to where they became visible at two different radio wavelengths. These start and finish points provided us with our cosmic speed camera.</p>
<p>Interestingly, the jet speed we measured was close to the “escape speed” from a neutron star. On Earth, this escape speed is <a href="https://www.britannica.com/science/escape-velocity">11.2 kilometres per second</a> – what rockets need to achieve to break free of Earth’s gravity. For a neutron star, that value is around half the speed of light.</p>
<p>Our work has introduced a new technique for measuring neutron star jet speeds. Our next steps will be to see how the jet speed changes for neutron stars with different masses and rotation rates. That will allow us to directly test theoretical models, taking us one step closer to figuring out how such powerful cosmic jets are launched.</p><img src="https://counter.theconversation.com/content/226729/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>James Miller-Jones receives funding from the Australian Research Council and the Western Australian State Government.</span></em></p>Powerful jets are launched from the most massive objects in our universe, but we don’t fully understand how. This measurement gets us a step closer to solving the mystery.James Miller-Jones, Professor, Curtin UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2258662024-03-27T17:09:15Z2024-03-27T17:09:15ZThe April 8 eclipse provides a rare opportunity to witness the sun’s superhot corona<figure><img src="https://images.theconversation.com/files/584383/original/file-20240326-16-cpzqx3.jpg?ixlib=rb-1.1.0&rect=0%2C2%2C1888%2C1057&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The corona of the sun can be clearly seen in this image taken in 2007.</span> <span class="attribution"><a class="source" href="https://images.nasa.gov/details/PIA09320">(NASA/JPL-Caltech/NRL/GSFC)</a></span></figcaption></figure><p>Being within a narrow path across Mexico, the United States and eastern Canada on April 8 will give a rare chance to see the hottest thing any human ever sees: the corona surrounding the sun.</p>
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Read more:
<a href="https://theconversation.com/on-april-8-2024-parts-of-ontario-quebec-the-maritimes-and-newfoundland-will-see-a-total-eclipse-of-the-sun-heres-how-to-get-ready-for-it-203382">On April 8, 2024, parts of Ontario, Québec, the Maritimes and Newfoundland will see a total eclipse of the sun. Here's how to get ready for it.</a>
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<p>The word “corona” means “crown” — during the eclipse, it becomes visible, and streaming plasma leaving the sun appears in amazing patterns.</p>
<p>This outer atmosphere shines with a strange whitish light, and is safe to look at once the bright surface of the sun is fully obscured. However, it is not safe to look at partial phases of the eclipse without <a href="https://theconversation.com/total-solar-eclipses-while-stunning-can-damage-your-eyes-if-viewed-without-the-right-protection-221381">suitable eye protection</a> such as an approved filter or a <a href="https://svs.gsfc.nasa.gov/14391/">shadow box</a>. </p>
<p>Humankind has been awed by this spectacle <a href="https://www.wired.com/2008/05/may-28-585-bc-predicted-solar-eclipse-stops-battle/">for a very long time without understanding it</a>. Astronomers now know the sun’s corona is heated to up to <a href="https://www.nasa.gov/science-research/heliophysics/nasas-parker-solar-probe-and-the-curious-case-of-the-hot-corona/">two million degrees Kelvin</a>, numerically almost equivalent to Celsius for such high temperatures. </p>
<p>What astronomers haven’t figured out yet is why the corona is so hot.</p>
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<figcaption><span class="caption">NASA scientists describe photographing the sun’s corona during the 2015 eclipse.</span></figcaption>
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<h2>Heat and density</h2>
<p>The surface of the sun has a temperature of <a href="https://scied.ucar.edu/learning-zone/sun-space-weather/surface-of-the-sun">only about 5,800 kelvins</a> (5,500 C). The reason that we can safely look at the corona but must avoid looking at the surface has to do with density: <a href="https://spaceplace.nasa.gov/sun-corona/en/">the corona is very thin</a>, and most of the light we see is reflected sunlight from the surface. </p>
<p>The sun’s surface has enough density that, at its temperature, it emits about <a href="https://www.pveducation.org/pvcdrom/properties-of-sunlight/solar-radiation-in-space">65 megawatts for each square meter</a>. Even diluted by <a href="https://earthsky.org/space/what-is-the-astronomical-unit/">distance from the sun of 150 million kilometres</a>, this is enough to cause immediate eye damage.</p>
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Read more:
<a href="https://theconversation.com/total-solar-eclipses-while-stunning-can-damage-your-eyes-if-viewed-without-the-right-protection-221381">Total solar eclipses, while stunning, can damage your eyes if viewed without the right protection</a>
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<p>Since the corona is such thin gas, despite its high temperature, it does not emit nor reflect much light. For this reason, we can see it only when the body of the sun is completely blocked by the moon. Otherwise the scattered light in our atmosphere completely overwhelms it.</p>
<p>The mystery of the corona’s heat <a href="https://www.americanscientist.org/article/revealing-the-true-solar-corona">puzzled 19th-century astronomers</a>. At the time, new instruments had been developed to study <a href="https://www.azooptics.com/Article.aspx?ArticleID=1984">the composition of celestial bodies</a>.</p>
<p>In 1704, Sir Isaac Newton had discovered that “white” light could be split into colors, a result <a href="https://library.si.edu/digital-library/book/optickstreatise00newta">published in <em>Opticks</em></a>. Unfortunately, his basic views about light were wrong and likely set back the development of optical science 100 years! </p>
<p>Only in the early 1800s were instruments developed, largely setting the stage for the <a href="https://www.zeiss.com/corporate/en/about-zeiss/past/history/locations.html">immensely profitable German optical industry</a>. This allowed scientists to find out what materials were made of by the light they emitted when heated. </p>
<p>A staple of such studies was the <a href="https://www.britannica.com/science/Bunsen-burner">Bunsen burner</a>, originally developed not to have a colour like other flames do.</p>
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<a href="https://images.theconversation.com/files/582669/original/file-20240318-16-fmoksh.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="a black circle surrounded by wispy white light against a navy background" src="https://images.theconversation.com/files/582669/original/file-20240318-16-fmoksh.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/582669/original/file-20240318-16-fmoksh.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=430&fit=crop&dpr=1 600w, https://images.theconversation.com/files/582669/original/file-20240318-16-fmoksh.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=430&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/582669/original/file-20240318-16-fmoksh.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=430&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/582669/original/file-20240318-16-fmoksh.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=540&fit=crop&dpr=1 754w, https://images.theconversation.com/files/582669/original/file-20240318-16-fmoksh.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=540&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/582669/original/file-20240318-16-fmoksh.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=540&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">A total solar eclipse in 2015 over Svalbard, Norway, reveals the streaming shapes in the solar wind pillars.</span>
<span class="attribution"><span class="source">(M. Druckmüller, S. Habbal, P. Aniol, P. Štarha)</span></span>
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<h2>Photography and astrophysics</h2>
<p>The parallel development of photography also helped <a href="https://history.aip.org/exhibits/cosmology/tools/tools-spectroscopy.htm">astronomy to turn into the science of astrophysics</a>, and the sun was an ideal first target for early instruments due to being very bright. </p>
<p>During the solar eclipse of 1868, emissions like the bright red known to be <a href="https://skyandtelescope.org/observing/guide-to-observing-the-sun-in-h-alpha092321050923/">from hydrogen were observed</a>. But when this light was broken down with a spectroscope, it also showed a yellow light that had never been observed on Earth. </p>
<p>This was determined to be a new element, named for its association with the sun (Greek <em>helios</em>). Only in 1895 was helium found on Earth, and in the strangest of places: <a href="https://www.smithsonianmag.com/history/how-scientists-discovered-helium-first-alien-element-1868-180970057/">radioactive ores</a>. </p>
<p>Almost all helium now used on Earth comes from natural gas fields, where it is trapped as it comes up from uranium and other decaying radioactive ores. The helium in the sun later became strong evidence for the Big Bang, in which the first nuclei, which were hydrogen, quickly underwent nuclear fusion to produce helium, but its discovery in the sun set the stage for expecting new elements there.</p>
<h2>A new mystery</h2>
<p>Once spectroscopy developed further in the late 19th century, indeed another mystery arose. Many elements had been discovered on Earth and put in systematic order by Russian chemist Dmitri Mendeleev as the “<a href="https://pubchem.ncbi.nlm.nih.gov/periodic-table">periodic table</a>.”</p>
<p>Surprisingly, many elements were also detected in solar spectra, usually when they absorbed specific wavelengths from the pure light coming from deep layers in the sun, <a href="https://imagine.gsfc.nasa.gov/science/toolbox/spectra1.html">leaving absorption lines</a>. Although the sun is made mostly of hydrogen and helium, these are not prominent in its spectrum. </p>
<p>However, in the corona, completely unknown lines were found. Following the lead of helium, it was felt that the sun must contain an element never observed on Earth, <a href="https://sunearthday.nasa.gov/2006/locations/coronium.php">promptly dubbed coronium</a>. Only in the 1940s was it realized that the emissions actually came from familiar elements, including iron. These were not initially recognized due to being highly stripped of the normal number of electrons going around their nuclei (normally 26 in iron), indicating extreme temperatures that rip atoms apart. </p>
<p>Even stranger, the further out one observed from the sun, the hotter the corona became.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/582445/original/file-20240318-20-t6q0rt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="a black circle surrounded by wisps of red and green" src="https://images.theconversation.com/files/582445/original/file-20240318-20-t6q0rt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/582445/original/file-20240318-20-t6q0rt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=441&fit=crop&dpr=1 600w, https://images.theconversation.com/files/582445/original/file-20240318-20-t6q0rt.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=441&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/582445/original/file-20240318-20-t6q0rt.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=441&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/582445/original/file-20240318-20-t6q0rt.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=554&fit=crop&dpr=1 754w, https://images.theconversation.com/files/582445/original/file-20240318-20-t6q0rt.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=554&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/582445/original/file-20240318-20-t6q0rt.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=554&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 2015 eclipse imaged in the light given off by highly ionized iron. The red indicates a temperature about one million degrees C, green about two million degrees C.</span>
<span class="attribution"><a class="source" href="https://doi.org/10.3847/2041-8213/abe775">(SOURCE)</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<h2>Solar winds and weather</h2>
<p>In the late 1950s, the physicist Eugene Parker found that such high temperatures for the solar corona meant that it could not be static: it had to <a href="https://news.uchicago.edu/explainer/what-is-solar-wind">be blowing off into space</a>. This prediction was verified by <a href="http://www.phy6.org/Education/whsolwi.html">spacecraft measurements in 1959</a>. </p>
<p>Since then, we have known that there is a solar wind, and that the magnetic field shown by coronal structures is carried off into space with it. The solar wind can bring energy to Earth, which penetrates near us when the magnetic field is opposed to that of our planet, bringing auroras and potentially hazardous “<a href="https://theconversation.com/space-weather-is-difficult-to-predict-with-only-an-hour-to-prevent-disasters-on-earth-159895">space weather</a>.”</p>
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Read more:
<a href="https://theconversation.com/larger-and-more-frequent-solar-storms-will-make-for-potential-disruptions-and-spectacular-auroras-on-earth-219183">Larger and more frequent solar storms will make for potential disruptions and spectacular auroras on Earth</a>
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<p>NASA’s <a href="https://science.nasa.gov/mission/parker-solar-probe/">Parker Solar Probe</a> is now nearing the inner regions of the corona, still trying to determine the exact origins of the solar wind. Parker, who passed away in 2022, saw initial results from this spacecraft trying to find exactly how the outrageously hot corona propels the solar wind. </p>
<p>Meanwhile, April 8 is a rare opportunity to safely view the sun’s glorious super-heated corona.</p><img src="https://counter.theconversation.com/content/225866/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Martin Connors receives funding from NSERC. </span></em></p>The solar corona can be seen during the solar eclipse on April 8. Astronomers are still trying to figure out the mysteries of the corona, including why it’s so hot.Martin Connors, Professor of Space Science and Physics, Athabasca UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2265582024-03-27T17:07:01Z2024-03-27T17:07:01ZThe total solar eclipse in North America could help shed light on a persistent puzzle about the Sun<figure><img src="https://images.theconversation.com/files/584141/original/file-20240325-24-ot473c.jpg?ixlib=rb-1.1.0&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/totality-during-2023-australian-total-solar-2344355767">aeonWAVE / Shutterstock</a></span></figcaption></figure><p>A <a href="https://science.nasa.gov/eclipses/types/#hds-sidebar-nav-1">total solar eclipse</a> takes place on <a href="https://science.nasa.gov/eclipses/future-eclipses/eclipse-2024/">April 8 across North America</a>. These events occur when the Moon passes between the Sun and Earth, completely blocking the Sun’s face. This plunges observers into a darkness similar to dawn or dusk.</p>
<p>During the upcoming eclipse, the path of totality, where observers experience the darkest part of the Moon’s shadow (the umbra), crosses Mexico, arcing north-east through Texas, the Midwest and briefly entering Canada before ending in Maine.</p>
<p>Total solar eclipses occur roughly <a href="https://www.nhm.ac.uk/discover/solar-eclipse-guide.html">every 18 months at some location on Earth</a>. The last total solar eclipse that crossed the US took place on August 21 2017. </p>
<p>An international team of scientists, led by Aberystwyth University, will be conducting experiments from <a href="https://www.fox4news.com/news/2024-eclipse-dallas-crowds-traffic">near Dallas</a>, at a location in the path of totality. The team consists of PhD students and researchers from Aberystwyth University, Nasa Goddard Space Flight Center in Maryland, and Caltech (California Institute of Technology) in Pasadena. </p>
<p>There is valuable science to be done during eclipses that is comparable to or better than what we can achieve via space-based missions. Our experiments may also shed light on a longstanding puzzle about the outermost part of the Sun’s atmosphere – its corona.</p>
<figure class="align-center ">
<img alt="Eclipse shadow" src="https://images.theconversation.com/files/584503/original/file-20240326-18-9yqs13.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/584503/original/file-20240326-18-9yqs13.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/584503/original/file-20240326-18-9yqs13.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/584503/original/file-20240326-18-9yqs13.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/584503/original/file-20240326-18-9yqs13.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/584503/original/file-20240326-18-9yqs13.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/584503/original/file-20240326-18-9yqs13.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=424&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The path of eclipse totality passes through Mexico, the US and Canada.</span>
<span class="attribution"><a class="source" href="https://svs.gsfc.nasa.gov/5186/">NASA's Scientific Visualization Studio</a></span>
</figcaption>
</figure>
<p>The Sun’s intense light is blocked by the Moon during a total solar eclipse. This means that we can observe the <a href="https://solarscience.msfc.nasa.gov/corona.shtml">Sun’s faint corona</a> with incredible clarity, from distances very close to the Sun, out to several solar radii. One radius is the distance equivalent to half the Sun’s diameter, about 696,000km (432,000 miles).</p>
<p>Measuring the corona is extremely difficult without an eclipse. It requires a special telescope <a href="https://www.space.com/what-is-a-coronagraph.html">called a coronagraph</a> that is designed to block out direct light from the Sun. This allows fainter light from the corona to be resolved. The clarity of eclipse measurements surpasses even coronagraphs based in space.</p>
<p>We can also observe the corona on a relatively small budget, compared to, for example, spacecraft missions. A persistent puzzle about the corona is the observation <a href="https://agupubs.onlinelibrary.wiley.com/doi/10.1002/9781119815600.ch2">that it is much hotter</a> than the photosphere (the visible surface of the Sun). As we move away from a hot object, the surrounding temperature should decrease, not increase. How the corona is heated to such high temperatures is one question we will investigate.</p>
<figure class="align-center ">
<img alt="Solar eclipse." src="https://images.theconversation.com/files/584507/original/file-20240326-20-xairh2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/584507/original/file-20240326-20-xairh2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=390&fit=crop&dpr=1 600w, https://images.theconversation.com/files/584507/original/file-20240326-20-xairh2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=390&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/584507/original/file-20240326-20-xairh2.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=390&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/584507/original/file-20240326-20-xairh2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=490&fit=crop&dpr=1 754w, https://images.theconversation.com/files/584507/original/file-20240326-20-xairh2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=490&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/584507/original/file-20240326-20-xairh2.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=490&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption"></span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-vector/solar-eclipse-diagram-1146598682">Andramin / Shutterstock</a></span>
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<p>We have two main scientific instruments. The first of these is Cip (coronal imaging polarimeter). Cip is also the Welsh word for “glance”, or “quick look”. The instrument takes images of the Sun’s corona with a polariser. </p>
<p>The light we want to measure from the corona is highly polarised, which means it is made up of waves that vibrate in a single geometric plane. A polariser is a filter that lets light with a particular polarisation pass through it, while blocking light with other polarisations. </p>
<p>The Cip images will allow us to measure fundamental properties of the corona, such as its density. It will also shed light on phenomena such as the solar wind. This is a stream of sub-atomic particles in the form of plasma – superheated matter – flowing continuously outward from the Sun. Cip could help us identify sources in the Sun’s atmosphere for certain solar wind streams.</p>
<p>Direct measurements of the magnetic field in the Sun’s atmosphere are difficult. But the eclipse data should allow us to study its fine-scale structure and trace the field’s direction. We’ll be able to see how far magnetic structures called large “closed” magnetic loops extend from the Sun. This in turn will give us information about large-scale magnetic conditions in the corona.</p>
<figure class="align-center ">
<img alt="Coronal loops." src="https://images.theconversation.com/files/584489/original/file-20240326-24-zlpsmc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/584489/original/file-20240326-24-zlpsmc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=442&fit=crop&dpr=1 600w, https://images.theconversation.com/files/584489/original/file-20240326-24-zlpsmc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=442&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/584489/original/file-20240326-24-zlpsmc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=442&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/584489/original/file-20240326-24-zlpsmc.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=555&fit=crop&dpr=1 754w, https://images.theconversation.com/files/584489/original/file-20240326-24-zlpsmc.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=555&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/584489/original/file-20240326-24-zlpsmc.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=555&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Coronal loops are found around sunspots and in active regions of the Sun.</span>
<span class="attribution"><a class="source" href="https://www.nasa.gov/image-article/coronal-loops-an-active-region-of-sun/">NASA/Solar Dynamics Observatory</a></span>
</figcaption>
</figure>
<p>The second instrument is Chils (coronal high-resolution line spectrometer). It collects high-resolution spectra, where light is separated into its component colours. Here, we are looking for a particular spectral signature of iron emitted from the corona. </p>
<p>It comprises three spectral lines, where light is emitted or absorbed in a narrow frequency range. These are each generated at a different range of temperatures (in the millions of degrees), so their relative brightness tells us about the coronal temperature in different regions. </p>
<p>Mapping the corona’s temperature informs advanced, computer-based models of its behaviour. These models must include mechanisms for how the coronal plasma is heated to such high temperatures. Such mechanisms might include the conversion of magnetic waves to thermal plasma energy, for example. If we show that some regions are hotter than others, this can be replicated in models. </p>
<p>This year’s eclipse also occurs during a time of heightened solar activity, so we could observe a <a href="https://www.swpc.noaa.gov/phenomena/coronal-mass-ejections">coronal mass ejection (CME)</a>. These are huge clouds of magnetised plasma that are ejected from the Sun’s atmosphere into space. They can affect infrastructure near Earth, causing problems for vital satellites. </p>
<p>Many aspects of CMEs are poorly understood, including their early evolution near the Sun. Spectral information on CMEs will allow us to gain information on their thermodynamics, and their velocity and expansion near the Sun.</p>
<p>Our eclipse instruments have recently been proposed for a space mission called <a href="https://www.surrey.ac.uk/research-projects/feasibility-study-moon-enabled-sun-occultation-mission-mesom">Moon-enabled solar occultation mission (Mesom)</a>. The plan is to orbit the Moon to gain more frequent and extended eclipse observations. It is being planned as a UK Space Agency mission involving several countries, but led by University College London, the University of Surrey and Aberystwyth University.</p>
<p>We will also have an advanced commercial 360-degree camera to collect video of the April 8 eclipse and the observing site. The video is valuable for public outreach events, where we highlight the work we do, and helps to generate public interest in our local star, the Sun.</p><img src="https://counter.theconversation.com/content/226558/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Huw Morgan 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 eclipse will allow scientists to get rare measurements of the Sun’s atmosphere.Huw Morgan, Reader in Physical Sciences, Aberystwyth UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2255022024-03-18T18:09:02Z2024-03-18T18:09:02ZFloating crystals slow stellar aging — for some stars, this can delay death by billions of years<p>Imagine the embers of a campfire, slowly dimming over time. That is the fate most stars in the universe face. After their nuclear fuel is spent, 98 per cent of stars — including our sun — will eventually become white dwarfs. These small, dense remnants are thought to <a href="https://esahubble.org/wordbank/white-dwarf/">simply cool down</a>, becoming ever fainter as the universe ages.</p>
<p>In 2019, astronomers discovered <a href="https://doi.org/10.3847/1538-4357/ab4989">a group of white dwarfs</a> that mysteriously stopped cooling. These “forever-young” stars remain at a near-constant surface temperature for at least eight billion years — an incredible length of time, considering the universe is <a href="https://www.space.com/24054-how-old-is-the-universe.html">13.8 billion years old</a>. </p>
<p>Something is fuelling these stars from within, but given that they had run out of their nuclear fuel source, scientists were unsure what could be keeping them shining so brightly. Our research, <a href="https://doi.org/10.1038/s41586-024-07102-y">recently published in <em>Nature</em></a>, presents the solution to this conundrum.</p>
<p>Using information gathered by the <a href="https://www.esa.int/Science_Exploration/Space_Science/Gaia">Gaia space observatory of the European Space Agency</a>, researchers discovered that some white dwarfs essentially stop cooling.</p>
<p>By studying how white dwarfs are distributed as a function of temperature (from hot to cold) <a href="https://sci.esa.int/web/gaia/-/61343-shedding-light-on-white-dwarfs-the-future-of-stars-like-our-sun">in the Gaia data</a>, astronomers noticed an accumulation of white dwarfs at intermediate temperatures. This indicates that some white dwarfs spend more time at these intermediate temperatures — eight billion years more than thought possible.</p>
