tag:theconversation.com,2011:/au/topics/titan-8340/articlesTitan – The Conversation2024-01-29T16:38:10Ztag:theconversation.com,2011:article/2221732024-01-29T16:38:10Z2024-01-29T16:38:10ZNasa’s Mars helicopter Ingenuity has ended its mission – its success paves the way for more flying vehicles on other planets and moons<figure><img src="https://images.theconversation.com/files/571847/original/file-20240129-15-v0glwl.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C2270%2C1360&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The Ingenuity helicopter on Mars.</span> <span class="attribution"><a class="source" href="https://mars.nasa.gov/resources/27421/ingenuity-at-two-years-on-mars/">NASA/JPL-Caltech/ASU/MSSS</a></span></figcaption></figure><p>It is difficult to emphasise the significance of the milestone surpassed by Nasa’s Mars helicopter, Ingenuity. </p>
<p>The little (1.8kg) helicopter <a href="https://mars.nasa.gov/resources/25608/nasas-perseverance-rover-lands-successfully-on-mars/">touched down with the Perseverance rover in 2021</a>. On 25 January, Nasa announced that the flying vehicle <a href="https://www.nasa.gov/news-release/after-three-years-on-mars-nasas-ingenuity-helicopter-mission-ends/">had to perform an emergency landing</a> which damaged one of its rotors and ended its mission. </p>
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<p>This reminds us that space exploration is still difficult to do. But Ingenuity’s three years on Mars proved that powered, controlled flight on Mars was possible. </p>
<p>The little helicopter lasted for far longer than had been planned and flew higher and further than many had envisaged. Beyond this Martian experiment, the rotorcraft’s success paves the way for other missions using flying vehicles to explore planets and moons.</p>
<p>The first landings on the Moon were static. The year 1969 was probably the most important one for space exploration, when <a href="https://www.nasa.gov/mission/apollo-11/">Apollo 11</a> and <a href="https://www.nasa.gov/mission/apollo-12/">Apollo 12</a> brought astronauts to the lunar surface, but 1970 was the year for planetary exploration. </p>
<p>In 1970, we had the <a href="https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1970-060A">first soft landing on another planet</a>, Venus. The first robotic sample delivered to Earth from the Moon. And the first robot rover to drive around another body (also the Moon). </p>
<p>Since then, following over 50 years of planetary exploration and technology development, there have only been a small number of successful surface missions, and even fewer were able to move. Venus was visited by a dozen static landers between 1970 and 1985, and never again. </p>
<h2>From rovers to helicopters</h2>
<p>Mars was only successfully landed on three times between 1971 and 1976 before the <a href="https://mars.nasa.gov/mars-exploration/missions/pathfinder/">Pathfinder lander</a> and Sojourner rover arrived in 1997. The European Huygens spacecraft then landed on Titan, the moon of Saturn, in 2005. </p>
<p>These attempts at reaching the surface are rare, extremely difficult, and, historically, the landers were hardly ever mobile. Yet the Nasa <a href="https://mars.nasa.gov/mer/mission/overview/">Mars rovers Spirit, Opportunity</a>, <a href="https://mars.nasa.gov/msl/home/">Curiosity</a>, and <a href="https://mars.nasa.gov/mars2020/">Perseverance</a> have all exceeded their designs and travelled further and further.</p>
<p>And Ingenuity flew.</p>
<p>It wasn’t the first spacecraft to fly. Those would be the balloons deployed by the <a href="https://nssdc.gsfc.nasa.gov/nmc/spacecraft/display.action?id=1984-128F">Soviet Vega 1 and 2 missions</a>, which floated over Venus in 1985. But Ingenuity had control, cameras, and connectivity. It took photos of its rover and of Mars from an entirely new perspective. It commanded the world’s attention and captured our hearts.</p>
<p>In Moscow, I had the chance to see models and replicas of the Vega balloons and the first lunar rover. They made a stronger impression on me than the Mars rover twins being used at Nasa’s Jet Propulsion Laboratory (JPL) in California. The Soviet missions were more audacious and different, and they were from generations ago, before my time and long before my career as a planetary scientist.</p>
<p>Ingenuity was audacious, original and completely new. The photos it took, of Perseverance, finding technology discarded from the descent module that carried it down to Mars and of the Martian vistas from a bird’s eye view, were breathtaking. Meanwhile, Perseverance also took videos of Ingenuity flying in the air. Nothing like it had ever seen before.</p>
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<img alt="CGI image of a silver drone with eight propellers over the Martian surface" src="https://images.theconversation.com/files/571881/original/file-20240129-23-b4r2m2.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/571881/original/file-20240129-23-b4r2m2.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=380&fit=crop&dpr=1 600w, https://images.theconversation.com/files/571881/original/file-20240129-23-b4r2m2.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=380&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/571881/original/file-20240129-23-b4r2m2.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=380&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/571881/original/file-20240129-23-b4r2m2.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=478&fit=crop&dpr=1 754w, https://images.theconversation.com/files/571881/original/file-20240129-23-b4r2m2.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=478&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/571881/original/file-20240129-23-b4r2m2.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=478&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">An artist’s impression of the Dragonfly spacecraft in flight.</span>
<span class="attribution"><a class="source" href="https://dragonfly.jhuapl.edu/Gallery/">NASA/Johns Hopkins APL/Steve Gribben</a></span>
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<h2>Future flights</h2>
<p>Ingenuity had a rough ride getting there, however. The entire Mars 2020 mission (of Perseverance, Ingenuity and their transport systems) was sudden. </p>
<p>Following Nasa’s withdrawal from the joint European Space Agency ExoMars programme, which included a Mars rover mission, the US space agency started developing one on its own. This rover, later named Perseverance, went from announcement to concept to development and launch in just seven-and-a-half years.</p>
<p>And Ingenuity wasn’t included onboard at first. As an idea, it was proposed late in the development phase of Mars 2020, and faced serious opposition. It added extra complexity, cost, risk and new failure modes. It was also driven by an engineering objective, with the possibility of a little outreach – the opportunity to communicate the mission’s science and engineering to the public – on the side.</p>
<p>Ingenuity wasn’t intended to last for very long. It was designed to prove helicopter flight in the thin Mars atmosphere. It targeted five short flights over a month. Possible outcomes included hard landings, toppling over, losing power if its solar panels were covered in dust, or losing communication when it was far from the rover (this happened several times). </p>
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<img alt="Large silver balloon being launched in the desert." src="https://images.theconversation.com/files/571874/original/file-20240129-25-1d0l8.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/571874/original/file-20240129-25-1d0l8.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/571874/original/file-20240129-25-1d0l8.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/571874/original/file-20240129-25-1d0l8.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/571874/original/file-20240129-25-1d0l8.jpeg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=425&fit=crop&dpr=1 754w, https://images.theconversation.com/files/571874/original/file-20240129-25-1d0l8.jpeg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=425&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/571874/original/file-20240129-25-1d0l8.jpeg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=425&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">Aerial robotic balloons, or aerobots, like this Nasa prototype, could one day explore Venus.</span>
<span class="attribution"><a class="source" href="https://www.jpl.nasa.gov/news/jpls-venus-aerial-robotic-balloon-prototype-aces-test-flights">Nasa / JPL-Caltech</a></span>
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<p>But it went way beyond expectations, surviving three years on the Martian surface, even through a dusty season, and making 72 flights. Much of its success was aided by the communication network that now exists at Mars. </p>
<p>Ingenuity receives instructions and transmits data to Perseverance, which communicates with a fleet of satellites that include the European ExoMars Trace Gas Orbiter, Nasa’s Maven spacecraft, and the Mars Reconnaissance Orbiter. These, in turn, communicate with two deep space networks on Earth, systems of radio antennas around the world that command and track spacecraft. </p>
<p>It took 50 years of planetary exploration to get here, but already we can see the impact on future exploration that Ingenuity’s mission is having. The next interplanetary rotorcraft will be the <a href="https://dragonfly.jhuapl.edu/">Dragonfly mission to Saturn’s moon Titan</a>. </p>
<p>It will be a very different from Ingenuity. It will weigh about a ton and fly with eight rotors. It is a huge vehicle designed to fly in Titan’s thick atmosphere. </p>
<p>One of the next Red Planet missions will be Mars Sample Return, aiming to collect sample containers of Martian soil being prepared and cached by Perseverance. This has been planned to be carried out with use of a rover, but the success of Ingenuity has led to the idea – and now the development – of <a href="https://mars.nasa.gov/msr/spacecraft/sample-recovery-helicopters/">a helicopter</a> to do that. </p>
<p>The future that Ingenuity has opened up for us is exciting. We’ll see helicopters on Mars and Venus, more balloons on Venus, swimming vehicles under the icy moons of Jupiter and Saturn, and maybe even an aeroplane or two.</p><img src="https://counter.theconversation.com/content/222173/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Kevin Olsen in an employee of the University of Oxford and receives funding from the UK Space Agency in support of Mars science.</span></em></p>Among the missions being planned is a huge helicopter drone to explore Saturn’s moon Titan.Kevin Olsen, UKSA Mars Science Fellow, Department of Physics, University of OxfordLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2093572023-08-15T12:34:52Z2023-08-15T12:34:52ZDiverse teams can improve engineering outcomes − but recent affirmative action decision may hinder efforts to create diverse teams<figure><img src="https://images.theconversation.com/files/542659/original/file-20230814-19-13t6qn.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C2113%2C1409&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">While Black and Hispanic workers made up 14% and 19% of the population in 2021, they made up only 9% and 8% of the STEM workforce. </span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/workers-talking-in-factory-royalty-free-image/156410607">John Fedele/The Image Bank via Getty Images</a></span></figcaption></figure><p>It may seem intuitive that teams made up of people with a diversity of perspectives, experiences and backgrounds lead to more effective and inclusive outcomes. But the <a href="https://theconversation.com/affirmative-action-lasted-over-50-years-3-essential-reads-explaining-how-it-ended-209273">recent U.S. Supreme Court decision</a> to <a href="https://theconversation.com/supreme-court-chief-justice-john-roberts-uses-conflicting-views-of-race-to-resolve-americas-history-of-racial-discrimination-209670">curb affirmative action</a> in higher education could <a href="https://www.bbc.com/worklife/article/20230726-how-changing-college-admissions-could-affect-the-us-workforce">hinder progress</a> toward <a href="https://doi.org/10.1007/s11162-023-09739-6">increasing diversity</a> in the <a href="https://blog.ucsusa.org/jacob-carter/supreme-court-rulings-will-reduce-diversity-in-stem-and-set-back-scientific-progress/">science and engineering fields</a>. </p>
<p>As a geographer and feminist scholar, <a href="https://scholar.google.com/citations?user=eqzjz_MAAAAJ">my work</a> centers on how diverse engineering teams can create space for better collaborations and outcomes. The first step to creating diverse teams is having diverse people with relevant engineering backgrounds, but this Supreme Court decision may <a href="https://sloanreview.mit.edu/article/how-outlawing-collegiate-affirmative-action-will-impact-corporate-america/">create more roadblocks</a> for people from underrepresented backgrounds pursuing the sciences.</p>
<h2>Affirmative action</h2>
<p><a href="https://www.britannica.com/topic/affirmative-action">Affirmative action</a> is the practice of universities giving special consideration to historically excluded groups, such as racial minorities and women. In addition to addressing past discrimination, the practice, born out of the 1960s <a href="https://www.nytimes.com/2022/10/31/us/politics/affirmative-action-history.html">civil rights movement</a>, ensures public institutions such as universities <a href="https://www.usnews.com/topics/subjects/affirmative_action">represent the populations they serve</a>. </p>
<p>Even with affirmative action, Black and Hispanic workers are already underrepresented in STEM fields. A 2021 study found they made up <a href="https://www.pewresearch.org/science/2021/04/01/stem-jobs-see-uneven-progress-in-increasing-gender-racial-and-ethnic-diversity/">only 9% and 8%</a>, respectively, of the total STEM workforce in the United States. At the same time, Black people and Hispanic people accounted for 14% and 19%, respectively, of <a href="https://www.census.gov/quickfacts/fact/table/US/PST045222">the national population</a>.</p>
<p>Even prior to the court’s decision, <a href="https://theconversation.com/how-to-involve-more-women-and-girls-in-engineering-55794">higher education</a> pipelines underrepresented women and people of color in engineering.</p>
<p>Engineering offers high salaries and job stability, but it also <a href="https://www.pewresearch.org/science/2021/04/01/stem-jobs-see-uneven-progress-in-increasing-gender-racial-and-ethnic-diversity/">lags far behind other STEM fields</a> in integrating diversity and creating inclusive company cultures. Diverse teams can help make sure a company’s products and services are relatable to a wide range of customers.</p>
<h2>A pipeline issue in engineering</h2>
<p>Still, it is challenging to create genuinely inclusive cultures. And to have diverse engineers, you first need diverse engineering students.</p>
<p>A <a href="https://www.diversityinresearch.careers/article/how-diversity-makes-better-engineering-teams">diverse engineering team</a> has historically been one that includes different talents – engineers, but also designers, architects and so on. However, now when experts like me point out a pipeline issue in engineering, we’re prioritizing <a href="https://www.scientificamerican.com/article/how-diversity-makes-us-smarter/">social diversity</a>. This includes gender, race, ethnicity, nationality and other identities. </p>
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<a href="https://images.theconversation.com/files/539619/original/file-20230726-19-wdarm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="Two engineers standing in a factory, the one on the left, a woman, is pointing, while the one on the right, a man, wears a hard hat." src="https://images.theconversation.com/files/539619/original/file-20230726-19-wdarm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/539619/original/file-20230726-19-wdarm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=399&fit=crop&dpr=1 600w, https://images.theconversation.com/files/539619/original/file-20230726-19-wdarm.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=399&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/539619/original/file-20230726-19-wdarm.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=399&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/539619/original/file-20230726-19-wdarm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=502&fit=crop&dpr=1 754w, https://images.theconversation.com/files/539619/original/file-20230726-19-wdarm.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=502&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/539619/original/file-20230726-19-wdarm.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"></a>
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<span class="caption">Teams of engineers with diverse backgrounds and perspectives can lead to new innovations and create supportive spaces.</span>
<span class="attribution"><a class="source" href="https://media.gettyimages.com/id/1306841982/photo/female-engineer-presentation-robotic-welding-process-to-her-team-in-testing-area-of-research.jpg?s=612x612&w=0&k=20&c=jkjgmPS7_r7F8ZHFOncCHbjln1LDgYGA1L9runr_ZQw=">Nitat Termmee/Moment via Getty</a></span>
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<p>The percentage of engineering bachelor’s degrees awarded to women and people of color in the United States has <a href="https://theconversation.com/how-to-involve-more-women-and-girls-in-engineering-55794">grown little</a> since 1998. <a href="https://swe.org/research/2023/degree-attainment/">Women account for 22%</a> of bachelor’s degrees <a href="https://theconversation.com/only-about-1-in-5-engineering-degrees-go-to-women-185256">in engineering</a>. <a href="https://swe.org/research/2018/women-of-color-in-early-career-a-swe-nsbe-collaborative-study/">Less than 4%</a> of all engineering degrees went to African American, Hispanic and Native American women. <a href="https://ira.asee.org/wp-content/uploads/2019/07/2018-Engineering-by-Numbers-Engineering-Statistics-UPDATED-15-July-2019.pdf">Hispanic and Black/African American students</a> account for 11.4% and 4.2% of engineering bachelor’s degrees, respectively.</p>
<p>Students cite <a href="https://www.higheredtoday.org/2021/02/11/lets-remake-racially-unsafe-stem-educational-spaces/">hostile climates</a> and racist and sexist stereotyping as reasons for leaving the major.</p>
<h2>Diverse teams in practice</h2>
<p>Despite these challenges, a year ago <a href="https://www.psu.edu/news/engineering/story/3d-printing-medical-devices-focus-2-million-nsf-grant/">I joined three senior women</a> guiding an intergenerational, diverse group of engineering researchers from the Georgia Institute of Technology and Penn State University.</p>
<p>The exceptionality of our project’s all-female engineering leadership offers a rare on-the-ground opportunity to evaluate how diverse engineering teams can enhance innovation and teamwork. <a href="https://www.psu.edu/news/engineering/story/3d-printing-medical-devices-focus-2-million-nsf-grant/">Our early study findings</a> – which have not yet been peer-reviewed – suggest that a diverse team creates a place for an array of opinions and strategies to flourish. </p>
<p>Compared with experiences with mostly homogeneous groups, members of this multigenerational team reported less hierarchy in group discussions, stronger self-assurance and a sense of solidarity and shared vision. Senior members fostered belonging, while early career members felt mentored and supported. </p>
<p>For example, our project focuses on designing customized pediatric masks and other medical devices. The members of this team reported feeling that their peers all shared a drive to improve quality of life for patients.</p>
<p><a href="https://www.forbes.com/sites/forbestechcouncil/2018/07/31/diversity-innovation-and-opportunity-why-you-need-a-diverse-product-engineering-team/?sh=380e1e903e33">Diverse engineering teams</a> bring a range of problem-solving skills together, which leads to <a href="https://www.npr.org/2020/07/27/895858974/creativity-and-diversity-how-exposure-to-different-people-affects-our-thinking">more creative outcomes</a>. In teams where members have a variety of backgrounds, perspectives and experiences, experts see more <a href="https://hbr.org/2016/11/why-diverse-teams-are-smarter">collaboration, productivity and a focus on socially beneficial outcomes</a>.</p>
<p>Allowing all team members to contribute equally results in <a href="https://www.imeche.org/news/news-article/feature-5-ways-diversity-enhances-engineering-projects">higher productivity</a>, boosts retention rates and creates smoother interactions. All this results in faster, more effective problem solving. </p>
<p>Homogeneous or nondiverse teams are more likely to experience <a href="https://www.britannica.com/science/groupthink">groupthink</a>. During groupthink, members lapse into consensus thinking and agree with each other rather than bringing more ideas forward. Groupthink happens more often when stakes are high or there’s uncertainty. </p>
<p>On the other hand, diverse teams tend to focus more on facts and may process them <a href="https://www.psychologytoday.com/us/blog/your-brain-work/202106/why-diverse-teams-outperform-homogeneous-teams">more carefully than homogeneous teams</a>. This is due to the <a href="https://fortune.com/2021/08/11/cognitive-diversity-leadership-styles-decision-making/">diversity of different experiences</a> that accompanies diverse workplaces. Carefully processing all the facts and considering multiple points of view can provide safer, more inclusive outcomes. </p>
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<figcaption><span class="caption">Diverse teams in engineering can lead to outcomes that work for more groups of people.</span></figcaption>
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<p>Diversity in human judgment, empathy and creativity is good for business, but it also benefits the common good. Creating opportunities for students from diverse backgrounds and experiences prepares all students – regardless of race or gender – for success in an <a href="https://www.census.gov/library/stories/2021/08/2020-united-states-population-more-racially-ethnically-diverse-than-2010.html">increasingly diverse nation</a>.</p><img src="https://counter.theconversation.com/content/209357/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Lorraine Dowler receives funding from the National Science Foundation. </span></em></p>Diverse teams can not only solve engineering problems more effectively, but the outcomes tend to be more inclusive, as a geographer and feminist scholar explains.Lorraine Dowler, Professor of Geography and Women's Gender and Sexuality Studies, Penn StateLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2086512023-07-12T12:39:51Z2023-07-12T12:39:51ZClassic literature still offers rich lessons about life in the deep blue sea<figure><img src="https://images.theconversation.com/files/536664/original/file-20230710-27-mgth0w.jpg?ixlib=rb-1.1.0&rect=0%2C8%2C5815%2C3234&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Novels about underwater adventures offer a glimpse at oceanic life.</span> <span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/underwater-ocean-royalty-free-image/1485125421?phrase=underwater&adppopup=true">fotograzia via Getty Images</a></span></figcaption></figure><p>When OceanGate, the deep-sea exploration enterprise, created a <a href="https://www.youtube.com/watch?v=Wi60tvRwRlE">promotional video</a> for its ill-fated US$250,000-per-head trip to see the wreck of the Titanic, it told prospective passengers to “Get ready for what Jules Verne could only imagine – a 12,500-foot journey to the bottom of the sea.” Those behind the video hoped viewers would recognize the allusion to the author of one of the most influential and widely read oceanic novels of all time, “<a href="https://www.worldcat.org/title/855909314">20,000 Leagues Under the Sea</a>.”</p>
<p>There are indeed eerie similarities between the 1870 French novel and the circumstances surrounding the Titan submersible, which <a href="https://www.nytimes.com/2023/06/20/us/missing-submarine-titanic-search.html">lost contact less than two hours into its descent</a> into the depths of the Atlantic.</p>
<p>In the novel, a supposedly indestructible vessel strikes an iceberg. A man of untold wealth dreams of voyaging to the bottom of the sea, sharing with a select few passengers a glimpse of the mysteries of the deep. He descends to the ocean floor in order to gawk at the wreckage of a great ship that sank years before. But later in the novel a technical problem in the submarine starts a race against time as crew members try to reach the surface before their oxygen tanks are empty. And not everyone survives.</p>
<p>For me, as the leader of a “<a href="https://ihr.asu.edu/blue-humanities">Blue Humanities” initiative at Arizona State University</a> that explores how the literature of the past can inform the present about the importance of the oceans, revisiting the novel served another purpose. It reaffirmed for me how classic literature – particularly stories about adventures at sea and, quite frankly, misadventures, as well – continues to serve as one of the best ways for humanity to educate itself about the largely unexplored realm.</p>
<figure class="align-right ">
<img alt="A character from Jules Verne's novel '20,000 Leagues Under the Sea' looks out a submarine." src="https://images.theconversation.com/files/536679/original/file-20230710-25-v6kppz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/536679/original/file-20230710-25-v6kppz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=888&fit=crop&dpr=1 600w, https://images.theconversation.com/files/536679/original/file-20230710-25-v6kppz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=888&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/536679/original/file-20230710-25-v6kppz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=888&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/536679/original/file-20230710-25-v6kppz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1116&fit=crop&dpr=1 754w, https://images.theconversation.com/files/536679/original/file-20230710-25-v6kppz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1116&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/536679/original/file-20230710-25-v6kppz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1116&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Jules Verne’s novel ‘20,000 Leagues Under the Sea’ follows a wealthy man who voyages to the bottom of the sea to explore a ship that sank years before.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/news-photo/captain-nemo-twenty-thousand-leagues-under-the-sea-jules-news-photo/869034230?adppopup=true">Marka/Universal Images Group Editorial via Getty Images</a></span>
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<h2>Exploring the ‘seven seas’</h2>
<p>Verne’s original title had “les mers” - seas, plural. A “league” (French “lieue”) was a measure that has been different lengths at different times in history. In the novel, it is just over 2 miles. So Verne was alluding to distance traveled, not depth of descent. The deepest place on Earth, the <a href="https://www.scientificamerican.com/article/the-mariana-trench-is-7-miles-deep-whats-down-there/">Mariana Trench</a> in the Pacific, is only 3½ leagues down, whereas the journey of the imaginary submarine, Captain Nemo’s Nautilus, is a 40,000-mile circumnavigation of what used to be called “the seven seas.”</p>