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<iframe width="440" height="260" src="https://www.youtube.com/embed/nkXR7bpmy7Q?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Interview with University of Victoria astrophysics researcher Simon Blouin.</span></figcaption>
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<h2>Stellar crystals</h2>
<p>White dwarfs are weird. A mere teaspoon of material from their cores <a href="https://astronomy.swin.edu.au/cosmos/W/white+dwarf">weighs several tonnes</a>. Under such extreme densities, matter can behave strangely. Even though the interiors of white dwarfs are millions of degrees hot, the density is high enough that they can freeze into a solid state. They form crystals out of the carbon, oxygen and other elements present in their interiors.</p>
<p>The formation of these crystals normally starts at the centre of the star, where density is highest. As the white dwarf cools down, more crystals are formed in successive layers until almost the whole star is completely solid.</p>
<p>However, this inside-out crystallization does not apply to all white dwarfs. We discovered that the heaviest elements present in white dwarfs are expelled from the crystals as they are formed, just as <a href="https://nsidc.org/learn/parts-cryosphere/sea-ice/science-sea-ice">salt is expelled from ice crystals</a> when seawater freezes.</p>
<p>The crystals become less dense than their surroundings, and float up like ice cubes in a glass of water. As the crystals do not stay in place, the core cannot simply freeze from the inside out.</p>
<p>The movements created by the floating crystals reshuffle the chemical layering inside the star. Gradually, the heaviest elements are transported toward the centre. This releases a steady flow of gravitational energy that keeps the star shining at a near-constant temperature for billions of years.</p>
<p>Floating crystals can pause the stellar aging process, providing a final energy source to otherwise dead stars.</p>
<h2>The exception or the rule?</h2>
<p>So far, this cooling pause has been conclusively identified only for a small fraction of the white dwarf population. The high masses and peculiar compositions of these anomalous white dwarfs suggest that they had quite violent histories. Most likely, they are the products of stellar mergers — events where two stars collide and combine.</p>
<p>But this may be just the tip of the iceberg. Based on our findings, we suspect that almost all white dwarfs, and not just the merged ones, experience some cooling pause during their evolution. However, this more universal cooling pause would be much shorter than the multi-billion-year interruption studied so far.</p>
<p><a href="https://doi.org/10.1093/mnras/stad1719">Observations are ongoing</a> to try to identify this shorter cooling pause in the rest of the white dwarf population.</p>
<h2>Cosmic clocks</h2>
<p>These findings have implications for stellar archaeology. The cooler the white dwarf, the older it must be. Just as archeologists use carbon-14 dating to determine the age of artifacts and reconstruct the history of a city or civilization, astronomers rely on white dwarf cooling to measure the ages of stars and understand the history of our Milky Way galaxy.</p>
<p>Our discovery makes this more complicated. A white dwarf with a certain temperature could be billions of years older than initially assumed because of the formation of these floating crystals. The key now is to figure out which stars experience this cooling pause and which do not.</p><img src="https://counter.theconversation.com/content/225502/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Simon Blouin receives funding from the Natural Sciences and Engineering Research Council of Canada. </span></em></p>Floating crystals can pause the stellar aging process, providing a final energy source to otherwise dead stars.Simon Blouin, CITA National Postdoctoral Fellow, Astrophysics, University of VictoriaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2227072024-03-13T19:13:22Z2024-03-13T19:13:22ZTotal solar eclipses provide an opportunity to engage with science, culture and history<figure><img src="https://images.theconversation.com/files/580943/original/file-20240311-16-li8vda.jpg?ixlib=rb-1.1.0&rect=0%2C5%2C3724%2C2146&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Throughout time, eclipses have inspired societies to understand the cosmos and its events.</span> <span class="attribution"><span class="source">(Shutterstock)</span></span></figcaption></figure><p>On April 8, 2024, there will be a total solar eclipse in Canada. This is an opportunity to experience, learn from and participate in the excitement and wonder. And rather than hiding inside, researchers have been communicating how people can safely enjoy this unique opportunity.</p>
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<strong>
Read more:
<a href="https://theconversation.com/on-april-8-2024-parts-of-ontario-quebec-the-maritimes-and-newfoundland-will-see-a-total-eclipse-of-the-sun-heres-how-to-get-ready-for-it-203382">On April 8, 2024, parts of Ontario, Québec, the Maritimes and Newfoundland will see a total eclipse of the sun. Here's how to get ready for it.</a>
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<p>Roughly every 18 months, the sun, moon and Earth come into perfect alignment and somewhere on Earth <a href="https://eclipse.gsfc.nasa.gov/SEatlas/SEatlas.html">experiences a solar eclipse</a>. During this phenomenon, the moon casts a roughly 250 km wide shadow onto Earth.</p>
<p>This ephemeral daytime darkness can be a once-in-a-lifetime experience. The last time Toronto experienced a total solar eclipse was on <a href="http://xjubier.free.fr/en/site_pages/solar_eclipses/xSE_GoogleMap3.php?Ecl=+19250124&Acc=2&Umb=1&Lmt=1&Mag=0&Lat=43.69660&Lng=-79.41391&Elv=162.0&Zoom=8&LC=1">Jan. 24, 1925</a>; the next total solar eclipse will occur in 120 years, on <a href="http://xjubier.free.fr/en/site_pages/solar_eclipses/xSE_GoogleMap3.php?Ecl=+21441026&Acc=2&Umb=1&Lmt=1&Mag=0&Lat=43.69629&Lng=-79.29982&Elv=127.0&Zoom=8&LC=1">Oct. 26, 2144</a>.</p>
<p>Our interpretation of, and response to, total solar eclipses has advanced enormously. Eclipses were once considered cosmic omens that predicted dying kings, good harvests or the need for new territorial treaties. Today, they provide a unique opportunity to consider the physical nature of the universe, and the cosmic privilege of witnessing the alignment of the moon and sun. </p>
<h2>Eclipses and knowledge creation</h2>
<p>Due to their sudden darkness, solar eclipses have been perceived <a href="https://www.cnn.com/2017/07/25/us/history-solar-eclipse/index.html">through history as catastrophic events</a>. Many societies developed stories to <a href="https://www.britannica.com/list/the-sun-was-eaten-6-ways-cultures-have-explained-eclipses">explain these unusual events</a>, often filled with fear and violence. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/580949/original/file-20240311-26-98odlu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="an illustration of a golden brown demon eating a yellow disc against a purple background" src="https://images.theconversation.com/files/580949/original/file-20240311-26-98odlu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/580949/original/file-20240311-26-98odlu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=451&fit=crop&dpr=1 600w, https://images.theconversation.com/files/580949/original/file-20240311-26-98odlu.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=451&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/580949/original/file-20240311-26-98odlu.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=451&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/580949/original/file-20240311-26-98odlu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=567&fit=crop&dpr=1 754w, https://images.theconversation.com/files/580949/original/file-20240311-26-98odlu.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=567&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/580949/original/file-20240311-26-98odlu.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=567&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 mural of the Hindu demon Rahu swallowing the moon at the temple Wat Phang La in southern Thailand.</span>
<span class="attribution"><a class="source" href="https://www.flickr.com/photos/anandajoti/10684670235/">(Anandajoti Bhikkhu/flickr)</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>Indian myths tell of an <a href="https://www.washingtonpost.com/graphics/2017/lifestyle/eclipse-myths/">immortal demon seeking revenge on Vishnu by trying to eat the sun and moon</a>. The Pomo, Indigenous people of Northern California, describe <a href="https://www.exploratorium.edu/eclipse/eclipse-stories-from-around-the-world">a huge angry bear trying to eat the sun</a>. In other mythologies, eclipses were thought to be heavenly forces removing our source of warmth and life.</p>
<p>Beliefs about eclipses motivated ancient Greek astronomers to create the <a href="https://doi.org/10.1371/journal.pone.0103275">antikythera mechanism</a>, a complex analog computer that predicted the timing of future eclipses with a precision of 30 minutes. These predictions were critical for Greek society as a solar eclipse could mean an upcoming death of the king, requiring the appointment of a pseudo-emperor to be killed instead.</p>
<p>Our reactions to eclipses have evolved, driving us to better understand the solar system and the universe at large. </p>
<p>During the eclipse on Aug. 18, 1868, astronomers Norman Lockyer and Pierre Janssen each studied the light from the solar corona to <a href="https://doi.org/10.1007/978-1-4614-5363-5">discover a new chemical element</a>. This chemical element was named helium, after the Greek word for the sun. </p>
<p>On May 29, 1919, Frank Watson Dyson and Arthur Stanley Eddington studied the <a href="https://doi.org/10.1098/rsta.1920.0009">bent path of starlight</a> during a total solar eclipse for the first experimental “<a href="https://timesmachine.nytimes.com/timesmachine/1919/11/10/118180487.pdf">triumph of Einstein’s theory</a>” of general relativity.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/580945/original/file-20240311-20-25sylo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="ancient greenish square fragments" src="https://images.theconversation.com/files/580945/original/file-20240311-20-25sylo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/580945/original/file-20240311-20-25sylo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/580945/original/file-20240311-20-25sylo.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/580945/original/file-20240311-20-25sylo.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/580945/original/file-20240311-20-25sylo.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/580945/original/file-20240311-20-25sylo.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/580945/original/file-20240311-20-25sylo.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">Fragments of an antikythera mechanism on display at a museum in Athens, Greece.</span>
<span class="attribution"><span class="source">(Shutterstock)</span></span>
</figcaption>
</figure>
<h2>Eclipse experiences</h2>
<p>Unlike many other cosmic events, such as meteor showers or comets, which require expensive telescopes or <a href="https://darksky.org/what-we-do/international-dark-sky-places/">dark sky places</a>, eclipses are a barrier-free celestial event. To safely enjoy the eclipse, one simply needs eclipse viewing glasses or <a href="https://www.jpl.nasa.gov/edu/learn/project/how-to-make-a-pinhole-camera/">a cardboard box</a>. </p>
<p>Many universities across Canada are using the opportunity of the total solar eclipse to engage with people to safely experience this astronomical phenomenon. For example, Queen’s University in Kingston, Canada is making <a href="https://www.queensu.ca/physics/2024-total-solar-eclipse/eclipse-glasses">120,000 eclipse glasses available</a> to make safe eclipse viewing possible for anyone.</p>
<p>In the spirit of education, hundreds of <a href="https://astrosociety.org/education-outreach/amateur-astronomers/eclipse-ambassadors/program.html">eclipse ambassadors</a> are heading to schools to engage with students about having a profound and safe experience during the eclipse. These ambassadors lead workshops on building inexpensive pinhole cameras to project the sun during the eclipse, explaining unique features that can be seen during eclipses, such as <a href="https://science.nasa.gov/resource/baileys-beads/">Bailey’s beads</a> and the <a href="https://www.nasa.gov/image-article/diamond-ring-effect/">diamond ring effect</a>, and helping everyone appreciate the vastness of the solar system.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/580952/original/file-20240311-20-8t2snr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="a black circle surrounded with a ring of light that is thicker in the lower righthand quadrant" src="https://images.theconversation.com/files/580952/original/file-20240311-20-8t2snr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/580952/original/file-20240311-20-8t2snr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=389&fit=crop&dpr=1 600w, https://images.theconversation.com/files/580952/original/file-20240311-20-8t2snr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=389&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/580952/original/file-20240311-20-8t2snr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=389&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/580952/original/file-20240311-20-8t2snr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=489&fit=crop&dpr=1 754w, https://images.theconversation.com/files/580952/original/file-20240311-20-8t2snr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=489&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/580952/original/file-20240311-20-8t2snr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=489&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 Baily’s Beads effect occurs when gaps in the moon’s rugged terrain allow sunlight to pass through in some places just before the total phase of the eclipse.</span>
<span class="attribution"><a class="source" href="https://science.nasa.gov/resource/baileys-beads/">(Aubrey Gemignani/NASA)</a></span>
</figcaption>
</figure>
<p>These efforts demonstrate the universal value of science, and promote science engagement beyond classrooms and institutions.</p>
<p>Not only is the upcoming eclipse being leveraged as an opportunity to inspire the next generation of scientists, but it is also being used for the advancement of scientific knowledge. Unlike the experiments of Dyson, Eddington and Lockyer that were limited to the academy, today’s institutions are mobilizing the public to conduct citizen science experiments. </p>
<p>Initiated by NASA, the <a href="https://eclipsemegamovie.org/goals">Eclipse Megamovie project</a> will use photos taken during totality of the solar eclipse to study the solar corona. In 2017, photos collected during the total eclipse helped researchers identify a plasma plume in the solar corona. The 2024 eclipse will help researchers study this plume in greater detail. </p>
<p>Anyone with a DSLR camera and a tripod can submit a picture of the total solar eclipse to the Eclipse Megamovie project. The public data collected for the 2024 eclipse will far exceed what could be accomplished by any one experiment or location.</p>
<p>April’s total solar eclipse, and others to come, will remind people that science is exciting and inspiring, and that scientific expertise is of profound universal value. Such a celestial coincidence is an opportunity to engage with local communities and discuss the origin and mechanics of our solar system, all while including the public in scientific discovery through crowd-sourcing images of their experience. </p>
<p>All that’s left is to hope for clear skies and marvel once more at the cosmos.</p><img src="https://counter.theconversation.com/content/222707/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Nikhil Arora receives funding from the National Sciences and Engineering Research Council of Canada.</span></em></p><p class="fine-print"><em><span>Mark Richardson is based at the Arthur B. McDonald Canadian Astroparticle Physics Research Institute, who has received funding from the Canada First Research Excellence Fund. </span></em></p>Eclipses have inspired myths, predictions and scientific discoveries. The total solar eclipse occurring on April 8 provides a once-in-a-lifetime opportunity to engage with science and the cosmos.Nikhil Arora, Postdoctoral fellow, Physics, Engineering Physics & Astronomy, Queen's University, OntarioMark Richardson, Manager for Education and Public Outreach, Adjunct Professor of Physics and Astronomy, Queen's University, OntarioLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2241132024-03-12T18:55:13Z2024-03-12T18:55:13ZSolar eclipses result from a fantastic celestial coincidence of scale and distance<figure><img src="https://images.theconversation.com/files/580531/original/file-20240307-28-al4bnq.jpg?ixlib=rb-1.1.0&rect=23%2C15%2C5247%2C3690&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Solar eclipses happen because of a few factors, including the Moon's size and distance from the Sun. </span> <span class="attribution"><a class="source" href="https://newsroom.ap.org/detail/EclipseKentucky/8b202fc6981149ebb1c59158d49e348d/photo?Query=eclipse&mediaType=photo&sortBy=&dateRange=Anytime&totalCount=478&digitizationType=Digitized&currentItemNo=7&vs=true&vs=true">AP Photo/Timothy D. Easley</a></span></figcaption></figure><p>On April 8, 2024, millions across the U.S. will have the once-in-a-lifetime chance to view a total solar eclipse. <a href="https://science.nasa.gov/eclipses/future-eclipses/eclipse-2024/where-when/">Cities including</a> Austin, Texas; Buffalo, New York; and Cleveland, Ohio, will have a direct view of this rare cosmic event that lasts for just a few hours.</p>
<p>While <a href="https://theconversation.com/astro-tourism-chasing-eclipses-meteor-showers-and-elusive-dark-skies-from-earth-207969">you can see many astronomical events</a>, such as <a href="https://theconversation.com/comets-101-everything-you-need-to-know-about-the-snow-cones-of-space-213342">comets</a> and meteor showers, from anywhere on Earth, eclipses are different. You need to travel to what’s called the <a href="https://theconversation.com/when-the-sun-goes-dark-5-questions-answered-about-the-solar-eclipse-81308">path of totality</a> to experience the full eclipse. Only certain places get an eclipse’s full show, and that’s because of scale. </p>
<p>The relatively small <a href="https://www.space.com/18135-how-big-is-the-moon.html">size of the Moon</a> and its shadow make eclipses truly once-in-a-lifetime opportunities. On average, total solar eclipses are visible somewhere on Earth once every few years. But from any one location on Earth, <a href="https://eclipse.gsfc.nasa.gov/SEcirc/SEcirc.html">it is roughly 375 years</a> between solar eclipses.</p>
<p><a href="https://science.psu.edu/astro/people/cxp137">I’m an astronomer</a>, but I have never seen a total solar eclipse, so I plan to drive to Erie, Pennsylvania, in the path of totality, for this one. This is one of the <a href="https://eclipse.gsfc.nasa.gov/SEmap/SEmapNA/TSENorAm2051.gif">few chances I have</a> to see a total eclipse without making a much more expensive <a href="https://theconversation.com/astro-tourism-chasing-eclipses-meteor-showers-and-elusive-dark-skies-from-earth-207969">trip to someplace more remote</a>. Many people have asked me why nearby eclipses are so rare, and the answer is related to the size of the Moon and its distance from the Sun.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/fmtGqOxxmEU?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Those in the path of totality will have the opportunity to see a total solar eclipse this April.</span></figcaption>
</figure>
<h2>Size and scale</h2>
<p>You can observe a solar eclipse when the Moon passes in front of the Sun, blocking some or all of the Sun from view. For people on Earth to be able to see an eclipse, the Moon, while orbiting around the Earth, must lie exactly along the observer’s line of sight with the Sun. Only some observers will see an eclipse, though, because not everyone’s view of the Sun will be blocked by the Moon on the day of an eclipse. </p>
<p>The fact that solar eclipses happen at all is a bit of a numerical coincidence. It just so happens <a href="https://science.nasa.gov/sun/facts/#hds-sidebar-nav-3">that the Sun</a> is approximately 400 times <a href="https://science.nasa.gov/moon/facts/#hds-sidebar-nav-3">larger than the Moon</a> and also 400 times more distant from the Earth. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/581049/original/file-20240311-22-9ovtoi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="A photo showing the Earth next to the Moon. The Earth is much larger." src="https://images.theconversation.com/files/581049/original/file-20240311-22-9ovtoi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/581049/original/file-20240311-22-9ovtoi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/581049/original/file-20240311-22-9ovtoi.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/581049/original/file-20240311-22-9ovtoi.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/581049/original/file-20240311-22-9ovtoi.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/581049/original/file-20240311-22-9ovtoi.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/581049/original/file-20240311-22-9ovtoi.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Earth’s size compared with the Moon. Distances not to scale.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/the-earth-and-moon-to-scale-royalty-free-image/136247709?phrase=earth+moon+size+comparison&adppopup=true">Laara Cerman/Leigh Righton/Stockbyte via Getty Images</a></span>
</figcaption>
</figure>
<p>So, even though the Moon is much smaller <a href="https://science.nasa.gov/sun/facts/">than the Sun</a>, it is just close enough to Earth to appear the same size as the Sun when seen from Earth. </p>
<p>For example, your pinky finger is much, much smaller than the Sun, but if you hold it up at arm’s length, it appears to your eye to be large enough to block out the Sun. The Moon can do the same thing – it can block out the Sun if it’s lined up perfectly with the Sun from your point of view. </p>
<h2>Path of totality</h2>
<p>When the Earth, Moon and Sun line up perfectly, the Moon <a href="https://science.nasa.gov/solar-system/skywatching/eclipses/solar-eclipses/2024-solar-eclipse/total-solar-eclipse-2024-the-moons-moment-in-the-sun/">casts a shadow onto the Earth</a>. Since the Moon is round, its shadow is round as it lands on Earth. The only people who see the eclipse are those in the area on Earth where the shadow lands at a given moment. </p>
<p>The Moon is continuously orbiting around the Earth, so as time goes on during the eclipse, the Moon’s shadow moves over the face of the Earth. Its shadow ends up looking like a thick line that can cover hundreds of miles in length. Astronomers call that line the <a href="https://science.nasa.gov/solar-system/skywatching/eclipses/new-nasa-map-details-2023-and-2024-solar-eclipses-in-the-us/">path of totality</a>. </p>
<p>From any given location along the path of totality, an observer can see the Sun completely eclipsed for a few minutes. Then, the shadow moves away from that location and the Sun slowly becomes more and more visible. </p>
<h2>A tilted orbit</h2>
<p>Solar eclipses don’t happen every single time the Moon passes in between Earth and the Sun. If that were the case, there would be a solar eclipse every month. </p>
<p>If you could float above the Earth’s North Pole and see the Moon’s orbit from above, you would see the Moon line up with the Sun once every time it orbits around the Earth, which is approximately once per month. From this high point of view, it looks like the Moon’s shadow should land on Earth every orbit. </p>
<p>However, if you could shift your perspective to look at the Moon’s orbit from the orbital plane, you would see that the Moon’s orbit is <a href="https://moon.nasa.gov/moon-in-motion/phases-eclipses-supermoons/overview/">tilted by about 5 degrees</a> compared with Earth’s orbit around the Sun. This tilt means that sometimes the Moon is too high and its shadow passes above the Earth, and sometimes the Moon is too low and its shadow passes below the Earth. An eclipse happens only <a href="https://svs.gsfc.nasa.gov/4324/">when the Moon is positioned just right</a> and its shadow lands on the Earth. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/JplGhSC-eGM?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">There isn’t an eclipse every time the Moon passes in front of the Sun because of the Moon’s tilted orbit around Earth.</span></figcaption>
</figure>
<p>As time goes on, the Earth and the Moon continue spinning, and <a href="https://www.youtube.com/watch?v=JplGhSC-eGM">eventually the Moon aligns with Earth’s orbit</a> around the Sun at the same moment the Moon passes between the Sun and the Earth. </p>
<p>While only certain cities are in the path of totality for this April’s eclipse, the entire U.S. is still close enough to this path that observers outside of the path of totality will see a <a href="https://nso.edu/for-public/eclipse-map-2024">partial eclipse</a>. In those locations, the Moon will appear to pass in front of part of the Sun, leaving a crescent shape of the Sun still visible at the moment of maximum eclipse.</p><img src="https://counter.theconversation.com/content/224113/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Christopher Palma 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>Many people will see a dazzling eclipse this April, but these events are possible only because of the sizes and precise distances between Earth, the Moon and the Sun.Christopher Palma, Teaching Professor, Department of Astronomy & Astrophysics, Penn StateLicensed as Creative Commons – attribution, no derivatives.tag: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>
<figure class="align-center zoomable">
<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>
</figcaption>
</figure>
<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>
<figure class="align-center zoomable">
<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>
</figcaption>
</figure>
<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>
</figure>
<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/2227092024-03-11T20:26:45Z2024-03-11T20:26:45ZArcheoastronomy uses the rare times and places of previous total solar eclipses to help us measure history<figure><img src="https://images.theconversation.com/files/580911/original/file-20240311-28-ygi764.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C1280%2C1280&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">A photograph of the 2017 total solar eclipse, taken at the Oregon State Fair Grounds, Salem, Ore.</span> <span class="attribution"><span class="source">(Dominic Hart/NASA)</span></span></figcaption></figure><p>In 648 BCE, the Greek poet Archilochus wrote that, “nothing can be surprising any more or impossible or miraculous, now that Zeus, father of the Olympians has <a href="https://articles.adsabs.harvard.edu/pdf/2020JAHH...23...47S">made night out of noonday</a>, hiding the light of the gleaming Sun.”</p>
<p>Total solar eclipses have fascinated and terrified people for centuries. Today, we know that total solar eclipses — like the <a href="https://theconversation.com/on-april-8-2024-parts-of-ontario-quebec-the-maritimes-and-newfoundland-will-see-a-total-eclipse-of-the-sun-heres-how-to-get-ready-for-it-203382">upcoming eclipse on April 8</a> — are caused by a cosmic coincidence when the moon comes between the Earth and the sun, momentarily blocking the sun from view. But in ancient times, the cause was unknown.</p>
<p>Nevertheless, the peoples of those eras took note. From all ends of the Earth, stories abound of day turning to night or <a href="https://eclipse2017.nasa.gov/eclipse-history">the sun being consumed</a>, and these records are opening up a new branch of study.</p>
<p><a href="https://www.jstor.org/stable/20170165">Astroarcheology</a> — also called archeoastronomy — uses astronomical records to help date key moments or events in history. Of all astronomical phenomena, total solar eclipses are among the best measuring sticks because they are only visible at a certain time and place. </p>
<p>Total solar eclipses are rare enough that a given spot on Earth is only likely to see <a href="https://articles.adsabs.harvard.edu/pdf/1982JBAA...92..124M">one every 375 years (on average)</a>. And when an eclipse does happen, it only appears as total to those who are <a href="https://eclipsewise.com/solar/SEatlas/SEatlas.html">along a narrow path on Earth</a>. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/580844/original/file-20240310-26-te2a9p.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="(drawing of a solar eclipse represented by a black circle surrounded by a white aura on a black background)" src="https://images.theconversation.com/files/580844/original/file-20240310-26-te2a9p.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/580844/original/file-20240310-26-te2a9p.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=464&fit=crop&dpr=1 600w, https://images.theconversation.com/files/580844/original/file-20240310-26-te2a9p.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=464&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/580844/original/file-20240310-26-te2a9p.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=464&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/580844/original/file-20240310-26-te2a9p.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=583&fit=crop&dpr=1 754w, https://images.theconversation.com/files/580844/original/file-20240310-26-te2a9p.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=583&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/580844/original/file-20240310-26-te2a9p.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=583&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 illustration of the solar eclipse that occurred on Jan. 22, 1898 in India.</span>
<span class="attribution"><a class="source" href="https://en.wikipedia.org/wiki/Solar_eclipse_of_January_22,_1898">(Edward Walter Maunder/British Astronomical Association)</a></span>
</figcaption>
</figure>
<h2>Identifying years</h2>
<p>This combination of rare time and place helps researchers narrow down the exact date ancient peoples viewed a recorded eclipse. Additional clues such as the time of day the eclipse occurred (morning, noon or evening), time of year (season) or the presence of bright planets can also help identify the exact eclipse.</p>
<p>For example, a record of total solar eclipse occurring near dawn in ancient Chinese texts pertaining to King Yi helped <a href="https://articles.adsabs.harvard.edu/pdf/2003JAHH....6...53L">identify the year his reign began</a>.</p>
<p>One of the oldest recorded eclipses is on a clay tablet from the city of <a href="https://www.britannica.com/place/Ugarit">Ugarit, in modern-day Syria</a>. The city was overthrown after the eclipse, making the tablet one of the last things written down by someone from that city. The inscription on the tablet reads: “… day of the new moon in ḫiyaru the Sun went down, its gate-keeper was [Rashap].”</p>
<p>The word ḫiyaru refers to a time of year around February/March, and Rashap is likely a planet. Armed with this information and knowledge that the city disappeared in the Bronze Age, researchers dated the tablet and eclipse to March 5, 1222 BCE, over 3,000 years ago, with the planet Mars <a href="https://doi.org/10.1038/338238a0">visible near to the eclipsed sun</a>. Thanks to this eclipse, we know that Ugarit fell after March 5, 1222 BCE. </p>
<p>Records like these help researchers identify precise dates in the ancient world.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/580919/original/file-20240311-17800-m97ekg.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="an illustration of text above a photograph of a grey clay tablet" src="https://images.theconversation.com/files/580919/original/file-20240311-17800-m97ekg.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/580919/original/file-20240311-17800-m97ekg.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=689&fit=crop&dpr=1 600w, https://images.theconversation.com/files/580919/original/file-20240311-17800-m97ekg.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=689&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/580919/original/file-20240311-17800-m97ekg.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=689&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/580919/original/file-20240311-17800-m97ekg.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=866&fit=crop&dpr=1 754w, https://images.theconversation.com/files/580919/original/file-20240311-17800-m97ekg.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=866&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/580919/original/file-20240311-17800-m97ekg.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=866&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Photograph and illustration of the clay tablet KTU 1.78 from Ugarit, in modern-day Syria, which mentions a total solar eclipse.</span>
<span class="attribution"><span class="source">(Dietrich and Loretz/University of Chicago Library)</span></span>
</figcaption>
</figure>
<h2>Changing predictions</h2>
<p>Precisely predicting future eclipses, or plotting the paths of historical eclipses, requires knowing the positions of the sun, moon and Earth. Computers can track the motions of each, but the challenge here is that these motions are not constant. As the moon causes tides in Earth’s oceans, the process also causes the moon to slowly drift away from the Earth and <a href="https://www.scientificamerican.com/article/earth-rotation-summer-solstice/">the length of day on Earth to slowly increase</a>. </p>
<p>Essentially, the length of a day on Earth is getting longer by roughly 18 microseconds every year, <a href="http://dx.doi.org/10.1098/rspa.2016.0404">or one second every 55,000 years</a>. After hundreds or thousands of years, that fraction of a second per day adds up to several hours.</p>
<p>The change in Earth’s day also affects dating historical eclipses — if the difference in the length of day is not corrected for, calculations may be inaccurate by thousands of kilometers. As such, when using eclipses to date historical events a correction must be applied; uncertainties in the correction can make <a href="https://doi.org/10.1093/pasj/56.1.215">ancient eclipse identifications</a> harder to pin down in the absence of <a href="https://www.jstor.org/stable/178278">additional information</a> to help <a href="https://articles.adsabs.harvard.edu/pdf/1995QJRAS..36..397Z">narrow down the possibilities</a>. </p>
<h2>Measuring changing day-lengths</h2>
<p>For those solar eclipses that are well established, they open a window into tracking Earth’s length-of-day across the centuries. By timing eclipses over the last 2,000 years, researchers have mapped out the length of Earth’s day over that same span. The value of 18 microseconds per year is an average, but sometimes the Earth slows down a bit more and sometimes a bit less. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/580922/original/file-20240311-139405-bs1pct.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="a graph showing day lengths over time" src="https://images.theconversation.com/files/580922/original/file-20240311-139405-bs1pct.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/580922/original/file-20240311-139405-bs1pct.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=413&fit=crop&dpr=1 600w, https://images.theconversation.com/files/580922/original/file-20240311-139405-bs1pct.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=413&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/580922/original/file-20240311-139405-bs1pct.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=413&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/580922/original/file-20240311-139405-bs1pct.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=518&fit=crop&dpr=1 754w, https://images.theconversation.com/files/580922/original/file-20240311-139405-bs1pct.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=518&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/580922/original/file-20240311-139405-bs1pct.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=518&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Change in length of day (lod) for Earth in milliseconds (0.001 s) as measured from eclipse records (black line). The red line shows the average change over 2,000 years, while the grey line shows what we would expect from tidal forces between the Earth and moon only. The green dashed line shows a model fit to the data in black.</span>
<span class="attribution"><a class="source" href="http://dx.doi.org/10.1098/rspa.2016.0404">(F.R. Stephenson, L.V. Morrison and C.Y. Hohenkerk)</a>, <a class="license" href="http://creativecommons.org/licenses/by/4.0/">CC BY</a></span>
</figcaption>
</figure>
<p>Tides alone can’t explain this pattern — there is something more going on between the moon and the Earth, and the cause is still unknown. This mystery, however, can be explored thanks to solar eclipses. </p>
<p>We can measure a change in length of a day on Earth with instruments now, but we wouldn’t be able to capture that change hundreds or thousands of years back in time without a precise measuring stick and records of eclipses over millennia and across the world. Total solar eclipses allow us to peer into not only our own history, but the history of the Earth itself.</p><img src="https://counter.theconversation.com/content/222709/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Sarah Sadavoy receives funding from the National Sciences and Engineering Research Council of Canada (NSERC). </span></em></p>Mentions of total solar eclipses in ancient history help researchers pinpoint precise dates of notable events.Sarah Sadavoy, Assistant Professor, Physics, Engineering Physics & Astronomy, Queen's University, OntarioLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2208242024-03-08T14:35:38Z2024-03-08T14:35:38ZApril’s eclipse will mean interruptions in solar power generation, which could strain electrical grids<figure><img src="https://images.theconversation.com/files/573902/original/file-20240206-16-om8k0f.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C3994%2C2658&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Solar panels in Brazil. </span> <span class="attribution"><a class="source" href="https://newsroom.ap.org/detail/7551d26521224cbf94340e255374a7a7?ext=true">AP Photo/Bruna Prado</a></span></figcaption></figure><p>During the most recent total solar eclipse visible in the U.S., on Aug. 21, 2017, the skies darkened as the Moon crossed in front of the Sun. It blocked out all sunlight – except for that from a golden ring visible around the Moon’s shape, called the corona. Not surprisingly, solar power generation across North America plummeted for several hours, from the first moment the Moon began to obscure the Sun to when the Sun’s disk was clear again. </p>
<p>On April 8, 2024, another <a href="https://theconversation.com/when-the-sun-goes-dark-5-questions-answered-about-the-solar-eclipse-81308">total solar eclipse</a> will track across the U.S., causing perhaps an even greater loss of solar power generation. Although this will be the second total solar eclipse visible in the U.S. in under seven years, these events are a rare occurrence. Nevertheless, they present a unique challenge to power grid operators.</p>
<p><a href="https://dornsife.usc.edu/profile/vahe-peroomian/">I am a space scientist</a> with a passion for teaching physics and astronomy. Though I have seen many partial eclipses of the Sun, I have yet to witness a total solar eclipse. My road trip to Bryce Canyon National Park in Utah in October 2023 to see the “ring of fire” <a href="https://theconversation.com/explainer-what-is-a-solar-eclipse-33019">annular solar eclipse</a> was unforgettable, and April 8 will surely find me handing out <a href="https://theconversation.com/turn-around-bright-eyes-heres-how-to-see-the-eclipse-and-protect-your-vision-203571">eclipse glasses</a> once again.</p>
<h2>When the Moon’s shadow blocks the Sun</h2>
<p>During <a href="https://theconversation.com/explainer-what-is-a-solar-eclipse-33019">a solar eclipse</a>, the Moon partially or completely blocks the view of the Sun. Since the Moon is nearly 400 times smaller than the Sun and nearly <a href="https://www.universetoday.com/17109/the-sun-and-the-moon/">400 times closer</a>, the <a href="https://www.forbes.com/sites/startswithabang/2017/02/08/the-strangest-eclipse-fact-of-all-the-moons-shadow-isnt-a-circle/?sh=be76f8c17bd3">Moon’s shadow</a>, visible from Earth, tapers to a width of <a href="https://cmase.uark.edu/_resources/pdf/nasa/NASAConnect/pathoftotality.pdf">70 to 100 miles</a> (112 to 161 kilometers).</p>
<p>Within this region, called the path of totality, observers see a total solar eclipse. Observers close to but outside this path witness a partial eclipse of the Sun, where the Moon covers a fraction of the Sun’s disk. </p>
<p>During the April 8, 2024, total solar eclipse, the <a href="https://science.nasa.gov/eclipses/future-eclipses/eclipse-2024/where-when/">path of totality</a> in the continental U.S. will extend from Texas in the south to Maine in the northeast. Elsewhere in the U.S., Miami will see a partial eclipse in which a maximum of 46% of the Sun’s disk is obscured. In Seattle, far from the path of totality, the Moon will cover only a maximum of <a href="https://www.timeanddate.com/eclipse/map/2024-april-8">20% of the Sun</a>. In southern Texas, where the path of totality first crosses into the U.S., the eclipse will last just under three hours, with totality a mere 4 minutes and 27 seconds. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/sOpYoO_SK7o?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">The path of the 2024 solar eclipse.</span></figcaption>
</figure>
<h2>Increasing reliance on solar power</h2>
<p>The worldwide trend toward renewable energy has seen a significant increase in solar, or photovoltaic, power generation in the last decade. Solar power generation capacity is set to <a href="https://www.iea.org/data-and-statistics/data-tools/renewable-energy-progress-tracker">double worldwide</a> between 2022 and 2028, and the U.S. now has the capacity to generate <a href="https://ember-climate.org/data-catalogue/yearly-electricity-data/">three times more solar energy</a> than at the time of the 2017 total solar eclipse.</p>
<p>The most obvious obstacle to solar power generation is cloud cover. On a cloudy day, the energy produced by solar panels drops to <a href="https://www.forbes.com/home-improvement/solar/solar-panels-cloudy-days-night/">10% to 25%</a> of its output on a sunny day. </p>
<p>The North American power transmission grid is divided into <a href="https://www.nerc.com/AboutNERC/keyplayers/Pages/default.aspx">six major regions</a> and <a href="https://alternativeenergy.procon.org/questions/what-is-the-electricity-grid/">more than 150</a> local and regional subgrids. Electrical system operators in each local grid continuously balance the amount of electricity production with the “load,” or the demand for electricity by consumers. </p>
<p>System operators can tap into energy from <a href="https://science.howstuffworks.com/environmental/energy/power.htm">various power generation mechanisms</a> like solar, wind, hydroelectric, natural gas and coal. Local grids can also import and export electricity to and from their grid as needed.</p>
<p>System operators have accurate models for the amount of solar power generated across the U.S. on a daily basis, and these models account for the parts of the continental U.S. that may have cloudy skies. By pairing solar power generation with battery storage, they can access electricity from solar even when the Sun isn’t shining – on cloudy days or at night. </p>
<p>To plan for an eclipse, electrical system operators need to figure out how much the energy production will drop and how much power people will draw from the reserves. On the day of the 2017 total solar eclipse, for example, solar power generation in the U.S. <a href="https://www.nrel.gov/docs/fy18osti/71147.pdf">dropped 25%</a> below average. </p>
<p>Because solar power production falls quickly during the eclipse’s peak, grid operators may need to tap into reserves at a rate that may strain the <a href="https://www.osha.gov/etools/electric-power/illustrated-glossary/transmission-lines">electrical transmission lines</a>. To try to keep things running smoothly, grid operators will rely on local reserves and minimize power transfer <a href="https://www.nrel.gov/docs/fy18osti/71147.pdf">between grids</a> during the event. This should lessen the burden on transmission lines in local grids and prevent temporary blackouts. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/573903/original/file-20240206-28-khlo8k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Electrical towers and power lines shown against a sunset." src="https://images.theconversation.com/files/573903/original/file-20240206-28-khlo8k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/573903/original/file-20240206-28-khlo8k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/573903/original/file-20240206-28-khlo8k.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/573903/original/file-20240206-28-khlo8k.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/573903/original/file-20240206-28-khlo8k.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/573903/original/file-20240206-28-khlo8k.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/573903/original/file-20240206-28-khlo8k.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">Solar eclipses can stress the power grid.</span>
<span class="attribution"><a class="source" href="https://newsroom.ap.org/detail/BidenInfrastructure/9a4ee5858ac74db78eb7d96b1961c275/photo?Query=power%20grid&mediaType=photo&sortBy=&dateRange=Anytime&totalCount=226&digitizationType=Digitized&currentItemNo=17&vs=true&vs=true">AP Photo/Matt Rourke</a></span>
</figcaption>
</figure>
<h2>Renewable energy during eclipses</h2>
<p>Solar isn’t the only type of renewable energy generation that goes down during an eclipse. Since it’s not as sunny, temperatures along the path of the eclipse fall by as much as <a href="https://eclipse2017.nasa.gov/temperature-change-during-totality">10 degrees Fahrenheit</a> (5.5 degrees Celsius). Lower temperatures lead to <a href="https://doi.org/10.1093/astrogeo/atx135">slower wind speeds</a> and less wind power generation. </p>
<p>During the August 2017 eclipse, the loss of renewable power generation added up to nearly <a href="https://www.nrel.gov/docs/fy18osti/71147.pdf">6 gigawatts</a>. That’s equivalent to the energy usage of <a href="https://www.energy.gov/eere/articles/how-much-power-1-gigawatt">600 million LED lightbulbs</a> or <a href="https://www.cnet.com/home/energy-and-utilities/gigawatt-the-solar-energy-term-you-should-know-about/">4.5 million homes</a>. </p>
<p>Grid operators compensated by planning ahead and increasing power generation at <a href="https://www.nrel.gov/docs/fy18osti/71147.pdf">natural gas and coal-powered plants</a>, which don’t depend on sunlight. </p>
<p>Over the duration of the eclipse, this increase in nonrenewable energy use led to approximately <a href="https://www.eia.gov/tools/faqs/faq.php?id=74&t=11">10 million pounds</a> of extra carbon dioxide emissions. That’s about the annual carbon dioxide emissions of 1,000 cars.</p>
<p>On April 8, <a href="https://theconversation.com/astro-tourism-chasing-eclipses-meteor-showers-and-elusive-dark-skies-from-earth-207969">eyes across the U.S. will turn upward</a> to catch a glimpse of the eclipsed Sun.</p>
<p>Thanks to the vigilance of electric grid operators, the lights should stay on, and observers won’t have to worry about anything but the stunning show in the sky.</p><img src="https://counter.theconversation.com/content/220824/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Vahe Peroomian has, in the past, received basic research funding from NASA and the National Science Foundation.</span></em></p>When the Moon blocks the Sun during an eclipse, utility suppliers have to pull power from the grid to make up for gaps in solar energy.Vahe Peroomian, Professor of Physics and Astronomy, USC Dornsife College of Letters, Arts and SciencesLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2250942024-03-07T18:23:33Z2024-03-07T18:23:33ZWe’re working out how to solve crimes in space – the final frontier of forensic science<p>Nasa’s Artemis program is scheduled to <a href="https://www.nasa.gov/specials/artemis/">return astronauts to the Moon</a> and establish a permanent orbiting laboratory by the end of the decade. </p>
<p>Meanwhile, private companies are making significant steps in taking paying customers further into space. As humanity’s footprint expands beyond the familiar terrains of Earth to the Moon and possibly beyond, an intriguing new field emerges from the final frontier: astroforensics. </p>
<p>This discipline, still in its infancy, is propelled by the inevitability of human nature. Space presents a unique and harsh environment for forensic investigations. Settings that present altered gravity, cosmic radiation, extremes in temperature, and the need for oxygen-providing climate systems provide a few examples of the unearthly variables that are faced by future explorers. </p>
<p>Unlike Earth, where gravity, a constant force, shapes many aspects of our reality, the <a href="https://www.nasa.gov/centers-and-facilities/glenn/what-is-microgravity/">significant reduction of gravity in space</a> introduces novel challenges in understanding how evidence behaves. This shift is crucial for forensic sciences like bloodstain pattern analysis, which relies heavily on gravitational effects to determine the circumstances under which blood stains are formed.</p>
<p>The thought of gravity in space immediately conjures images of astronauts hauntingly suspended in the void of space or floating gymnastics in the <a href="https://www.nasa.gov/international-space-station/">International Space Station (ISS)</a>. </p>
<p>However, true zero gravity exists far away from any celestial bodies. When close to a body such as a Moon or a planet, there will be a gravitational influence, including when in orbit around a planet like Earth. </p>
<p>Therefore, most environments in space have low or microgravity rather than zero gravity. Given that gravity is ubiquitous and largely constant, we pay very little attention to it, usually automatically factoring it in to calculations as a constant without a second thought. </p>
<h2>Altered gravity</h2>
<p>But for a forensic science discipline like bloodstain pattern analysis, gravity
plays a critical role in how airborne liquid blood interacts with a surface and creates stain patterns. <a href="https://en.wikipedia.org/wiki/Bloodstain_pattern_analysis">Bloodstain pattern analysis</a> is the use of fluid dynamics, physics, and mathematics to understand the flight and origin of blood and interpret how it was deposited on a surface in criminal investigations.</p>
<p><a href="https://www.sciencedirect.com/science/article/pii/S2665910724000070">In a recently published study</a>, we and our colleagues sought to understand the beginning principles of how the altered gravity environment of space will affect future forensic science disciplines. </p>
<p>For this study, published in Forensic Science International: Reports, we used a <a href="https://www.nasa.gov/mission/parabolic-flight/">parabolic flight research plane</a> that induces short periods of microgravity because of its up-and-down flight path. This type of flight has colloquially been referred to as the “vomit comet”. </p>
<p>During this period of freefalling microgravity, a number of blood drops would be projected onto a piece of paper, and the resulting bloodstain was then analysed using routine earthbound protocols. While the concept sounds simple, there was a challenge in creating a safe and controllable area to conduct experiments in a plane that was basically falling to Earth for 20 seconds. </p>
<p>Therefore, the experimental environment had to be attached to the cabin of the
research plane, and all bloodstain generation and documentation made easily controllable. Experiments were conducted inside a repurposed paediatric incubation chamber, referred to as a glove box. This chamber is used in space medicine research for studying haemorrhage control. </p>
<p>A synthetic analogue of blood was used instead of real blood due to biohazard concerns in the cabin of the plane. This analogue substitute mimicked the physical properties of blood’s viscosity and surface tension. To initiate the experiment, the analogue blood was loaded into a syringe, and once microgravity was induced in free-fall, the syringe was manually depressed to project the blood across 20cm onto a sheet of white paper. </p>
<p>While this bears little resemblance to true criminal scenarios, it is the interaction between the blood and the surface that is of interest to the forensic investigator –- rather than the actual mechanism of projection. The blood-stained papers were then photographed and analysed as per normal procedures.</p>
<p>We found that microgravity does indeed change the behaviour of the blood
drops and the stains they create. On Earth, blood tends to fall in a parabolic manner, with gravity pulling down on it until it strikes a surface. But in this case, the blood continued to travel in a straight line until it hit the surface.</p>
<p>This straight-line flight path is a fluid example of inertia in action. However, with a distance of only 20cm, this had minimal effect on the subsequent pattern. </p>
<p>This difference would become more apparent over larger distances, but the operational limitation of the parabolic research aircraft means it would be difficult to recreate effectively. The second key observation was the spreading action of the blood upon striking the surface. </p>