<p>Verne’s novel and other classics – such as Herman Melville’s “<a href="https://www.worldcat.org/title/1263807806">Moby-Dick</a>” in 1851, and Thomas Hardy’s 1912 poem on the sinking of the Titanic, “<a href="https://www.poetryfoundation.org/poems/47266/the-convergence-of-the-twain">The Convergence of the Twain</a>” – are allegories of nature shattering the hubris of technology.</p>
<p>In Melville’s novel, the great white whale rams the good ship Pequod and drags Captain Ahab to a watery death. </p>
<p>For Hardy, <a href="https://www.historyonthenet.com/the-titanic-why-did-people-believe-titanic-was-unsinkable">the claim that the Titanic was “unsinkable</a>” is a prime example of human arrogance. In his poem, he imagines how sea-worms – “grotesque, slimed, dumb, indifferent” – now crawl over the gilded mirrors that were meant to “glass the opulent.”</p>
<h2>Unexplored depths</h2>
<p>The ocean bed remains an alien world. Like outer space, it is truly a final frontier. Indeed, it is often said that <a href="https://whalebonemag.com/know-more-about-mars-bottom-ocean/">we know more about Mars than we do about the bottom of the sea</a>. The National Ocean Service reminds us that the seas cover more than two-thirds of the planet. Still, “more than eighty percent of this vast, underwater realm remains <a href="https://oceanservice.noaa.gov/facts/exploration.html">unmapped, unobserved, and unexplored</a>.”</p>
<p>The mysteriousness of what lurks down there makes the seabed a prime location for fantasy. This can be seen in <a href="https://www.nationalgeographic.com/history/article/atlantis">Plato’s ancient idea of a lost kingdom called Atlantis</a>. And it can also be seen in the enduring idea of the <a href="https://www.rmg.co.uk/stories/topics/what-mermaid">mermaid</a>, or the comic world of SpongeBob SquarePants – which was created by a marine science educator, the late <a href="https://variety.com/2018/tv/news/spongebob-squarepants-creator-dead-dies-stephen-hillenburg-1203037362/">Stephen Hillenburg</a>.</p>
<p>There is an ingrained human fear of sinking below the waves. This fear is depicted in such haunting paintings as Théodore Géricault’s “<a href="https://smarthistory.org/theodore-gericault-raft-of-the-medusa/">The Raft of the Medusa</a>” and J.M.W. Turner’s “<a href="https://www.tate.org.uk/art/artworks/turner-the-shipwreck-n00476">The Shipwreck</a>.” So too, from the Greek tragedy of “<a href="https://fitzmuseum.cam.ac.uk/objects-and-artworks/highlights/context/stories-and-histories/the-death-of-hippolytus#:%7E:text=As%20he%20leaves%20his%20home,tell%20Theseus%20of%20the%20disaster.">Hippolytus” by Euripides</a> to “<a href="https://www.tor.com/2009/10/13/the-way-the-world-ends-john-wyndhams-lemgthe-kraken-wakeslemg/">The Kraken Wakes</a>,” a 1953 novel by science fiction writer John Wyndham, there is terror at the idea of a monster rising from the deep.</p>
<figure class="align-center ">
<img alt="A photo of the Titanic sitting on the ocean floor." src="https://images.theconversation.com/files/536665/original/file-20230710-19-7wbdbv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/536665/original/file-20230710-19-7wbdbv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=407&fit=crop&dpr=1 600w, https://images.theconversation.com/files/536665/original/file-20230710-19-7wbdbv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=407&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/536665/original/file-20230710-19-7wbdbv.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=407&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/536665/original/file-20230710-19-7wbdbv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=511&fit=crop&dpr=1 754w, https://images.theconversation.com/files/536665/original/file-20230710-19-7wbdbv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=511&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/536665/original/file-20230710-19-7wbdbv.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=511&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">A spare anchor sits in its well on the forepeak of the shipwrecked Titanic.</span>
<span class="attribution"><a class="source" href="https://www.gettyimages.com/detail/photo/forepeek-of-titanic-shipwreck-royalty-free-image/520112444?phrase=titanic&adppopup=true">Ralph White via Getty Images</a></span>
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<p>In our world of <a href="https://www.nrdc.org/bio/lauren-kubiak/marine-biodiversity-dangerous-decline-finds-new-report">marine biodiversity loss</a>, <a href="https://insideclimatenews.org/news/08062016/coral-bleaching-alarms-scientists-climate-change-global-warming-great-barrier-reef/">bleached coral</a> and <a href="https://marinesanctuary.org/blog/ocean-acidification/">ocean acidification</a>, we need positive as well as paranoid imaginings of the deep. The literature of the sea gives us not only tales of maritime bravery and catastrophe, but also compelling imagery that fosters a more sobering understanding of the threats to the world’s oceans and oceanic life.</p>
<h2>Among the first</h2>
<p>Jules Verne was indeed a pioneer of the celebration of underwater life that has been the mission of natural history documentaries from Jacques Cousteau’s “<a href="https://www.youtube.com/watch?v=xr4FrELKfvk">The Silent World</a>” in 1956 to Sir David Attenborough’s “<a href="https://www.bbcearth.com/shows/blue-planet">The Blue Planet</a>” in 2001.</p>
<p>It was only with the invention of the submarine that humans could reach more than a few feet below the surface of the waves. In the 1620s the Dutch inventor <a href="http://scihi.org/cornelis-drebbel-submarine/">Cornelis Drebbel</a> descended into the River Thames in a bell-shaped submersible powered by oars, his oxygen supplied by setting fire to saltpeter. </p>
<p>At the end of the 18th century there were <a href="https://archive.org/details/robertfultonsubm00parsrich/page/n15/mode/2up">rudimentary attempts at designing military submarines</a>, including a French one called the Nautilus, which gave Verne the name for his imaginary invention. His more immediate inspiration was the <a href="https://www.thevintagenews.com/2016/08/02/priority-plongeur-french-submarine-launched-1863-first-world-propelled-mechanical-rather-human-power/">Plongeur</a>, designed for the French navy in the early 1860s. It reached a depth of 30 feet – or 9 meters – and could stay underwater for two hours. </p>
<p>Verne saw a model of it at the <a href="https://library.brown.edu/cds/paris/worldfairs.html#de1867">1867 Exposition Universelle</a> in Paris, where he also learned about a recent discovery: the mechanical power of electricity. He put the two things together and set about writing a novel about an electrically powered submarine with an invincible hull, snaking under the oceans at unprecedented speed.</p>
<p>In the initial draft, the fabulously wealthy and cultured Captain Nemo is a Polish nobleman and political radical in flight from the Russian imperialism that has destroyed his family and homeland. But <a href="https://frenchquest.com/2020/11/08/hidden-treasures-the-manuscripts-of-twenty-thousand-leagues-under-the-sea/">Verne’s publisher made him remove the politics</a>, since Russia was a French ally at the time, so Nemo becomes a figure of mysterious origins. <a href="http://www.verniana.org/volumes/10/HTML/Bertman.html">The name, meaning “no one,</a>” was taken from the pseudonym for Odysseus, the original maritime voyager of Western literature and main character in Homer’s poem “The Odyssey.”</p>
<p>Nemo is both a hero and a murderous hater of humankind. Disillusioned by the modern world, he takes refuge in the wonders of the deep.</p>
<p>Verne read deeply in the nascent science of marine biology, poring over such works as M.F. Maury’s pioneering “<a href="https://library.si.edu/digital-library/book/physicalgeograp00maura">The Physical Geography of the Sea</a>,” published in 1855. By incorporating Maury’s research into an adventure story, Verne was able to educate readers of all ages about the astonishing richness of marine life. The novel is filled with detailed catalogs of fish and corals, delighted observations of organic forms ranging from sharks and whales to mollusks and tiny phosphorescent zoophytes. Like <a href="https://press.uchicago.edu/ucp/books/book/chicago/A/bo27616248.html">Melville in “Moby-Dick</a>” a few years before him and the great environmentalist Rachel Carson in her “<a href="https://loa.org/books/699-the-sea-trilogy">Sea Trilogy</a>” nearly a century after him, Verne braids together scientific taxonomy and poetic imagery. Melville’s novel vividly realizes barnacles and squid as well as whales and sharks. Carson even makes the reader empathize with slimy eels. So too, Verne’s novel includes dozens of sentences <a href="https://www.gutenberg.org/files/2488/2488-h/2488-h.htm">such as this</a>:</p>
<blockquote>
<p>Then, as specimens of other genera, blowfish resembling a dark brown egg, furrowed with white bands, and lacking tails; globefish, genuine porcupines of the sea, armed with stings and able to inflate themselves until they look like a pin cushion bristling with needles; seahorses common to every ocean; flying dragonfish with long snouts and highly distended pectoral fins shaped like wings, which enable them, if not to fly, at least to spring into the air; spatula-shaped paddlefish whose tails are covered with many scaly rings; snipefish with long jaws, excellent animals twenty-five centimeters long and gleaming with the most cheerful colors; bluish gray dragonets with wrinkled heads; myriads of leaping blennies with black stripes and long pectoral fins, gliding over the surface of the water with prodigious speed; delicious sailfish that can hoist their fins in a favorable current like so many unfurled sails; splendid nurseryfish on which nature has lavished yellow, azure, silver, and gold; yellow mackerel with wings made of filaments; bullheads forever spattered with mud, which make distinct hissing sounds; sea robins whose livers are thought to be poisonous; ladyfish that can flutter their eyelids; finally, archerfish with long, tubular snouts, real oceangoing flycatchers, armed with a rifle unforeseen by either Remington or Chassepot: it slays insects by shooting them with a simple drop of water.</p>
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<p>The scientist <a href="https://jbshaldane.org/">J.B.S. Haldane</a> once said, “The world will not perish for want of wonders, but for want of wonder.” Perhaps it is now time to reawaken a sense of wonder at the life of the oceans by returning to such classics of marine literature.</p><img src="https://counter.theconversation.com/content/208651/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jonathan Bate 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>The recent tragedy of the Titan submersible bore striking parallels to one of the most widely read novels about life at sea.Jonathan Bate, Foundation Professor of Environmental Humanities, Arizona State UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2091032023-07-06T20:35:04Z2023-07-06T20:35:04ZA combination of social, organizational and technical factors caused the Titan’s implosion<figure><img src="https://images.theconversation.com/files/535971/original/file-20230706-29-76pbqj.jpg?ixlib=rb-1.1.0&rect=0%2C5%2C3656%2C2424&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Edward Cassano, speaking at a news conference, led the search team that found the remains of the submersible. </span> <span class="attribution"><span class="source">(AP Photo/Carolyn Thompson)</span></span></figcaption></figure><iframe style="width: 100%; height: 100px; border: none; position: relative; z-index: 1;" allowtransparency="" allow="clipboard-read; clipboard-write" src="https://narrations.ad-auris.com/widget/the-conversation-canada/a-combination-of-social-organizational-and-technical-factors-caused-the-titans-implosion" width="100%" height="400"></iframe>
<p>The implosion that took the lives of five souls who made the perilous deep sea voyage to the Titanic shipwreck is not your typical disaster. But perhaps the OceanGate Titan submersible craft was <a href="https://nationalpost.com/pmn/news-pmn/canada-news-pmn/a-preoccupation-with-failure-why-the-titan-submersible-was-doomed-from-the-start-2">doomed from the start</a>.</p>
<p>On July 6, OceanGate announced that it <a href="https://oceangateexpeditions.com/">would be suspending all exploration and commercial operations</a>, and that their Pacific Northwest headquarters in Everett, Wash., <a href="https://www.kptv.com/2023/06/23/oceangates-pnw-offices-closed-indefinitely-after-ceo-dies-submersible/">would be closing indefinitely</a>.</p>
<p>In the wake of the disaster at sea on June 18, these actions are reflective of a company that is in the midst of a crisis of continuity as the overall future of the organization is uncertain.</p>
<p>Given the disaster, it is surprising that the advertising web pages for future Titanic excursions have not yet been taken down. Perhaps it is reflective of a rapidly evolving situation with a company in crisis. </p>
<h2>Reasons for failure</h2>
<p>Concepts explaining the Titan’s failure can be traced back to <a href="https://www.mindtherisk.com/literature/157-man-made-disasters-by-barry-a-turner">ideas developed 45 years ago</a>. Barry Turner, an organizational sociologist and safety pioneer, <a href="https://catalogue.nla.gov.au/Record/65580">studied long-forgotten disasters</a>. Turner analyzed catastrophes like <a href="https://www.bgs.ac.uk/case-studies/aberfan-1966-landslide-case-study/">the 1966 Aberfan disaster in Wales</a>, where 144 people were killed after waste from coal mining spilled into their village.</p>
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Read more:
<a href="https://theconversation.com/history-repeats-itself-the-titan-submersible-implosion-mirrors-past-disasters-208420">History repeats itself: The Titan submersible implosion mirrors past disasters</a>
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<p>Turner suggested that the interaction of social, organizational and technical processes were key to causing disaster.</p>
<p>Advances in the study of socio-technical problems continue to inform our understanding of unusual technological disasters like submarine implosions. Both <a href="https://doi.org/10.1177/1086026603262031">normal accident theory</a> and the concept of <a href="https://doi.org/10.1111/j.1468-5973.1996.tb00077.x">high-reliability organizations</a> help in understanding the big picture causes of the Titan submersible implosion.</p>
<h2>Normal accidents</h2>
<p>During the mid-1980s, sociologist Charles Perrow established <a href="https://www.eventsafetyalliance.org/news/2016/11/9/normal-accident-theory-explained">normal accident theory</a>. His premise was that machines, technologies and support systems were extremely complex and tightly coupled. An accident, then, could be considered an inevitable — normal — outcome.</p>
<p>Perrow analyzed situations of failure, like the <a href="https://www.nrc.gov/reading-rm/doc-collections/fact-sheets/3mile-isle.html">1979 Three Mile Island Nuclear Power Plant meltdown</a>. He considered nuclear safety by looking at <a href="https://press.princeton.edu/books/paperback/9780691004129/normal-accidents">some serious accidents, some trivial incidents, problems of reliability and management and the special characteristics of the nuclear power system</a>.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/535900/original/file-20230705-25-s5ak77.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="four cooling towers of a nuclear power plant in the distance" src="https://images.theconversation.com/files/535900/original/file-20230705-25-s5ak77.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/535900/original/file-20230705-25-s5ak77.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/535900/original/file-20230705-25-s5ak77.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/535900/original/file-20230705-25-s5ak77.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/535900/original/file-20230705-25-s5ak77.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/535900/original/file-20230705-25-s5ak77.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/535900/original/file-20230705-25-s5ak77.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>
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<span class="caption">Reactor Unit 2 at the Three Mile Island Nuclear Power Plant experienced a partial meltdown in 1979. The site was shut down completely in 2019, and is currently being decommissioned.</span>
<span class="attribution"><span class="source">(J. Rozdilsky)</span>, <span class="license">Author provided</span></span>
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<p>Perrow sought to establish a basis for understanding why accidents will happen involving high-risk systems that someone has decided we cannot live without. Harms from a nuclear meltdown can impact society as whole. But it is complicated considering the demands for divestment from fossil fuels. Arguments can be made from both sides as to <a href="https://www.bbc.com/news/science-environment-34114392">whether society can live with nuclear energy or not</a>.</p>
<p>However, in the case of the Titan submersible, a small group of people decided that the rewards outweighed the risks for getting a close-up view of the shipwreck. Accidents due to manned exploration of a treacherous 111-year-old shipwreck site, while tragic, <a href="https://www.cbsnews.com/news/titanic-tragedy-the-failure-of-oceangate-submersible-titan/">are limited to direct participants</a>.</p>
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Read more:
<a href="https://theconversation.com/titanic-submersible-catastrophic-implosion-questions-remain-about-the-costs-and-ethics-of-rescuing-tourist-expeditions-208163">Titanic submersible 'catastrophic implosion': questions remain about the costs and ethics of rescuing tourist expeditions</a>
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<h2>High-reliability organizations</h2>
<p>In the 1990s, <a href="https://www.nature.com/articles/477404a">debate ensued over causes of technological disasters</a>. Dangers of normal accidents were balanced against the safety culture of high-reliability organizations.</p>
<p>In his 1993 book, <a href="https://press.princeton.edu/books/paperback/9780691021010/the-limits-of-safety"><em>The Limits of Safety</em></a>, political scientist Scott Sagan asked: Are normal accidents inevitable? Or can the combination of interactive complexity and tight coupling be safely managed?</p>
<p>In supporting the safe management of complex technologies, high-reliability organizations emerged. They have a track record of decades of safety with risky technologies. Notwithstanding rare exceptions resulting in disasters like <a href="https://www.nrc.gov/reading-rm/doc-collections/fact-sheets/chernobyl-bg.html">Chernobyl</a> or <a href="https://www.nrc.gov/reading-rm/doc-collections/fact-sheets/japan-events.html">Fukushima</a>, nuclear power plant operators are high-reliability organizations. </p>
<p>A nuclear navy is also a high-reliability organization. <a href="https://doi.org/10.1177/014920639502100403">Studies of a nuclear submarine’s organizational culture</a> suggested specific social-technical interactions occur. Higher levels of knowledge along with technical experience are necessary. The result of the interaction is to transform a high-risk system into a high reliability system.</p>
<h2>Acknowledging complexity</h2>
<p>A <a href="https://europepmc.org/article/nbk/nbk542883">characteristic of high-reliability organizations</a> is the reluctance to simplify anything. They accept that the tasks at hand are complex, with a real potential to fail in new unexpected ways.</p>
<p>Photographs of the interior of the ill-fated Titan submersible show bare walls with no resemblance to a stereotypical cockpit with its bells and whistles. Photographs of the interior of James Cameron’s Titanic exploration submersible, the <a href="https://www.newsweek.com/how-james-cameron-submersible-compares-oceangate-titan-1808594">Deep Sea Challenger</a>, appear to resemble a more complicated cockpit with controllers and gauges on the walls.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"1671980973754294285"}"></div></p>
<p>OceanGate admitted to using several pieces of off-the-shelf technology that streamlined construction and made the submersible simple to operate. For example, <a href="https://www.cbsnews.com/news/titanic-submarine-missing-video-game-xbox-controller-is-that-normal/">modified video game controllers were used for controlling the Titan</a> submersible.</p>
<p>OceanGate acted to simplify an otherwise complex endeavour, and appear to not have behaved as a high-reliability organization.</p>
<h2>A wake-up call</h2>
<p>The implosion of the Titan is a wake-up call for exploration or tourism companies who plan to continue to send people to inhospitable environments like the <a href="https://www.nbcnews.com/news/world/titanic-sub-search-catastrophic-implosion-rcna90744">extreme conditions present 12,500 feet below the ocean’s surface</a>. If not doing so at present, these companies should mimic the organizational culture of high-reliability organizations.</p>
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Read more:
<a href="https://theconversation.com/what-was-the-catastrophic-implosion-of-the-titan-submersible-an-expert-explains-208359">What was the 'catastrophic implosion' of the Titan submersible? An expert explains</a>
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<p>While eliminating the risk of death is not possible with <a href="https://www.cbc.ca/radio/quirks/bobs-blog-titan-submersible-mars-1.6886336">extreme travel to outer space or the deep sea bottom</a>, the main goal of companies undertaking such excursions should be to attempt to reduce the loss of life to the maximum achievable extent.</p><img src="https://counter.theconversation.com/content/209103/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Jack L. Rozdilsky 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>Complex endeavours require complex risk management, and high-reliability organizations recognize this. OceanGate did not plan for the complexity of its operations, with tragic consequences.Jack L. Rozdilsky, Associate Professor of Disaster and Emergency Management, York University, CanadaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2084642023-06-27T06:06:16Z2023-06-27T06:06:16ZThe Titan disaster investigation has begun. An expert explains what might happen next<p>The United States Coast Guard is now <a href="https://edition.cnn.com/2023/06/26/us/submersible-titanic-implosion-deaths-monday/index.html">leading the investigation</a> into the Titan submersible, looking for answers about why it imploded, and what actions should be taken next.</p>
<p>A multinational search for the Titan came to a halt on Thursday, when a remotely operated vehicle (ROV) found five pieces of debris sprawled across the seabed, some 500 metres from the Titanic shipwreck. The vessel experienced a catastrophic implosion at some point during its journey, with all five passengers presumed dead. </p>
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<a href="https://theconversation.com/what-was-the-catastrophic-implosion-of-the-titan-submersible-an-expert-explains-208359">What was the 'catastrophic implosion' of the Titan submersible? An expert explains</a>
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<p>For now, details elude us – and it could be days, or even weeks, before we receive meaningful updates on the investigation’s progress. Similar past events, such as the 2019 <a href="https://www.nytimes.com/2020/04/20/world/europe/russian-submarine-fire-losharik.html">fire in the Russian submarine Losharik</a>, have shown how sensitively the details of such investigations should be treated. </p>
<p>The Titan disaster happened in international waters, in a commercially operated vessel, and with victims of different nationalities. Officials will likely want to be certain about any details released – and some may not be disclosed at all.</p>
<h2>What happens next?</h2>
<p>The Titan, a research and exploration sub <a href="https://podcasts.apple.com/us/podcast/stockton-rush-manned-submersibles-science-exploration/id1515818448?i=1000493347762">owned by US company OceanGate</a>, lost contact with its surface vessel on Sunday morning, about one hour and 45 minutes after its departure.</p>
<p>Chief investigator Jason Neubauer said the US Coast Guard will receive help from Canada, France and the United Kingdom. He said authorities had already mapped the accident site, and the inquiry will aim to address several questions, including:</p>
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<li>what may have happened to cause the implosion?</li>
<li>how can safety be improved for future submersible voyages?</li>
<li>what civil or criminal charges should be laid in relation to the events, if any?</li>
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<p>Recovery operations in remote parts of the ocean are painstakingly complex, with myriad variables to consider. We can expect the Titan investigation will <a href="https://www.nytimes.com/2023/06/22/us/titanic-submersible-search-rescue-costs.html">cost millions of dollars</a>.</p>
<h2>Harsh conditions</h2>
<p>The investigation is being carried out at depths of about 3,800m, some 600km from the nearest coastline. The same vessel that identified the initial debris – a deep-sea ROV called <a href="https://pelagic-services.com/web2/index.php/odysseus-rov-system/">Odysseus 6K</a> – is <a href="https://www.cbc.ca/news/canada/newfoundland-labrador/titan-submerisble-investigation-1.6889066">reportedly also being used</a> to look for the vessel’s remaining parts. </p>
<p>Manufacturer Pelagic Research Services <a href="https://edition.cnn.com/2023/06/26/us/submersible-titanic-implosion-deaths-monday/index.html">told CNN</a> the ROV’s lifting capabilities had “been utilised and continue to be utilised”, and that missions would continue for about a week. However, we don’t know whether any debris has been recovered yet.</p>
<p>ROVs can collect vast amounts of data for deep-sea operations, including video footage and sensor readings. Ideally, an ROV will be able to reliably and quickly transmit data back to a support vessel or onshore facility, since real-time data transfer is often needed to make important decisions on the fly. </p>
<p>That said, even if Odysseus 6K delivers on this, some parts of the Titan may never be found. They may have disintegrated during the implosion, drifted too far away from the search area, or be obscured by other debris. </p>
<p>Underwater hazards, harsh weather and strong currents all add to the challenge – especially by <a href="https://pubmed.ncbi.nlm.nih.gov/37249969/">limiting visibility</a>. In the deep ocean, turbidity (haziness) and the absence of natural light means visibility is close to zero. Here, only sonar technology (which uses sound waves) may be used for navigation, mapping and locating objects of interest.</p>
<p>Any debris recovered will undoubtedly be valuable. Debris is physical evidence of the implosion, so analysing it will provide information (such as damage patterns and fractures) that can be used to infer the source of the implosion and the forces involved. </p>
<p>Experts can also conduct chemical analyses of the residue on the wreckage. However, this is affected by seawater, so a prompt recovery will be important.</p>
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<a href="https://theconversation.com/an-expert-explains-what-safety-features-a-submersible-should-have-208187">An expert explains what safety features a submersible should have</a>
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<p>The Titan’s remote location means investigators won’t have the luxury of having the quick support offered by coastal rescue stations that can rapidly deploy search and rescue assets and diving teams. </p>
<p>They’ll have to rely on specialised resources, such as large vessels and aircraft with extended range capabilities. Aircraft can provide an elevated platform for visual observation and aerial mapping, as well as remote sensing technologies including radar systems and thermal imaging sensors. </p>
<h2>Finding the remains</h2>
<p>Chief investigator Neubauer has said <a href="https://www.bbc.com/news/66015811">searching for victims’</a> remains is on the agenda. But the chances of actually finding them will depend on various factors, including the cause of the implosion, the depth at which it happened, and the surrounding conditions. </p>
<p>A severe implosion may have resulted in extensive fragmentation and scattering of both the submersible’s structure and human remains. Remains can be swept away in currents, or tampered with by marine life.</p>
<p>They also behave differently depending on whether they’re recovered from <a href="https://www.proquest.com/openview/a65eb1a2d459fb92ea04605ef098497a/1.pdf?pq-origsite=gscholar&cbl=47323">non-sequestered environments</a> (exposed in the water) or <a href="https://pubmed.ncbi.nlm.nih.gov/23232544/">sequestered environments</a> (enclosed in a vessel). In the former scenario, bodies are often <a href="https://pubmed.ncbi.nlm.nih.gov/15166773/">consumed by animals</a> and decomposition causes <a href="https://www.semanticscholar.org/paper/Disappearance-of-soft-tissue-and-the-of-human-from-Haglund/5f5ec4ccf2ebabce7b9bd3106df77a4f78ecf1db">disarticulation</a>, wherein the bones gradually separate at the joints. However, garments can sometimes help to <a href="https://thehill.com/changing-america/well-being/569067-doctor-explains-why-21-human-feet-in-sneakers-may-have-washed-on/">keep things together</a>.</p>
<p>The effort to locate remains may involve observation from long-range aircraft and patrol vessels, or may even rely on radar, sonar or satellite imagery. If remains are located deep underwater, recovering them may involve using a specialised hoisting system designed to handle the challenges of a deep-sea environment.</p>
<h2>Sharing responsibility</h2>
<p>The Titan investigation will involve coordination between multiple entities, including maritime authorities, coast guard services and search and rescue organisations. </p>
<p>It will be subject to international agreements such as the <a href="https://www.imo.org/en/About/Conventions/Pages/International-Convention-on-Maritime-Search-and-Rescue-(SAR).aspx">International Convention on Maritime Search and Rescue</a>, as well as international law such as
the <a href="https://onboard.sosmediterranee.org/knowledge-base/article-98-duty-to-render-assistance/#">duty to render assistance</a>, which is enshrined in the United Nations Convention on the Law of the Sea. This requires that all vessels, regardless of their flag, have a legal obligation to render assistance to any person in distress at sea.</p>
<p>For now, we can only speculate on what the Titan investigation might produce. All we can do is wait, and hope that whatever answers do emerge will be put to good use to make sure something like this never happens again. </p>
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Read more:
<a href="https://theconversation.com/why-is-extreme-frontier-travel-booming-despite-the-risks-208201">Why is extreme 'frontier travel' booming despite the risks?</a>
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<img src="https://counter.theconversation.com/content/208464/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Paola A. Magni 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 Titan disaster happened in international waters, in a commercially operated vessel, and with victims of different nationalities. Any details that emerge will likely be treated with sensitivity.Paola A. Magni, Senior Lecturer in Forensic Science, Murdoch UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2083592023-06-23T01:31:13Z2023-06-23T01:31:13ZWhat was the ‘catastrophic implosion’ of the Titan submersible? An expert explains<p>The four day-long search for the missing Titan submersible has come to a <a href="https://www.theguardian.com/world/2023/jun/22/titanic-sub-titan-debris-field-search-area-latest">tragic end</a>. Reports have confirmed the vessel was subject to a “catastrophic implosion” at some point during its voyage towards the Titanic shipwreck, which would have killed all five passengers instantly.</p>
<p>A debris field comprising “five different major pieces of debris” of various sections of the submersible was found on the sea floor by a remotely operated vehicle, about 500 metres away from the bow of the Titanic, officials said. </p>
<p>These findings are in line with previous news that an acoustic signature “consistent with an implosion” was detected by the US Navy on the same day the Titan began its descent. </p>
<p>The navy’s seabed sensors detected the signature in the general area the vessel was diving when it lost communication with its mothership. At the time the signature was considered “not definitive”. </p>
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<a href="https://theconversation.com/an-expert-explains-what-safety-features-a-submersible-should-have-208187">An expert explains what safety features a submersible should have</a>
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<h2>What is a ‘catastrophic implosion’?</h2>
<p>We can assume the implosion actually happened on the first day of the dive – but perhaps not exactly at the same time communication was lost with the mothership. But why did it happen?</p>
<p>Most, if not all, submersibles and submarines operating at depth have a pressure vessel made of a single metallic material with high yield strength. This is typically steel for relatively shallow depths (roughly less than 300m), or titanium for deeper depths. </p>
<p>A titanium or thick steel pressure vessel is usually a spherical shape that can withstand the crushing pressures you might expect at 3,800m – the depth at which the Titanic wreck lies.</p>
<p>The Titan, however, was different. Its pressure vessel was made of a combination of titanium and composite carbon fibre. This is somewhat unusual from a structural engineering perspective since, in a deep diving context, titanium and carbon fibre are materials with vastly different properties. </p>
<p>Titanium is elastic and can adapt to an extended range of stresses without any measurable permanent strain remaining after the return to atmospheric pressure. It shrinks to adjust to pressure forces, and re-expands as these forces are alleviated. A carbon-fibre composite, on the other hand, is much stiffer and does not have the same kind of elasticity.</p>
<p>We can only speculate about what happened with the combination of these two technologies, which do not dynamically behave the same way under pressure. </p>
<p>But what we can say almost certainly is that there would have been some kind of loss of integrity due to the differences between these materials. A composite material could potentially suffer from “delamination”, which leads to a separation of the layers of reinforcement. </p>
<p>This would have created a defect which triggered an instantaneous implosion due to the underwater pressure. Within less than one second, the vessel — being pushed down on by the weight of a 3,800m column of water — would have immediately crumpled in from all sides. </p>
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<h2>The final moments</h2>
<p>When everything is designed, manufactured and tested perfectly, you’ve got a shape close enough to perfection that can withstand the overall pressure being applied from all directions. In this scenario, the material can “breathe” – shrink and expand as needed with depth. The Titan’s implosion means this was not happening. </p>
<p>The implosion itself would have killed everyone within less than 20 milliseconds. In fact, the human brain can’t even process information at this speed. As much as the news is devastating, perhaps it is somewhat reassuring the Titan’s passengers would not have suffered a terrifying and drawn-out end. </p>
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<a href="https://theconversation.com/why-is-extreme-frontier-travel-booming-despite-the-risks-208201">Why is extreme 'frontier travel' booming despite the risks?</a>
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<img src="https://counter.theconversation.com/content/208359/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Eric Fusil is affiliated with the Royal Institution of Naval Architects and Engineers Australia</span></em></p>Deep underwater, the Titan submersible would have been crushed in less than a second once a defect cracked the hull.Eric Fusil, Associate Professor, School of Electrical and Mechanical Engineering, University of AdelaideLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2082002023-06-22T04:49:31Z2023-06-22T04:49:31ZDisaster, opulence, and the merciless ocean: why the Titanic disaster continues to enthral<figure><img src="https://images.theconversation.com/files/533354/original/file-20230622-14002-235bwm.jpg?ixlib=rb-1.1.0&rect=0%2C0%2C1440%2C814&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">
</span> <span class="attribution"><span class="source">Royal Museums Greenwich</span></span></figcaption></figure><p>The question on many minds this week is why did some of the world’s richest men risk death to venture to the bottom of the sea in a cold and cramped <a href="https://www.nytimes.com/2023/06/20/us/oceangate-titanic-missing-submersible.html">“experimental” submersible</a> for a chance to glimpse the wreck of the Titanic? </p>
<p>The “unsinkable” ship that sunk on its maiden voyage across the Atlantic in 1912 after colliding with an iceberg is arguably the world’s most well-known boat. The Titanic is recognisable to more of the world’s population than, say, the Niña, the Pinta, and the Santa Maria (Christopher Colombus’s fleet that launched the Spanish conquest of the Americas), or Captain Cook’s HMS Endeavour (the tall ship that set in motion the British conquest of Australia). The Endeavour’s long-forgotten wreck was found scuttled off the coast of Rhode Island <a href="https://theconversation.com/has-captain-cooks-ship-endeavour-been-found-debate-rages-but-heres-whats-usually-involved-in-identifying-a-shipwreck-176363">just last year</a>.</p>
<p>The Titanic’s maiden voyage and calamitous end was one of the biggest news stories of 1912, and has continued to fascinate us ever since. The disaster inspired songs and multiple films in the twentieth century, including James Cameron’s 1997 epic romance, which long reigned as the <a href="https://en.wikipedia.org/wiki/List_of_highest-grossing_films#Timeline_of_highest-grossing_films">highest-grossing film of all time</a>. More recently, Titanic exhibitions that invite visitors to examine relics and <a href="https://titanicexhibition.com/nyc/#sec_instafeed">explore the ship’s recreated rooms have attracted huge crowds in New York, Seville and Hong Kong</a>. </p>
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<span class="caption">The sinking of the Titanic as depicted in Untergang der Titanic, a 1912 illustration by Willy Stöwer.</span>
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<h2>Opulence and immigrants</h2>
<p>There are two reasons why we are so drawn to the Titanic, and why the super-rich are apparently willing to part with their money and even risk their lives to catch a glimpse of its broken hull.</p>
<p>The first is its opulence. The White Start Line that built the Titanic advertised the ship as the most luxurious ever to set sail. Wealthy passengers paid up to £870 for the privilege of occupying the Titanic’s most expensive and spacious first-class cabins. To put this 110-year-old money in perspective, when the first world war broke out in 1914, infantry soldiers in the British army were paid a basic salary of around £20 per year. </p>
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<span class="caption">Titanic departing Southampton on 10 April 1912.</span>
<span class="attribution"><span class="source">Wikipedia</span></span>
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<p>Titanic movies and exhibitions are popular because audiences enjoy the voyeurism of gazing on the ship’s beautiful furnishings, the stunning clothes worn by its rich and beautiful passengers, and their elaborate meals in fancy restaurants. First-class passengers feasted on <a href="https://online.ucpress.edu/gastronomica/article-abstract/9/4/32/93511/The-Night-the-Good-Ship-Went-Down-Three-Fateful">multi-course dinners</a> with salmon, steak, and pâté de foie gras. Chefs in Australia and around the globe occasionally <a href="https://www.timeout.com/melbourne/things-to-do/titanic-dining-experience">recreate Titanic meals</a> for curious clients.</p>
<p>Hundreds of poor immigrant passengers, represented by Jack (played by Leonardo DiCaprio) in Cameron’s movie, were also aboard the Titanic. They lived in crowded quarters and enjoyed less thrilling meals such as boiled beef and potatoes. If their ilk were the only people on board the Titanic, the ship would arguably have faded quickly from memory.</p>
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<h2>The power of the sea</h2>
<p>The fact the Titanic was touted as unsinkable also adds to its allure. The ship, whose name evoked its massive size, was engineered to cheat the ocean. When it departed England it symbolised man’s domination over nature. At the bottom of the Atlantic, it serves as a visceral reminder of the indomitable sea’s awesome power.</p>
<p>The same two factors - the excess of the voyage, and its defeat by the sea – are now driving the current global interest in the Titan submersible disaster. Few world events garner so much attention, including statements from Downing Street and the White House, and live news blogs from The New York Times and the Guardian.</p>
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<a href="https://theconversation.com/titanic-submersible-catastrophic-implosion-questions-remain-about-the-costs-and-ethics-of-rescuing-tourist-expeditions-208163">Titanic submersible 'catastrophic implosion': questions remain about the costs and ethics of rescuing tourist expeditions</a>
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<p>The Titan, like the Titanic, commands our attention because of its obscenely rich passengers, who each reportedly paid US$250,000 (or between four and five times the average US salary) to visit the wreck of the famous ship that battled the sea and lost. </p>
<p>And then there is the intriguing mystery and power of the sea. News outlets are publishing helpful graphics that try to teach our terrestrial brains to comprehend just how deep the ocean is, and how far below the sea’s surface the Titanic and possibly the Titan lie. </p>
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<span class="caption">The Titanic’s bow, photographed in June 2004.</span>
<span class="attribution"><span class="source">Wikipedia</span></span>
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<h2>The limits of human knowledge</h2>
<p>Last night I spied <a href="https://neal.fun/deep-sea/">Neal Argawal’s Deep Sea</a> website circulating on social media. The site allows viewers to scroll from the sea surface to the sea floor, diving down past images of various marine animals that inhabit different oceanic depths. </p>
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<p>At 114 metres is an orca, and 332m marks the the deepest depth a human has ever reached using SCUBA gear. It takes a lot of scrolling to descend to the Titanic almost 4,000m below the waves. </p>
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Read more:
<a href="https://theconversation.com/has-captain-cooks-ship-endeavour-been-found-debate-rages-but-heres-whats-usually-involved-in-identifying-a-shipwreck-176363">Has Captain Cook's ship Endeavour been found? Debate rages, but here's what's usually involved in identifying a shipwreck</a>
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<p>Besides gross income inequality, reflecting on the Titan and the Titanic invite us to confront just how little we can “see” of the sea in this age of mass surveillance. Not even the powerful US navy, assisted by the Canadian, UK and French governments, can muster the resources and technology required to locate, let alone rescue, the missing submersible. </p>
<p>As the sea seems to have swallowed yet another ship, we are reminded of limits of human knowledge and mastery over the ocean.</p><img src="https://counter.theconversation.com/content/208200/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Kristie Patricia Flannery receives funding from the Australian Research Council.</span></em></p>What makes billionaires risk their lives to see the Titanic wreck?Kristie Patricia Flannery, Research Fellow, Institute for Humanities and Social Sciences, Australian Catholic UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/2081632023-06-21T22:51:54Z2023-06-21T22:51:54ZTitanic submersible ‘catastrophic implosion’: questions remain about the costs and ethics of rescuing tourist expeditions<figure><img src="https://images.theconversation.com/files/533315/original/file-20230621-23-8fpk5h.jpg?ixlib=rb-1.1.0&rect=0%2C244%2C5607%2C3786&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">The vessel Polar Prince towing OceanGate Expeditions submersible vessels from St. John's, N.L., as it leaves to tour the Titanic wreck site on May 29, 2023.</span> <span class="attribution"><span class="source">(Shutterstock)</span></span></figcaption></figure><p>The U.S. Coast Guard announced Thursday <a href="https://www.theguardian.com/world/2023/jun/21/titanic-sub-timeline-titan-submersible-missing-vessel">that debris found on the seafloor</a> was identified as belonging to the Titan, <a href="https://www.theglobeandmail.com/canada/article-missing-titanic-tourist-sub-explained/">the OceanGate submersible that had disappeared on June 18</a>. Teams from different countries — including the United States, Canada, the United Kingdom and Germany — were conducting search missions under a very tight timeline. </p>
<p>The discovery, close to the site of the Titanic, indicates the end of search-and-rescue operations for the five people onboard, who were killed in a ‘<a href="https://www.cnn.com/2023/06/22/us/submersible-titanic-oceangate-search-thursday/index.html">catastrophic implosion</a>,’ according to the Coast Guard.</p>
<p>As one of the largest international marine search-and-rescue operations, the incident raised questions about risk management, search-and-rescue operations, costs and ethical aspects of responses.</p>
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<h2>Ocean incidents</h2>
<p>A significant number of economic activities — including shipping, fishing and offshore oil and gas drilling — are conducted in marine environments. These activities can lead to occurrences of accidents and casualties of different types. </p>
<p>Annually, a large number of incidents happen in the Canadian marine environment. Between 2011 and 2020, <a href="https://www.tsb.gc.ca/eng/stats/marine/2021/ssem-ssmo-2021.html">284 occurrences were reported each year</a> that had an annual average of 15.6 fatalities during the same period. </p>
<p>These numbers suggest that relative to the huge number of marine activities and the number of incidents, conventional marine-based operations are relatively safe and the emergency responses to them are effective. </p>
<h2>An unusual situation</h2>
<p>The search-and-rescue operations <a href="https://oceangate.com/our-subs/titan-submersible.html">for the Titan</a> have been proven to be unusual, as measured by the complexity, costs, time sensitivity and scale. Unlike search-and-rescue operations on the ground that can be undertaken by volunteers and with little or no equipment, marine search and rescue is a <a href="https://www.ccg-gcc.gc.ca/publications/search-rescue-recherche-sauvetage/sar-canada-res-eng.html">highly specialized operation</a>. </p>
<p>It requires high-tech equipment, tools, training, co-ordination and capacity. In the current case, <a href="https://www.nbcnews.com/news/world/live-blog/missing-titanic-submersible-live-updates-rcna90315">the search area was not measured in square kilometres or miles</a> — rather, it was in cubic measurements (3D), because the vessel could have been anywhere around the surface, in shallow or deep waters, <a href="https://www.nytimes.com/live/2023/06/20/us/titanic-missing-submarine">or on the ocean floor</a>.</p>
<p>While there are capable teams with the needed equipment and training for most marine disasters, they are not sufficient to cover a large area with limited information or uncertainty about the situation. </p>
<p><div data-react-class="InstagramEmbed" data-react-props="{"url":"https://www.instagram.com/p/Ctup4lQs5SP","accessToken":"127105130696839|b4b75090c9688d81dfd245afe6052f20"}"></div></p>
<h2>Operational outcomes</h2>
<p>This search operation was among the costliest in recent history. We need to wait to see how much of this cost will be covered by insurance, OceanGate or the public. </p>
<p>This event will generate significant discussions around the public burden of private risks and risk-taking behaviours, and how risks in certain areas are regulated. And it could count for about one-third of Canada’s annual average marine fatalities if it’s considered a Canadian incident.</p>
<p>Particularly, it will bring to the forefront questions about <a href="https://www.seattletimes.com/nation-world/extreme-travel-rescue-operations-are-expensive-and-who-pays-is-unclear/">balancing acceptable risks with available emergency response capacities</a>, including search-and-rescue. </p>
<h2>Risk assessments</h2>
<p>When embarking on risky operations, such as deep-sea touristic exploration, two elements need to be added to risk assessments: 1) Do we have adequate and timely internal and external capacity to handle a potential incident?; and 2) What are the total response costs of an incident? </p>
<p>While certain risky activities or operations may be acceptable based on a private assessment of risk, they may not be acceptable if we ponder these two aspects.</p>
<figure class="align-center ">
<img alt="A small submersible is seen underwater." src="https://images.theconversation.com/files/533316/original/file-20230621-27-kan0vv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/533316/original/file-20230621-27-kan0vv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=384&fit=crop&dpr=1 600w, https://images.theconversation.com/files/533316/original/file-20230621-27-kan0vv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=384&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/533316/original/file-20230621-27-kan0vv.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=384&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/533316/original/file-20230621-27-kan0vv.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=483&fit=crop&dpr=1 754w, https://images.theconversation.com/files/533316/original/file-20230621-27-kan0vv.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=483&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/533316/original/file-20230621-27-kan0vv.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=483&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">OceanGate’s Titan submersible dives underwater.</span>
<span class="attribution"><span class="source">(OceanGate Expeditions via AP)</span></span>
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<p>Unfortunately, many conventional risk assessments, particularly in the private sector organizations, do not pay sufficient attention to available emergency response capacities. </p>
<p>When considering <a href="https://www.outlookindia.com/business/titan-submersible-here-s-a-timeline-of-how-rescue-mission-is-unfolding-in-the-atlantic-ocean-news-296702">the Titan’s search-and-rescue operation</a>, it became clear this small emergency surpassed the capacity of the resources that were operating in the area.</p>
<p>Teams from other places and countries joined the effort, but it took several days for a unified command centre for search-and-rescue to take shape.</p>
<p>Conducting a survey of available emergency response capacities to risk assessments can make a significant difference in risk management and regulation.</p>
<p>Similarly, many current risk assessments do not fully include emergency response costs in their calculations. While it is not a major consideration for many regular daily activities and operations because the emergency response is within regular possibilities, certain operations — particularly on remote marine environments — ought to add these costs into their risk assessment. </p>
<p>In doing so, risks may become more or less acceptable in terms of mitigation policies and regulations. Incorporating these aspects into risk assessments and regulations could help ensure that private operators provide additional safety and risk mitigation measures and assume responsibility for incurred costs.</p><img src="https://counter.theconversation.com/content/208163/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Ali Asgary does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>A team of rescuers has located debris from the Titan, indicating the end of search-and-rescue efforts. Risky undertakings need to assess the cost and capacity of any potential rescue needs.Ali Asgary, Professor, Disaster & Emergency Management, Faculty of Liberal Arts & Professional Studies & Director, CIFAL York, York University, CanadaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1812412022-05-19T20:01:31Z2022-05-19T20:01:31ZWhat’s it like to be on Venus or Pluto? We studied their sand dunes and found some clues<figure><img src="https://images.theconversation.com/files/458386/original/file-20220418-22-1t0v2e.jpeg?ixlib=rb-1.1.0&rect=0%2C0%2C4045%2C5085&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Sand blown by wind into ripples within Victoria Crater at Meridiani Planum on Mars, as photographed by NASA's Mars Reconnaissance Orbiter on October 3, 2006.</span> <span class="attribution"><a class="source" href="https://photojournal.jpl.nasa.gov/catalog/PIA08813">NASA/JPL-Caltech/University of Arizona/Cornell/Ohio State University</a></span></figcaption></figure><p>What is it like to be on the surface of Mars or Venus? Or even further afield, such as on Pluto, or Saturn’s moon Titan? </p>
<p>This curiosity has driven advances in space exploration since Sputnik 1 was launched <a href="https://www.nationalgeographic.org/thisday/oct4/ussr-launches-sputnik/">65 years</a> ago. But we’re only beginning to scratch the surface of what is knowable about other planetary bodies in the Solar System.</p>