<p>In the typical gravity environment of Earth, liquid blood drops will undergo a series of stages in the stain creation process. This entails the droplet’s collapse, the formation of a small wave, and the spread into a final stain shape. </p>
<p>However, when gravity is eliminated from this action, the spreading action is inhibited by the dominating force of surface tension and cohesion, resulting in a stain shape and size that is smaller than its terrestrial twin.</p>
<p>We are at the beginning of a new research era, exploring the impact of the extra-
terrestrial environment upon the behaviour of forensic evidence. Still, the impact of this research is not only limited to forensic sciences but more traditional natural sciences as well, such as <a href="https://ntrs.nasa.gov/citations/19890015838">fluid dynamics in spacecraft design</a> and analysing faults in space forensic engineering following a spacecraft malfunction. </p>
<p>In order to expand research in this new forensic discipline, larger microgravity environments will be required and the authors would be more than happy to operate the galaxy’s first extraterrestrial forensic science laboratory.</p><img src="https://counter.theconversation.com/content/225094/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Zack Kowalske received funding from the International Association of Bloodstain Pattern Analysts' Dan Rahn Research Grant. </span></em></p><p class="fine-print"><em><span>Graham Williams 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>If we need to use forensic techniques in space, we’ll need to understand how things behave differently in microgravity.Graham Williams, Professor of Forensic Science, University of HullZack Kowalske, PhD Researcher, Staffordshire UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2243872024-03-06T17:45:13Z2024-03-06T17:45:13ZSpacesuits need a major upgrade for the next phase of exploration<figure><img src="https://images.theconversation.com/files/579865/original/file-20240305-18-mik4ri.jpg?ixlib=rb-1.1.0&rect=11%2C0%2C3822%2C2160&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.nasa.gov/news-release/nasa-taps-axiom-space-for-first-artemis-moonwalking-spacesuits/">NASA</a></span></figcaption></figure><p>Humans have long dreamed of setting foot on the Moon and other planetary bodies such as Mars. Since the 1960s, space travellers have donned suits designed to protect them from the vacuum of space and stepped out into the unknown.</p>
<p>However, <a href="https://spacenews.com/polaris-dawn-private-astronaut-mission-slips-to-mid-2024/">the Polaris Dawn mission</a>, which is to include the first spacewalk organised by a private company, has been delayed. This is due to complications with the design and development of a suitable spacesuit. </p>
<p>Moon suits are also one of the key elements of Nasa’s Artemis lunar programme that have yet to be delivered. A report released in November 2023 said that the contractor making the suits is having <a href="https://www.gao.gov/products/gao-24-106256#:%7E:text=To%20develop%20Artemis%20space%20suits,report%20examining%20the%20Artemis%20enterprise.">to revisit aspects of the design provided by Nasa</a>, which could introduce delays.</p>
<p>Yet <a href="https://time.com/5802128/alexei-leonov-spacewalk-obstacles/">the first spacewalk</a>, by the Soviet cosmonaut Alexei Leonov, took place in 1965. Later, <a href="https://www.nasa.gov/the-apollo-program/">12 Nasa astronauts would walk on the lunar surface</a>, between 1969 and 1972, using technology that would be eclipsed by today’s smartphones. So it’s not unreasonable to ask why it can still be difficult to design and build spacesuits to do the same thing.</p>
<p>Much has changed since the Apollo missions planted flags on the Moon. The <a href="https://www.cnbc.com/video/2024/01/20/us-china-india-japan-and-others-are-rushing-back-to-the-moon.html">geopolitics driving space travel have shifted</a>, and spacesuits are no longer expected to be just a form of protection. Instead, they are a critical way to improve the productivity of astronauts. This involves a rethink of not just the suits themselves, but the technology that supports them.</p>
<figure class="align-center ">
<img alt="Crew Dragon approaching the ISS" src="https://images.theconversation.com/files/579872/original/file-20240305-30-sdnkjj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/579872/original/file-20240305-30-sdnkjj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/579872/original/file-20240305-30-sdnkjj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/579872/original/file-20240305-30-sdnkjj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/579872/original/file-20240305-30-sdnkjj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/579872/original/file-20240305-30-sdnkjj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/579872/original/file-20240305-30-sdnkjj.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">The Polaris Dawn mission uses modified version of the Crew Dragon spacecraft to perform the first commercial spacewalk.</span>
<span class="attribution"><a class="source" href="https://www.nasa.gov/image-article/view-of-spacex-crew-dragon-endeavour-approaching-station/">Nasa</a></span>
</figcaption>
</figure>
<p>An array of powerful telecommunications technologies to connect astronauts with space stations and ground control sits alongside multisensory cameras, temperature readers and proximity sensors in present-day spacesuits.</p>
<p>Situational awareness – understanding key elements in the environment, such as the health of an astronaut – is a core tenet for modern spacesuit design and critical for the operator’s safety. The ability of a suit to track heart rate and other vital signs is important in a vacuum, where levels of oxygen need constant monitoring. </p>
<p>Expectations around the risks astronauts take have changed for the better. And the level of investment it takes to produce a spacesuit necessitates that it can be used for future tasks that may include lunar settlement in the next few decades.</p>
<p>The trade off that engineers must make when incorporating wearable technology like those already mentioned is weight. Will greater situational awareness result in a spacesuit that is too heavy to move in effectively? </p>
<p>When Elon Musk first hinted at challenges with the extravehicular activity spacesuit for Polaris Dawn <a href="https://twitter.com/SpaceX/status/1745941814165815717">in a presentation to SpaceX employees in January</a>, it was not difficulties with connected technology that he discussed, but of redesigning “the suit so that you actually move around in it”.</p>
<h2>Situational awareness</h2>
<p>However, when talking about mobility in a spacesuit, you need to consider the tasks that you want that mobility to support. </p>
<p>Before the advent of modern spacesuits, Apollo astronauts struggled to carry out missions. When drilling into the surface of the Moon with a hand drill to collect samples, astronauts found it difficult to provide enough downwards force to counteract the Moon’s weaker gravity. It was not until the <a href="https://www.sciencedirect.com/science/article/abs/pii/S0094576522002879">invention of a zero-gravity drill</a>, decades later, that this problem would be addressed.</p>
<p>The current exploration of <a href="https://digital-library.theiet.org/content/books/ce/pbce131e">pneumatic exoskeletons</a>, providing the support necessary for movement in low gravity could be part of a solution. However, newer spacesuits may also need to interface with hardware, like robotic drills that exist outside the suit. This will also necessitate more mobility in spacesuits. </p>
<h2>Working with robots</h2>
<p>Offloading tasks, previously carried out by humans, to robots will be part of the future of space exploration. It’s a primary way that engineers will also be able to enhance the mobility of astronauts in spacesuits.</p>
<p>For example, when an astronaut goes on a spacewalk to inspect the condition of part of a space station and make any possible repairs, they are supported by a robotic arm that ensures they don’t float off into space. While jointed, this arm is rigid and can limit an astronaut’s movement.</p>
<p>An approach currently being explored to extend this range of movement is a climbing robot, that is attached to both the astronaut and the space station, that an individual can control through their spacesuit. This would allow the astronaut to move around the space station faster and with a greater range of movement than before, allowing them to reach and repair hard-to-access areas like corners.</p>
<p>While the eventual hope is that robots themselves can assess any damage to the space station and repair it, due to possible disruptions in normal operations, humans must be ready to step in. Possible disruptions could be natural, like a small meteor shower damaging the robot, or human-made, like hacking carried by a hostile group or state.</p>
<p>For the types of activities we want to accomplish in the future, this human-robot collaboration will be instrumental. Building a base on the Moon, as both <a href="https://www.smithsonianmag.com/science-nature/four-things-weve-learned-about-nasas-planned-base-camp-on-the-moon-180980589/">the US</a> and <a href="https://spacenews.com/china-attracts-moon-base-partners-outlines-project-timelines/">China</a> plan to do, will involve construction work and drilling, which humans will not be able to accomplish alone. Modern spacesuits will need to provide an interface to work with this new technology, and we can expect the suits to evolve in step with robotics.</p>
<p>The relationship between humans and robots is changing. It will go beyond spacewalks and robots’ previous uses as limited tools, to a situation where they are cooperative partners in space. The objectives of ten or 20 years from now, like building lunar settlements, exploring mineral deposits on the Moon and efficiently repairing space station modules can only be achieved using robotics. </p>
<p>Modern spacesuits will be a key foundation of this collaborative relationship, forming the interface where astronauts and robots can work together to achieve shared goals. So when we do once again leave our footprints on other worlds, we will no longer be alone.</p><img src="https://counter.theconversation.com/content/224387/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Yang Gao has received funding from UKRI, UKSA and ESA on conducting space related research. </span></em></p>The next generation of spacesuit needs to do more than simply protect an astronaut from the vacuum of space.Yang Gao, Professor of Robotics, Head of Centre for Robotics Research, King's College LondonLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2245642024-02-27T16:00:16Z2024-02-27T16:00:16ZA black hole discovery could force us to rethink how galaxies came to be<figure><img src="https://images.theconversation.com/files/578316/original/file-20240227-30-ntlqbc.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C3834%2C2155&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://webbtelescope.org/contents/media/images/2021/026/01F8QS893NVRJ6EYF0S46237KP?page=1&Tag=Active%20Galaxies/Quasars">NASA, ESA, Joseph Olmsted (STScI)</a></span></figcaption></figure><p>Peering deep into the infancy of the universe, the European Southern Observatory’s Very Large Telescope (VLT) recently confirmed the discovery of <a href="https://www.nature.com/articles/s41550-024-02195-x">the brightest and fastest growing quasar</a>. Quasars are <a href="https://esahubble.org/wordbank/quasar/">luminous objects in the night sky</a> powered by gas falling into a large black hole at the centre of a galaxy. </p>
<p>The discovery of this record-breaking object was fascinating enough. But another crucial aspect to the announcement is that it raises big questions about galaxy formation in the early universe. In particular, it remains puzzling how this quasar, which existed less than two billion years after the Big Bang, could have grown so large so quickly. Probing this conundrum could even lead to a rethink of how galaxies came to be.</p>
<p>Black holes, the densest objects in the universe, are given this name because their gravitational pull is so incredibly strong that not even light can escape their grasp. How then, can a black hole be the origin of such an intense light source? </p>
<p>Well, in some galaxies, <a href="https://science.nasa.gov/universe/black-holes/">where the black hole is sufficiently large</a>, matter is being drawn in at a ferociously high rate. As it spirals in, violent collisions between gases, dust, and stars result in the emission of huge amounts of light energy. The bigger the black hole, the more violent the collisions and the more light is emitted.</p>
<p>The quasar that was the subject of the latest study, known as J0529-4351, has a mass equivalent to 17 billion suns and is incredibly large. There is a spiralling disk of matter spanning a width of seven light years at the centre of the galaxy and the black hole is growing by accreting (accumulating) this matter. The disk’s width is comparable to the distance between Earth and <a href="https://www.britannica.com/place/Alpha-Centauri">the next nearest star system, Alpha Centauri</a>. </p>
<h2>Hiding in plain sight</h2>
<p>The black hole is growing rapidly by consuming a record-breaking amount of mass, equivalent to one sun each day. This intense accretion of matter releases an amount of radiative energy that’s equivalent to a quadrillion (thousand trillion) suns. </p>
<p>This raises the question of why an object so bright has only just been identified in the night sky, despite decades of astronomical observations. It turns out that this sneaky quasar had been hiding in plain sight.</p>
<p>Despite its astonishing luminosity, J0529-4351 is very distant, meaning that it seamlessly blends in among a sea of dimmer stars that lie much closer to Earth. In fact, this quasar is so far away that the light it emits takes a whopping 12 billion years to reach us here on Earth. </p>
<p>The age of the universe is around 13.7 billion years. So this quasar existed just 1.7 billion years after the <a href="https://science.nasa.gov/universe/the-big-bang/">Big Bang, at the beginning of the Universe</a>. </p>
<p>The universe’s expansion following the Big Bang is what permits us to measure the distance to, and therefore the age of, this quasar. A long-known simple <a href="https://www.bbc.co.uk/bitesize/guides/zphppv4/revision/3">formula called Hubble’s law</a>, states that knowing the velocity that an object is moving away from us allows us to calculate how far away it is.</p>
<figure class="align-center ">
<img alt="Very Large Telescope" src="https://images.theconversation.com/files/578312/original/file-20240227-26-rw2ozs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/578312/original/file-20240227-26-rw2ozs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/578312/original/file-20240227-26-rw2ozs.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/578312/original/file-20240227-26-rw2ozs.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/578312/original/file-20240227-26-rw2ozs.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=501&fit=crop&dpr=1 754w, https://images.theconversation.com/files/578312/original/file-20240227-26-rw2ozs.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=501&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/578312/original/file-20240227-26-rw2ozs.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=501&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The object was confirmed using the Very Large Telescope facility in Chile.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/cerro-paranal-atacama-desert-chile-jan-750390019">Framalicious / Shutterstock</a></span>
</figcaption>
</figure>
<p>The collisions that occur as matter spirals into this quasar’s black hole raise it to scorching temperatures of 10,000°C. Under these conditions, the atoms in the system emit a characteristic spectrum of light. </p>
<p>These discrete frequencies of light form a sort of barcode that astronomers can use to identify the elemental compositions of objects in the night sky. As an object that’s emitting light moves away from us, the frequency of that observed light undergoes a shift, much like how the sound frequency of an ambulance siren shifts depending on whether it is driving towards or away from you. </p>
<p>This shift seen in astronomical objects is <a href="http://csep10.phys.utk.edu/OJTA2dev/ojta/c2c/galaxies/expanding/lookback_tl.html">known as redshift</a>. This, along with Hubble’s Law, has permitted both the age and the distance (both these properties are linked in cosmology) of J0529-4351 to be confirmed.</p>
<p>This bright beacon from the early universe has raised an important question that is baffling astronomers: how could this black hole, in such a relatively short period of time, grow so fast into such a massive object? Under well accepted models of the early universe, it should have taken longer for it to grow to this size. </p>
<p>What’s more, by tuning the artificial intelligence (AI) models used to scan telescope data for these unusual objects, more could still be found in the coming years. If they resemble J0529-4351, physicists would need to seriously rethink their models of the early universe and galaxy formation.</p>
<p>The fastest-growing black hole ever observed will be the perfect target for a system <a href="https://www.mpe.mpg.de/ir/gravityplus">called Gravity+</a>, an upcoming upgrade to an instrument on the Very Large Telescope called an interferometer. This interferometer is an ingenious way of combining data from the four separate telescopes that actually make up the VLT. </p>
<p>Gravity+ is designed to accurately measure the rotational speed and mass of black holes directly, especially those that lie far away from the Earth. </p>
<p>Furthermore, <a href="https://elt.eso.org/">the European Southern Observatory’s’s Extremely Large Telescope</a>, a 39-metre diameter reflecting telescope, is currently under construction in the Chilean Atacama Desert. This is designed for detecting the optical and near-infrared wavelengths characteristic of distant quasars and will make identifying and characterising such elusive objects even more likely in the future.</p><img src="https://counter.theconversation.com/content/224564/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Robin Smith 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 discovery raises big questions about widely accepted models of galaxy formation.Robin Smith, Senior Lecturer in Physics, Sheffield Hallam UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2243182024-02-26T17:19:30Z2024-02-26T17:19:30ZA Nasa mission that collided with an asteroid didn’t just leave a dent – it reshaped the space rock<figure><img src="https://images.theconversation.com/files/577638/original/file-20240223-18-v91s4p.jpeg?ixlib=rb-1.1.0&rect=0%2C0%2C1917%2C1080&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://images.nasa.gov/details/PIA25329">NASA/Johns Hopkins APL/Steve Gribben</a></span></figcaption></figure><p>A frequent idea in sci-fi and apocalyptic films is that of an asteroid
striking Earth and causing global devastation. While the probabilities of this kind of mass extinction occurring on our planet are incredibly small, they are not zero. </p>
<p>The results of Nasa’s Dart mission to the asteroid Dimorphos <a href="https://www.nature.com/articles/s41550-024-02200-3">have now been published</a>. They contain fascinating details about the composition of this asteroid and whether we can defend Earth against incoming space rocks.</p>
<p><a href="https://science.nasa.gov/mission/dart/">The Double Asteroid Redirection Test (Dart)</a> was a spacecraft mission that launched in November 2021. It was sent to an asteroid called Dimorphos and commanded to collide with it, head on, in September 2022. </p>
<p>Dimorphos posed and poses no threat to Earth in the near future. But the mission was designed to see if deflecting an asteroid away from a collision course with Earth was possible through “kinetic” means – in other words, a direct impact of a human-made object on its surface. </p>
<p>Asteroid missions are never easy. The relatively small size of these objects (compared to planets and moons) means there is no appreciable gravity to enable spacecraft to land and collect a sample. </p>
<p>Space agencies have launched a number of spacecraft to asteroids in recent times. For example, the Japanese space agency’s (Jaxa) <a href="https://www.isas.jaxa.jp/en/missions/spacecraft/current/hayabusa2.html">Hayabusa-2</a> mission reached the asteroid Ryugu in 2018, the same year Nasa’s <a href="https://theconversation.com/five-space-exploration-missions-to-look-%20out-for-in-2023-195839">Osiris-Rex</a> mission rendezvoused with the asteroid Bennu.</p>
<p>The Japanese Hayabusa missions (1 and 2) fired a small projectile at the surface as they approached it. They would then collect the debris as it flew by. </p>
<h2>High-speed collision</h2>
<p>However, the Dart mission was special in that it was not sent to deliver samples of asteroid material to labs on Earth. Instead, it was to fly at high speed into the space rock and be destroyed in the process.</p>
<p>A high-speed collision with an asteroid needs incredible precision. Dart’s target of Dimorphos was actually part of a <a href="https://science.nasa.gov/solar-system/asteroids/didymos/">double asteroid</a> system, known as a binary because the smaller object orbits the larger one. This binary contained both Didymus – the larger of the two objects – and Dimorphos, which behaves effectively as a moon.</p>
<p>The simulations of <a href="https://www.nature.com/articles/s41550-024-02200-3">what has happened to Dimorphos</a> show that while we might expect to see a very large crater on the asteroid from Dart’s impact, it is more likely that it has, in fact, changed the shape of the asteroid instead. </p>
<figure class="align-center ">
<img alt="Dimorphos." src="https://images.theconversation.com/files/577962/original/file-20240226-24-ninx49.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/577962/original/file-20240226-24-ninx49.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/577962/original/file-20240226-24-ninx49.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/577962/original/file-20240226-24-ninx49.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/577962/original/file-20240226-24-ninx49.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/577962/original/file-20240226-24-ninx49.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/577962/original/file-20240226-24-ninx49.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=566&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Dimorphos, as pictured by the Dart spacecraft.</span>
<span class="attribution"><a class="source" href="https://science.nasa.gov/mission/dart/">NASA</a></span>
</figcaption>
</figure>
<h2>Ant hitting two buses</h2>
<p>The collision was of a mass of 580kg hitting an asteroid of roughly 5 billion kg. For comparison, this is equivalent to an ant hitting two buses. But the spacecraft is also travelling around 6 kilometres per second. </p>
<p>The simulation results based on observations of the asteroid Dimorphos have shown that the asteroid now orbits around its larger companion, Didymus, 33 minutes slower than before. Its orbit has gone from 11 hours, 55 minutes to 11 hours, 22 minutes. </p>
<p>The momentum change to the core of Dimorphos is also higher than one would predict from the direct impact, which may seem impossible at first. However, the asteroid is quite weakly constructed, consisting of loose rubble held together by gravity. The impact caused a lot of material to be blown off of Dimorphos. </p>
<p>This material is now travelling in the opposite direction to the impact. This acts <a href="http://www.dynamicscience.com.au/tester/solutions1/war/newton/recoilless.htm">like a recoil</a>, slowing down the asteroid.</p>
<p>Observations of all the <a href="https://www.newscientist.com/article/2340837-photo-shows-10000-km-debris-tail-caused-by-%20dart-asteroid-smash/">highly reflective material that has been shed from Dimorphos</a> allows scientists to estimate how much of it has been lost from the asteroid. Their result is roughly 20 million kilograms – equivalent to about six of the Apollo-era Saturn V rockets fully loaded with fuel. </p>
<p>Combining all the parameters together (mass, speed, angle and amount of material lost) and simulating the impact has allowed the researchers to be fairly confident about the answer. Confident not only regarding the grain size of the material coming from Dimorphos, but also that the asteroid has limited cohesion and the surface must be constantly altered, or reshaped, by minor impacts.</p>
<figure class="align-center ">
<img alt="Artist's impression of Chicxulub asteroid." src="https://images.theconversation.com/files/577961/original/file-20240226-24-p85pi2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/577961/original/file-20240226-24-p85pi2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/577961/original/file-20240226-24-p85pi2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/577961/original/file-20240226-24-p85pi2.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/577961/original/file-20240226-24-p85pi2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/577961/original/file-20240226-24-p85pi2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/577961/original/file-20240226-24-p85pi2.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=502&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">The dinosaurs were wiped out by a 10km-wide asteroid that hit Earth 66 million years ago.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/planet-earth-big-asteroid-space-potentially-2107872635">Buradaki / Shutterstock</a></span>
</figcaption>
</figure>
<p>But what does this tell us about protecting ourselves from an asteroid impact? Significant recent impacts on Earth have included the <a href="https://blogs.nasa.gov/planetarydefense/2023/02/15/remembering-the-chelyabinsk-impact-10-years-ago-and-looking-to-the-future/">meteor</a> which broke up in the sky over the city of Chelyabinsk, Russia, in 2013, and the infamous <a href="https://earthsky.org/space/what-is-the-tunguska-explosion/">Tunguska
impact</a> over a remote part of Siberia in 1908. </p>
<p>While these were not the kinds of events that are able to cause mass extinctions – like the 10km object that wiped out the dinosaurs when it struck our planet 66 million years ago – the potential for damage and loss of life with smaller objects such as those at Chelyabinsk and Tunguska is very high.</p>
<p>The Dart mission cost US$324 million (£255 million), which is low for a space mission, and with its development phase completed, a similar mission to go and deflect an asteroid heading our way could be launched more cheaply. </p>
<p>The big variable here is how much warning we will have, because a change in orbit of 30 minutes – as was observed when Dart struck Dimorphos – will make little difference if the asteroid is already very close to Earth. However, if we can predict the object path from further out – preferably outside the Solar System – and make small changes, this could be enough to divert the path of an asteroid away from our planet.</p>