<p>Our <a href="https://doi.org/10.1038/s41550-022-01669-0">new study</a>, published today in Nature Astronomy, shows how some unlikely candidates – namely sand dunes – can provide insight into what weather and conditions you might experience if you were standing on a far-off planetary body. </p>
<h2>What’s in a grain of sand?</h2>
<p>English poet William Blake <a href="https://www.poetryfoundation.org/poems/43650/auguries-of-innocence">famously wondered</a> what it means “to see a world in a grain of sand”. </p>
<p>In our research, we took this quite literally. The idea was to use the mere presence of sand dunes to understand what conditions exist on a world’s surface. </p>
<p>For dunes to even exist, there are a pair of “<a href="https://theconversation.com/exo-earths-and-the-search-for-life-elsewhere-a-brief-history-33096">Goldilocks</a>” criteria that must be satisfied. First is a supply of erodible but durable grains. There must also be winds fast enough to make those grains hop across the ground – but not fast enough to carry them high into the atmosphere.</p>
<p>So far, the direct measurement of winds and sediment has only been possible on Earth and Mars. However, we have observed wind-blown sediment features on multiple other bodies (and even <a href="https://doi.org/10.1073/pnas.1612176114">comets</a>) by satellite. The very presence of such dunes on these bodies implies the Goldilocks conditions are met.</p>
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<img alt="" src="https://images.theconversation.com/files/460205/original/file-20220428-18-ofmyhl.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/460205/original/file-20220428-18-ofmyhl.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=400&fit=crop&dpr=1 600w, https://images.theconversation.com/files/460205/original/file-20220428-18-ofmyhl.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=400&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/460205/original/file-20220428-18-ofmyhl.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=400&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/460205/original/file-20220428-18-ofmyhl.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=503&fit=crop&dpr=1 754w, https://images.theconversation.com/files/460205/original/file-20220428-18-ofmyhl.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=503&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/460205/original/file-20220428-18-ofmyhl.png?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">
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<span class="caption">Windblown features on (from top left, clockwise) Earth, Mars, Titan, Venus, Pluto and Triton have been imaged by satellites.</span>
<span class="attribution"><span class="source">Nature Astronomy/Image adapted from Gunn and Jerolmack (2022)</span></span>
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<p>Our work focused on Venus, Earth, Mars, Titan, Triton (Neptune’s largest moon) and Pluto. Unresolved debates about these bodies have gone on for decades. </p>
<p>How do we square the apparent wind-blown features on Triton’s and Pluto’s surfaces with their thin, tenuous atmospheres? Why do we see such prolific sand and dust activity on Mars, despite measuring winds that seem too weak to sustain it? </p>
<p>And does Venus’s thick and stiflingly hot atmosphere move sand in a similar way to how air or water move on Earth?</p>
<figure class="align-center ">
<img alt="Mars ripples" src="https://images.theconversation.com/files/461935/original/file-20220509-7428-n5ash3.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/461935/original/file-20220509-7428-n5ash3.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/461935/original/file-20220509-7428-n5ash3.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/461935/original/file-20220509-7428-n5ash3.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/461935/original/file-20220509-7428-n5ash3.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/461935/original/file-20220509-7428-n5ash3.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/461935/original/file-20220509-7428-n5ash3.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">Windblown ripples on the Bagnold Dunes on Mars were photographed by the rover Curiosity.</span>
<span class="attribution"><span class="source">NASA/JPL-Caltech/MSSS</span></span>
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<h2>Furthering the debate</h2>
<p>Our study offers predictions for the winds required to move sediment on these bodies, and how easily that sediment would break apart in those winds. </p>
<p>We constructed these predictions by piecing together results from a host of other research papers, and testing them against all the experimental data we could get our hands on.</p>
<p>We then applied the theories to each of the six bodies, drawing on telescope and satellite measurements of variables including gravity, atmospheric composition, surface temperature, and the strength of sediments.</p>
<p>Studies before ours have looked at either the wind speed threshold required to move sand, or the strength of various sediment particles. Our work combined these together – looking at how easily particles could break apart in sand-transporting weather on these bodies.</p>
<p>For example, we know Titan’s equator has sand dunes – but we aren’t sure of what sediment encircles the equator. Is it pure <a href="https://www.pnas.org/doi/10.1073/pnas.0608561103">organic haze</a> raining down from the atmosphere, or is it mixed with denser ice?</p>
<p>As it turns out, we discovered loose aggregates of organic haze would disintegrate upon collision if they were blown by the winds at Titan’s equator. </p>
<p>This implies Titan’s dunes probably aren’t made of purely organic haze. To build a dune, sediment must be blown around in the wind for a long time (some of Earth’s dune sands are a <a href="https://doi.org/10.1038/ngeo985">million years</a> old).</p>
<p>We also found wind speeds would have to be excessively fast on Pluto to transport either methane or nitrogen ice (which is what Pluto’s dune sediments were hypothesised to be). This calls into question whether “dunes” on Pluto’s plain, <a href="https://www.nasa.gov/feature/scientists-probe-mystery-of-pluto-s-icy-heart">Sputnik Planitia</a>, are dunes at all.</p>
<p>They may instead be <a href="https://doi.org/10.1016/j.earscirev.2020.103350">sublimation waves</a>. These are dune-like landforms made from the sublimation of material, instead of sediment erosion (such as those seen on Mars’s north polar cap).</p>
<p>Our results for Mars suggest more dust is generated from wind-blown sand transport on Mars than on Earth. This suggests our models of the Martian atmosphere may not be effectively capturing Mars’s strong “<a href="https://earthobservatory.nasa.gov/images/41161/katabatic-winds-rake-terra-nova-bay">katabatic</a>” winds, which are cold gusts that blow downhill at night.</p>
<h2>Potential for space exploration</h2>
<p>This study comes at an interesting stage of space exploration.</p>
<p>For Mars, we have a relative abundance of observations; five space agencies are conducting active missions in orbit, or in situ. Studies such as ours help inform the objectives of these missions, and the paths taken by rovers such as <a href="https://www.youtube.com/watch?v=4czjS9h4Fpg">Perseverance</a> and <a href="https://theconversation.com/on-its-first-try-chinas-zhurong-rover-hit-a-mars-milestone-that-took-nasa-decades-161078">Zhurong</a>.</p>
<p>In the outer reaches of the Solar System, Triton has not been observed in detail since the NASA Voyager 2 flyby in 1989. There is currently a <a href="https://doi.org/10.3847/PSJ/abf654">mission proposal</a> which, if selected, would have a probe launched in 2031 to study Triton, before annihilating itself by flying into Neptune’s atmosphere.</p>
<p>Missions planned to Venus and Titan in the coming decade will revolutionise our understanding of these two. NASA’s <a href="https://www.nasa.gov/dragonfly/dragonfly-overview/index.html">Dragonfly</a> mission, slated to leave Earth in 2027 and arrive on Titan in 2034, will land an uncrewed helicopter on the moon’s dunes.</p>
<p>Pluto was observed during a 2015 <a href="https://www.youtube.com/watch?v=NEdvyrKokX4">flyby</a> by NASA’s ongoing New Horizons mission, but there are no plans to return.</p>
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<a href="https://theconversation.com/jupiter-saturn-uranus-neptune-why-our-next-visit-to-the-giant-planets-will-be-so-important-and-just-as-difficult-175918">Jupiter, Saturn, Uranus, Neptune: why our next visit to the giant planets will be so important (and just as difficult)</a>
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<img src="https://counter.theconversation.com/content/181241/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Andrew Gunn received funding from the National Aeronautics and Space Agency. </span></em></p>There are many bodies in the solar system we can’t easily access. But observations of their winds and sediments reveal a surprising amount.Andrew Gunn, Lecturer, Monash UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1463582020-09-18T11:50:53Z2020-09-18T11:50:53ZThe four most promising worlds for alien life in the solar system<figure><img src="https://images.theconversation.com/files/358659/original/file-20200917-14-1qdn4n4.jpg?ixlib=rb-1.1.0&rect=36%2C36%2C1238%2C782&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">NASA's Curiosity Rover takes a selfie on Mars in June, 2018.</span> <span class="attribution"><a class="source" href="https://www.jpl.nasa.gov/spaceimages/details.php?id=PIA22486">NASA/JPL-Caltech/MSSS</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span></figcaption></figure><p>The Earth’s biosphere contains all the known ingredients necessary for life as we know it. Broadly speaking these are: liquid water, at least one source of energy, and an inventory of biologically useful elements and molecules.</p>
<p>But the recent discovery of possibly biogenic phosphine <a href="https://theconversation.com/venus-could-it-really-harbour-life-new-study-springs-a-surprise-145981">in the clouds of Venus</a> reminds us that at least some of these ingredients exist elsewhere in the solar system too. So where are the other most promising locations for extra-terrestrial life?</p>
<h2>Mars</h2>
<p>Mars is one of the most Earth-like worlds in the solar system. It has a 24.5-hour day, polar ice caps that expand and contract with the seasons, and a large array of surface features that were sculpted by water during the planet’s history.</p>
<figure class="align-center ">
<img alt="Red planet Mars in space with polar ice caps visible" src="https://images.theconversation.com/files/358594/original/file-20200917-24-fwl0h9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/358594/original/file-20200917-24-fwl0h9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/358594/original/file-20200917-24-fwl0h9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/358594/original/file-20200917-24-fwl0h9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/358594/original/file-20200917-24-fwl0h9.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/358594/original/file-20200917-24-fwl0h9.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/358594/original/file-20200917-24-fwl0h9.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Mars has polar ice caps.</span>
<span class="attribution"><a class="source" href="https://upload.wikimedia.org/wikipedia/commons/0/02/OSIRIS_Mars_true_color.jpg">ESA & MPS for OSIRIS Team MPS/UPD/LAM/IAA/RSSD/INTA/UPM/DASP/IDA)</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
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</figure>
<p>The detection of <a href="https://www.sciencemag.org/news/2018/07/liquid-water-spied-deep-below-polar-ice-cap-mars">a lake beneath</a> the southern polar ice cap and methane in the Martian atmosphere (which varies with the seasons and even the <a href="https://agupubs.onlinelibrary.wiley.com/doi/abs/10.1029/2019GL083800">time of day</a>) make Mars a very interesting candidate for life. Methane is significant as it can be produced by biological processes. But the actual source for the methane on Mars is not yet known.</p>
<p>It is possible that life may have gained a foothold, given the <a href="https://advances.sciencemag.org/content/4/6/eaar3330">evidence</a> that the planet once had a much more benign environment. Today, Mars has a very thin, dry atmosphere comprised almost entirely of carbon dioxide. This offers scant protection from solar and cosmic radiation. If Mars has managed to retain some reserves of water beneath its surface, it is not impossible that life may still exist. </p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/life-on-mars-europe-commits-to-groundbreaking-mission-to-bring-back-rocks-to-earth-128328">Life on Mars? Europe commits to groundbreaking mission to bring back rocks to Earth</a>
</strong>
</em>
</p>
<hr>
<h2>Europa</h2>
<p>Europa was discovered by Galileo Galilei in 1610, along with Jupiter’s three other larger moons. It is slightly smaller than Earth’s moon and orbits the gas giant at a distance of some 670,000km once every 3.5 days. Europa is constantly squeezed and stretched by the competing gravitational fields of Jupiter and the other <a href="https://www.universetoday.com/44796/galilean-moons/">Galilean moons</a>, a process known as tidal flexing. </p>
<p>The moon is believed to be a geologically active world, like the Earth, because the strong tidal flexing heats its rocky, metallic interior and keeps it partially molten.</p>
<figure class="align-center ">
<img alt="Jupiter's white with brown streaks moon Europa in space," src="https://images.theconversation.com/files/358637/original/file-20200917-14-1hfzvc8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/358637/original/file-20200917-14-1hfzvc8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=444&fit=crop&dpr=1 600w, https://images.theconversation.com/files/358637/original/file-20200917-14-1hfzvc8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=444&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/358637/original/file-20200917-14-1hfzvc8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=444&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/358637/original/file-20200917-14-1hfzvc8.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=557&fit=crop&dpr=1 754w, https://images.theconversation.com/files/358637/original/file-20200917-14-1hfzvc8.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=557&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/358637/original/file-20200917-14-1hfzvc8.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=557&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Europa’s icy surface is a good sign for alien hunters.</span>
<span class="attribution"><a class="source" href="https://photojournal.jpl.nasa.gov/catalog/PIA19048">NASA/JPL-Caltech/SETI Institute</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>The surface of Europa is a vast expanse of water ice. Many scientists think that beneath the frozen surface is a layer of liquid water – a global ocean – which is prevented from freezing by the heat from flexing and which maybe over 100km deep. </p>
<p>Evidence for this ocean includes geysers erupting through <a href="https://www.nature.com/articles/s41550-019-0933-6">cracks in the surface ice</a>, a <a href="http://ffden-2.phys.uaf.edu/webproj/212_spring_2015/Justin_Long/Justin_Long/magnetic.html">weak magnetic field</a> and <a href="https://www.sciencedirect.com/science/article/abs/pii/S0019103599961870?via%3Dihub">chaotic terrain</a> on the surface, which could have been deformed by ocean currents swirling beneath. This icy shield insulates the subsurface ocean from the extreme cold and vacuum of space, as well as Jupiter’s ferocious radiation belts.</p>
<p>At the bottom of this ocean world it is conceivable that we might find <a href="https://oceanservice.noaa.gov/facts/vents.html">hydrothermal vents</a> and ocean floor volcanoes. On Earth, such features often support very rich and diverse ecosystems.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/europa-there-may-be-life-on-jupiters-moon-and-two-new-missions-will-pave-the-way-for-finding-it-122551">Europa: there may be life on Jupiter's moon and two new missions will pave the way for finding it</a>
</strong>
</em>
</p>
<hr>
<h2>Enceladus</h2>
<p>Like Europa, <a href="https://solarsystem.nasa.gov/moons/saturn-moons/enceladus/in-depth/">Enceladus</a> is an ice-covered moon with a subsurface ocean of liquid water. Enceladus orbits Saturn and first came to the attention of scientists as a potentially habitable world following the <a href="https://solarsystem.nasa.gov/resources/806/bursting-at-the-seams-the-geyser-basin-of-enceladus/">surprise discovery</a> of enormous geysers near the moon’s south pole.</p>
<p>These jets of water escape from large cracks on the surface and, given Enceladus’ weak gravitational field, spray out into space. They are clear evidence of an underground store of liquid water.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"906891543780323328"}"></div></p>
<p>Not only was water detected in these geysers but also an array of organic molecules and, crucially, tiny grains of rocky silicate particles that can only be present if the sub-surface ocean water was in physical contact with the rocky ocean floor at a <a href="https://solarsystem.nasa.gov/missions/cassini/science/enceladus/">temperature of at least 90˚C</a>. This is very strong evidence for the existence of hydrothermal vents on the ocean floor, providing the chemistry needed for life and localised sources of energy. </p>
<h2>Titan</h2>
<p>Titan is the largest moon of Saturn and the only moon in the solar system with a substantial atmosphere. It contains a thick orange haze of complex organic molecules and a methane weather system in place of water – complete with seasonal rains, dry periods and surface sand dunes created by wind.</p>
<figure class="align-center ">
<img alt="Yellow/orange moon Titan in space" src="https://images.theconversation.com/files/358645/original/file-20200917-16-17xgwya.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/358645/original/file-20200917-16-17xgwya.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/358645/original/file-20200917-16-17xgwya.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/358645/original/file-20200917-16-17xgwya.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/358645/original/file-20200917-16-17xgwya.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/358645/original/file-20200917-16-17xgwya.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/358645/original/file-20200917-16-17xgwya.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Titan’s atmosphere makes it look like a fuzzy orange ball.</span>
<span class="attribution"><a class="source" href="https://photojournal.jpl.nasa.gov/catalog/PIA14602">NASA/JPL-Caltech/Space Science Institute</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>The atmosphere consists mostly of nitrogen, an important chemical element used in the construction of proteins in all known forms of life. Radar observations have detected the presence of <a href="https://theconversation.com/titan-first-global-map-uncovers-secrets-of-a-potentially-habitable-moon-of-saturn-126985">rivers and lakes</a> of liquid methane and ethane and possibly the presence of cryovolcanoes – volcano-like features that erupt liquid water rather than lava. This suggests that Titan, like Europa and Enceladus, has a sub-surface reserve of liquid water.</p>
<p>At such an enormous distance from the Sun, the surface temperatures on Titan are a frigid -180˚C – way too cold for liquid water. However, the bountiful chemicals available on Titan has raised speculation that lifeforms – potentially with fundamentally different chemistry to terrestrial organisms – <a href="https://www.space.com/8547-strange-discovery-titan-leads-speculation-alien-life.html">could exist</a> there.</p><img src="https://counter.theconversation.com/content/146358/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Gareth Dorrian does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.</span></em></p>The clouds of Venus may harbour alien life. But where else?Gareth Dorrian, Post Doctoral Research Fellow in Space Science, University of BirminghamLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1269852019-11-20T15:02:44Z2019-11-20T15:02:44ZTitan: first global map uncovers secrets of a potentially habitable moon of Saturn<figure><img src="https://images.theconversation.com/files/302643/original/file-20191120-467-1jdql0z.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Titan imaged in the near infrared by the Cassini orbiter on November 13, 2015. </span> <span class="attribution"><span class="source">NASA/JPL/University of Arizona/University of Idaho</span></span></figcaption></figure><p>There are just three moons in our solar system that measure more than 5,000km across. Of these, Jupiter’s moons Ganymede and Callisto are airless and have ancient heavily cratered surfaces. But Saturn’s largest moon, Titan, abounds in landscapes that are eerily Earth-like – and it may even harbour life.</p>
<p>But we have had a rather limited view of what’s lurking beneath the thick atmosphere of this mysterious world. A new study, <a href="https://nature.com/articles/s41550-019-0917-6">published in Nature Astronomy</a>, however, unveils the first geomorphologic map to cover the whole of Titan. This is important because it shows how Titan’s various kinds of terrain relate to each other. </p>
<p>Despite the fact that Titan’s “bedrock” is ice, its surface is so cold (-180°C) that the ice is sufficiently strong and rigid to behave just like rock on Earth. Furthermore, Titan is the only moon with a dense atmosphere, having a surface pressure that is one and a half times that of Earth’s.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/302003/original/file-20191115-66941-10ciwu5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/302003/original/file-20191115-66941-10ciwu5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=207&fit=crop&dpr=1 600w, https://images.theconversation.com/files/302003/original/file-20191115-66941-10ciwu5.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=207&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/302003/original/file-20191115-66941-10ciwu5.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=207&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/302003/original/file-20191115-66941-10ciwu5.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=260&fit=crop&dpr=1 754w, https://images.theconversation.com/files/302003/original/file-20191115-66941-10ciwu5.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=260&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/302003/original/file-20191115-66941-10ciwu5.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=260&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Near-infrared image of Titan’s surface brightness.</span>
<span class="attribution"><a class="source" href="https://photojournal.jpl.nasa.gov/catalog/PIA22770">NASA/JPL-Caltech/Univ. Arizona</a></span>
</figcaption>
</figure>
<p>In common with Earth, by far the most abundant atmospheric gas on Titan is nitrogen. The moon’s second most abundant gas is methane, which makes Titan Earth-like in a different but very remarkable way. The gaseous methane can condense to form clouds from which droplets of liquid methane can fall like rain. Methane rainfall erodes the surface, carves out channels, and drains into depressions to form methane seas and lakes. Evaporation back into the atmosphere completes the cycle, so Titan has a methane cycle to match Earth’s <a href="https://en.m.wikipedia.org/wiki/Water_cycle">water cycle</a>.</p>
<p>Despite two Titan flybys by NASA’s Voyager probes in 1980 and 1981, we knew little about the moon’s surface until the <a href="https://theconversation.com/bittersweet-feeling-as-cassini-mission-embarks-on-its-grand-finale-ahead-of-death-plunge-76670">Cassini spacecraft</a> arrived to orbit Saturn between 2005 and 2017. This is because sunlight causes the molecules of methane high in Titan’s atmosphere to <a href="https://theconversation.com/saturns-moon-titan-may-harbour-simple-life-forms-and-reveal-how-organisms-first-formed-on-earth-81527">link into larger molecules</a>, making a high-altitude smog that the Voyager cameras could not see through. </p>
<p>But Cassini was equipped to cope with this, carrying an imaging radar system and near-infrared and thermal infrared cameras that could detect radiation reflected or emitted from the ground in specific wavelengths that the smog does little to obstruct. Cassini also sent a <a href="https://sci.esa.int/web/education/-/45751-the-huygens-probe-lands-on-titan">lander called Huygens</a> down to the surface by parachute, giving us unimpeded visual views from below the clouds – albeit of only a small area.</p>
<h2>A global map</h2>
<p>The most detailed images to inform the new geological map come from the radar. These cover slightly less than half the globe so, to achieve global coverage, other Cassini data had to be used to fill in the gaps. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/301732/original/file-20191114-26211-xlys2m.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/301732/original/file-20191114-26211-xlys2m.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/301732/original/file-20191114-26211-xlys2m.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=340&fit=crop&dpr=1 600w, https://images.theconversation.com/files/301732/original/file-20191114-26211-xlys2m.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=340&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/301732/original/file-20191114-26211-xlys2m.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=340&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/301732/original/file-20191114-26211-xlys2m.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=428&fit=crop&dpr=1 754w, https://images.theconversation.com/files/301732/original/file-20191114-26211-xlys2m.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=428&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/301732/original/file-20191114-26211-xlys2m.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=428&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Global map of Titan’s major geomorphologic units.</span>
<span class="attribution"><a class="source" href="https://www.nasa.gov/">NASA/JPL/ASU</a>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>Six major units are on the global map, depicted at a scale of 1:20 million. Plains make up 65% of the globe, these are smooth and dark, possibly because of smog-derived sooty particles on the ground. In a belt hugging the equator, the plains are overlaid by extensive fields of dunes (17% of the globe by area), sculpted by winds that blow from west to east. </p>
<p>These dunes are not sand grains made of quartz as they would be on Earth, nor grains of water ice, but particles made from organic molecules that presumably originated from the atmosphere in the same way as the dark colouring of the plains (derived from smog).</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/302014/original/file-20191115-66971-oxw5mm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/302014/original/file-20191115-66971-oxw5mm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/302014/original/file-20191115-66971-oxw5mm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/302014/original/file-20191115-66971-oxw5mm.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/302014/original/file-20191115-66971-oxw5mm.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/302014/original/file-20191115-66971-oxw5mm.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/302014/original/file-20191115-66971-oxw5mm.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/302014/original/file-20191115-66971-oxw5mm.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 400km wide area of Titan seen by imaging radar.</span>
<span class="attribution"><span class="source">NASA/JPL-Caltech/ASI</span></span>
</figcaption>
</figure>
<p>Exposed icy bedrock is apparent in places where neither plains nor dunes have covered it. This is divided into a “hummocky” unit (14% of the globe) characterised by hilly and mountainous ground. There are some branching valleys here (including some seen by the Huygens lander), but such valleys are more extensively developed in a unit named “labyrinth” (1.5% of the globe), which is perhaps ice mixed with organic material that has been more strongly cut by methane rivers.</p>
<p>Impact craters occupy just 0.4% of the globe, and there are only 23 that are more than 20km in diameter. Their scarcity attests to Titan’s active geology – erosion of high ground, burial under sediments, and possibly erasure by volcanism (spewing out ice instead of molten rock).</p>
<h2>Land of lakes</h2>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/301739/original/file-20191114-26217-r97f8r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/301739/original/file-20191114-26217-r97f8r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/301739/original/file-20191114-26217-r97f8r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=331&fit=crop&dpr=1 600w, https://images.theconversation.com/files/301739/original/file-20191114-26217-r97f8r.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=331&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/301739/original/file-20191114-26217-r97f8r.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=331&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/301739/original/file-20191114-26217-r97f8r.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=415&fit=crop&dpr=1 754w, https://images.theconversation.com/files/301739/original/file-20191114-26217-r97f8r.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=415&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/301739/original/file-20191114-26217-r97f8r.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=415&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Area within 35 degrees of each of Titan’s poles. There are many more lakes in the north than in the south.</span>
<span class="attribution"><span class="source">Lopes et al. (2019), nature</span></span>
</figcaption>
</figure>
<p>Titan’s polar regions contain over 650 lakes or seas covering 1.5% of the total surface area. Some are currently dry, but many are filled by liquid methane. Parts of the shoreline of the second largest lake, named Ligeia Mare, which is 400km across and up to 170 metres deep, have an odd shape suggesting that either the lake level has risen, or that parts of the land surface have sunk due to tectonic forces. Elsewhere, and on other lakes, there are shoreline features suggestive of wave action and river deltas.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/301748/original/file-20191114-26250-1xpzmeq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/301748/original/file-20191114-26250-1xpzmeq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/301748/original/file-20191114-26250-1xpzmeq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=543&fit=crop&dpr=1 600w, https://images.theconversation.com/files/301748/original/file-20191114-26250-1xpzmeq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=543&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/301748/original/file-20191114-26250-1xpzmeq.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=543&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/301748/original/file-20191114-26250-1xpzmeq.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=683&fit=crop&dpr=1 754w, https://images.theconversation.com/files/301748/original/file-20191114-26250-1xpzmeq.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=683&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/301748/original/file-20191114-26250-1xpzmeq.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=683&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Ligeia Mare with a shoreline symptomatic of a drowned landscape of river valleys.</span>
<span class="attribution"><span class="source">NASA/JPL-Caltech/ASI/Cornell</span></span>
</figcaption>
</figure>
<p>If Titan is home to any microbial life, this is much more likely to be in Titan’s <a href="https://phys.org/news/2019-07-habitability-titan-ocean.html">water ocean</a> deep in its interior, rather than at the surface. But understanding the distribution of landscapes documented in the global map is a vital step towards understanding the environments and history of this amazing world. </p>
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Read more:
<a href="https://theconversation.com/flying-on-saturns-moon-titan-what-we-could-discover-with-nasas-new-dragonfly-mission-119823">Flying on Saturn’s moon Titan: what we could discover with NASA's new Dragonfly mission</a>
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Read more:
<a href="https://theconversation.com/how-geological-maps-made-the-apollo-moon-landings-worthwhile-117539">How geological maps made the Apollo moon landings worthwhile</a>
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<img src="https://counter.theconversation.com/content/126985/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>David Rothery is co-leader of the European Space Agency's Mercury Surface and Composition Working Group, and a Co-Investigator on MIXS (Mercury Imaging X-ray Spectrometer) that is now on its way to Mercury on board the European Space Agency's Mercury orbiter BepiColombo. He has received funding from the UK Space Agency and the Science & Technology Facilities Council for work related to Mercury BepiColombo, and is currently funded by the European Commission under its Horizon 2020 programme for work on planetary geological mapping (776276 Planmap). He is author of Planet Mercury - from Pale Pink Dot to Dynamic World (Springer, 2015), Moons: A Very Short Introduction (Oxford University Press, 2015) and Planets: A Very Short Introduction (Oxford University Press, 2010). He is Educator on the Open University's free learning Badged Open Course (BOC) on Moons and its equivalent FutureLearn Moons MOOC, and chair of the Open University's level 2 course on Planetary Science and the Search for Life.</span></em></p>Saturn’s largest moon has been fully mapped for the first time.David Rothery, Professor of Planetary Geosciences, The Open UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1241632019-10-02T20:13:42Z2019-10-02T20:13:42ZWhat moons in other solar systems reveal about planets like Neptune and Jupiter<figure><img src="https://images.theconversation.com/files/295058/original/file-20191001-173407-17sejqu.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Exomoons orbiting an exoplanet outside our solar system.</span> <span class="attribution"><a class="source" href="https://www.shutterstock.com/image-illustration/beautiful-exoplanet-exomoons-orbiting-alien-binary-744849175?src=2ZJlWkTDSoIH0Tay3OeqBw-1-1">Dotted Yeti/Shutterstock.com</a></span></figcaption></figure><p>What is the difference between a planet-satellite system as we have with the Earth and Moon, versus a binary planet – two planets orbiting each other in a cosmic do-si-do?</p>
<p><a href="http://www.astro.ucla.edu/%7Ehansen">I am an astronomer</a> interested in planets orbiting nearby stars, and gas giants – Jupiter, Saturn, Uranus and Neptune in our solar system – are the largest and easiest planets to detect. The crushing pressure within their gassy atmosphere means they are unlikely to be hospitable to life. But the rocky moons orbiting such planets could have conditions that are more welcoming. Last year, astronomers discovered a planet-sized exomoon orbiting another gas giant planet outside our solar system.</p>
<p><a href="https://advances.sciencemag.org/content/5/10/eaaw8665">In a new paper</a>, I argue that this exomoon is really what is called a captured planet.</p>
<h2>Is the first detected ‘exomoon’ really a moon?</h2>
<p>True Earth analogues, that orbit Sun-like stars, are very hard to detect, even with the large <a href="http://keckobservatory.org">Keck telescopes</a>. The task is easier if the host star is less massive. But then the planet has to be closer to the star to be warm enough, and the star’s gravitational tides may trap the planet in a state with a permanent hot side and a permanent cold side. This makes such planets less attractive as a potential location that could harbor life. When gas giants orbiting Sun-like stars have rocky moons, these may be more likely places to find life.</p>
<p>In 2018, two astronomers from Columbia University reported the first tentative <a href="http://doi.org/10.1126/sciadv.aav1784">observation of an exomoon</a> – a satellite orbiting a planet that itself orbits another star. One curious feature was that this exomoon <a href="http://exoplanet.eu/catalog/kepler-1625_b_i/">Kepler-1625b-i</a> was much more massive than any moon found in our solar system. It has a mass similar to Neptune and orbits a planet similar in size to Jupiter. </p>
<p>Astronomers expect moons of planets like Jupiter and Saturn to have masses only a few percent of Earth. But this new exomoon was almost a thousand times larger than the corresponding bodies of our solar system – moons like Ganymede and Titan which orbit Jupiter and Saturn, respectively. It is very difficult to explain the formation of such a large satellite using current models of moon formation.</p>
<p>In a new model I developed, I discuss how <a href="https://advances.sciencemag.org/content/5/10/eaaw8665">such a massive exomoon</a> forms through a different process, wherein it is really a captured planet.</p>
<p>All planets, large and small, start by gathering together asteroid-sized bodies to make a rocky core. At this early stage in the evolution of a planetary system, the rocky cores are still surrounded by a gaseous disk left over from the formation of the parent star. If a core can grow fast enough to reach a mass equivalent to 10 Earths, then it will have the gravitational strength to pull gas in from the surrounding space and grow to the massive size of Jupiter and Saturn. However, this gaseous accumulation is short-lived, as the star is draining away most of the gas in the disk, the dust and gas surrounding a newly formed star.</p>
<p>If there are two cores growing in close proximity, then they compete to capture rock and gas. If one core gets slightly larger, it gains an advantage and can capture the bulk of the gas in the neighborhood for itself. This leaves the second body without any further gas to capture. The increased gravitational pull of its neighbor drags the smaller body into the role of a satellite, albeit a very large one. The former planet is left as a super-sized moon, orbiting the planet that beat it out in the race to capture gas.</p>
<h2>A remnant core as a look back into history</h2>
<p>Viewed in this context, the captured planet is unlikely to be habitable. Growing planetary cores have gaseous envelopes, which make them more like Uranus and Neptune – a mix of rocks, ice and gas that would have become a Jupiter if it had not been so rudely cut off by its larger neighbor. </p>
<p>However, there are other implications that are almost as interesting. Studying the cores of giant planets is very difficult, because they are buried under several hundred Earth masses of hydrogen and helium. Currently, the <a href="https://www.nasa.gov/mission_pages/juno/main/index.html">JUNO mission</a> is attempting to do this for Jupiter. However, studying the properties of this exomoon may enable astronomers to see the naked core of a giant gaseous planet when it is stripped of its gaseous envelope. This can provide a snapshot of what Jupiter may have looked like before it grew to its current enormous size.</p>
<p>This exomoon system Kepler-1625b-i is right at the edge of what is detectable with current technology. There may be many more objects like this that could be uncovered with future improvements in telescope capabilities. As astronomers’ census of exoplanets continues to grow, systems like the exomoon and its host highlight an issue that will become more important as we go forward. This exomoon reveals that the properties of a planet are not solely a consequence of its mass and position, but can depend on its history and the environment in which it formed. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/295064/original/file-20191001-173358-h4rsv6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/295064/original/file-20191001-173358-h4rsv6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=474&fit=crop&dpr=1 600w, https://images.theconversation.com/files/295064/original/file-20191001-173358-h4rsv6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=474&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/295064/original/file-20191001-173358-h4rsv6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=474&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/295064/original/file-20191001-173358-h4rsv6.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=596&fit=crop&dpr=1 754w, https://images.theconversation.com/files/295064/original/file-20191001-173358-h4rsv6.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=596&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/295064/original/file-20191001-173358-h4rsv6.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=596&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="caption">Exomoons may reveal secrets about how gas giants like Jupiter formed and what is in their core.</span>
<span class="attribution"><a class="source" href="https://www.jpl.nasa.gov/news/press_kits/juno/science/">JPL/NASA</a></span>
</figcaption>
</figure><img src="https://counter.theconversation.com/content/124163/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Bradley Hansen 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>A giant exomoon hundreds of times the size of Earth is revealing secrets about how giant planets like Jupiter and Saturn formed. They might also help astronomers find planets where life may thrive.Bradley Hansen, Professor of Physics and Astronomy, University of California, Los AngelesLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1198232019-07-04T09:26:01Z2019-07-04T09:26:01ZFlying on Saturn’s moon Titan: what we could discover with NASA’s new Dragonfly mission<figure><img src="https://images.theconversation.com/files/282485/original/file-20190703-126340-166nr0f.png?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Artist's impression of the Dragonfly landing.</span> <span class="attribution"><span class="source">NASA</span></span></figcaption></figure><p>Flying on other worlds is the next leap in the exploration of our solar system. The <a href="https://www.nasa.gov/press-release/mars-helicopter-to-fly-on-nasa-s-next-red-planet-rover-mission/">Mars Helicopter</a> will piggyback on the <a href="https://mars.nasa.gov/mars2020/">NASA Mars 2020 rover mission</a> to demonstrate the technology. But this is only the start. The real prize will be the Dragonfly mission in 2026, sending a drone to Saturn’s largest moon, Titan – <a href="https://www.nasa.gov/press-release/nasas-dragonfly-will-fly-around-titan-looking-for-origins-signs-of-life/">as just announced by NASA</a>.</p>
<p>For a craft to become airborne, it needs air or, more generally, an atmosphere. Only a handful of objects in our solar system fit that bill. Titan boasts an atmosphere thicker than Earth’s, which has shrouded this world in mystery for a long time. Studies have shown Titan may be able to <a href="https://theconversation.com/saturns-moon-titan-may-harbour-simple-life-forms-and-reveal-how-organisms-first-formed-on-earth-81527">host primitive lifeforms</a> and is the ideal place to study how life may have arisen on our own planet.</p>
<p>Titan is the second largest moon in the solar system behind Jupiter’s <a href="https://solarsystem.nasa.gov/moons/jupiter-moons/ganymede/in-depth/">Ganymede</a>. In fact, Titan’s diameter of 5,149km is larger than the planet Mercury’s at 4,880km. Its atmosphere consists mainly of nitrogen (96%), similar to Earth’s atmosphere (80% nitrogen, the rest being oxygen and less than 1% of other trace gases). The <a href="https://theconversation.com/bittersweet-feeling-as-cassini-mission-embarks-on-its-grand-finale-ahead-of-death-plunge-76670">Cassini spacecraft</a> orbited Saturn from 2004 until 2017 and was the first to use radar and other instruments to peer underneath Titan’s clouds during numerous flybys. </p>
<p>The <a href="https://solarsystem.nasa.gov/missions/cassini/mission/spacecraft/huygens-probe/">Huygens probe</a> touched down on Titan’s surface in 2005. It revealed that Titan is the only world in our solar system other than Earth with a currently active hydrological cycle – complete with rain, rivers and lakes, some of them more than 100 metres deep. The only difference is that it is not water raining from the clouds.</p>
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<img alt="" src="https://images.theconversation.com/files/282655/original/file-20190704-51312-khs2y3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/282655/original/file-20190704-51312-khs2y3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/282655/original/file-20190704-51312-khs2y3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/282655/original/file-20190704-51312-khs2y3.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/282655/original/file-20190704-51312-khs2y3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/282655/original/file-20190704-51312-khs2y3.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/282655/original/file-20190704-51312-khs2y3.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">
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<span class="caption">Titan imaged by Cassini.</span>
<span class="attribution"><span class="source">NASA/JPL-Caltech/Univ. Arizona/Univ. Idaho</span></span>
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</figure>
<p>Because Saturn and its moons are about ten times further from the sun than the Earth, temperatures there are so low (-179°C on average) that water is frozen solid at all times and behaves like rocks on Earth. Instead, hydrocarbons such as methane, a gas at temperatures typical for Earth, condense into a liquid that fills the lakes. Other complex organic (meaning carbon-based) molecules form in Titan’s atmosphere and fall like snow. This snow is then rearranged into dunes by wind.</p>
<p>The Dragonfly mission will land in 2034 in the relative safety of one of those dune fields called Shangri-La. From there, it will fly to different locations to investigate the nature of the organic material. One important aspect of the mission is to shed light on the processes that led to the origin of life on Earth. We know that macromolecules such as DNA and proteins formed from simpler organic molecules such as amino acids. But we haven’t pinned down the exact intermediate steps in this process – something that we may be able to observe on Titan. </p>
<h2>Current life?</h2>
<p>With all these building blocks around, there is speculation about whether life – for example, in the form of microorganisms – could exist on Titan. But how likely is this? It is thought that life at the very basic level needs at least three ingredients: liquid water, a carbon source and an energy source.</p>
<p>Though there is plenty of carbon around on Titan, the cold temperatures keep water in its solid form as ice and also limit the energy available. However, liquid water may exist below the frozen surface. We also know that water plumes erupting from neighbouring moon Enceladus do rain down onto Titan’s upper atmosphere, <a href="https://theconversation.com/saturns-moon-titan-may-harbour-simple-life-forms-and-reveal-how-organisms-first-formed-on-earth-81527">providing a key source of oxygen</a>.</p>
<p>There are many forms of microorganism that can live under extreme conditions on Earth – <a href="https://oceanservice.noaa.gov/facts/extremophile.html">so-called extremophiles</a>. But even among those, basic life functions seize at temperatures below -20°C. So for life to exist on Titan, we would need to stretch the envelope of suitable conditions we know from Earth quite far. But then again, life on Earth is the only example we know of to date and we may be limited in our imagination. Even if it looks only like a remote possibility, the Dragonfly mission will properly assess the habitability of Titan and look out for signs of potential life, past or present.</p>
<p>A compelling target to address both how life arose on Earth and whether it currently exists is the 80km diameter <a href="http://titancraters.blogspot.com/2016/01/selk.html">Selk impact crater</a>, which is one of the flight destinations. Here, the impact that created it in relatively recent times on the geological timescale melted water ice and provided energy in the form of heat to allow such reactions to take place.</p>
<p>Flying a drone on Titan promises to be an out-of-this-world experience that also takes us back in time!</p><img src="https://counter.theconversation.com/content/119823/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Christian Schroeder 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>Titan may host primitive lifeforms and could tell us how life arose on our own planet.Christian Schroeder, Senior Lecturer in Environmental Science and Planetary Exploration, University of StirlingLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/1001622018-07-20T07:25:21Z2018-07-20T07:25:21ZCapturing the shadow of Saturn’s moon Titan from right here on Earth<figure><img src="https://images.theconversation.com/files/228551/original/file-20180720-142423-5iics4.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">NASA's Cassini spacecraft captures Saturn's largest moon, Titan, passes in front of the planet and its rings.</span> <span class="attribution"><a class="source" href="https://saturn.jpl.nasa.gov/resources/5441/titan-up-front/">NASA/JPL-Caltech/Space Science Institute</a></span></figcaption></figure><p><a href="https://solarsystem.nasa.gov/moons/saturn-moons/titan/overview/">Titan</a> is <a href="https://solarsystem.nasa.gov/planets/saturn/overview/">Saturn</a>’s largest moon, and it is more like a planet than a moon in many respects.</p>
<p>It has a thick atmosphere as well as wind, rivers, lakes made of hydrocarbons such as methane, and a liquid water ocean. Understanding its atmosphere may help us in the search for life on other planets.</p>
<p>Hence the excitement this July when a rare opportunity was available to further study Titan, from right here on Earth. On July 18 at 11:05pm (WAST, Western Australian time) Titan passed in front of a faint star, as seen by observers across most of Australia.</p>
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Read more:
<a href="https://theconversation.com/the-secrets-of-titan-cassini-searched-for-the-building-blocks-of-life-on-saturns-largest-moon-83441">The secrets of Titan: Cassini searched for the building blocks of life on Saturn's largest moon</a>
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<p>This event, known as an <a href="https://www.space.com/33946-occultations.html">occultation</a>, lasted only a few minutes and about 2% of the star’s light was blocked by Titan’s atmosphere.</p>
<p>The effect was so small it required large telescopes and a special camera to record it. But the data gathered should have profound implications for our understanding of an atmosphere on another world.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/228381/original/file-20180719-142423-dk5z13.png?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/228381/original/file-20180719-142423-dk5z13.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/228381/original/file-20180719-142423-dk5z13.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=405&fit=crop&dpr=1 600w, https://images.theconversation.com/files/228381/original/file-20180719-142423-dk5z13.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=405&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/228381/original/file-20180719-142423-dk5z13.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=405&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/228381/original/file-20180719-142423-dk5z13.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=509&fit=crop&dpr=1 754w, https://images.theconversation.com/files/228381/original/file-20180719-142423-dk5z13.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=509&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/228381/original/file-20180719-142423-dk5z13.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=509&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">Saturn’s moon Titan compared (by diameter) to the Earth and its Moon.</span>
<span class="attribution"><a class="source" href="https://commons.wikimedia.org/wiki/File:Titan,_Earth_%26_Moon_size_comparison.jpg">Wikimedia/The Conversation</a></span>
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<h2>Examining Titan’s atmosphere</h2>
<p>Scientists have developed a very clever technique to examine Titan’s atmosphere using stellar occultations. As Titan enters and exits an occultation, the star’s light would illuminate the atmosphere from behind, but be blocked by the moon itself. </p>
<p>Scientists then record subtle changes in brightness of the star over a few minutes, which represents a profile of the atmosphere’s density with height. </p>
<p>This method was used to study Titan’s atmosphere before, during a stellar occultation in 2003.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/228150/original/file-20180718-142405-1mq54j.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/228150/original/file-20180718-142405-1mq54j.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/228150/original/file-20180718-142405-1mq54j.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=417&fit=crop&dpr=1 600w, https://images.theconversation.com/files/228150/original/file-20180718-142405-1mq54j.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=417&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/228150/original/file-20180718-142405-1mq54j.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=417&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/228150/original/file-20180718-142405-1mq54j.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=524&fit=crop&dpr=1 754w, https://images.theconversation.com/files/228150/original/file-20180718-142405-1mq54j.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=524&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/228150/original/file-20180718-142405-1mq54j.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=524&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Artist’s concept of Cassini’s June 4, 2010, flyby of Saturn’s moon Titan.</span>
<span class="attribution"><a class="source" href="https://www.jpl.nasa.gov/news/news.php?feature=2625">NASA/JPL</a></span>
</figcaption>
</figure>