<p>We can expect to see more of these missions in the future, not only because of interest in the science surrounding asteroids, but because the ease of removing material from them means that private companies might want to step up their ideas of <a href="https://www.wired.com/story/things-are-looking-up-for-asteroid-mining/">mining these space rocks</a> for precious metals.</p><img src="https://counter.theconversation.com/content/224318/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 mission provided details about how to deflect an asteroid should one threaten Earth in future.Ian Whittaker, Senior Lecturer in Physics, Nottingham Trent UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2236182024-02-23T17:16:47Z2024-02-23T17:16:47ZSatellites are burning up in the upper atmosphere – and we still don’t know what impact this will have on the Earth’s climate<figure><img src="https://images.theconversation.com/files/577600/original/file-20240223-16-tqd752.jpg?ixlib=rb-1.1.0&rect=25%2C16%2C5566%2C4174&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-illustration/satellite-hurtling-through-space-burning-enters-113962255">Paul Fleet / shutterstock</a></span></figcaption></figure><p>Elon Musk’s SpaceX has announced it will dispose of 100 Starlink satellites over the next six months, after it <a href="https://spacenews.com/spacex-to-deorbit-100-older-starlink-satellites/">discovered a design flaw</a> that may cause them to fail. Rather than risk posing a threat to other spacecraft, SpaceX will “de-orbit” these satellites to burn up in the atmosphere. </p>
<p>But atmospheric scientists are increasingly concerned that this sort of <a href="https://www.cbc.ca/radio/quirks/study-space-junk-pollution-1.7010373">apparent fly-tipping</a> by the space sector will cause further climate change down on Earth. One team recently, and unexpectedly, found <a href="https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10614211/">potential ozone-depleting metals</a> from spacecraft in the stratosphere, the atmospheric layer where the ozone layer is formed. </p>
<p>The relative “low earth orbit” where <a href="https://www.copernicus.eu/en/about-copernicus/infrastructure-overview/discover-our-satellites">satellites</a> monitoring Earth’s <a href="https://www.copernicus.eu/en">ecosystems</a> are found is increasingly congested – Starlink alone has more than 5,000 spacecraft in orbit. Clearing debris is therefore a priority for the space sector. Newly launched spacecraft must also be removed from orbit within 25 years (the US recently implemented a stricter <a href="https://www.fcc.gov/document/fcc-adopts-new-5-year-rule-deorbiting-satellites-0">five-year rule</a>) either by moving upwards to a so-called “graveyard orbit” or down into the Earth’s atmosphere. </p>
<p>Lower orbiting satellites are usually designed to use any remaining fuel and the pull of the Earth’s gravity to re-enter the atmosphere. In a controlled reentry, the spacecraft enters the atmosphere at a pre-set time to land in the most remote part of the Pacific Ocean at <a href="https://explorersweb.com/point-nemo-spacecraft-graveyard/">Point Nemo</a> (aka the spacecraft cemetery). In an uncontrolled re-entry, spacecraft are left to follow a “natural demise” and burn up in the atmosphere.</p>
<p>Nasa and the European Space Agency promote this form of disposal as part of a design philosophy called “design for demise”. It is an environmental challenge to build, launch and operate a satellite robust enough to function in the hostility of space yet also able to break up and burn up easily on re-entry to avoid dangerous debris reaching the Earth’s surface. It’s still a work in progress.</p>
<p>Satellite operators must prove their design and re-entry plans have a low “human-hit” rate before they are awarded a license. But there is limited concern regarding the impact on Earth’s upper atmosphere during the re-entry stage. This is not an oversight.</p>
<p>Initially, neither the space sector nor the astrophysics community considered burning up satellites on re-entry to be a serious environmental threat – to the atmosphere, at least. After all, the number of spacecraft particles released is small when compared with 440 tonnes of <a href="https://science.nasa.gov/solar-system/meteors-meteorites/">meteoroids</a> that enter the atmosphere daily, along with volcanic ash and human-made pollution from industrial processes on Earth.</p>
<h2>Bad news for the ozone layer?</h2>
<p>So are atmospheric climate scientists overreacting to the presence of spacecraft particles in the atmosphere? Their concerns draw on 40 years of research into the cause of the ozone holes above the south and north poles, that were first widely observed in the 1980s. </p>
<p>Today, they now know that ozone loss is caused by human-made <a href="https://gml.noaa.gov/hats/publictn/elkins/cfcs.html#:%7E:text=Chlorofluorocarbons%20(CFCs)%20are%20nontoxic%2C,as%20solvents%2C%20and%20as%20refrigerants.">industrial gases</a>, which combine with natural and very high altitude <a href="https://www.bas.ac.uk/data/our-data/publication/polar-stratospheric-clouds-satellite-observations-processes-and-role-in-ozone/">polar stratospheric clouds</a> or mother of pearl clouds. The surfaces of these ethereal clouds act as catalysts, turning benign chemicals into more active forms that can rapidly <a href="https://uk-air.defra.gov.uk/research/ozone-uv/moreinfo?view=arctic-ozone-hole">destroy ozone</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/577628/original/file-20240223-24-fpxid9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Colourful cloud in night sky" src="https://images.theconversation.com/files/577628/original/file-20240223-24-fpxid9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/577628/original/file-20240223-24-fpxid9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/577628/original/file-20240223-24-fpxid9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/577628/original/file-20240223-24-fpxid9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/577628/original/file-20240223-24-fpxid9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/577628/original/file-20240223-24-fpxid9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/577628/original/file-20240223-24-fpxid9.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">Mother of pearl cloud in the stratosphere above Norway.</span>
<span class="attribution"><a class="source" href="https://www.shutterstock.com/image-photo/mother-pearl-cloud-norway-245-1849794832">Uwe Michael Neumann / shutterstock</a></span>
</figcaption>
</figure>
<p>Dan Cziczo is an atmospheric scientist at Purdue University in the US, and a co-author of the recent study that found ozone depleting substances in the stratosphere. He explains to me that the question is whether the new particles from spacecraft will help the formation of these clouds and lead to ozone loss at a time when the Earth’s atmosphere is just <a href="https://theconversation.com/how-science-saved-the-ozone-layer-218839">beginning to recover</a>. </p>
<p>Of more concern to atmospheric scientists such as Cziczo is that only a few new particles could create more of these types of polar clouds – not only at the upper atmosphere, but also in the lower atmosphere, where cirrus clouds form. Cirrus clouds are the thin, wispy ice clouds you might spot high in the sky, above six kilometres. They tend to let heat from the sun pass through but then trap it on the way out, so in theory more cirrus clouds could add extra global warming on top of what we are already seeing from greenhouse gases. But this is uncertain and <a href="https://blogs.esa.int/campaignearth/2023/03/23/in-the-icy-mountains-of-norway-a-fons-researcher-is-studying-how-clouds-affect-global-warming/">still being studied</a>.</p>
<p>Cziczo also explains that from anecdotal evidence we know that the high-altitude clouds above the poles are changing – but we don’t know yet what is causing this change. Is it natural particles such as meteoroids or volcanic debris, or unnatural particles from spacecrafts? This is what we need to know.</p>
<h2>Concerned, but not certain</h2>
<p>So how do we answer this question? We have some research from atmospheric scientists, spacecraft builders and astrophysicists, but it’s not rigorous or focused enough to make informed decisions on which direction to take. Some astrophysicists claim that alumina (aluminium oxide) particles from spacecraft will cause chemical reactions in the atmosphere that <a href="https://www.space.com/starlink-satellite-reentry-ozone-depletion-atmosphere">will likely trigger ozone destruction</a>. </p>
<p>Atmospheric scientists who study this topic in detail have not made this jump as there isn’t enough scientific evidence. We know particles from spacecraft are in the stratosphere. But what this means for the ozone layer or the climate is still unknown.</p>
<p>It is tempting to overstate research findings to garner more support. But this is the path to research hell – and deniers will use poor findings at a later date to discredit the research. We also don’t want to use populist opinions. But we’ve also learnt that if we wait until indisputable evidence is available, it may be too late, as with the loss of ozone. It’s a constant dilemma.</p>
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<p class="fine-print"><em><span>Fionagh Thomson has carried out consultancy work for the UK space agency. She is an elected member of the sustainability committees for the Royal Astronomical Society and the European Astronomical society. </span></em></p>We know particles from spacecrafts are in the stratosphere. But what this means for the ozone layer or the climate is still unknown.Fionagh Thomson, Senior Research Fellow (visual ethnographer), Durham UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2240412024-02-21T17:27:54Z2024-02-21T17:27:54ZThe brightest object ever observed in the night sky is a black hole that’s growing by the equivalent of one Sun a day<figure><img src="https://images.theconversation.com/files/576981/original/file-20240221-28-83koz3.jpg?ixlib=rb-1.1.0&rect=5%2C5%2C3828%2C2149&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/black-hole-slowly-rotating-space-event-2012670551">Merlin74 / Shutterstock</a></span></figcaption></figure><p><a href="https://www.nature.com/articles/s41550-024-02195-x">A new study</a> published in Nature Astronomy describes the most luminous object ever observed by astronomers. It is a black hole with a mass of 17 billion Suns, swallowing a greater amount of mass than the Sun every single day.</p>
<p>It has been known about for several decades, but since it is so bright, astronomers assumed it must be a nearby star. Only recent observations revealed its extreme distance and luminosity.</p>
<p>The object has been dubbed J0529-4351. This name simply refers to its coordinates on the celestial sphere – a way of projecting the objects in the sky onto the inside of a sphere. It is a type of <a href="https://esahubble.org/wordbank/quasar/">object called a quasar</a>.</p>
<p>The physical nature of quasars was initially unknown. But in 1963, the visible light from a <a href="https://www.wired.com/2008/08/dayintech-0805/">quasar called 3C 273</a> was split into all its wavelengths (known as its spectrum). This showed that it was located nearly 2 billion light years away. </p>
<p>Given how bright 3C 273 appears to us, and how far away it is, it must be extremely luminous – a term in astronomy that refers to the amount of light emitted by an object in a unit of time. The only known power source for such extreme luminosity was through material falling into a <a href="https://science.nasa.gov/universe/black-holes/">supermassive black hole</a>. Quasars are therefore the most actively growing black holes in the universe.</p>
<h2>Power source</h2>
<p>Supermassive black holes often sit at the centres of galaxies. As with all quasars, J0529-4351 is powered by material, mostly super-heated hydrogen and helium gas, falling into its black hole from the surrounding galaxy. </p>
<p>Roughly one times the Sun’s mass is falling into this black hole every day. Exactly how so much gas can be channelled into the centre of galaxies to increase the mass of black holes is an unanswered question in astrophysics.</p>
<p>At the galaxy’s centre, the gas forms into a thin disk shape. The properties of viscosity (resistance to the flow of matter in space) and friction in the thin disk help heat the gas to tens of thousands of degrees Celsius. This is hot enough to glow when viewed at ultraviolet and visible light wavelengths. It is that glow that we can observe from Earth. </p>
<p>At around 17 billion Suns in mass, J0529-4351 is not the most massive known black hole. One object, at the centre of the galaxy cluster Abell 1201, is <a href="https://www.space.com/largest-known-black-hole-discovered-through-gravitational-lensing">equivalent to 30 billion Suns</a>. However, we need to bear in mind that because of the time taken for light to travel across the vast distance between this object and Earth, we are witnessing it when the universe was only 1.5 billion years old. Its is now around 13.7 billion years old. </p>
<p>So this black hole must have been growing, or accreting, at this rate for a significant fraction of the age of the universe by the time it was observed. The authors believe the gas accretion by the black hole is happening close to the limit placed by the laws of physics. Faster accretion causes a more luminous disk of gas around the black hole which in turn can halt any more material falling in.</p>
<h2>Story of the discovery</h2>
<p>J0529-4351 has been known about for decades, but despite having an accretion disk of gas 15,000 times larger than our Solar System and occupying its own galaxy – which is probably close to the size of the Milky Way – it is so far away, it appears as a single point of light in our telescopes.</p>
<p>This means it is difficult to distinguish from the billions of stars in our own galaxy. To discover that it is in fact a distant, powerful, supermassive black hole required some more complex techniques. Firstly, astronomers collected light from the middle of the infrared waveband (light with much longer wavelengths than those we can see). </p>
<p>Stars and quasars look quite different to one another at those wavelengths. To confirm the observation, a spectrum was taken (much as it was with the quasar 3C 273), using the <a href="https://rsaa.anu.edu.au/observatories/telescopes/anu-23m-telescope">Australian National University’s 2.3 metre telescope</a> at Siding Spring Observatory, New South Wales. </p>
<p>And, as with 3C 273, the spectrum revealed both the nature of the object and how far away it was – 12 billion light years. This highlighted how extreme its luminosity must be.</p>
<h2>Detailed checks</h2>
<p>Despite these measurements, a number of checks needed to be made to confirm the true luminosity of the quasar. Firstly, astronomers needed to make sure that the light had not been magnified by a source in the sky that was closer to Earth. Much like lenses used in spectacles or binoculars, galaxies can act as lenses. They are so dense that they can bend and magnify the light of more distant sources that are perfectly aligned behind them. </p>
<p>Data from the European Space Agency’s Gaia satellite, which has extremely precise measurements of J0529-4351’s position, was used to determine that J0529-4351 is truly a single non-lensed source of light in the sky. This is backed up by more detailed spectra taken with the <a href="https://www.eso.org/public/unitedkingdom/teles-instr/paranal-observatory/vlt/">European Southern Observatory’s Very Large Telescope</a> (VLT) facility in Chile. </p>
<p>J0529-4351 is likely to become a very significant tool for the future study of quasars and black hole growth. The mass of black holes is a fundamental property but is very difficult to measure directly, as there is no standard set of weighing scales for such absurdly large, mysterious objects. </p>
<p>One technique is to measure the effect the black hole has on more diffuse gas orbiting it in large clouds, called the “broad line region”. This gas is revealed in the spectrum through wide “emission lines”, which are caused by electrons jumping between specific energy levels in the ionised gas. </p>
<p>The width of these lines is directly related to the mass of the black hole, but the calibration of this relationship is very poorly tested for the most luminous objects such as J0529-4351. However, because it is so physically large and so luminous, J0529-4351 will be observable by a new instrument being installed on the VLT, <a href="https://www.eso.org/public/unitedkingdom/teles-instr/paranal-observatory/vlt/vlt-instr/gravity+/">called Gravity+</a>. </p>
<p>This instrument will give a direct measurement of the black hole mass and calibrate the relationships used to estimate masses in other high-luminosity objects.</p><img src="https://counter.theconversation.com/content/224041/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Philip Wiseman works at the University of Southampton and is funded by the Science and Technology Facilities Council.</span></em></p>The extreme object could tell us more about the environment around black holes.Philip Wiseman, Research Fellow, Astronomy, University of SouthamptonLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2219602024-02-21T13:18:55Z2024-02-21T13:18:55ZI’ve been studying astronaut psychology since Apollo − a long voyage to Mars in a confined space could raise stress levels and make the journey more challenging<figure><img src="https://images.theconversation.com/files/573911/original/file-20240206-24-4temqb.jpg?ixlib=rb-1.1.0&rect=8%2C33%2C5551%2C3667&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Crew members in space will spend lots of time together during future missions to Mars. </span> <span class="attribution"><a class="source" href="https://newsroom.ap.org/detail/SpaceXCrewReturn/41b0e682eeec43f6aac091d3c00d4cb2/photo?Query=astronauts%20in%20orbit&mediaType=photo&sortBy=&dateRange=Anytime&totalCount=656&digitizationType=Digitized&currentItemNo=28&vs=true&vs=true">NASA via AP</a></span></figcaption></figure><p>Within the next few decades, NASA aims to land humans on the Moon, set up a lunar colony and use the lessons learned to send people to Mars as part of its <a href="https://www.nasa.gov/specials/artemis/">Artemis program</a>.</p>
<p>While researchers know that space travel can stress space crew members both physically and mentally and test their ability to work together in close quarters, missions to Mars will amplify these challenges. Mars is far away – <a href="https://www.space.com/16875-how-far-away-is-mars.html">millions of miles from Earth</a> – and a mission to the red planet will take two to two and a half years, between travel time and the Mars surface exploration itself.</p>
<p><a href="https://nickkanas.com/home/">As a psychiatrist</a> <a href="https://pubmed.ncbi.nlm.nih.gov/17571662/">who has studied</a> space <a href="https://doi.org/10.3357/ASEM.2430.2009">crew member interactions</a> in orbit, I’m interested in the stressors that will occur during a Mars mission and how to mitigate them for the benefit of future space travelers.</p>
<h2>Delayed communications</h2>
<p>Given the great distance to Mars, <a href="https://blogs.esa.int/mex/2012/08/05/time-delay-between-mars-and-earth/">two-way communication between crew members and Earth</a> will take about 25 minutes round trip. This delayed contact with home won’t just hurt crew member morale. It will likely mean space crews won’t get as much real-time help from Mission Control during onboard emergencies. </p>
<p>Because these communications travel at the speed of light and can’t go any faster, experts are coming up with <a href="https://doi.org/10.1007/978-3-031-16723-2">ways to improve communication efficiency</a> under time-delayed conditions. <a href="https://doi.org/10.1007/978-3-319-18869-0">These solutions might include</a> texting, periodically summarizing topics and encouraging participants to ask questions at the end of each message, which the responder can answer during the next message.</p>
<h2>Autonomous conditions</h2>
<p>Space crew members <a href="https://doi.org/10.1007/978-3-031-16723-2">won’t be able to communicate</a> with Mission Control in real time to plan their schedules and activities, so they’ll need to conduct their work <a href="https://doi.org/10.1007/978-3-319-18869-0">more autonomously</a> than astronauts working on orbit on the International Space Station.</p>
<p>Although studies during space simulations on Earth have suggested that crew members can <a href="https://doi.org/10.1007/978-3-031-16723-2">still accomplish mission goals</a> under highly autonomous conditions, researchers need to learn more about how these conditions affect crew member interactions and their relationship with Mission Control. </p>
<p>For example, Mission Control personnel usually advise crew members on how to deal with problems or emergencies in real time. That won’t be an option during a Mars mission.</p>
<p>To study this challenge back on Earth, scientists could run a series of simulations where crew members have varying degrees of contact with Mission Control. They could then see what happens to the interactions between crew members and their ability to get along and conduct their duties productively.</p>
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<iframe width="440" height="260" src="https://www.youtube.com/embed/nM_fmLxzqhQ?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Simulations, like the Mars500 mission, could help researchers learn about the effects of isolation and autonomy astronauts will deal with during a Mars mission.</span></figcaption>
</figure>
<h2>Crew member tension</h2>
<p>Being <a href="https://doi.org/10.1007/978-3-031-16723-2">confined with a small group of people</a> for a long period of time can lead to <a href="https://link.springer.com/book/10.1007/978-3-319-18869-0">tension and interpersonal strife</a>. </p>
<p>In my research team’s <a href="https://link.springer.com/book/10.1007/978-3-031-16723-2">studies of on-orbit crews</a>, <a href="https://link.springer.com/book/10.1007/978-3-319-18869-0">we found that</a> when experiencing interpersonal stress in space, crew members might <a href="https://pubmed.ncbi.nlm.nih.gov/17571662/">displace this tension</a> by blaming Mission Control for scheduling problems or not offering enough support. This can lead to crew-ground misunderstandings and hurt feelings.</p>
<p>One way to deal with interpersonal tension on board would be to schedule time each week for the crew members to discuss interpersonal conflicts during planned “bull sessions.” <a href="https://pubmed.ncbi.nlm.nih.gov/17571662/">We have found</a> that commanders who are supportive can improve crew cohesion. A supportive commander, or someone trained in anger management, could facilitate these sessions to help crew members understand their interpersonal conflicts before their feelings fester and harm the mission.</p>
<h2>Time away from home</h2>
<p>Spending <a href="https://doi.org/10.1007/978-3-031-16723-2">long periods of time</a> away from home can <a href="https://link.springer.com/book/10.1007/978-3-319-18869-0">weigh on crew members’ morale</a> in space. Astronauts miss their families and report being concerned about the well-being of their family members back on Earth, especially when someone is sick or in a crisis.</p>
<p>Mission duration can also affect astronauts. A Mars mission will have three phases: the outbound trip, the stay on the Martian surface and the return home. Each of these phases <a href="https://doi.org/10.3357/AMHP.5857.2021">may affect crew members differently</a>. For example, the excitement of being on Mars might boost morale, while boredom during the return may sink it.</p>
<h2>The disappearing-Earth phenomenon</h2>
<p>For astronauts in orbit, seeing the Earth from space <a href="https://doi.org/10.1016/j.actaastro.2018.08.004">serves as a reminder</a> that their home, family and friends aren’t too far away. But for crew members traveling to Mars, watching <a href="https://doi.org/10.1007/978-3-031-16723-2">as the Earth shrinks</a> to an insignificant dot in the heavens could result in a <a href="https://link.springer.com/book/10.1007/978-3-319-18869-0">profound sense of isolation and homesickness</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/573914/original/file-20240206-22-v522cp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Earth, shown from space, against a dark background." src="https://images.theconversation.com/files/573914/original/file-20240206-22-v522cp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/573914/original/file-20240206-22-v522cp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=313&fit=crop&dpr=1 600w, https://images.theconversation.com/files/573914/original/file-20240206-22-v522cp.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=313&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/573914/original/file-20240206-22-v522cp.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=313&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/573914/original/file-20240206-22-v522cp.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=393&fit=crop&dpr=1 754w, https://images.theconversation.com/files/573914/original/file-20240206-22-v522cp.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=393&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/573914/original/file-20240206-22-v522cp.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=393&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Seeing Earth disappear could make crew members feel isolated.</span>
<span class="attribution"><a class="source" href="https://newsroom.ap.org/detail/Apollo8/59f63a61bbc043a5905411daa45d9dba/photo?Query=earth%20from%20space&mediaType=photo&sortBy=&dateRange=Anytime&totalCount=457&digitizationType=Digitized&currentItemNo=4&vs=true&vs=true">AP Photo</a></span>
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<p>Having telescopes on board that will allow the crew members to see Earth as a beautiful ball in space, or giving them access to virtual reality images of trees, lakes and family members, could help mitigate any disappearing-Earth effects. But these countermeasures could just as easily lead to deeper depression as the crew members reflect on what they’re missing.</p>
<h2>Planning for a Mars mission</h2>
<p><a href="https://doi.org/10.1134/S1019331614020063">Researchers studied</a> some of these issues during the <a href="https://www.esa.int/Science_Exploration/Human_and_Robotic_Exploration/Mars500/Mars500_study_overview">Mars500 program</a>, a collaboration between the Russian and other space agencies. During Mars500, six men were isolated for 520 days in a space simulator in Moscow. They underwent periods of delayed communication and autonomy, and they simulated a landing on Mars. </p>
<p>Scientists learned a lot from that simulation. But many features of a real Mars mission, <a href="https://www.nasa.gov/learning-resources/for-kids-and-students/what-is-microgravity-grades-5-8/">such as microgravity</a>, and some dangers of space – meteoroid impacts, the disappearing-Earth phenomenon – aren’t easy to simulate. </p>
<p>Planned missions under the <a href="https://www.nasa.gov/specials/artemis/">Artemis program</a> will allow researchers to learn more about the pressures astronauts will face during the journey to Mars.</p>
<p>For example, NASA is planning a <a href="https://www.nasa.gov/mission/gateway/">space station called Gateway</a>, which will orbit the Moon and serve as a relay station for lunar landings and a mission to Mars. Researchers could simulate the outbound and return phases of a Mars mission by sending astronauts to Gateway for six-month periods, where they could introduce Mars-like delayed communication, autonomy and views of a receding Earth. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/0vDkDYHvg8E?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">NASA’s planned Gateway space station will orbit the Moon.</span></figcaption>
</figure>
<p>Researchers could simulate a Mars exploration on the Moon by having astronauts conduct tasks similar to those anticipated for Mars. This way, crew members could better prepare for the psychological and interpersonal pressures that come with a real Mars mission. These simulations could improve the chances of a successful mission and contribute to astronaut well-being as they venture into space.</p><img src="https://counter.theconversation.com/content/221960/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Nick Kanas received research funding as a Principal Investigator from NASA and the National Space Biomedical Research Institute from 1995 to 2010.</span></em></p>Can astronauts spend prolonged time in close quarters millions of miles from Earth without killing each other?Nick Kanas, Professor Emeritus of Psychiatry, University of California, San FranciscoLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2238772024-02-20T18:24:56Z2024-02-20T18:24:56ZCybersecurity for satellites is a growing challenge, as threats to space-based infrastructure grow<figure><img src="https://images.theconversation.com/files/576506/original/file-20240219-26-38pqkp.jpg?ixlib=rb-1.1.0&rect=17%2C0%2C3976%2C2994&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-illustration/satellite-over-earth-119852509">Andrzej Puchta / Shutterstock</a></span></figcaption></figure><p>In today’s interconnected world, <a href="https://www.esa.int/Enabling_Support/Preparing_for_the_Future/Discovery_and_Preparation/Space_technology_for_life_on_Earth">space technology forms the backbone</a> of our global communication, navigation and security systems. Satellites orbiting Earth are pivotal for everything from GPS navigation to international banking transactions, making them indispensable assets in our daily lives and in global infrastructure.</p>
<p>However, as our dependency on these celestial guardians escalates, so too does their allure to adversaries who may seek to compromise their functionality through cyber means. A satellite’s service could be interrupted, or at worst the spacecraft could be disabled. The expansion of the digital realm into space has opened new frontiers for cyber threats, posing unprecedented challenges.</p>
<p>This emerging battleground highlights the urgent need for robust cybersecurity measures to protect our space assets from sophisticated attacks that threaten global stability and security. </p>
<p>Recent cyber incidents, such as the <a href="https://news.viasat.com/blog/corporate/ka-sat-network-cyber-attack-overview">2022 attack on the KA-SAT network</a>, highlight the immediate vulnerability of satellites. The network, owned by global communications giant Viasat, faced a sophisticated cyber assault that disrupted its services across Europe. While the perpetrators have not been officially confirmed, many suspect Russia’s involvement.</p>
<p>As we witness an increase in state-sponsored attacks and the commercialisation of hacking tools, the stakes for securing space assets extend beyond technical challenges to encompass potential disruption to the world economy and diplomatic relations between countries that operate satellite networks. The focus on space security has been thrown into the spotlight recently by the claim that Russia is developing a <a href="https://theconversation.com/russias-space-weapon-anti-satellite-systems-are-indiscriminate-posing-a-risk-to-everyones-spacecraft-223935">space-based anti-satellite weapon</a> – possibly one that’s nuclear-powered.</p>
<h2>Evolving threats</h2>
<p>The shift from analogue to digital has transformed space technology vulnerabilities, <a href="https://www.lse.ac.uk/ideas/projects/space-policy/publications/Cyberattacks-on-Satellites#:%7E:text=Cyber%2Dattacks%20on%20satellites%20are,operators%20for%20obvious%20commercial%20reasons.">exposing them to a spectrum of cyber threats</a>. Initially, from the late 1950s onwards, concerns centred around physical tampering and espionage, but as the technology advanced, digital vulnerabilities became the forefront of security challenges. </p>
<p>With adversaries now employing artificial intelligence (AI) and machine learning to find new vulnerabilities, the complexity of attacks goes well beyond traditional strategies for defending satellites.</p>
<p>Early breaches such as the <a href="https://www.usni.org/magazines/proceedings/2021/february/asat-goes-cyber#:%7E:text=In%20late%201998%2C%20a%20joint,although%20direct%20evidence%20is%20scarce.">hacking of US-German satellites in 1998</a> were precursors to the complex cybersecurity landscape we navigate today. Modern adversaries leverage sophisticated techniques to exploit vulnerabilities in satellite communications and data transmission, aiming to disrupt, intercept, or corrupt the invaluable data they carry. </p>
<p>This evolution signifies a pivotal shift in how we must approach the security of space technology, underscoring the importance of anticipating and mitigating digital threats. This includes end-to-end encryption to make data transmission harder to hack or disrupt, and better detection of suspicious activity in advance of an attack. There’s a cost to implementing these security measures, however, such as limitations on computer processing power and bandwidth.</p>
<h2>Vulnerabilities in the void</h2>
<p>The isolation of satellites in orbit and their reliance on wireless communications expose them to specific threats such as signal jamming, spoofing – disguising communications from a suspicious source as those of a known, trusted source – and the interception of data. </p>
<p>Additionally, the limitations on processing power and bandwidth in space exacerbate the challenge of implementing routine software updates and patches, leaving systems vulnerable to exploitation. </p>
<p>Software vulnerabilities within satellite systems can be exploited from great distances, allowing attackers to potentially take control of them. This vulnerability is compounded by the ever-increasing complexity of satellites and their software. </p>
<p>The void of space does not shield these assets from cyber adversaries; instead, it presents a domain rife with unique challenges. These challenges require innovative solutions.</p>
<p>In response to these escalating cyber threats, a united front has formed among space agencies, technology companies and security experts. This effort is focused on developing robust defence mechanisms to protect satellites and other space-based technologies. </p>
<p>Key initiatives include establishing secure communication protocols, implementing end-to-end encryption for data transmission, and deploying AI-powered anomaly detection systems to identify suspicious activities in satellite networks. Beyond initiatives by <a href="https://www.nasa.gov/general/nasa-issues-new-space-security-best-practices-guide/">Nasa</a> and the <a href="https://www.esa.int/Space_Safety">European Space Agency (Esa)</a>, <a href="https://www.weforum.org/agenda/2022/05/increased-cybersecurity-for-space-based-services/">other international collaborations</a> have taken shape, reflecting a widespread commitment to space cybersecurity. </p>
<p>Agreements among countries in the <a href="https://www.forbes.com/advisor/business/what-is-five-eyes/">Five Eyes intelligence alliance</a> (consisting of the US, UK, Canada, Australia and New Zealand) and partnerships with private-sector leaders in space technology underscore the global acknowledgment of the importance of securing space assets. These cooperative endeavours are crucial not only for safeguarding national security interests, but for ensuring the uninterrupted operation of the myriad services that rely on space technology.</p>
<h2>Cyber defences in space</h2>
<p>The development of AI-driven security protocols and quantum encryption is poised to revolutionise the protection of space assets. </p>
<p>AI-driven security offers the potential to predict and counteract cyber threats in real-time, continually adapting to new challenges. However, this technology is still under development and faces significant challenges, including the availability of limited data sets for training in the unique context of space. </p>
<p>Similarly, <a href="https://www.ibm.com/topics/quantum-cryptography">quantum encryption</a> in theory offers impervious security by making use of the field of physics known as quantum mechanics. But this is still in the research and development stage for space applications – practical deployment of such technologies in space will require a great deal more innovation and testing.</p>
<h2>Global implications</h2>
<p>Cybersecurity in space extends far beyond the technical realm, affecting international relations, cooperation, and competition. There is a drive towards greater protection for space infrastructure. International collaboration would be ideal to achieve this, but such an aim faces challenges due to competing interests and varying levels of trust between nations. </p>
<p>The economic repercussions of cyberattacks on space infrastructure are profound. A significant cyber incident could cost billions in damages, disrupting global services and requiring extensive resources for mitigation and recovery. </p>
<p>The complex interplay between the need for collective security measures, the hurdles in achieving global cooperation, and the potential for catastrophic economic impact underscores the intricate relationships between cybersecurity in space, international relations, and economic stability.</p>
<p>Progress in cybersecurity measures in outer space is not just a technical necessity but a global imperative, to safeguard the future of space exploration and the integrity of critical space infrastructure. Addressing the evolving landscape of cyber threats demands ongoing vigilance, innovation, and a unified approach among all those involved in spaceflight.</p><img src="https://counter.theconversation.com/content/223877/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Sylvester Kaczmarek is chief technology officer at OrbiSky Systems.</span></em></p>The capability for attacking satellites in space using cyber technology is advancing fastSylvester Kaczmarek, Chief Technology Officer, Imperial College LondonLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2239352024-02-19T18:27:05Z2024-02-19T18:27:05ZRussia’s space weapon: anti-satellite systems are indiscriminate, posing a risk to everyone’s spacecraft<figure><img src="https://images.theconversation.com/files/576566/original/file-20240219-22-dvgtci.jpg?ixlib=rb-1.1.0&rect=11%2C22%2C7657%2C5725&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/telecommunication-satellite-providing-global-internet-network-2375569273">NicoElNino / Shutterstock</a></span></figcaption></figure><p>In a week where national security has <a href="https://www.theguardian.com/us-news/2024/feb/12/trump-nato-russia-comments-republicans">taken centre stage in Washington</a>, the White House confirmed on Thursday that it had evidence that Russia was developing a <a href="https://www.bbc.co.uk/news/world-us-canada-68309496">space-based nuclear anti satellite weapon</a>.</p>
<p>John Kirby, the National Security Council spokesperson, <a href="https://www.theguardian.com/us-news/2024/feb/15/russia-anti-satellite-weapon-space-white-house">informed reporters</a> that the White House believe Russia’s programme to be “troubling”, despite “no immediate threat to anyone’s safety”. </p>
<p>The problem is that, depending on what type of weapon this is, the consequences of using it could be indiscriminate – threatening everyone’s satellites and causing a breakdown of the vital services that come from space infrastructure.</p>
<p>The White House revelations come after House Intelligence Committee Chairman Mike
Turner urged the administration, late on Wednesday, to declassify information
concerning what he called a “serious national security threat”. There were then several days <a href="https://news.sky.com/story/republican-warns-of-national-security-threat-amid-fears-of-russian-space-weapon-13071884">of comments</a> and speculation about Russia <a href="https://nymag.com/intelligencer/article/u-s-officials-dont-freak-out-about-russian-nukes-in-space.html">either being ready to launch a nuclear weapon into space</a>, or deploying an anti-satellite <a href="https://spacenews.com/white-house-confirms-it-has-intelligence-on-russians-anti-satellite-weapon-but-says-no-immediate-threat/">weapon powered by nuclear energy</a>.</p>
<p>Kirby did not fully outline the nature of the threat, <a href="https://www.independent.co.uk/news/world/americas/us-politics/national-security-threat-update-russia-b2497015.html">but he added</a> that officials believed the weapons system was not an “active capability” and had not been deployed. To reassure those listening, Kirby said that the weapon was not one that could be used to cause physical destruction on Earth but that the White House was monitoring Russian activity and would “continue to take it very seriously”.</p>
<p>During a visit to Albania on Thursday, Secretary of State Antony Blinken confirmed the news and stated that he expected to have more to say soon, adding that the Biden administration was “also conferring with allies and partners on the issue”.</p>
<p>While discussing the matter with Indian Foreign Minister Jaishankar and Chinese
Foreign Minister Wang Yi at the <a href="https://securityconference.org/en/">Munich Security Conference</a>, Blinken is <a href="https://www.independent.co.uk/news/world/europe/joe-biden-ap-russia-antony-blinken-washington-b2497667.html">reported</a> to have “emphasised that the pursuit of this capability should be a matter of concern”.</p>
<h2>Denials from Russia</h2>
<p>Moscow immediately denied the existence of such a programme and <a href="https://www.reuters.com/world/kremlin-dismisses-us-warning-about-russian-nuclear-capability-space-2024-02-15/">stated</a> that it was a “malicious fabrication” created by the Biden administration to pressurise Congress into passing the USD$97bn (£77bn) <a href="https://edition.cnn.com/2024/02/12/politics/senate-foreign-aid-bill-ukraine/index.html">foreign aid bill</a>, $60bn of which was destined for Ukraine. Kremlin spokesman Dmitry Peskov <a href="https://www.reuters.com/world/kremlin-dismisses-us-warning-about-russian-nuclear-capability-space-2024-02-15/">told reporters</a>: “It is obvious that the White House is trying, by hook or by crook, to encourage Congress to vote on a bill to allocate money; this is obvious”. </p>
<p><a href="https://www.whitehouse.gov/briefing-room/speeches-remarks/2024/02/16/remarks-by-president-biden-on-the-reported-death-of-aleksey-navalny/">At a press conference</a> on the death of Russian opposition leader Alexei Navalny, Joe Biden stated that there was “no nuclear threat to the people of America or anywhere else in the world with what Russia is doing at the moment”.</p>
<figure class="align-center ">
<img alt="Orbital debris" src="https://images.theconversation.com/files/576569/original/file-20240219-20-pya8br.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/576569/original/file-20240219-20-pya8br.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/576569/original/file-20240219-20-pya8br.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/576569/original/file-20240219-20-pya8br.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/576569/original/file-20240219-20-pya8br.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/576569/original/file-20240219-20-pya8br.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/576569/original/file-20240219-20-pya8br.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">Space is already crowded with human-made objects and anti-satellite weapons can make the situation much worse.</span>
<span class="attribution"><a class="source" href="https://orbitaldebris.jsc.nasa.gov/photo-gallery/">NASA ODPO</a></span>
</figcaption>
</figure>
<p>The president added that there was “no evidence that they have made a decision to go forward with doing anything in space either”. If Moscow did decide to go ahead with the programme it would be contrary to the <a href="https://www.unoosa.org/pdf/publications/STSPACE11E.pdf">Outer Space Treaty</a> which 130 countries have signed onto, including Russia.</p>
<p>The treaty prohibits “nuclear weapons or any other kinds of weapons of mass
destruction” in orbit or stationing weapons in outer space “in any other manner”.
Anti-satellite weapons are nothing new. <a href="https://swfound.org/media/9550/chinese_asat_fact_sheet_updated_2012.pdf">China launched a
weapon</a> to destroy a non-operational weather satellite in January 2007. </p>
<p>While the temptation to launch a nuclear strike in space may seem alluring to nations looking to challenge US dominance in the domain, such actions come at huge risk. It is not necessarily the destruction of objects in space from Earth that should be the primary concern when it comes to anti-satellite weapons more generally, but the effect they have in space.</p>
<h2>Mass of debris</h2>
<p>The destruction of any celestial object creates a mass of debris varying in size from a few millimetres to several centimetres. Currently, there are hundreds of millions of tracked pieces of space debris orbiting <a href="https://earth.org/space-junk-what-is-it-what-can-we-do-about-it/">the Earth</a>.</p>
<p>The speed at which this space debris is travelling makes it a major hazard to other satellites and entities in space such as the International Space Station (ISS), which has to change course in order to avoid collisions which can cause widespread damage. The ISS has had to <a href="https://www.space.com/international-space-station-space-debris-spacex-dragon-spacecraft-arrival">changed course 32 times since 1999</a>.</p>
<p>Once space debris has been created, it is almost impossible to control the trajectory after the strike or the orbital pattern it will take around the Earth. This can put a nation’s space assets – such as its satellites – at the same risk of destruction as that of an adversary. This situation has been described in similar terms to that applied to nuclear weapons on Earth, <a href="https://www.guspaceinitiative.org/contentmaster/mutually-assured-destruction-in-low-earth-orbit">in terms of mutually assured destruction</a>.</p>
<p>If a nuclear strike were to be conducted by a nation in space with the intention of destroying satellites and also to demonstrate both an ability and willingness to use nuclear weapons more generally, it would be next to impossible to control the consequences of such an action.</p>
<p>It would be fairly certain that such a strike would have the intended effect in reducing the space capabilities of an opponent. For example, an attack on US assets could disable the satellite-based global positioning system (GPS) that is relied on by western nations. </p>
<p>There is, however, the very real possibility that it would also destroy the space assets of the nation behind the attack, as well as allies and friends of that same nation. This could lead to tensions being raised and lead to a loss of that country’s support.</p>
<p>The inability to control the effects of attacks in space, whether they originate from a weapon in space or on the Earth, makes such actions subject to a great degree of consideration and debate in all nations that are active in the space domain.</p><img src="https://counter.theconversation.com/content/223935/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>Destroying satellites in space can lead to cascades that are hard to predict.Matthew Powell, Teaching Fellow in Strategic and Air Power Studies, University of PortsmouthDafydd Townley, Teaching Fellow in International Security, University of PortsmouthLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2237022024-02-17T17:01:41Z2024-02-17T17:01:41ZIs Russia looking to put nukes in space? Doing so would undermine global stability and ignite an anti-satellite arms race<p>Fresh U.S. <a href="https://www.voanews.com/a/us-confirms-russia-pursuing-space-based-anti-satellite-system-/7489975.html">intelligence</a> circulating in Congress reportedly indicates that Russia is developing an <a href="https://www.space.com/anti-satellite-weapons-asats">anti-satellite</a> weapon in space with a <a href="https://www.politico.com/news/2024/02/14/house-intel-national-security-threat-russia-space-power-00141473">nuclear component</a>.</p>
<p>News reports speculating about what the weapon could be abounded after Rep. Mike Turner, R-Ohio, chair of the House Intelligence Committee, released <a href="https://www.cnn.com/2024/02/14/politics/house-intel-chairman-serious-national-security-threat/index.html">a cryptic but alarming statement</a> on Feb. 14, 2024, regarding the information, which he framed as a “serious national security threat.” Some sources suggested a <a href="https://www.cnn.com/videos/world/2024/02/17/russian-nuclear-space-weapon-oren-liebermann-lklv-cntmwknd-vpx.cnn">nuclear weapon</a>. Others suspect a <a href="https://www.reuters.com/technology/space/russia-seen-highly-unlikely-put-nuclear-warhead-space-2024-02-15/">weapon that is nuclear-powered</a> but not a nuclear warhead.</p>
<p>The White House <a href="https://www.whitehouse.gov/briefing-room/press-briefings/2024/02/15/press-briefing-by-press-secretary-karine-jean-pierre-and-white-house-national-security-communications-advisor-john-kirby-3/">confirmed</a> the following day that the Russian system under development is a space-based anti-satellite weapon and that if it were deployed, it would violate the <a href="https://www.unoosa.org/oosa/en/ourwork/spacelaw/treaties/outerspacetreaty.html">1967 Outer Space Treaty</a>, which bans weapons of mass destruction in space. The Kremlin responded by <a href="https://www.reuters.com/world/kremlin-dismisses-us-warning-about-russian-nuclear-capability-space-2024-02-15/">dismissing the reports</a> as a “malicious fabrication.” </p>
<p>While the exact weapon remains unknown to the public, the events raise the specter of nuclear weapons in space at a tense time. Relations between the United States and Russia are at their lowest in decades, and Russia is currently waging a war of aggression in Ukraine. </p>
<p>As a <a href="https://ucigcc.org/people/spenser-warren/">scholar of nuclear strategy</a>, I know the U.S. reports come at a time when the nuclear world order is shifting significantly. <a href="https://aparc.fsi.stanford.edu/publication/chinas-nuclear-enterprise">China</a> and <a href="https://www.armscontrol.org/act/2023-01/news/north-korea-plans-expand-nuclear-arsenal#:%7E:text=After%20an%20unprecedented%20year%20of,have%2040%E2%80%9350%20nuclear%20warheads.">others</a> are <a href="https://www.theguardian.com/world/2023/oct/20/china-expanding-nuclear-arsenal-much-faster-than-predicted-us-report-says">expanding</a> and <a href="https://carnegieendowment.org/2022/07/18/striking-asymmetries-nuclear-transitions-in-southern-asia-pub-87394">modernizing</a> their arsenals. <a href="https://foreignpolicy.com/2023/05/07/iran-nuclear-deal-jcpoa-us-trump-biden-nonproliferation-diplomacy/">Iran</a> is <a href="https://www.wsj.com/world/middle-east/iran-maintains-steady-expansion-of-nuclear-program-46df894a">close</a> to being able to produce a <a href="https://theconversation.com/iran-and-the-us-appear-unlikely-to-reach-a-new-nuclear-deal-leaving-everyone-more-unsafe-190100">nuclear weapon</a>. <a href="https://thebulletin.org/2024/02/even-in-the-face-of-russian-aggression-a-nuclear-eurodeterrent-is-still-a-bad-idea/">Other countries</a> may eventually want their <a href="https://carnegieendowment.org/2023/02/13/south-korea-s-nuclear-flirtations-highlight-growing-risks-of-allied-proliferation-pub-89015">own</a> nuclear weapons.</p>
<p>At the same time, <a href="https://warontherocks.com/2023/09/proliferate-dont-obliterate-how-responsive-launch-marginalizes-anti-satellite-capabilities/">several countries</a> are developing <a href="https://hir.harvard.edu/anti-satellite-weapons-and-the-emerging-space-arms-race/">new weapons</a> to attack targets in space. This list includes <a href="https://meduza.io/en/feature/2021/11/18/russia-s-asat-missile-test-in-context">Russia</a>, the <a href="https://time.com/6168148/space-weapons-ban-harris/">U.S.</a>, <a href="https://thediplomat.com/2022/06/chinas-directed-energy-weapons-and-counterspace-applications/">China</a> and <a href="https://www.orfonline.org/expert-speak/asat-weapons">India</a>, although none currently field weapons in space.</p>
<h2>Cold War schemes</h2>
<p>The recent revelations about Russian space weapons raise the specter that countries may decide to deploy nuclear weapons in space at some point. Some have tried before.</p>
<p>The <a href="https://doi.org/10.1080/09592296.2022.2062130">U.S.</a> and <a href="https://doi.org/10.1080/10736700600861418">Soviet Union</a> <a href="https://apnews.com/article/russia-space-nuclear-satellite-threats-5da6e43c9b4fdb04269ca85a5381aa4a">researched</a> nuclear detonations in space during the Cold War. In the late 1960s, the Soviets tested a missile <a href="https://www.popularmechanics.com/military/weapons/a27888/the-secret-soviet-space-weapon-mistaken-for-a-ufo/">that could be placed in low Earth orbit</a> and be capable of coming out of orbit and <a href="https://www.ausairpower.net/APA-Sov-FOBS-Program.html">carrying a nuclear warhead</a> to Earth.</p>
<figure class="align-center ">
<img alt="A man stands in front of red, blue and white flags and next to large rockets." src="https://images.theconversation.com/files/576287/original/file-20240217-28-sdnnvv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/576287/original/file-20240217-28-sdnnvv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=390&fit=crop&dpr=1 600w, https://images.theconversation.com/files/576287/original/file-20240217-28-sdnnvv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=390&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/576287/original/file-20240217-28-sdnnvv.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=390&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/576287/original/file-20240217-28-sdnnvv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=490&fit=crop&dpr=1 754w, https://images.theconversation.com/files/576287/original/file-20240217-28-sdnnvv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=490&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/576287/original/file-20240217-28-sdnnvv.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=490&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Russian President Vladimir Putin delivers a speech during his visit to the Vostochny cosmodrome on April 12, 2022.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/russian-president-vladimir-putin-delivers-a-speech-during-news-photo/1239929978?adppopup=true">Yevgeny Biyatov/Sputnik/AFP via Getty Images</a></span>