<p>But in 2005, when <a href="https://saturn.jpl.nasa.gov/">Cassini’s</a> Huygens lander arrived at Titan and descended to its surface, the atmospheric profile measured from its instruments did not match that derived from the 2003 occultation. This fuelled the question of how variable is the state of Titan’s atmosphere.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/228164/original/file-20180718-142417-1hgve61.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/228164/original/file-20180718-142417-1hgve61.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/228164/original/file-20180718-142417-1hgve61.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=765&fit=crop&dpr=1 600w, https://images.theconversation.com/files/228164/original/file-20180718-142417-1hgve61.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=765&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/228164/original/file-20180718-142417-1hgve61.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=765&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/228164/original/file-20180718-142417-1hgve61.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=961&fit=crop&dpr=1 754w, https://images.theconversation.com/files/228164/original/file-20180718-142417-1hgve61.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=961&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/228164/original/file-20180718-142417-1hgve61.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=961&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Composite of Titans surface taken by Huygens at different heights.</span>
<span class="attribution"><span class="source">ESA/NASA/JPL/University of Arizona</span></span>
</figcaption>
</figure>
<p>Since the Cassini mission ended in 2017, NASA’s Karsten Schindler said there was keen interest in any new atmospheric observations from occultations:</p>
<blockquote>
<p>Occultations remain the only means to study Titan’s upper atmosphere and its evolution for the foreseeable future.</p>
</blockquote>
<h2>Countdown to the July occultation</h2>
<p>So how were the latest observations made, and how was the data gathered?</p>
<p>From the air, the plan was for the July 18 occultation to be recorded by a camera mounted on a telescope of the Stratospheric Observatory of Infrared Astronomy <a href="https://www.nasa.gov/mission_pages/SOFIA/index.html">(SOFIA)</a> on board a Boeing 747 aircraft.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/228145/original/file-20180718-142435-pzv82d.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/228145/original/file-20180718-142435-pzv82d.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/228145/original/file-20180718-142435-pzv82d.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=347&fit=crop&dpr=1 600w, https://images.theconversation.com/files/228145/original/file-20180718-142435-pzv82d.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=347&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/228145/original/file-20180718-142435-pzv82d.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=347&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/228145/original/file-20180718-142435-pzv82d.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=436&fit=crop&dpr=1 754w, https://images.theconversation.com/files/228145/original/file-20180718-142435-pzv82d.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=436&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/228145/original/file-20180718-142435-pzv82d.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=436&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">SOFIA takes off from Christchurch International Airport in 2017.</span>
<span class="attribution"><span class="source">SOFIA/ Waynne Williams</span></span>
</figcaption>
</figure>
<p>That’s right: a telescope mounted inside a modified passenger plane imaging an object more than 1 billion kilometres away! SOFIA would fly above the clouds between Australia and New Zealand.</p>
<p>From the ground, several facilities across Australia were to attempt to record the occultation.</p>
<p>The University of Western Australia’s <a href="http://www.zt.ems.uwa.edu.au/">Zadko Telescope</a>, located about 80km north of Perth (see map, below), was identified by NASA as a ground facility sensitive enough to contribute to the project. </p>
<iframe src="https://www.google.com/maps/embed?pb=!1m14!1m12!1m3!1d2388.822095869977!2d115.71176221504176!3d-31.356613427959715!2m3!1f0!2f0!3f0!3m2!1i1024!2i768!4f13.1!5e1!3m2!1sen!2sau!4v1532067433110" width="100%" height="500" frameborder="0" style="border:0" allowfullscreen=""></iframe>
<p>The most obvious deal breaker was the weather. July is one of the wettest months at the Zadko telescope site. But, as we found out, there were other unforseen challenges. </p>
<h2>Three days to occultation</h2>
<p>NASA’s Karsten Schindler arrived at the UWA research site, at Gingin, on Monday July 16, armed with a case filled with delicate cameras, cables and electronics.</p>
<p>The camera was the key to record the event. The current Zadko telescope camera cannot record fast enough to capture the rapid changes in brightness of the occulted star. </p>
<p>The Zadko Telescope was fitted out with a fast shooting (a frame every few seconds), NASA camera, more like a movie camera than a standard astronomical camera. After hours of installation, the new imaging system needed to be tested.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/228387/original/file-20180719-142420-f10uxn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/228387/original/file-20180719-142420-f10uxn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/228387/original/file-20180719-142420-f10uxn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=450&fit=crop&dpr=1 600w, https://images.theconversation.com/files/228387/original/file-20180719-142420-f10uxn.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=450&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/228387/original/file-20180719-142420-f10uxn.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=450&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/228387/original/file-20180719-142420-f10uxn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=566&fit=crop&dpr=1 754w, https://images.theconversation.com/files/228387/original/file-20180719-142420-f10uxn.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=566&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/228387/original/file-20180719-142420-f10uxn.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">Ground occultation team: John Kennwell, Arie Verveer, Karsten Schindler with the Zadko Telescope in the background.</span>
</figcaption>
</figure>
<p>Unfortunately, the observatory roof would not open because of a faulty sensor. No Monday test, but hey, we still had Tuesday to test the system? Onsite engineers scrambled to fix the sensor ready for Tuesday.</p>
<h2>Two days to occultation</h2>
<p>On Tuesday, I received the following text message from the site.</p>
<blockquote>
<p>11:07pm: Rain sensor working but clouded out … cheers Arie. So no chance testing the camera and weather forecast for Wednesday was bleak.</p>
</blockquote>
<h2>The day of occultation</h2>
<p>Despite the cloud and nearly constant rain showers, team occulation (Karsten, Arie and John) were on site ready to start pointing the telescope and activate the imaging. </p>
<p>“Up to 10pm it was still raining,” Karsten told me the next morning. “Then a miracle happened.”</p>
<p>Less than an hour before the event, and he said the weather changed.</p>
<p>“The clouds seemed to vaporise away, leaving a totally cloudless sky with 100% visibility. I have never seen anything like it.” </p>
<p>The team swung into action, pointing the telescope at the target star, focusing the camera. At the designated occulation time 11:05pm, Karsten hit the image acquisition button, enabling the camera to take hundreds of images over a few minutes.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/what-cassinis-mission-revealed-about-saturns-known-and-newly-discovered-moons-83430">What Cassini's mission revealed about Saturn's known and newly discovered moons</a>
</strong>
</em>
</p>
<hr>
<p>Eager to see if the data contained the signature of an occulation, the team performed a preliminary analysis within minutes. Yes, there was a clear occulation signature, a big dip in the brightness of the star at exactly the predicted time of the occulation.</p>
<p>Next morning I was informed that SOFIA had also captured the event. </p>
<p>The data recorded from the Australian ground stations and by SOFIA will be analysed over the coming weeks and published in peer reviewed journals.</p>
<p>But one thing the journals won’t highlight is the excitement of the observation, and the enormous effort by a few individuals who helped acquire this data that should hopefully give us a better understanding of the atmosphere of Titan.</p><img src="https://counter.theconversation.com/content/100162/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>David Coward receives funding from the Australian Research Council Center of Excellence: OzGrav CE170100004
</span></em></p>Titan is more than a billion kilometres from our Sun but occasionally it’s shadow can be seen here on Earth, with the right technology. That’s what scientists gathered in Western Australia to observe.David Coward, Associate professor, The University of Western AustraliaLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/840162017-09-15T12:01:07Z2017-09-15T12:01:07ZCassini crashes: it’s time for a new mission to explore the possibility of life on Saturn’s moons<figure><img src="https://images.theconversation.com/files/186100/original/file-20170914-21553-12tp9ok.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Cassini in front of The Lord of the Rings.</span> <span class="attribution"><span class="source">NASA</span></span></figcaption></figure><p>NASA’s Cassini mission has made its “<a href="https://theconversation.com/mission-over-the-final-countdown-to-cassinis-fatal-plunge-into-saturn-83873">death plunge</a>” into the swirling clouds of Saturn after 20 years of exploring the planet and its moons. It’s been amazingly successful, making headlines with groundbreaking discoveries throughout its journey. But today the headlines are more like obituary notices, looking back at the mission’s <a href="https://theconversation.com/a-look-back-at-cassinis-incredible-mission-to-saturn-before-its-final-plunge-into-the-planet-83226">spectacular achievements</a>. </p>
<p>Cassini discovered <a href="https://theconversation.com/what-cassinis-mission-revealed-about-saturns-known-and-newly-discovered-moons-83430">new moons</a> around Saturn, found evidence for <a href="https://theconversation.com/the-chemistry-that-could-feed-life-within-saturns-moon-enceladus-study-gives-clue-ahead-of-flyby-49683">an ocean below the surface</a> of the moon Enceladus and even managed to land a probe on the satellite Titan (the Huygens probe). It also observed <a href="https://theconversation.com/the-beauty-and-mystery-of-saturns-rings-revealed-by-the-cassini-mission-83492">unusual features in the rings</a> of the planet and recorded an enormous, hurricane-like storm whirling around its north pole. Surely, we must now know everything about Saturn and its moons?</p>
<p>Fortunately, scientists are never satisfied, and the answer to one question usually leads to at least three new questions. The discoveries from Cassini and Huygens have resulted in a whole series of issues that require further investigation. Two of the main targets for future exploration are Titan and Enceladus.</p>
<h2>Signs of life</h2>
<p>Before Huygens <a href="https://www.nasa.gov/content/ten-years-ago-huygens-probe-lands-on-surface-of-titan">parachuted down onto Titan’s surface</a> in January 2005, all we knew about the moon was that it was cold (about 100K or -173.15°C) and had a thick atmosphere (mostly of nitrogen, but with traces of methane), which prevented us from seeing the surface. Huygens revealed networks of valleys and rivers cutting through hills to the shoreline of an inland sea. Subsequent observations by instruments on-board Cassini have given us a greatly expanded understanding of Titan’s landscape – with an entire <a href="https://planetarynames.wr.usgs.gov/Page/TITAN/target">gazetteer of named features</a>, from mountains to plains and oceans to ponds.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/186171/original/file-20170915-8093-wh4z8g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/186171/original/file-20170915-8093-wh4z8g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=255&fit=crop&dpr=1 600w, https://images.theconversation.com/files/186171/original/file-20170915-8093-wh4z8g.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=255&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/186171/original/file-20170915-8093-wh4z8g.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=255&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/186171/original/file-20170915-8093-wh4z8g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=321&fit=crop&dpr=1 754w, https://images.theconversation.com/files/186171/original/file-20170915-8093-wh4z8g.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=321&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/186171/original/file-20170915-8093-wh4z8g.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=321&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Titan.</span>
<span class="attribution"><span class="source">Imsofinite</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>We must now try to understand what they are, how they formed and how they change with the seasons. We need to learn about tides and ocean icebergs, to define a climate cycle and to determine the composition of the land masses – are they derived from basalt, the most common rock type in the solar system, or are they frozen ice and mud? Does Titan have a rocky core overlain directly by an icy mantle, or does it have an ocean below the surface? If so, is it made up of water? </p>
<p>This all matters because what we have learnt about Titan from Cassini and Huygens has confirmed that <a href="https://theconversation.com/saturns-moon-titan-may-harbour-simple-life-forms-and-reveal-how-organisms-first-formed-on-earth-81527">it has an active chemistry</a>, based on methane and ammonia. We know that these substances, when irradiated by the sun, result in interesting mixes of chemicals that are precursors to amino acids and other biologically important molecules. The freezing temperature of Titan’s surface precludes anything being alive – but how far below the surface do you have to go before the environment becomes sufficiently balmy for a cryophile to be comfortable? Without a dedicated mission to Titan, we will not find out.</p>
<p>Cassini’s exploration of Titan was always one of the main goals of the mission, with a few larger moons also scheduled for observation. But early in the mission, it became clear that Enceladus should be a prime target too. Anomalies in data observed as the spacecraft flew past Enceladus were subsequently verified as resulting from a <a href="http://www.igpp.ucla.edu/public/journal-club/2008.09-12.(Sep-Dec).Journal.Club.Papers/2008.10.29.Journal.Club.Papers/additional.reference.papers.for.Friday.seminar.Oct.31.2008/Dougherty.et.al.Science.2006.Identification%20of%20a%20Dynamic%20Atmosphere%20at%20Enceladus%20with%20the%20Cassini%20Magnetometer.1406.pdf">large plume of gas and dust</a> venting from the surface close to the south pole. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/186174/original/file-20170915-8065-t6lbre.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/186174/original/file-20170915-8065-t6lbre.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=371&fit=crop&dpr=1 600w, https://images.theconversation.com/files/186174/original/file-20170915-8065-t6lbre.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=371&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/186174/original/file-20170915-8065-t6lbre.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=371&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/186174/original/file-20170915-8065-t6lbre.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=466&fit=crop&dpr=1 754w, https://images.theconversation.com/files/186174/original/file-20170915-8065-t6lbre.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=466&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/186174/original/file-20170915-8065-t6lbre.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=466&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Plumes on Enceladus.</span>
<span class="attribution"><span class="source">NASA</span></span>
</figcaption>
</figure>
<p>This was further investigated by Cassini, flying past Enceladus at different altitudes – the closest of which was at 25km. The data it collected helped scientists resolve the plume into a series of vents through cracks in the surface. It became clear that, like <a href="https://theconversation.com/new-water-plumes-from-jupiters-moon-europa-raise-hopes-of-detecting-microbial-life-66019">Jupiter’s icy moon Europa</a>, Enceladus was home to an ocean below the icy crust. </p>
<p>Scientists also managed to identify <a href="https://theconversation.com/icy-plumes-bursting-from-saturns-moon-enceladus-suggest-it-could-harbour-life-38673">grains of dust</a>, water-rich ice and gases including methane, ammonia and carbon dioxide – plus traces of other <a href="https://theconversation.com/the-chemistry-that-could-feed-life-within-saturns-moon-enceladus-study-gives-clue-ahead-of-flyby-49683">organic molecules</a> – in the plume. This lead to to much speculation about the possibility of life in the ocean. </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/186173/original/file-20170915-8125-yrxu74.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/186173/original/file-20170915-8125-yrxu74.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/186173/original/file-20170915-8125-yrxu74.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/186173/original/file-20170915-8125-yrxu74.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/186173/original/file-20170915-8125-yrxu74.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/186173/original/file-20170915-8125-yrxu74.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/186173/original/file-20170915-8125-yrxu74.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">Enceladus.</span>
<span class="attribution"><span class="source">NASA</span></span>
</figcaption>
</figure>
<p>Like Titan, Enceladus is now recognised as one of the solar system’s most likely locations for extraterrestrial life. A recent report of <a href="http://science.sciencemag.org/content/356/6334/155">hydrogen in Enceladus’ plume</a> has given that recognition even greater prominence. That’s because hydrogen is expected to be released as a byproduct of reactions between water and rock. Scientists believe that ocean water on Enceladus collides with rock, becomes heated, reacts chemically and rises up in the ocean via “hydrothermal vents”. That happens in the Earth’s oceans, too. And here, the chemically charged water around these vents supports a rich ecology of microbes and other life forms.</p>
<h2>A single mission?</h2>
<p>Follow-up missions to Saturn, Titan and Enceladus have all been proposed to both the European Space Agency and NASA, but none has yet been accepted and taken forward to the planning stage.</p>
<p>There might be a case for combining a mission to Titan with a mission to Enceladus to investigate the opportunities for life close to Saturn. I am not sure what such a mission would look like. Certainly there should be a spacecraft orbiting Titan and Enceladus, to gather additional information prior to launching vessels to the surface of both moons. Would these vessels be “penetrators” so they could pierce the ice of Enceladus? Or should they be balloons to float down through the atmosphere of Titan? I don’t know, but a possible name for the mission could be EnTiRE – Enceladus and Titan Research and Exploration. You heard it here first…</p>
<p>Of course, one should not forget the “Lord of the Rings” itself. There are still many unknown aspects of the giant planet that would be worth going back to investigate, such as the composition and formation of its unusual rings. And what about that huge, hexagonal-shaped hurricane at the north pole? Is there something comparable at the south pole? How do such weather systems form – and, more to the point, given the <a href="https://theconversation.com/hurricanes-may-be-getting-more-severe-do-we-need-a-whole-new-category-to-describe-them-83782">current catastrophic hurricanes</a> experienced recently on Earth, can we learn anything from Saturn about our own atmospheric disturbances? </p>
<p>Given the timescale for mission planning, alongside the time it takes to get to the Saturnian system, it will realistically be at least another 20 years before Cassini’s successor arrives. Until then, we will have to rely on the next generation of Earth-based telescopes to help us explore Saturn and its fascinating satellites.</p><img src="https://counter.theconversation.com/content/84016/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Monica Grady receives funding from the STFC. She is a Fellow of the Natural History Museum and a Trustee of Lunar Mission One.</span></em></p>As Cassini’s titanic mission comes to an end, we need to start thinking ahead. A combined mission to explore Saturn’s moons Titan and Enceladus would be a good place to start.Monica Grady, Professor of Planetary and Space Sciences, The Open UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/834412017-09-13T05:03:41Z2017-09-13T05:03:41ZThe secrets of Titan: Cassini searched for the building blocks of life on Saturn’s largest moon<figure><img src="https://images.theconversation.com/files/185043/original/file-20170907-8405-bovg44.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Cassini captures Saturn's largest moon, Titan.</span> <span class="attribution"><a class="source" href="https://saturn.jpl.nasa.gov/resources/5631/">NASA/JPL-Caltech/SSI</a></span></figcaption></figure><p>Lakes and seas of liquid methane, rain from hydrocarbon clouds, and evidence of poisonous hydrogen cyanide in the atmosphere of Titan were just some of the discoveries the Cassini probe made of Saturns’s largest moon.</p>
<p>The space probe has now made its final pass of Titan as it heads towards its grand finale plunge into the ringed planet later this week.</p>
<p>Dubbed Cassini’s “<a href="https://saturn.jpl.nasa.gov/mission/grand-finale/cassini-end-of-mission-timeline/">goodbye kiss</a>” by NASA, Titan has been the subject of much scrutiny by the probe, with <a href="https://saturn.jpl.nasa.gov/mission/grand-finale/cassini-quick-facts/">127 flybys</a> on its 13-year mission exploring the planetary system. </p>
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<em>
<strong>
Read more:
<a href="https://theconversation.com/a-look-back-at-cassinis-incredible-mission-to-saturn-before-its-final-plunge-into-the-planet-83226">A look back at Cassini's incredible mission to Saturn before its final plunge into the planet</a>
</strong>
</em>
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<p>One of Cassini’s greatest feats is its contribution to untangling the complicated chemistry of Titan, no doubt one of the more chemically diverse objects in our Solar System. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/185044/original/file-20170907-8366-117iuxa.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/185044/original/file-20170907-8366-117iuxa.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/185044/original/file-20170907-8366-117iuxa.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=321&fit=crop&dpr=1 600w, https://images.theconversation.com/files/185044/original/file-20170907-8366-117iuxa.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=321&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/185044/original/file-20170907-8366-117iuxa.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=321&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/185044/original/file-20170907-8366-117iuxa.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=403&fit=crop&dpr=1 754w, https://images.theconversation.com/files/185044/original/file-20170907-8366-117iuxa.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=403&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/185044/original/file-20170907-8366-117iuxa.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=403&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">One last look at Titan on Cassni’s final journey.</span>
<span class="attribution"><a class="source" href="https://saturn.jpl.nasa.gov/resources/7756/">NASA/JPL-Caltech</a></span>
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</figure>
<p>We have known for some time that the combination of ultraviolet rays from the Sun and particle bombardment has altered the mainly nitrogen and methane atmosphere over time.</p>
<p>This chemistry has sustained a thick, orange smog layer surrounding the entire body, shrouding Titan’s oceans and landscape from view prior to Cassini’s arrival.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/185045/original/file-20170907-9189-j35vvb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/185045/original/file-20170907-9189-j35vvb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/185045/original/file-20170907-9189-j35vvb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=602&fit=crop&dpr=1 600w, https://images.theconversation.com/files/185045/original/file-20170907-9189-j35vvb.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=602&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/185045/original/file-20170907-9189-j35vvb.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=602&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/185045/original/file-20170907-9189-j35vvb.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=756&fit=crop&dpr=1 754w, https://images.theconversation.com/files/185045/original/file-20170907-9189-j35vvb.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=756&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/185045/original/file-20170907-9189-j35vvb.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=756&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 murky orange disk of Saturn’s moon Titan.</span>
<span class="attribution"><a class="source" href="https://saturn.jpl.nasa.gov/resources/3797/">NASA/JPL/Space Science Institute</a></span>
</figcaption>
</figure>
<h2>Probing Titan</h2>
<p>With Cassini’s <a href="https://saturn.jpl.nasa.gov/the-journey/the-spacecraft/">toolkit of advanced sensing instruments</a> – combined with atmospheric sampling by the <a href="https://saturn.jpl.nasa.gov/mission/spacecraft/huygens-probe/">Huygens probe</a> during its 2005 descent to the surface – the mission has developed a comprehensive picture of Titan’s chemistry.</p>
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<iframe width="440" height="260" src="https://www.youtube.com/embed/TMxL3ZhO8A8?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Touchdown on Titan with the Huygens probe.</span></figcaption>
</figure>
<p>Intriguingly, on top of the hundreds of molecules accounted for, chemical models developed here on Earth incorporating Cassini data predict the existence of even more complex material. </p>
<p>Of potential significance to biochemistry, these molecules have evaded observation over the relatively short Cassini mission, being either out of view or present at levels below the detection limits of the equipment.</p>
<p>Even if only formed in small quantities in the atmosphere it is plausible that these life-bearing species have built up on the surface over Titan’s history.
So what are these chemicals and how do they come to be?</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/185593/original/file-20170912-26996-9vh08g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/185593/original/file-20170912-26996-9vh08g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/185593/original/file-20170912-26996-9vh08g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/185593/original/file-20170912-26996-9vh08g.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/185593/original/file-20170912-26996-9vh08g.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/185593/original/file-20170912-26996-9vh08g.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/185593/original/file-20170912-26996-9vh08g.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/185593/original/file-20170912-26996-9vh08g.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=754&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">This composite image shows an infrared view of Saturn’s moon Titan from Cassini’s flyby in November 2015. The near-infrared wavelengths in this image allow Cassini’s vision to penetrate the haze and reveal the moon’s surface.</span>
<span class="attribution"><a class="source" href="https://saturn.jpl.nasa.gov/resources/6278/">NASA/JPL/University of Arizona/University of Idaho</a></span>
</figcaption>
</figure>
<h2>Cyanide snow</h2>
<p>Unlike Earth, oxygen atoms are rather scarce in Titan’s atmosphere. Water is locked as surface ice and there appear to be no abundant sources of O₂ gas. </p>
<p>In oxygen’s place, we see nitrogen play a more significant role in Titan’s atmospheric chemistry.</p>
<p>Here, common products of nitrogen reactions are the cyanide family of compounds, of which hydrogen cyanide (HCN) is the simplest and most abundant.</p>
<p>As the numbers of cyanide molecules build up at lower, colder altitudes they form cloud layers of large floppy polymers (tholins) and budding ice aerosols.</p>
<p>As the aerosols descend to the surface, shells of methane and ethane ice form further layers on the exterior. This acts to protect the inner organic material on its descent to the surface before being dispersed in hydrocarbon lakes and seas.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/185600/original/file-20170912-28358-81yzcj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/185600/original/file-20170912-28358-81yzcj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/185600/original/file-20170912-28358-81yzcj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=437&fit=crop&dpr=1 600w, https://images.theconversation.com/files/185600/original/file-20170912-28358-81yzcj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=437&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/185600/original/file-20170912-28358-81yzcj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=437&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/185600/original/file-20170912-28358-81yzcj.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=549&fit=crop&dpr=1 754w, https://images.theconversation.com/files/185600/original/file-20170912-28358-81yzcj.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=549&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/185600/original/file-20170912-28358-81yzcj.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=549&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Cassini’s view of Titan’s high northern latitudes in May 2012, the lakes on the left are full of liquid hydrocarbons while those on the top right are only partially filled, or represent saturated ground or mudflat.</span>
<span class="attribution"><a class="source" href="https://saturn.jpl.nasa.gov/resources/5714/">NASA/JPL-Caltech/ASI/Cornell</a></span>
</figcaption>
</figure>
<p>Surprisingly it is these cyanide compounds, chemicals closely associated with <a href="https://emergency.cdc.gov/agent/cyanide/basics/facts.asp">toxicity and death</a> to Earthly lifeforms, that may actually provide avenues for life-bearing biomolecules to form in space environments.</p>
<p>Some <a href="http://pubs.acs.org/doi/abs/10.1021/jz501648q">simulations predict</a> that cyanides trapped in ices and exposed to space radiation can lead to the synthesis of amino acids and DNA nucleobase structures – the building blocks of life on Earth.</p>
<p>Excited by these predictions and their implications toward astrobiology, chemists have rushed to explore these reactions in the laboratory.</p>
<h2>Synchrotron experiments: Titan-in-a-can</h2>
<p>Our contributions to astrochemistry have focused on simulating the atmosphere of Titan and its cyanide haze.</p>
<p>With a specialised gas cell installed at the Australian Synchrotron, we are able to replicate the cold temperatures associated with Titan’s cloud layers. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/185596/original/file-20170912-6178-t6zdtn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/185596/original/file-20170912-6178-t6zdtn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/185596/original/file-20170912-6178-t6zdtn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=379&fit=crop&dpr=1 600w, https://images.theconversation.com/files/185596/original/file-20170912-6178-t6zdtn.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=379&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/185596/original/file-20170912-6178-t6zdtn.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=379&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/185596/original/file-20170912-6178-t6zdtn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=477&fit=crop&dpr=1 754w, https://images.theconversation.com/files/185596/original/file-20170912-6178-t6zdtn.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=477&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/185596/original/file-20170912-6178-t6zdtn.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=477&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Cassini’s spectrum view of the southern polar vortex shows a signature of frozen hydrogen cyanide molecules (HCN).</span>
<span class="attribution"><a class="source" href="https://saturn.jpl.nasa.gov/resources/6100/">NASA/JPL-Caltech/ASI/University of Arizona/SSI/Leiden Observatory and SRON</a></span>
</figcaption>
</figure>
<p>By injecting cyanides (the friendlier variety) into our cell we can determine the size, structure and density of Titan aerosols as they grow over time; <a href="http://pubs.rsc.org/en/content/articlelanding/2017/cp/c6cp08110j">probing with infrared light</a> from the facility. </p>
<p>These results have provided us with a list of signatures for which we can locate cyanide aerosols using infrared astronomy.</p>
<p>The next step will be to seed these aerosols with organic species to determine if they can be identified in extraterrestrial atmospheres.</p>
<p>Perhaps these signals will act as a beacon for future explorations designed to search for complex organic material in more remote space locations – potentially even on the “giant Earth” exoplanets in distant star systems.</p>
<h2>Life off Earth</h2>
<p>Space provides us a unique perspective to turn back the pages of chemistry.
Among the planets, moons and stars - and the not quite emptiness between - we can study the initial reactions thought to have started chemistry here on Earth.</p>
<p>Using ever more sensitive telescopes and advanced spacecraft, we have uncovered chemical nurseries - pockets of gas and ice exerted to harsh space radiation - in our Solar System and beyond.</p>
<p>Such cold, icy objects as Titan, the moons of Jupiter, Trans-Neptunian Objects (such as Pluto and other minor bodies in the Kuiper belt and beyond), as well as microscopic interstellar dust particles, all generate higher-order organic molecules from simple chemical ingredients.</p>
<hr>
<p>
<em>
<strong>
Read more:
<a href="https://theconversation.com/cloudy-with-a-chance-of-life-how-to-find-alien-life-on-distant-exoplanets-50603">Cloudy with a chance of life: how to find alien life on distant exoplanets</a>
</strong>
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</p>
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<p>As far as we know, the lack of heat and liquid water precludes life to exist at these worlds. </p>
<p>However, we can look for clues regarding life’s origins on a primitive Earth. Were life-bearing chemicals delivered via comet impact, or made in-house near the early ocean shores or deep sea volcanoes? Observing the chemistry of distant objects could one day provide the answers.</p>
<p>These forays into our chemical history have been enabled by the significant steps we have taken in our exploration of space including, as a glowing example, the resounding success of Cassini’s exploration of Titan.</p><img src="https://counter.theconversation.com/content/83441/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Courtney Ennis receives funding from the Australian Research Council (DECRA Scheme). </span></em></p>The Cassini space probe discovered liquid lakes, poisonous gases and the basic elements of life on Saturn’s moon, Titan.Courtney Ennis, Research Fellow, La Trobe UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/815272017-07-27T09:21:51Z2017-07-27T09:21:51ZSaturn’s moon Titan may harbour simple life forms – and reveal how organisms first formed on Earth<figure><img src="https://images.theconversation.com/files/179969/original/file-20170727-8497-16uhpy3.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">False colour mosaic made from infrared data collected by the Cassini spacecraft.</span> <span class="attribution"><span class="source">NASA / JPL-Caltech / Space Science Institute</span></span></figcaption></figure><p>How chemical reactions on a lifeless planet floating around in the cold darkness of space can suddenly give rise to living organisms is one of the biggest questions in science. We don’t even know whether the molecular building blocks of life on Earth were created here or whether they were brought here by comets and meteorites.</p>
<p>Using data from the NASA/ESA <a href="https://www.nasa.gov/mission_pages/cassini/main/index.html">Cassini mission</a>, we have now discovered <a href="http://sci.esa.int/cassini-huygens/59350-has-cassini-found-a-universal-driver-for-prebiotic-chemistry-at-titan/">molecules</a> on Saturn’s largest moon Titan which we think drive the production of complex organic compounds. These are molecules that have never been seen in our solar system before. The <a href="https://saturn.jpl.nasa.gov/news/2385/cassini-spacecraft-reveals-evidence-of-tholin-formation-at-high-altitudes-in-titans-atmosphere/">discovery</a> of such fascinating chemistry not only makes Titan a great contender for hosting some sort of primitive life, it also makes it the ideal place to study how life may have arisen from chemical reactions on our own planet.</p>
<p>The molecular building blocks of life are organic compounds including amino acids that can be assembled into proteins, RNA and DNA in living cells. To date, scientists have found these compounds in meteorites, comets and interstellar dust. But the problem is that these materials formed millions of years ago, which means we have no way of knowing how they were created.</p>
<p>Excitingly, it seems these compounds are being created on Titan today. Sunlight and energetic particles from Saturn’s <a href="https://en.wikipedia.org/wiki/Magnetosphere">magnetosphere</a> drive reactions in the moon’s upper atmosphere, which is dominated by nitrogen, methane and hydrogen. These lead to <a href="https://www.esa.int/Our_Activities/Space_Science/Cassini-Huygens/Organic_building_blocks_discovered_in_Titan_s_atmosphere">larger organic compounds</a> which drift downwards to form the moon’s characteristic “haze” and the <a href="https://www.nasa.gov/feature/jpl/titans-dunes-and-other-features-emerge-in-new-images">extensive dunes</a> – eventually reaching the surface. </p>
<figure class="align-right zoomable">
<a href="https://images.theconversation.com/files/179962/original/file-20170727-25706-ctpyt2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/179962/original/file-20170727-25706-ctpyt2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/179962/original/file-20170727-25706-ctpyt2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=849&fit=crop&dpr=1 600w, https://images.theconversation.com/files/179962/original/file-20170727-25706-ctpyt2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=849&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/179962/original/file-20170727-25706-ctpyt2.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=849&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/179962/original/file-20170727-25706-ctpyt2.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1067&fit=crop&dpr=1 754w, https://images.theconversation.com/files/179962/original/file-20170727-25706-ctpyt2.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1067&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/179962/original/file-20170727-25706-ctpyt2.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1067&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 chemical reactions in Titan’s atmosphere. The carbon chain anions are in the green box.</span>
<span class="attribution"><span class="source">ESA</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>To make these surprising discoveries, <a href="http://iopscience.iop.org/article/10.3847/2041-8213/aa7851">published in the Astrophysical Journal Letters</a>, the Cassini spacecraft dipped through Titan’s upper atmosphere. Using data beamed back to Earth, we identified the presence of negatively charged molecules called “carbon chain anions”. These appear to “seed” the larger organic compounds observed at the moon – such as <a href="https://www.nasa.gov/mission_pages/cassini/multimedia/pia17240.html">polyaromatic hydrocarbons</a> and <a href="https://news.cornell.edu/stories/2016/07/hydrogen-cyanide-titan-key-possible-prebiotic-conditions">cyanopolynnes</a> – which could serve as key ingredients for early forms of life. Laboratory experiments have also shown that amino acids <a href="https://science.nasa.gov/science-news/science-at-nasa/2010/30dec_titan">could exist there</a>, but the instruments on Cassini are not equipped to detect them. </p>
<p>Negatively charged molecules like these are rare in space environments as they want to react and combine with other molecules – meaning they can be quickly lost. When present, however, they appear to be a crucial “missing link” between simple molecules and complex organic compounds.</p>
<p>So could life currently exist on Titan? It’s not impossible. Water plumes erupting from another of Saturn’s moons, Enceladus, <a href="https://theconversation.com/nasa-saturn-moon-enceladus-is-able-to-host-life-its-time-for-a-new-mission-76102">provides a key source of oxygen</a>, which rains down onto Titan’s upper atmosphere. Titan has even been judged the <a href="http://www.bbc.co.uk/news/science-environment-15863549">most likely place</a> beyond the Earth to host life by the Planetary habitability index. But life there would likely be quite primitive due to the cold conditions. The presence of liquid methane and ethane seas also means potential organisms would have to function quite differently to those on Earth. </p>
<h2>Tracing life on Earth</h2>
<p>Remarkably, similar processes are observed in vast molecular clouds beyond our solar system, where stars are born. After the first stars in the universe entered their death throes and fused together heavier elements, <a href="http://www.bbc.com/news/science-environment-29368984">rich organic chemistry</a> took place. In these environments, negatively charged molecules have been shown to act as a catalyst for the formation of larger organics, which could then be transferred to solar systems and comets forming from the cloud.</p>
<p>Complex interstellar chemistry has led to the theory that the building blocks of life could have been delivered to Earth from comets which once formed in these molecular clouds. ESA’s Rosetta mission <a href="https://theconversation.com/building-blocks-of-life-found-among-organic-compounds-on-comet-67p-what-philae-discoveries-mean-45379">detected the amino acid glycine</a> when visiting Comet 67P/Churymov-Gerasimenko. However, the new discovery makes it entirely possible that similar processes of creating complex organics, and thus life, took place on Earth instead.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/179964/original/file-20170727-25715-13klfsr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/179964/original/file-20170727-25715-13klfsr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=620&fit=crop&dpr=1 600w, https://images.theconversation.com/files/179964/original/file-20170727-25715-13klfsr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=620&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/179964/original/file-20170727-25715-13klfsr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=620&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/179964/original/file-20170727-25715-13klfsr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=779&fit=crop&dpr=1 754w, https://images.theconversation.com/files/179964/original/file-20170727-25715-13klfsr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=779&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/179964/original/file-20170727-25715-13klfsr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=779&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Haze in Titan’s atmosphere.</span>
<span class="attribution"><span class="source">wikipedia</span></span>
</figcaption>
</figure>
<p>Titan’s dense nitrogen and methane atmosphere is similar to the early Earth’s, some 2.5-4 billion years ago. At this time, before the build-up of oxygen occurred, large quantities of methane resulted in organic chemistry similar to that observed at Titan today. The moon is therefore a high priority target in the search for the beginnings of life. </p>
<p>By making long-term, detailed observations of Titan, we may one day be able to trace the journey from small to large chemical species in order to understand how complex organic molecules are produced. Perhaps we may even be able catch the sudden change from complex organic molecules to living organisms. Follow-up observations of Titan’s atmosphere are already underway using powerful ground-based telescopes such as <a href="http://www.almaobservatory.org/en/home/">ALMA</a>. Further missions to explore Titan are also in the works – it is crucial that these are equipped to detect the signatures of life.</p>
<h2>Universal driver</h2>
<p>The fact that we now see the same chemistry occurring at Titan as in molecular clouds is fascinating, as it indicates the universal nature of these processes. The question now is, could this also be happening within other atmospheres rich in nitrogen and methane, such as at Pluto or Neptune’s moon Triton? What about the thousands of exoplanets discovered in recent years, circling nearby stars? </p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/179966/original/file-20170727-25749-qpjn5c.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/179966/original/file-20170727-25749-qpjn5c.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/179966/original/file-20170727-25749-qpjn5c.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/179966/original/file-20170727-25749-qpjn5c.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/179966/original/file-20170727-25749-qpjn5c.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=425&fit=crop&dpr=1 754w, https://images.theconversation.com/files/179966/original/file-20170727-25749-qpjn5c.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=425&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/179966/original/file-20170727-25749-qpjn5c.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=425&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Radar images reveal lakes on Titan’s surface.</span>
<span class="attribution"><span class="source">NASA/JPL-Caltech/ASI/USGS</span></span>
</figcaption>
</figure>
<p>The concept of a universal pathway towards the building blocks of life has implications for what we need to look for in the onward search for life in the universe. If we detect the molecules just seen on Titan in another environment, we would know that much larger organics and therefore amino acids could possibly exist there.</p>
<p>Future missions, such as <a href="https://www.jwst.nasa.gov/">NASA’s James Webb Space Telescope</a> and ESA’s exoplanet mission Plato, are set to further study these processes within our solar system and at planets orbiting nearby stars. The UK is even planning its own exoplanet mission, <a href="http://www.twinkle-spacemission.co.uk/">Twinkle</a>, which will also search for signatures of organic molecules.</p>
<p>Although we haven’t detected life itself, the presence of complex organic molecules at Titan, comets and within the interstellar medium means we are certainly coming close to finding its beginnings. And it’s all thanks to Cassini’s near 20-year exploratory journey. So spare a thought for this magnificent spacecraft as it ends its mission in September with a final <a href="https://saturn.jpl.nasa.gov/mission/grand-finale/overview/">death-plunge</a> into Saturn’s atmosphere.</p><img src="https://counter.theconversation.com/content/81527/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Ravi Desai receives funding from the Science and Technology Facilities Council.</span></em></p>Scientists discover rare molecules on Titan which suggests it’s creating the building blocks of life.R D, PhD Candidate in Physics, UCLLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/766702017-04-26T08:56:29Z2017-04-26T08:56:29ZBittersweet feeling as Cassini mission embarks on its ‘grand finale’ ahead of death plunge<figure><img src="https://images.theconversation.com/files/166657/original/file-20170425-12650-1k2x71.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Saturn eclipsing the sun, seen from behind by the Cassini orbiter. Earth is the small dot between the rings on the upper, left-hand side.