</figcaption>
</figure>
<p>Neither country placed nuclear weapons in space permanently. Both were parties to the Outer Space Treaty and the <a href="https://treaties.un.org/pages/showDetails.aspx?objid=08000002801313d9">1963 Partial Test Ban Treaty</a>, which outlawed nuclear detonations in space. Moscow and Washington negotiated these treaties to contain the Cold War arms race.</p>
<p>These treaties constrained behavior in the late Cold War. However, Russian <a href="https://carnegieendowment.org/2017/03/30/after-deployment-what-russian-violations-of-inf-treaty-pub-68514">violations</a> of nuclear arms control treaties, as well as <a href="https://2017-2021.state.gov/u-s-withdrawal-from-the-inf-treaty-on-august-2-2019/">U.S.</a> and <a href="https://www.csis.org/analysis/russia-suspends-new-start-and-increases-nuclear-risks">Russian</a> <a href="https://www.brookings.edu/articles/the-looming-us-withdrawal-from-the-open-skies-treaty/">withdrawal</a> from <a href="https://www.armscontrol.org/act/2023-06/news/russia-formally-withdraws-cfe-treaty">various treaties</a> <a href="https://carnegieendowment.org/2021/12/13/u.s.-exit-from-anti-ballistic-missile-treaty-has-fueled-new-arms-race-pub-85977">since 2002</a>, suggest they may not in the future.</p>
<h2>Nukes in space</h2>
<p>But why would a country want space nukes? There are a few reasons.</p>
<p>Countries could point space-based nuclear weapons toward Earth. In theory, weapons from space could avoid early detection radars and missile defenses. However, there are significant disadvantages to firing nuclear weapons <a href="https://rlg.fas.org/810104-space.htm">directly from space</a>.</p>
<p>Placing weapons in space to strike targets on Earth may have defensive or offensive motivations. Weapons that evade missile defenses might ensure nuclear deterrence. This is a defensive strategy intended to prevent aggression against the state that placed them in space.</p>
<p>Alternatively, these weapons may help a country achieve a first-strike capability. A first strike requires the ability to destroy enough of an adversary’s nuclear weapons – or the nuclear command, control and communications systems necessary to manage them – to prevent nuclear retaliation.</p>
<p>Countries could point space-based weapons toward other regions of space, like the <a href="https://www.atlanticcouncil.org/blogs/new-atlanticist/russian-nuclear-anti-satellite-weapons-would-require-a-firm-us-response-not-hysteria/#:%7E:text=Nuclear%2Darmed%20ASATs%20would%20cause%20mass%20destruction&text=In%20part%20through%20the%20Space,satellite%20would%20be%20highly%20inefficient.">Russian weapon under development</a>. This conjures images of nuclear weapons <a href="https://ntrs.nasa.gov/api/citations/20205008370/downloads/Nuclear_Devices_for_Planetary_Defense_ASCEND_2020_FINAL_2020-10-02.pdf">striking asteroids to defend Earth</a> from a collision. </p>
<h2>Satellite killers</h2>
<p>The reality is less dramatic but no less worrisome. The most likely use would be to destroy an enemy’s military satellites. Damaging navigation satellites would hinder an adversary’s ability to fight a war. Both <a href="https://www.thedefensepost.com/2024/01/18/precision-strike-missile-seeker/">precision-strike</a> weapons and <a href="https://spacenews.com/u-s-military-doubles-down-on-gps-despite-vulnerabilities/">ground-based forces</a> rely on satellite constellations like GPS or the Russian <a href="https://gssc.esa.int/navipedia/index.php/GLONASS_General_Introduction">GLONASS</a> system to find and reach targets.</p>
<p>Countries may also want the ability to destroy an enemy’s space weapons, including space-based missile defenses. While no country has deployed these weapons yet, leaders may fear future capabilities and deploy space weapons first to hedge against this threat.</p>
<p>Most dangerously, these weapons could destroy or damage <a href="https://aerospace.csis.org/wp-content/uploads/2023/01/130223_MV_SpaceNuclearFinal.pdf">satellites critical</a> to an enemy’s <a href="https://www.airuniversity.af.edu/AUPress/Book-Reviews/Display/Article/3299649/nuclear-command-control-and-communications-a-primer-on-us-systems-and-future-ch/">nuclear command, control and communications system</a>, including early warning satellites that track missile launches and communication satellites that relay military orders.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/-xl0C6K2Nug?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">The idea of attacking an enemy’s satellites has a long history.</span></figcaption>
</figure>
<p>Nuclear weapons damage satellites because of a <a href="https://www.osti.gov/biblio/6852629">wave of gamma radiation</a> that is created by a nuclear detonation. This radiation <a href="https://apps.dtic.mil/sti/tr/pdf/ADA531197.pdf">damages critical subsystems</a> within a satellite.</p>
<p>But such weapons produce significant drawbacks. A detonation would damage any satellites within range of the gamma radiation – including those of the attacking country, its allies and neutral countries.</p>
<p>However, a space-based nuclear anti-satellite weapon may have some advantages over other options for attacking countries. <a href="https://carnegieendowment.org/2021/11/17/dangerous-fallout-of-russia-s-anti-satellite-missile-test-pub-85804">Ground-based</a> <a href="https://www.tandfonline.com/doi/full/10.1080/14777622.2023.2277253">anti-satellite systems</a> <a href="https://www.airandspaceforces.com/russian-asat-test-underlines-need-for-defensive-space-tech/">can only reach targets</a> in low Earth orbit.</p>
<p>Even a nuclear-powered anti-satellite weapon in space would create <a href="https://www.youtube.com/watch?v=5A9izi9zFYI">a novel threat</a> without a nuclear warhead. Such a device would have a greater range than anti-satellite weapons on the ground and could perform its mission over an extended period of time. Both factors would increase the number of satellites it could damage or destroy.</p>
<p>Many of the satellites a country may want to take out are located at <a href="https://carnegieendowment.org/2021/12/16/protecting-valuables-establishing-keep-out-zones-around-high-altitude-satellites-pub-85964">higher orbits</a> beyond the range of ground-based systems. This is true for <a href="https://aerospace.csis.org/wp-content/uploads/2023/01/130223_MV_SpaceNuclearFinal.pdf">some of the U.S. systems</a> that Russia may want to target.</p>
<p>The Kremlin’s interest in space weapons could be an attempt to <a href="https://doi.org/10.1080/13523260.2022.2090070">reduce America’s capability to fight a war</a>; threaten nuclear command, control and communications systems; or hedge against space-based missile defenses. Alternatively, the Russian defense industry <a href="https://www.chathamhouse.org/2021/09/advanced-military-technology-russia/04-russian-space-systems-and-risk-weaponizing-space">may drive their development</a> for profit.</p>
<h2>New arms race?</h2>
<p>Whatever their initial purpose, placing nuclear weapons in space could be destabilizing. While there is not a universally accepted definition of strategic stability, scholars frequently <a href="https://www.amacad.org/publication/new-technologies-strategic-stability">define it as a combination</a> of crisis stability, based on the risk of nuclear escalation during a military crisis, and arms race stability – when countries can avoid <a href="https://doi.org/10.2307/2669307">actions and reactions that spiral</a> into a <a href="https://theconversation.com/the-nuclear-arms-races-legacy-at-home-toxic-contamination-staggering-cleanup-costs-and-a-culture-of-government-secrecy-210262">costly and dangerous</a> arms race.</p>
<p>Space-based nuclear weapons increase the risk that a country would resort to nuclear weapons during a crisis. Both weapons pointing toward Earth and those aimed at targets in space create incentives to use nuclear weapons preemptively. </p>
<p>The threat of either strike creates <a href="https://carnegieendowment.org/2018/08/08/escalation-through-entanglement-how-vulnerability-of-command-and-control-systems-raises-risks-of-inadvertent-nuclear-war-pub-77028">use-it-or-lose-it pressure</a>, <a href="http://dx.doi.org/10.26153/tsw/10220">incentivizing</a> a preemptive nuclear strike to limit the damage an adversary can do. In turn, a preemptive nuclear strike would likely <a href="https://thebulletin.org/2024/02/escalating-to-de-escalate-with-nuclear-weapons-research-shows-its-a-particularly-bad-idea/">provoke further escalation</a>, eventually ending in a total nuclear war.</p>
<p>Placing nuclear weapons in space could spark a new arms race. Because one purpose of space weapons is to destroy an adversary’s space weapons, the U.S. may respond to Russian weapons with their own. Russia may then counter with new weapons to maintain its advantage. Others, like China, may react to American weapons, which <a href="https://doi.org/10.1080/10736700.2015.1039309">could prompt a response</a> from India, followed by one from Pakistan.</p>
<p>Escalatory pressures and the threat of an arms race exist even if the first mover places weapons in space defensively. <a href="https://www.jstor.org/stable/26891884">Introducing space weapons</a> could create what <a href="https://doi.org/10.2307/2009187">international relations</a> <a href="https://www.jstor.org/stable/2009958">scholars</a> <a href="https://doi.org/10.1080/09636410903133050">call</a> a <a href="https://www.oxfordreference.com/display/10.1093/oi/authority.20110803100451770">security dilemma</a>: actions that enhance one country’s security but make another insecure.</p>
<p>Defensive and offensive weapons are <a href="https://doi.org/10.2307/2600696">often indistinguishable</a>. The weapons that could enhance one country’s security by hedging against space-based missile defense could also be used offensively against nuclear command, control and communications systems. Even if leaders in one country thought the other was acting defensively today, there is no way to know they will not act offensively tomorrow.</p><img src="https://counter.theconversation.com/content/223702/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Spenser A. Warren 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>Russia isn’t likely to put nuclear missiles in space, but their reported anti-satellite weapon is just as alarming. An expert on nuclear strategy explains.Spenser A. Warren, Postdoctoral Fellow in Technology and International Security, University of California, San DiegoLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2232472024-02-12T19:33:22Z2024-02-12T19:33:22ZNewborn gas planets may be surprisingly flat – new research<p>A new planet starts its life in a rotating circle of gas and dust, a cradle known as a <a href="https://esahubble.org/wordbank/circumstellar-disc/">protostellar disc</a>. My colleagues and I have used computer simulations to show that newborn gas planets in these discs are likely to have surprisingly flattened shapes. This finding, <a href="https://www.aanda.org/articles/aa/full_html/2024/02/aa48753-23/aa48753-23.html">published in Astronomy and Astrophysics Letters</a>, could add to our picture of exactly how planets form.</p>
<p>Observing protoplanets that have just formed and are still within their protostellar discs is extremely difficult. Until now only three such young protoplanets have been observed, with two of them in the same system, PDS 70.</p>
<p>We need to find systems that are young, and close enough for our telescopes to be able to detect the dim light from the planet itself and distinguish it from that of the disc. The whole process of planetary formation lasts only a few million years which is nothing more than a blink of an eye in astrophysical scales. This means we need to have luck to catch them in the act of forming.</p>
<p>Our research group performed computer simulations to determine the properties of gaseous protoplanets under a variety of thermal conditions in the planets’ cradles. </p>
<p>The simulations have enough resolution to be able to follow the evolution of a protoplanet in the disc from an early stage, when it is just a mere condensation within the disc. Such simulations are computationally demanding and were run on <a href="https://dirac.ac.uk/">DiRAC, the UK’s astrophysics supercomputing facility</a>.</p>
<p>Typically, multiple planets form within a disc. The study found that protoplanets have a shape known as oblate spheroids, like Smarties or M&M’s, rather than being spherical. They grow by drawing gas predominantly through their poles rather than their equators. </p>
<p>Technically, the planets in our Solar System are also oblate spheroids but their flattening is small. <a href="https://spaceplace.nasa.gov/planets-round/en/#:%7E:text=Mercury%20and%20Venus%20are%20the,bit%20thicker%20in%20the%20middle.">Saturn has a flattening of 10%, Jupiter 6%, whereas Earth a mere 0.3%</a>.</p>
<p>In comparison, the typical flattening of protoplanets is 90%. Such a flattening will affect the observed properties of protoplanets, and it needs to be taken into account when interpreting observations.</p>
<h2>How planets start off</h2>
<p>The most widely accepted theory for planet formation <a href="https://faculty.ucr.edu/%7Ekrice/coreacc.html#:%7E:text=The%20most%20commonly%20accepted%20mechanism,to%20accrete%20a%20gaseous%20envelope.">is that of “core accretion”</a>. According to this model, tiny dust particles smaller than sand collide with each other, group together and progressively grow into larger and larger bodies. This is effectively what happens to the dust under your bed when it isn’t cleaned. </p>
<p>Once a core of dust with enough massive forms, it draws gas from the disc to form a gas giant planet. This bottom-to-top approach would take a few million years. </p>
<p>The opposite, top-to-bottom approach, is the <a href="https://blog.planethunters.org/tag/disk-instability/">theory of disc instability</a>. In this model, the protostellar discs that attend young stars are gravitationally unstable. In other words, they are too heavy to be maintained and so fragment into pieces, which evolve into planets. </p>
<p>The theory of core accretion has been around for a long time and it can explain many aspects of how our Solar System formed. However, disc instability can better explain some of the exoplanetary systems we have discovered in recent decades, such as those where a gas giant planet orbits very very far from its host star.</p>
<p>The appeal of this theory is that planet formation happens very fast, within a few thousand years, which is consistent with observations that suggest planets exist in very young discs.</p>
<p>Our study focused on gas giant planets formed via the model of disc instability. They are flattened because they form from the compression of an already flat structure, the protostellar disc, but also because of how they rotate. </p>
<h2>No flat Earths</h2>
<p>Although these protoplanets overall are very flattened, their cores, which will eventually evolve into gas giant planets as we know them, are less flattened – only by about 20%. This is just twice the flattening of Saturn. With time they are expected to become more spherical.</p>
<p>Rocky planets, like Earth and Mars, cannot form via disc instability. They are thought to form by slowly assembling dust particles to pebbles, rocks, kilometre-sized objects and eventually planets. They are too dense to be significantly flattened even when they are newly born. There is no possibility that Earth was flattened at such a high degree when it as young.</p>
<p>But our study does support a role for disc instability in the case of some worlds in some planetary systems.</p>
<p>We are now moving from the era of exoplanet discoveries to the era of exoplanet characterisation. Many new observatories are set to become operational. These will help discover more protoplanets embedded in their discs. Predictions from computer models are also becoming more sophisticated. </p>
<p>The comparison between these theoretical models and observations is bringing us closer and closer to understanding the origins of our Solar System.</p><img src="https://counter.theconversation.com/content/223247/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Dimitris Stamatellos receives funding from the Science and Technology Facilities Council (STFC).</span></em></p>The observation could fill in gaps in our knowledge about planet formation.Dimitris Stamatellos, Associate Professor in Astrophysics, University of Central LancashireLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2156532024-02-11T13:50:28Z2024-02-11T13:50:28ZAn astronomer’s lament: Satellite megaconstellations are ruining space exploration<figure><img src="https://images.theconversation.com/files/574233/original/file-20240207-22-qbjsk9.jpg?ixlib=rb-1.1.0&rect=0%2C35%2C6000%2C3952&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Telescopes have to contend with light pollution from satellites.</span> <span class="attribution"><span class="source">(Shutterstock)</span></span></figcaption></figure><p>I used to love rocket launches when I was younger. During every launch, I imagined what it would feel like to be an astronaut sitting in the spacecraft, listening to that final countdown and then feeling multiple gees push me up through the atmosphere and away from our blue marble. </p>
<p>But as I learned more about the <a href="https://www.technologyreview.com/2018/06/22/142160/this-is-how-many-people-wed-have-to-send-to-proxima-centauri-to-make-sure-someone-actually/">severe limitations of human spaceflight</a>, I turned my attention to the oldest and most accessible form of space exploration: the science of astronomy.</p>
<p>Since 2019, I’ve watched my unencumbered enthusiasm for rocket launches soften to tepid interest, and finally sour to outright dread. <a href="https://globalnews.ca/news/9910084/the-new-space-race-2023/">The corporate space race</a>, led by SpaceX, is entirely responsible for this transformation in my mindset. </p>
<p>I am worried by the complete shift to the move-fast-and-break-things attitude that comes from the tech sector instead of government scientific agencies. I am put off by the <a href="https://press.uchicago.edu/ucp/books/book/chicago/A/bo184287883.html">colonialist language and billionaire-worship</a> of private corporations. I am increasingly furious at the <a href="https://www.startribune.com/string-lights-sky-not-ufo-starlink-satellite-internet/600324333/">nonexistent public education</a> and lack of transparency offered by these companies. </p>
<p>The final nail in the coffin for my love of rocket launches came with <a href="https://www.cnn.com/videos/business/2022/04/04/spacex-satellite-pollution-gothere-cnn-plus.cnn">SpaceX’s Starlink satellite megaconstellations</a>.</p>
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Read more:
<a href="https://theconversation.com/soon-1-out-of-every-15-points-of-light-in-the-sky-will-be-a-satellite-170427">Soon, 1 out of every 15 points of light in the sky will be a satellite</a>
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<h2>Crowded orbits</h2>
<p>The corporate space race is well underway, with private companies flooding Low Earth Orbit with <a href="https://planet4589.org/space/con/conlist.html">thousands of mass-produced satellites</a>. In previous decades, the prohibitively high cost of launch kept the rate of increase and total number of satellites from growing too rapidly. But launches have been getting steadily cheaper for years.</p>
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<iframe width="440" height="260" src="https://www.youtube.com/embed/OFfV33_eYPI?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Al Jazeera reports on the impacts of Starlink satellites.</span></figcaption>
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<p>SpaceX has launched thousands of their own Starlink communication satellites, as well as hundreds of satellites for their direct competitors. <a href="https://www.illdefined.space/2023-global-space-activity-dashboards/">Half of all launches worldwide in 2023</a> were SpaceX rockets. </p>
<p>As an astronomer, I’m painfully aware of what these thousands of new satellites have done to the night sky worldwide. They reflect sunlight long after the sky has grown dark, looking like moving stars. </p>
<p>Starlink satellites are the most numerous and occupy some of the lowest orbits, so they make up the majority of the satellites seen in the sky. </p>
<p>Last year, SpaceX launched one of the <a href="https://doi.org/10.1038/s41586-023-06672-7">brightest objects in the sky</a> on behalf of another company: BlueWalker 3, a satellite with the same sky-footprint as a small house. They plan to operate a fleet of dozens, <a href="https://rdcu.be/drQOU">each as bright</a> as the brightest stars in the sky.</p>
<h2>Lost information and knowledge</h2>
<p>These satellites are now increasingly obstructing telescopic space exploration, <a href="https://www.nytimes.com/2024/01/09/science/astronomy-telescopes-satellites-spacex-starlink.html">both on the ground</a> and <a href="https://doi.org/10.1038/s41550-023-01903-3">in space</a>. Astronomers are the canaries in the coal mine for this rapidly expanding experiment in orbit: we see these satellites increasingly affecting our research every day.</p>
<p>I have watched over the past five years as satellite streaks in my own research images from the <a href="https://www.cfht.hawaii.edu/">Canada-France-Hawaii Telescope</a> have changed from an unusual occurrence to lost data in nearly every image.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/568276/original/file-20240108-25-vkyhs5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="a series of grey boxes with white streaks" src="https://images.theconversation.com/files/568276/original/file-20240108-25-vkyhs5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/568276/original/file-20240108-25-vkyhs5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=491&fit=crop&dpr=1 600w, https://images.theconversation.com/files/568276/original/file-20240108-25-vkyhs5.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=491&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/568276/original/file-20240108-25-vkyhs5.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=491&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/568276/original/file-20240108-25-vkyhs5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=617&fit=crop&dpr=1 754w, https://images.theconversation.com/files/568276/original/file-20240108-25-vkyhs5.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=617&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/568276/original/file-20240108-25-vkyhs5.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=617&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
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<span class="caption">A composite of 29 individual exposures from the Canada-France-Hawaii Telescope on Maunakea, taken in August 2022. The horizontal and diagonal white lines are bright satellites that unexpectedly flew through the field of view during observations, covering any objects behind them.</span>
<span class="attribution"><span class="source">(P. Cowan/W. Fraser/S. Lawler/CLASSY Survey Team/CFHT)</span></span>
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<p>Astronomy is the only way to learn about the universe, the overwhelming majority of which can never be explored by humans. The farthest human-made object from Earth is the <a href="https://voyager.jpl.nasa.gov/mission/status/">Voyager 1 probe</a>, now eight times farther from the sun than Neptune after 46 years continuously travelling significantly faster than a speeding bullet. </p>
<p>But even if Voyager 1 was pointed directly toward our nearest neighbouring star, Proxima Centauri (it’s not), it would take over 100,000 years to get there. We are light-years away from having technology that can robotically explore even our neighbouring solar systems on a human timescale, let alone bring humans out to the stars.</p>
<p>The vast majority of astronomy research is carried out by telescopes on Earth: large optical telescopes on remote mountaintops, large radio telescopes in radio-quiet zones that are meticulously maintained, as well as smaller telescopes scattered around the world.</p>
<p>There are a handful of telescopes in Low Earth Orbit that also have to <a href="https://skyandtelescope.org/astronomy-news/satellite-trails-mar-hubble-images/">contend with light pollution</a> from Starlink and other megaconstellations. There are also a <a href="https://webb.nasa.gov/content/about/orbit.html">handful of telescopes outside Earth orbit</a> which can only operate for a few years, unlike ground-based facilities that can be maintained and enhanced with new technologies for decades.</p>
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<a href="https://images.theconversation.com/files/574239/original/file-20240207-28-qmjb00.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="a large white dome looms against a dark sky" src="https://images.theconversation.com/files/574239/original/file-20240207-28-qmjb00.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/574239/original/file-20240207-28-qmjb00.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/574239/original/file-20240207-28-qmjb00.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/574239/original/file-20240207-28-qmjb00.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/574239/original/file-20240207-28-qmjb00.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/574239/original/file-20240207-28-qmjb00.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/574239/original/file-20240207-28-qmjb00.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>
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<span class="caption">The Canada-Hawaii-France telescope, located on the summit of Mauna Kea, a dormant volcano located on the island of Hawaii.</span>
<span class="attribution"><span class="source">(Shutterstock)</span></span>
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<h2>Government regulation needed</h2>
<p>Space exploration using Earth-based telescopes is growing increasingly less effective as more bright and radio-loud satellites are placed between Earth and the stars. But there are much worse problems ahead if corporations continue launching satellites: atmospheric pollution on launch and <a href="https://doi.org/10.1073/pnas.2313374120">reentry</a>, ground casualty risks from <a href="https://doi.org/10.1038/s41550-022-01718-8">reentries</a>, and the very real possibility of a <a href="https://doi.org/10.1038/s41598-021-89909-7">runaway collisional cascade in orbit</a>, referred to as the Kessler Syndrome.</p>
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Read more:
<a href="https://theconversation.com/a-rapidly-growing-rocket-industry-could-undo-decades-of-work-to-save-the-ozone-layer-unless-we-act-now-198982">A rapidly growing rocket industry could undo decades of work to save the ozone layer – unless we act now</a>
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<p>Satellites are an incredibly useful part of our lives, but there are limits to how many can safely orbit Earth. Current regulations on launches and orbital operations by governments are very weak, and are not set up for the current regime of thousands of new satellites per year. </p>
<p>Regulation on the number of satellites in orbit would force corporations toward technology improvements and service models that use fewer satellites, keeping orbit usable for future generations.</p>
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Read more:
<a href="https://theconversation.com/its-not-too-late-to-save-the-night-sky-but-governments-need-to-get-serious-about-protecting-it-158394">It's not too late to save the night sky, but governments need to get serious about protecting it</a>
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<p>Ask your government representatives to support <a href="https://www.asc-csa.gc.ca/eng/transparency/consultations/what-we-heard-consulting-canadians-modern-regulatory-framework-space.asp">satellite regulation</a>, and expansion of <a href="https://crtc.gc.ca/eng/internet/internet.htm">rural broadband</a>. Get out and enjoy your <a href="https://www.cleardarksky.com/maps/lp/large_light_pollution_map.html">dark skies</a>, before they change. </p>
<p>With proper regulation, our oldest form of space exploration can continue. I desperately hope we never reach a point where the natural patterns in the sky are drowned out by anthropogenic ones, but without regulation, corporations will get us there soon.</p><img src="https://counter.theconversation.com/content/215653/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Samantha Lawler receives research funding from the Natural Sciences and Engineering Research Council of Canada.</span></em></p>Megaconstellations of satellites are hindering the most powerful tool for space exploration: telescopes.Samantha Lawler, Associate professor, Astronomy, University of ReginaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2223072024-02-08T13:21:28Z2024-02-08T13:21:28ZA new generation of spaceplanes is taking advantage of the latest in technology<figure><img src="https://images.theconversation.com/files/572455/original/file-20240131-25-t35ou5.jpeg?ixlib=rb-1.1.0&rect=5%2C0%2C1911%2C1281&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Dream Chaser would ferry cargo, and eventually crew, to low-Earth orbit.</span> <span class="attribution"><a class="source" href="https://images.nasa.gov/details/AFRC2017-0124-015">Ken Ulbrich / NASA</a></span></figcaption></figure><p><a href="https://www.nasa.gov/space-shuttle/">Nasa’s space shuttle</a> operated in low-Earth orbit for 30 years before its retirement in 2011. However, the US space agency’s <a href="https://www.nasa.gov/humans-in-space/orion-spacecraft/">replacement for this vehicle, Orion</a>, returned to the conical capsule design familiar from the Apollo missions. This was because Nasa intended that this newer craft be used for exploring targets in deep space, such as the Moon.</p>
<p>But in recent years, we have seen a return of the spaceplane design. <a href="http://news.bbc.co.uk/1/hi/sci/tech/8601172.stm">Since 2010</a>, the US Space Force (and formerly the US Air Force) has been <a href="https://www.spaceforce.mil/News/Article-Display/Article/3628417/united-states-space-force-launches-seventh-x-37b-mission/#:%7E:text=KENNEDY%20SPACE%20CENTER%2C%20Fla.,Space%20Center%20Launch%20Complex%2039A.">launching a robotic spaceplane called the X-37B</a> into low Earth orbit on classified missions. China has its own <a href="https://www.space.com/china-space-plane-depoyed-mystery-objects">military spaceplane called Shenlong</a>. </p>
<p>This year could see a test flight of the company Sierra Space’s <a href="https://www.sierraspace.com/dream-chaser-spaceplane/">Dream Chaser</a> – the first commercial spaceplane capable of orbital flight. If all goes well, the vehicle could be used to resupply the International Space Station (ISS) with cargo and, eventually, crew. </p>
<p>Spaceplanes can fly or glide in the Earth’s atmosphere and land on runways rather than using parachutes to land in water or flat ground like capsules. They’re also more manoeuvrable as the spacecraft reenters the atmosphere, increasing the area of the Earth’s surface where landing is possible from a specific re-entry point. </p>
<p>Spaceplanes also allow a gentler but longer flight path during re-entry and a softer landing, which is easier on crew and cargo than capsules, which can land with a thump. A runway also allows ground support crews and infrastructure to be ready at the landing location.</p>
<h2>Cost and complexity</h2>
<p>But spaceplanes are more complex and heavier than an equivalent capsule. The winged body shape poses a particular challenge for designing thermal protection systems (TPS) – the heat-resistant materials that protect the craft from scorching temperatures on re-entry. These additional costs mean it’s impractical to design a spaceplane for a single flight. They need to be used again and again to be viable.</p>
<figure class="align-center ">
<img alt="X-37B." src="https://images.theconversation.com/files/572489/original/file-20240131-27-2o63f0.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/572489/original/file-20240131-27-2o63f0.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/572489/original/file-20240131-27-2o63f0.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/572489/original/file-20240131-27-2o63f0.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/572489/original/file-20240131-27-2o63f0.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/572489/original/file-20240131-27-2o63f0.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/572489/original/file-20240131-27-2o63f0.jpeg?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">The US Space Force’s X-37B carries no crew, and its missions are classified.</span>
<span class="attribution"><a class="source" href="https://www.spaceforce.mil/Multimedia/Photos/igphoto/2003113618/">Staff Sgt. Adam Shanks / US Space Force</a></span>
</figcaption>
</figure>
<p>There has been interest in spaceplanes from the earliest days of human spaceflight. A military spaceplane project called <a href="https://apps.dtic.mil/sti/citations/ADA303832">Dyna-Soar</a> was started in the US in 1957, then cancelled just after construction started. The vehicle was sophisticated for its time, built using a metal alloy that is able to withstand high temperatures and featuring a heat shield on the front that could be detached after it returned from space, so that the pilot could see clearly as he was landing.</p>
<p>The space shuttle, which entered service in 1981, was the first operational spaceplane. It was supposed to launch more often than it did and have <a href="https://www.popularmechanics.com/space/rockets/a36304153/nasa-space-shuttle/">greater reusability</a> but it turned out that extensive refurbishment was required between launches. It did, however, demonstrate the ability to return astronauts and large cargo from orbit.</p>
<p>Other space agencies invested in the 1980s and 1990s, in Europe, with <a href="https://www.esa.int/About_Us/ESA_history/History_Hermes_spaceplane_1987">the Hermes spaceplane</a>, and Japan, with <a href="https://www.flightglobal.com/japan-stops-work-on-hope-x-spaceplane-/33798.article">the HOPE vehicle</a>. Both programmes were cancelled in large part because of cost. The Soviet Union developed its own <a href="https://airandspace.si.edu/stories/editorial/soviet-buran-shuttle-one-flight-long-history">shuttle-like vehicle called Buran</a>, which successfully flew to space once in 1988. The programme was cancelled after the collapse of the Soviet Union.</p>
<h2>Feeling the heat</h2>
<p>Spaceplanes have specific requirements for the final part of their journeys – as they return from space. <a href="https://www.faa.gov/sites/faa.gov/files/about/office_org/headquarters_offices/avs/III.4.1.7_Returning_from_Space.pdf">During atmospheric re-entry</a>, they are heated to over one thousand degrees Celsius as they travel at hypersonic speeds of over seven kilometres per second – more than 20 times the speed of sound. A blunt nose design (where the edge of the spacecraft is rounded) is an ideal shape because it reduces build-up of heat at the foremost part of the vehicle.</p>
<figure class="align-center ">
<img alt="Space shuttle, STS-132" src="https://images.theconversation.com/files/573023/original/file-20240202-19-du1hll.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/573023/original/file-20240202-19-du1hll.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/573023/original/file-20240202-19-du1hll.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/573023/original/file-20240202-19-du1hll.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/573023/original/file-20240202-19-du1hll.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=501&fit=crop&dpr=1 754w, https://images.theconversation.com/files/573023/original/file-20240202-19-du1hll.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=501&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/573023/original/file-20240202-19-du1hll.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=501&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">On launch, the space shuttle was attached to the side of a large external propellant tank.</span>
<span class="attribution"><a class="source" href="https://images.nasa.gov/details/sts132-s-047">NASA / JSC</a></span>
</figcaption>
</figure>
<p>Even so, the expected temperatures experienced by the craft can still be as high as 1600°C, necessitating a thermal protection system on the outside of the vehicle. <a href="https://www.centennialofflight.net/essay/Evolution_of_Technology/TPS/Tech41.htm">The space shuttle TPS</a> included ceramic tiles that were especially heat resistant and a reinforced carbon-carbon matrix that was capable of withstanding temperatures as high as 2400°C. </p>
<p>The <a href="https://www.nasa.gov/history/20-years-ago-remembering-columbia-and-her-crew/">loss of the Columbia shuttle</a> during re-entry in 2003, causing the deaths of seven astronauts, was the result of a breach in the TPS on the leading edge of the wing. This resulted from a piece of insulating foam flying off the shuttle’s external tank during Columbia’s launch and hitting the wing. </p>
<p>This foam issue was recurrent with the shuttle because of the way it launched on the side of the external propellant tank. But newer spaceplane designs will fly atop conventional rockets, where falling foam isn’t a problem.</p>
<p>An effective TPS remains vital for the <a href="https://www.nasa.gov/wp-content/uploads/2016/08/2015_nasa_technology_roadmaps_ta_9_entry_descent_landing_final.pdf">future success of spaceplanes</a>, as are systems that monitor the TPS performance in real time.</p>
<h2>Current vehicles</h2>
<p>There are currently two operating spaceplanes, one Chinese and one American, that can reach orbit. Little information is available on China’s Shenlong, but <a href="https://www.boeing.com/defense/autonomous-systems/x37b">the US military’s X-37B</a> is better known. Weighing close to five tonnes at launch, the nine metre-long, uncrewed vehicle is launched using a conventional rocket and lands autonomously on a runway at the end of its mission. </p>
<p>The X-37B’s TPS uses tiles similar to the shuttle over the lower surface with a lower-cost alternative to reinforced <a href="https://en.wikipedia.org/wiki/Reinforced_carbon%E2%80%93carbon">carbon-carbon</a> called Tufroc, developed for the X37B, on the nose and leading edges.</p>
<p>They should soon be joined by Dream Chaser, which was was developed by the company to carry both cargo and astronauts, but Nasa wants to prove its safety before carrying people by using it to carry cargo to the space station first. The ability to return comparatively fragile cargo to the surface because of a softer landing is a key capability. The tiles that protect Dream Chaser are made from silica, and <a href="https://www.nasaspaceflight.com/2023/09/dream-chaser-tps/">each has a unique shape</a> matched to the area on the vehicle they are designed to protect.</p>
<figure class="align-center ">
<img alt="Dream Chaser" src="https://images.theconversation.com/files/573027/original/file-20240202-27-ml7rkh.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/573027/original/file-20240202-27-ml7rkh.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=900&fit=crop&dpr=1 600w, https://images.theconversation.com/files/573027/original/file-20240202-27-ml7rkh.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=900&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/573027/original/file-20240202-27-ml7rkh.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=900&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/573027/original/file-20240202-27-ml7rkh.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1130&fit=crop&dpr=1 754w, https://images.theconversation.com/files/573027/original/file-20240202-27-ml7rkh.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1130&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/573027/original/file-20240202-27-ml7rkh.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1130&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Dream Chaser undergoing evaluation at Nasa’s Neil Armstrong Test Facility.</span>
<span class="attribution"><a class="source" href="https://twitter.com/NASAglenn/status/1753108059004825754/photo/1">NASA</a></span>
</figcaption>
</figure>
<h2>Future developments</h2>
<p>There is continued interest in spaceplanes because of their ability to return crew and cargo to a runway. The demand for this capability is limited now. But if the costs of launching to space continue falling and an expansion of industry in space raises demand, they will become an increasingly viable alternative to capsules.</p>
<p>Longer term, there is also potential for spaceplanes capable of reaching orbit after taking off from a runway. The challenges of developing these single-stage-to-orbit (SSTO) vehicles is considerable. However, <a href="https://www.colorado.edu/faculty/kantha/sites/default/files/attached-files/70494-96876_-_kyle_borg_-_may_8_2015_853_am_-_borg_matula_skylon_report.pdf">concepts such as the Skylon vehicle</a> are leading to technical developments that could eventually support development of an SSTO craft.</p>
<p>For the foreseeable future, spaceplanes look promising for the following reasons: new design techniques, improved materials for the TPS, advanced computer modelling and simulation tools for optimising different aspects of design and flight parameters and continuous improvements in propulsion systems. </p>
<p>Given that several governments, space agencies, and private companies worldwide are investing heavily in spaceplane research and development, we could see a future where flights with these vehicles become routine.</p><img src="https://counter.theconversation.com/content/222307/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>Spaceplanes seemed out of favour when the shuttle was retired in 2011; they now seem to be making a comeback.Oluwamayokun Adetoro, Senior Lecturer, Mechanical and Aerospace Engineering, Brunel University LondonJames Campbell, Reader, Brunel University LondonLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2198922024-02-05T13:30:46Z2024-02-05T13:30:46ZUS Moon landing marks new active phase of lunar science, with commercial launches of landers that will study solar wind and peer into the universe’s dark ages<figure><img src="https://images.theconversation.com/files/567940/original/file-20240104-21-s3p58r.jpg?ixlib=rb-1.1.0&rect=4%2C17%2C2991%2C1868&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The dark, far side of the Moon is the perfect place to conduct radio astronomy. </span> <span class="attribution"><a class="source" href="https://newsroom.ap.org/detail/LunarEclipse/704e3da2df90473486270e23aa73419d/photo?Query=moon&mediaType=photo&sortBy=&dateRange=Anytime&totalCount=399&digitizationType=Digitized&currentItemNo=12&vs=true&vs=true">AP Photo/Rick Bowmer</a></span></figcaption></figure><p>For the first time since 1972, NASA <a href="https://www.intuitivemachines.com/im-1">landed a craft on the surface of the Moon</a> in February 2024. But the agency didn’t do it alone – instead, it partnered with commercial companies. Thanks to new technologies and <a href="https://www.nasa.gov/commercial-lunar-payload-services/">public-private partnerships</a>, the scientific projects brought to the Moon on this craft and on future missions like it will open up new realms of scientific possibility. </p>
<p>As parts of several projects launching this year, teams of scientists, including myself, will conduct radio astronomy from the south pole and the far side of the Moon.</p>
<p>NASA’s <a href="https://www.nasa.gov/commercial-lunar-payload-services/">commercial lunar payload services program</a>, or CLPS, will use uncrewed landers to conduct NASA’s first science experiments from the Moon in over 50 years. The CLPS program differs from past space programs. Rather than NASA building the landers and operating the program, commercial companies will do so in a public-private partnership. NASA identified <a href="https://www.nasa.gov/commercial-lunar-payload-services/clps-providers/">about a dozen companies</a> to serve as vendors for landers that will go to the Moon. </p>
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<iframe width="440" height="260" src="https://www.youtube.com/embed/q3gePeT3yxg?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">CLPS will send science payloads to the Moon in conjunction with the Artemis program’s crewed missions.</span></figcaption>
</figure>
<p>NASA buys space on these landers for <a href="https://science.nasa.gov/lunar-science/clps-deliveries/">science payloads</a> to fly to the Moon, and the companies design, build and insure the landers, as well as contract with rocket companies for the launches. Unlike in the past, NASA is one of the customers and not the sole driver. </p>
<h2>Peregrine and Odysseus, the first CLPS landers</h2>
<p>The first two CLPS payloads are scheduled to launch during the first two months of 2024. There’s the <a href="https://science.nasa.gov/lunar-science/clps-deliveries/to2-astrobotic/">Astrobotics payload</a>, which launched Jan. 8 before its lander, named Peregrine, <a href="https://www.space.com/astrobotic-peregrine-moon-lander-headed-to-earth">experienced a fuel issue</a> that cut its journey to the Moon short. </p>
<p>Next, there’s the <a href="https://science.nasa.gov/lunar-science/clps-deliveries/op-to2-intuitive-machines/">Intuitive Machines payload</a>. Intuitive Machines’ lander, named Odysseus, <a href="https://www.intuitivemachines.com/im-1">landed near the south pole of the Moon</a> on Feb. 22, 2024. NASA has also planned a <a href="https://science.nasa.gov/lunar-science/clps-deliveries/">few additional landings</a> – about two or three per year – for each of the next few years.</p>
<p>I’m a <a href="https://www.colorado.edu/faculty/burns/">radio astronomer</a> and co-investigator on NASA’s <a href="https://www.colorado.edu/ness/projects/radiowave-observations-lunar-surface-photoelectron-sheath-rolses">ROLSES program</a>, otherwise known as Radiowave Observations at the Lunar Surface of the photoElectron Sheath. ROLSES was built by the NASA Goddard Space Flight Center and is led by <a href="https://science.gsfc.nasa.gov/sci/bio/natchimuthuk.gopalswamy-1">Natchimuthuk Gopalswamy</a>. </p>
<p>The ROLSES instrument landed on the Moon as <a href="https://www.intuitivemachines.com/_files/ugd/7c27f7_51f84ee63ea744a9b7312d17fefa9606.pdf">one of six NASA payloads</a> on the Intuitive Machines lander in February. Between ROLSES and another mission scheduled for the lunar far side in two years, LuSEE-Night, our teams will land NASA’s first two radio telescopes on the Moon by 2026. </p>
<h2>Radio telescopes on the Moon</h2>
<p>The Moon – particularly the far side of the Moon – is an ideal place to do radio astronomy and study signals from extraterrestrial objects such as the Sun and the Milky Way galaxy. On Earth, the ionosphere, which <a href="https://theconversation.com/earths-magnetic-field-protects-life-on-earth-from-radiation-but-it-can-move-and-the-magnetic-poles-can-even-flip-216231">contains Earth’s magnetic field</a>, distorts and absorbs radio signals below the <a href="https://www.fcc.gov/general/fm-radio">FM band</a>. These signals might get scrambled or may not even make it to the surface of the Earth.</p>
<p>On Earth, there are also TV signals, satellite broadcasts and defense radar systems <a href="https://theconversation.com/radio-interference-from-satellites-is-threatening-astronomy-a-proposed-zone-for-testing-new-technologies-could-head-off-the-problem-199353">making noise</a>. To do higher sensitivity observations, you have to go into space, away from Earth. </p>
<p>The Moon is what scientists call <a href="https://www.sciencefocus.com/space/what-is-tidal-locking">tidally locked</a>. One side of the Moon is always facing the Earth – the “<a href="https://www.rmg.co.uk/stories/topics/what-man-moon">man in the Moon</a>” side – and the other side, <a href="https://theconversation.com/whats-on-the-far-side-of-the-moon-111306">the far side</a>, always faces away from the Earth. The Moon has no ionosphere, and with about 2,000 miles of rock between the Earth and the far side of the Moon, there’s no interference. It’s radio quiet. </p>
<p>For our first mission with ROLSES, which launched in February 2024, we will collect data about environmental conditions on the Moon near its south pole. On the Moon’s surface, <a href="https://theconversation.com/solar-storms-can-destroy-satellites-with-ease-a-space-weather-expert-explains-the-science-177510">solar wind</a> directly strikes the lunar surface and creates a charged gas, called <a href="https://www.psfc.mit.edu/vision/what_is_plasma">a plasma</a>. Electrons lift off the negatively charged surface to form a highly ionized gas. </p>
<p>This doesn’t happen on Earth because <a href="https://theconversation.com/earths-magnetic-field-protects-life-on-earth-from-radiation-but-it-can-move-and-the-magnetic-poles-can-even-flip-216231">the magnetic field deflects</a> the solar wind. But there’s no global magnetic field on the Moon. With a low frequency radio telescope like ROLSES, we’ll be able to measure that plasma for the first time, which could help scientists figure out how to keep astronauts safe on the Moon. </p>
<p>When astronauts walk around on the surface of the Moon, they’ll pick up different charges. It’s like walking across the carpet with your socks on – when you reach for a doorknob, a spark can come out of your finger. The same kind of discharge happens on the Moon from the charged gas, but it’s potentially more harmful to astronauts. </p>
<h2>Solar and exoplanet radio emissions</h2>
<p>Our team is also going to use ROLSES to look at the Sun. The Sun’s surface releases shock waves that send out highly energetic particles and low radio frequency emissions. We’ll use the radio telescopes to measure these emissions and to see bursts of low-frequency radio waves from shock waves within the solar wind.</p>
<p>We’re also going to examine the Earth from the surface of the Moon and use that process as a template for <a href="https://theconversation.com/nasas-tess-spacecraft-is-finding-hundreds-of-exoplanets-and-is-poised-to-find-thousands-more-122104">looking at radio emissions from exoplanets</a> that may harbor life <a href="https://theconversation.com/are-there-any-planets-outside-of-our-solar-system-164062">in other star systems</a>. </p>
<p>Magnetic fields are important for life because they shield the planet’s surface from the <a href="https://theconversation.com/the-scorching-winds-on-the-surface-of-the-sun-and-how-were-forecasting-them-44098">solar/stellar wind</a>. </p>
<p>In the future, our team hopes to use specialized arrays of antennas on the far side of the Moon to observe nearby stellar systems that are known to have exoplanets. If we detect the same kind of radio emissions that come from Earth, this will tell us that the planet has a magnetic field. And we can measure the strength of the magnetic field to figure out whether it’s strong enough to shield life.</p>
<h2>Cosmology on the Moon</h2>
<p>The Lunar Surface Electromagnetic Experiment at Night, or <a href="https://www.colorado.edu/ness/projects/lunar-surface-electromagnetics-experiment-night-lusee-night">LuSEE-Night</a>, will fly in early 2026 to the far side of the Moon. LuSEE-Night marks scientists’ first attempt to do cosmology on the Moon.</p>
<p>LuSEE-Night is a novel collaboration between NASA and the Department of Energy. Data will be sent back to Earth using a communications satellite in lunar orbit, <a href="https://www.esa.int/Science_Exploration/Human_and_Robotic_Exploration/A_pathway_for_communicating_at_the_Moon">Lunar Pathfinder</a>, which is funded by the European Space Agency.</p>
<p>Since the far side of the Moon is <a href="https://cosmicdawn.astro.ucla.edu/lunar_telescopes.html">uniquely radio quiet</a>, it’s the best place to do cosmological observations. During the two weeks of lunar night that happen every 14 days, there’s no emission coming from the Sun, and there’s no ionosphere. </p>
<p>We hope to study an unexplored part of the early universe called the <a href="https://www.astronomy.com/science/the-beginning-to-the-end-of-the-universe-the-cosmic-dark-ages/">dark ages</a>. The dark ages refer to before and just after the formation of the very first stars and galaxies in the universe, which is beyond what the <a href="https://webb.nasa.gov/">James Webb Space Telescope</a> can study.</p>
<p>During the dark ages, the universe was less than 100 million years old – today the universe is 13.7 billion years old. The universe was full of hydrogen <a href="https://theconversation.com/after-our-universes-cosmic-dawn-what-happened-to-all-its-original-hydrogen-65527">during the dark ages</a>. That hydrogen radiates through the universe at low radio frequencies, and when new stars turn on, they ionize the hydrogen, producing a radio signature in the spectrum. Our team hopes to measure that signal and learn about how the earliest stars and galaxies in the universe formed.</p>
<p>There’s also a lot of potential new physics that we can study in this last unexplored cosmological epoch in the universe. We will investigate the nature of <a href="https://theconversation.com/dark-matter-the-mystery-substance-physics-still-cant-identify-that-makes-up-the-majority-of-our-universe-85808">dark matter</a> and early <a href="https://theconversation.com/explainer-the-mysterious-dark-energy-that-speeds-the-universes-rate-of-expansion-40224">dark energy</a> and test our fundamental models of physics and cosmology in an unexplored age.</p>
<p>That process is going to start in 2026 with the LuSEE-Night mission, which is both a fundamental physics experiment and a cosmology experiment.</p>
<p><em>This is an updated version of an article originally published on Feb. 5, 2024.</em></p><img src="https://counter.theconversation.com/content/219892/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jack Burns receives funding from NASA.</span></em></p>Projects under NASA’s CLPS program – including the Odysseus lander that made it to the lunar surface – will probe unexplored questions about the universe’s formation.Jack Burns, Professor of Astrophysical and Planetary Sciences, University of Colorado BoulderLicensed 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>
<figure class="align-center zoomable">
<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.