</span> <span class="attribution"><span class="source">NASA/JPL/Space Science Institute</span></span></figcaption></figure><p>It’s the slow beginning of what will be a violent end for the Cassini mission. At 10.00 BST on April 26, the spacecraft became the first ever to dive between Saturn and its spectacular innermost ring. This marks the start of its “grand finale” consisting of 22 daring orbits – enabling a new era of science. Then, on September 15, it will crash into the planet’s atmosphere and burn up. It is sure to be a sad but proud moment for those of us who have worked on the mission.</p>
<p>Cassini was <a href="https://www.nasa.gov/feature/jpl/cassini-completes-final-and-fateful-titan-flyby">initially set on its path to destruction</a> on April 22 when it flew by Saturn’s moon Titan. The spacecraft has used Titan not just as a fascinating scientific target in itself, but also to provide the gravitational slingshots needed to tweak, crank and change its orbit. It is Titan that gave it the impetus to penetrate the 2,400km gap between the rings and the planet every week before the mission ends.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/166647/original/file-20170425-25594-1a7v5wn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/166647/original/file-20170425-25594-1a7v5wn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/166647/original/file-20170425-25594-1a7v5wn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=337&fit=crop&dpr=1 600w, https://images.theconversation.com/files/166647/original/file-20170425-25594-1a7v5wn.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=337&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/166647/original/file-20170425-25594-1a7v5wn.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=337&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/166647/original/file-20170425-25594-1a7v5wn.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/166647/original/file-20170425-25594-1a7v5wn.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/166647/original/file-20170425-25594-1a7v5wn.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">Grand finale orbits.</span>
<span class="attribution"><span class="source">NASA/JPL-Caltech</span></span>
</figcaption>
</figure>
<p>During the next few months, the instrument teams have several new observations to make in this region. These include understanding a new radiation belt <a href="https://saturn.jpl.nasa.gov/resources/1851/">discovered inside the rings early in the mission</a> and taking close-up pictures of the rings and other features. It will also image Saturn’s cloud tops at close range, weigh its ring system (which will indicate just how old it is), sample the atmosphere of the planet and its rings, and measure Saturn’s internal structure.</p>
<h2>Hazardous journey</h2>
<p>But there are risks. The ring plane includes a lot of particles. These vary from micron-sized grains (a millimetre is equal to 1,000 microns) to mansion-sized chunks – and they could all collide with the spacecraft. Although Cassini’s path in the gap between Saturn and the rings has fewer particles than in the visible rings, we don’t know exactly how few.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/166663/original/file-20170425-12658-sqmwvz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/166663/original/file-20170425-12658-sqmwvz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=360&fit=crop&dpr=1 600w, https://images.theconversation.com/files/166663/original/file-20170425-12658-sqmwvz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=360&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/166663/original/file-20170425-12658-sqmwvz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=360&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/166663/original/file-20170425-12658-sqmwvz.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=452&fit=crop&dpr=1 754w, https://images.theconversation.com/files/166663/original/file-20170425-12658-sqmwvz.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=452&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/166663/original/file-20170425-12658-sqmwvz.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=452&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Artist’s impression of the particles in Saturn’s rings.</span>
<span class="attribution"><span class="source">Judy Schmidt/Flickr</span>, <a class="license" href="http://creativecommons.org/licenses/by-sa/4.0/">CC BY-SA</a></span>
</figcaption>
</figure>
<p>However, it is thought that the risks of a significant dust hit in the ring plane are low. At the large relative speed – a maximum of 124,000km per hour – a hit could be a significant problem for the spacecraft. So, as Cassini flies through the ring plane, its <a href="http://www.esa.int/Our_Activities/Space_Science/Cassini-Huygens/Communicating_from_space_gaining_a_grip_on_antennas">high-gain antenna</a> will be oriented to provide a shield for the rest of the spacecraft and its instruments. This was successfully done early in the mission when it was first inserted into orbit around Saturn, crossing outside the main rings.</p>
<p>The only protruding features beyond the shield are a 10-metre electric field antennae and an 11-metre magnetometer boom (used to make magnetic observations). These should make it possible to monitor dust impacts, each of which makes a tiny plume of plasma (loose and electrically charged particles) as the spacecraft and booms are impacted. Hopefully, no large impact will disable the spacecraft.</p>
<p>Indeed, the best computer models show that <a href="https://saturn.jpl.nasa.gov/faq/#end_of_mission">this should not happen</a>. But even if it does, the spacecraft will eventually crash into Saturn – as it’s supposed to. That is important. Cassini must not crash onto interesting targets in the quest to find extraterrestrial lifeforms – particularly the moons Enceladus and Titan. These are subject to “planetary protection” which means we cannot put probes there which could carry contamination from Earth in the form of microbes.</p>
<p>The spacecraft will be useful until the very moment it burns up – it will be sending back data continuously. These last measurements of the composition of Saturn’s atmosphere, rotation rate and interior structure will be totally unique.</p>
<h2>Personal highlights</h2>
<p>I’ve been privileged to work on Cassini for 28 years. We proposed our instrument, the electron spectrometer, which measures the energy and direction of electrons, in 1989, and were selected to develop it in 1990. We then secured funding, and built, tested and calibrated the instrument before the launch in 1997. </p>
<p>The <a href="https://www.nasa.gov/image-feature/oct-15-1997-launch-of-cassini-to-saturn">launch itself</a> was a tense time. The powerful Titan IV rocket lifted off near dawn in October 1997, went behind a cloud from our vantage point and then thankfully emerged serenely on its way to Saturn, reaching the planet on July 1 2004. I remember nervously watching in the middle of the night as Cassini burned its engines for an excruciating 96 minutes to slow the spacecraft into Saturn orbit. Luckily it all went smoothly.</p>
<p>Cassini has operated at Saturn for almost half a Saturn year. It’s made <a href="https://theconversation.com/water-weather-new-worlds-cassini-mission-revealed-saturns-secrets-76195">many discoveries</a> – in fact, it has rewritten the textbooks on the Saturn system. We now know that Saturn has 45 more moons than previously thought – placing the total now at 62.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/166667/original/file-20170425-22270-1t26u25.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/166667/original/file-20170425-22270-1t26u25.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=615&fit=crop&dpr=1 600w, https://images.theconversation.com/files/166667/original/file-20170425-22270-1t26u25.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=615&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/166667/original/file-20170425-22270-1t26u25.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=615&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/166667/original/file-20170425-22270-1t26u25.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=773&fit=crop&dpr=1 754w, https://images.theconversation.com/files/166667/original/file-20170425-22270-1t26u25.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=773&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/166667/original/file-20170425-22270-1t26u25.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=773&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Titan seen by Cassini.</span>
<span class="attribution"><span class="source">NASA</span></span>
</figcaption>
</figure>
<p>At Titan, Cassini <a href="https://phys.org/news/2014-06-nasa-titan-potential-prebiotic-chemistry.html">found prebiotic chemistry</a> – which means the moon is essentially a frozen version of what the Earth was several billion years ago. Cassini also discovered that the moon has <a href="https://www.nasa.gov/feature/jpl/cassini-explores-a-methane-sea-on-titan">three large seas and a number of smaller lakes</a> made of liquid methane. </p>
<p>At Enceladus, Cassini discovered water-rich plumes from a subsurface ocean and found that the ocean is salty. It recently also confirmed that chemical reactions between water and rock on the moon can provide enough energy in the water <a href="https://theconversation.com/nasa-saturn-moon-enceladus-is-able-to-host-life-its-time-for-a-new-mission-76102">to feed microbial life</a>. There have been many other incredible discoveries about the other icy moons, the atmosphere and the magnetosphere.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/164865/original/image-20170411-26720-1avikn7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/164865/original/image-20170411-26720-1avikn7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/164865/original/image-20170411-26720-1avikn7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=218&fit=crop&dpr=1 600w, https://images.theconversation.com/files/164865/original/image-20170411-26720-1avikn7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=218&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/164865/original/image-20170411-26720-1avikn7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=218&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/164865/original/image-20170411-26720-1avikn7.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=274&fit=crop&dpr=1 754w, https://images.theconversation.com/files/164865/original/image-20170411-26720-1avikn7.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=274&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/164865/original/image-20170411-26720-1avikn7.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=274&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Enceladus’s south polar plumes, as seen by Cassini, November 30, 2010.</span>
<span class="attribution"><a class="source" href="https://photojournal.jpl.nasa.gov/catalog/PIA17184">NASA/JPL-Caltech/Space Science Institute</a></span>
</figcaption>
</figure>
<p>Some of the <a href="https://saturn.jpl.nasa.gov/news/2385/cassini-spacecraft-reveals-evidence-of-tholin-formation-at-high-altitudes-in-titans-atmosphere/">key discoveries we made</a> with the electron spectrometer include large amounts of hydrocarbons and nitriles (a form of organic compound) in Titan’s atmosphere. These fall through the atmosphere and may form the dunes seen on Titan’s surface. We also uncovered Saturn’s ring atmosphere and ionosphere, and found weak atmospheres at the moons Rhea and Dione. An important discovery was that of water clusters and charged dust particles in plumes at Enceladus, helping us to understand that it has a subsurface ocean.</p>
<p>Needless to say, it has truly been an honour to be a part of the Cassini mission and a privilege to work with colleagues, postdocs and students through the years. As the mission heads towards its end, the overwhelming feeling is that this has been one of humankind’s most spectacular voyages of discovery. </p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/xrGAQCq9BMU?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Daring dive.</span></figcaption>
</figure>
<p>But there are tantalising discoveries yet to be made. Enceladus has just recently joined Mars and Jupiter’s moon Europa in the top three likely locations for life beyond Earth in our solar system. I’m <a href="https://theconversation.com/decades-of-attempts-show-how-hard-it-is-to-land-on-mars-heres-how-we-plan-to-succeed-in-2021-69734">involved in the continued search for life on Mars</a> with the ExoMars 2020 rover and at Jupiter’s icy moons with the <a href="http://sci.esa.int/juice/">JUICE mission</a>. NASA also plans the Europa Clipper mission. Now, Cassini has shown us that we must go back to Titan and Enceladus, too.</p><img src="https://counter.theconversation.com/content/76670/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Andrew Coates receives funding from STFC and UKSA. </span></em></p>One of the most successful space exploration missions of all time still has a lot left to uncover.Andrew Coates, Professor of Physics, Deputy Director (Solar System) at the Mullard Space Science Laboratory, UCLLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/674632016-10-24T19:07:08Z2016-10-24T19:07:08ZThere’s no ‘Mars curse’ – it’s just very hard to land there<p>Hopes of another successful landing on Mars were dashed last week when the Schiaparelli probe <a href="https://theconversation.com/what-missing-lander-means-for-europes-quest-to-find-life-on-mars-67338">went missing in action</a> during its descent onto the Red Planet.</p>
<p>Pictures released over the weekend from NASA’s Mars Reconnaissance Orbiter appear to show a parachute and a disturbed area of the Martian landscape. Early investigations suggest that the lander’s parachute <a href="http://www.esa.int/Our_Activities/Space_Science/ExoMars/Schiaparelli_descent_data_decoding_underway">opened earlier than planned</a>, and caused the lander to plummet to the surface from as high as 4km, possibly exploding on impact. </p>
<p>The good news to be salvaged from this wreckage is that the lander was watched very closely during its descent, both by the Mars Express orbiter and by a radio telescope in India, so engineers should be able to fully understand the chain of events that led to the crash. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/142853/original/image-20161024-26467-1nsa2yr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/142853/original/image-20161024-26467-1nsa2yr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/142853/original/image-20161024-26467-1nsa2yr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=338&fit=crop&dpr=1 600w, https://images.theconversation.com/files/142853/original/image-20161024-26467-1nsa2yr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=338&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/142853/original/image-20161024-26467-1nsa2yr.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=338&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/142853/original/image-20161024-26467-1nsa2yr.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=424&fit=crop&dpr=1 754w, https://images.theconversation.com/files/142853/original/image-20161024-26467-1nsa2yr.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=424&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/142853/original/image-20161024-26467-1nsa2yr.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 stages of Schiaparelli’s planned descent.</span>
<span class="attribution"><a class="source" href="http://exploration.esa.int/mars/57465-exomars-2016-schiaparelli-descent-sequence/">ESA/ATG medialab</a></span>
</figcaption>
</figure>
<p>The Schiaparelli lander was only one part of the <a href="http://www.esa.int/Our_Activities/Space_Science/ExoMars/What_is_ExoMars">ExoMars</a> project, a joint venture between the European Space Agency (ESA) and Russia to determine whether life has ever existed on Mars. Its landing was partly meant as a dress rehearsal for the ExoMars rover, which will hopefully touch down in 2020. </p>
<p>Although Thursday’s landing went awry, the overall mission was not without success. The <a href="http://www.esa.int/Our_Activities/Space_Science/ExoMars/Trace_Gas_Orbiter_instruments">Trace Gas Orbiter</a>, which had transported the lander from Earth, entered into Martian orbit successfully before releasing its ill-fated payload. This satellite will play a crucial role in the future ExoMars rover mission, relaying communications between Earth and the Martian surface.</p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/142784/original/image-20161023-15963-gmbufh.gif?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/142784/original/image-20161023-15963-gmbufh.gif?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/142784/original/image-20161023-15963-gmbufh.gif?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=414&fit=crop&dpr=1 600w, https://images.theconversation.com/files/142784/original/image-20161023-15963-gmbufh.gif?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=414&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/142784/original/image-20161023-15963-gmbufh.gif?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=414&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/142784/original/image-20161023-15963-gmbufh.gif?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=520&fit=crop&dpr=1 754w, https://images.theconversation.com/files/142784/original/image-20161023-15963-gmbufh.gif?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=520&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/142784/original/image-20161023-15963-gmbufh.gif?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=520&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Before and after images of Schiaparelli’s landing site, from NASA’s Mars Reconnaissance Orbiter.</span>
<span class="attribution"><a class="source" href="http://exploration.esa.int/mars/58482-mars-reconnaissance-orbiter-view-of-schiaparelli-landing-site/">NASA/JPL-Caltech/MSSS</a></span>
</figcaption>
</figure>
<h2>The ‘curse’ strikes again?</h2>
<p>This was ESA’s first attempt to land on Mars, and its failure has perhaps predictably prompted fresh references to the supposed “<a href="http://arstechnica.com/science/2016/03/with-todays-launch-europe-and-russia-seek-to-break-the-mars-curse/">Mars curse</a>”. </p>
<p>Over the decades we’ve been exploring the Red Planet, several missions have <a href="https://www.theguardian.com/science/2016/oct/20/total-recall-of-unsuccessful-mars-lander-schiaparelli-exomars">gone astray</a>, starting with the very first landing attempt by the Soviet <a href="http://nssdc.gsfc.nasa.gov/nmc/spacecraftDisplay.do?id=1971-045D">Mars 2</a> mission in 1971. More recently, NASA’s <a href="http://mars.nasa.gov/msp98/orbiter/">Climate Orbiter</a> missed its orbit insertion in 1998, and the UK’s plucky <a href="http://www.beagle2.com/">Beagle 2</a> lander failed to send back a signal to Earth on Christmas day 2003.</p>
<p>All in all, 44 missions have been <a href="http://mars.nasa.gov/programmissions/missions/log/">sent to Mars</a>, of which 26 have been full or partial failures, and 18 successful. So if we’re keeping score, our crude Martian success rate is 41%. </p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"789202948681297920"}"></div></p>
<p>But how bad is that really, compared with our other planetary targets? Take our nearest planet, Venus. So far, <a href="https://en.wikipedia.org/wiki/List_of_missions_to_Venus">40 missions have set off with the prime mission of studying our cloudy neighbour</a>, of which 22 (or 55%) were successes. </p>
<p>Bear in mind too that most failures on both Venus and Mars were during the early era of planetary exploration – and since then our knowledge, experience and computing power have all increased vastly.</p>
<h2>Bumpy landings</h2>
<p>What if we look specifically at planetary landings, rather than all missions? Does the “curse” stack up there? </p>
<p>Nine spacecraft have successfully landed on Venus (admittedly, they <a href="http://www.space.com/44-venus-second-planet-from-the-sun-brightest-planet-in-solar-system.html">didn’t last long</a>), compared with the seven that have made it onto Mars intact. What’s more, the most recent Venusian probe touched down in 1984, compared with the 2013 arrival of the Curiosity rover on Mars. So Venus seems to have rather fallen out favour, despite it being apparently easier to land there.</p>
<p><div data-react-class="Tweet" data-react-props="{"tweetId":"789950459582685184"}"></div></p>
<p>What about other worlds? Our track records for Venus and Mars both pale in comparison with Saturn’s moon Titan, which has a 100% success rate – albeit from one mission, ESA’s Huygens lander, which arrived in 2004. </p>
<p>These examples bring us closer to understanding the real “curse” of Mars, which is down to a combination of the two things that make it extra hard to land there: the planet’s very thin and variable atmosphere, and its gravitational pull.</p>
<p>Assuming that any Mars lander survives its voyage across space, the first thing it encounters is Mars’s atmosphere. Although much, much thinner than Earth’s, it is thick enough to require a substantial heat shield to protect the probe from being scorched. As on Earth, the angle of atmospheric entry needs to be perfect – and this is made harder by Mars’s unpredictable weather. A global dust storm, as often rage on Mars for weeks, could lead to a landing being called off before it even touches the atmosphere.</p>
<p>Should your lander get through the atmosphere intact, it will still be falling at a breakneck speed towards the surface. Mars’s gravity, although only one-third of Earth’s, is still a substantial tug towards a rocky surface. Parachutes won’t slow your lander down enough to survive on arrival on the surface, so a different tack is needed. The Mars Exploration Rovers, Spirit and Opportunity, both cushioned their landings with giant inflatable balls – but these are at the mercy of the rocky terrain. Curiosity’s “Sky Crane”, a part of the lander that hovered on rockets long enough to lower the car-sized rover onto the surface, was an audacious piece of engineering. We’ll see if this will work a second time when NASA attempts to repeat the feat with its <a href="http://mars.nasa.gov/mars2020/mission/rover/">2020 rover</a>. </p>
<figure class="align-center zoomable">
<a href="https://images.theconversation.com/files/142854/original/image-20161024-26486-j4naw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=1000&fit=clip"><img alt="" src="https://images.theconversation.com/files/142854/original/image-20161024-26486-j4naw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/142854/original/image-20161024-26486-j4naw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=337&fit=crop&dpr=1 600w, https://images.theconversation.com/files/142854/original/image-20161024-26486-j4naw.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=337&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/142854/original/image-20161024-26486-j4naw.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=337&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/142854/original/image-20161024-26486-j4naw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=423&fit=crop&dpr=1 754w, https://images.theconversation.com/files/142854/original/image-20161024-26486-j4naw.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=423&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/142854/original/image-20161024-26486-j4naw.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=423&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px"></a>
<figcaption>
<span class="caption">Curiosity’s audacious ‘sky crane’ manoeuvre.</span>
<span class="attribution"><a class="source" href="http://mars.nasa.gov/msl/multimedia/images/?ImageID=3650">NASA</a></span>
</figcaption>
</figure>
<p>Contrast that with Venus, where the thick atmosphere makes a soft parachute landing an extremely effective option. The real challenge is keeping your spacecraft working in the planet’s hideously hot and corrosive conditions. </p>
<p>On Titan, meanwhile, the weaker gravity and thick atmosphere work together to make landing a much safer bet – once you’ve managed to get your craft safely to such a distant outpost of the solar system. </p>
<p>Given recent big successes like ESA’s <a href="http://www.esa.int/Our_Activities/Space_Science/Rosetta">Rosetta</a> and NASA’s <a href="http://mars.nasa.gov/msl/">Curiosity</a> rover, it is all the more galling when things don’t quite come off. There will certainly be some crestfallen people at ESA headquarters this week – from the engineers whose efforts have been dashed, to the researchers left with no data to crunch.</p>
<p>But we (and those who fund the missions) shouldn’t shy away from difficult things. The aim of the ExoMars mission is to find evidence of life, which would revolutionise our understanding of our own place in nature. That prize has to be worth a shot.</p><img src="https://counter.theconversation.com/content/67463/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Helen Maynard-Casely has received funding from NASA.</span></em></p>Recent high-profile disappointments make it tempting to this our efforts to explore Mars are cursed. But landing anywhere in space is hard – not least on the Red Planet.Helen Maynard-Casely, Instrument Scientist, Australian Nuclear Science and Technology OrganisationLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/634172016-08-03T11:35:47Z2016-08-03T11:35:47ZSpace submarines will allow us to explore the seas of icy moons<figure><img src="https://images.theconversation.com/files/132778/original/image-20160802-17177-wta4kg.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">Artist's impression of a cryobot and submarine in the ice on Jupiter's Europa</span> <span class="attribution"><span class="source">NASA/JPL</span></span></figcaption></figure><p>One of the most profound and exciting breakthroughs in planetary science in the last two decades has been the discovery of <a href="http://www.jpl.nasa.gov/news/news.php?feature=4635">liquid methane lakes</a> on the surface of Saturn’s largest moon Titan, and <a href="http://solarsystem.nasa.gov/europa/overview.cfm">liquid oceans</a> under the icy surfaces of many of the giant gas planets’ other moons. Thrillingly, these some of these “waters” <a href="https://theconversation.com/the-moon-was-a-first-step-mars-will-test-our-capabilities-but-europa-is-the-prize-37253">may actually harbour life</a>.</p>
<p>Unfortunately, we don’t know much about them. Probes such as Juno and Cassini can only get so close. Also, subsurface oceans can only be sensed indirectly. The European Space Agency’s <a href="http://www.esa.int/Our_Activities/Space_Science/Cassini-Huygens/Huygens_spacecraft">Huygens</a> probe did land on Titan in 2005, but on a solid surface rather than on liquid. So how can we explore these seas? </p>
<p>An exciting idea being explored is developing submarines to send through space to the moons. Over the next two years, NASA is devoting half a million dollars to researching the prospect of <a href="https://www.nasa.gov/content/titan-submarine-exploring-the-depths-of-kraken">sending such a vehicle to Titan</a>. But there are <a href="http://www.kiss.caltech.edu/workshops/titan2010/presentations/aharonson.pdf">other studies out there, too</a> – with targets including Jupiter’s Europa and Ganymede, and Saturn’s Enceladus. But are such missions actually <a href="http://dx.doi.org/10.1016/j.cryogenics.2015.09.009">within our technological reach</a>?</p>
<h2>The challenges of a Titan submarine</h2>
<p><a href="https://saturn.jpl.nasa.gov/resources/725/">Kraken Mare</a> is thought to be the largest sea on Titan with an area of 400,000 square kilometres – larger than Earth’s Caspian Sea. But it’s not made of water – we have good evidence that this is instead a <a href="http://www.esa.int/Our_Activities/Space_Science/Cassini-Huygens/Profile_of_a_methane_sea_on_Titan">lake of methane</a>, ethane and nitrogen.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/132758/original/image-20160802-17177-14aq5vd.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/132758/original/image-20160802-17177-14aq5vd.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=366&fit=crop&dpr=1 600w, https://images.theconversation.com/files/132758/original/image-20160802-17177-14aq5vd.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=366&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/132758/original/image-20160802-17177-14aq5vd.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=366&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/132758/original/image-20160802-17177-14aq5vd.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=460&fit=crop&dpr=1 754w, https://images.theconversation.com/files/132758/original/image-20160802-17177-14aq5vd.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=460&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/132758/original/image-20160802-17177-14aq5vd.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=460&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Cassini radar image of the northern region of Kracken Mare on Titan showing the large island of Mayda Insula.</span>
<span class="attribution"><span class="source">NASA/Jet Propulsion Laboratory-Caltech/Agenzia Spaziale Italiana.</span></span>
</figcaption>
</figure>
<p>So what would a submarine on Titan look like? It turns out that a design like a traditional submarine, with a high “aspect ratio” (ten times as long as it is wide), would minimise drag and could fit inside a launch vehicle. Most deep space missions operate autonomously and a submarine would be no different. However, they would have to go to the surface for periods of time. Radio and microwave signals get absorbed very quickly in oceans, so to send a signal back to Earth the antenna would have to be above the surface. </p>
<p>Another issue is electrical power – this obviously cannot be provided by solar panels as it is on many spacecraft. As part of a <a href="http://dx.doi.org/10.1016/j.cryogenics.2015.09.009">recent study</a>, engineers investigated various alternatives, including compact nuclear reactors and fuel cells, but concluded these were too heavy. Instead, they proposed that electricity could be generated from the radioactive decay of plutonium – a technique <a href="http://mars.nasa.gov/mars2020/files/mep/MMRTG_FactSheet_update_10-2-13.pdf">similar to that powering Cassini</a>.</p>
<p>Some of the shallow shorelines of Kraken Mare are only 30-40 metres deep but it is thought to be 150 metres at its deepest. As you dive down beneath the surface the pressure increases because of the weight of the liquid above. On Earth, you can feel this in your ears when swimming underwater. Liquid methane is about half as dense as water and gravity on Titan is about seven times weaker than Earth, similar to our moon. So submarines diving down 150 meters on Titan don’t need to withstand the same pressure as they would on Earth.</p>
<figure>
<iframe width="440" height="260" src="https://www.youtube.com/embed/NnKxbdpLP5E?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Credit: NASA/NIAC.</span></figcaption>
</figure>
<p>A huge difficulty with these missions is to package the submarine into a system that can be launched on a rocket, survive in deep space during the roughly seven-year cruise to Titan, and then make it through a hypersonic descent to the ocean. It turns out that spaceplanes, such as the <a href="https://www.theguardian.com/science/2010/dec/01/space-vehicle-earth">X-37</a>, are ideal and would work well when descending into Titan’s thick hydrocarbon atmosphere. The spaceplane would launch from Earth on top of a rocket with the submarine inside. Once at the Saturnian system, the spaceplane would then land on Kraken Mare and deploy the submarine.</p>
<p>But perhaps the hardest thing will be to control the temperature inside the submarine – even though the sea is a somewhat frigid -180°C, the radioactive decay of the plutonium produces a lot of heat that needs to be dissipated.</p>
<h2>Descending to the depths of subsurface oceans</h2>
<p>Some tens of kilometres below the icy surface of Europa, meanwhile, we have good evidence that there could be a liquid salt water ocean. In fact, there could be subsurface liquid water oceans on a number of the moons of Jupiter, Saturn, and possibly Uranus and Neptune. As water is a prerequisite for life on Earth, this raises the exciting notion that these moons may be habitable. This is why many planetary scientists are interested in ideas to explore under the ice – either with submarines or <a href="http://www.jpl.nasa.gov/missions/europa-mission/">ice penetrating radar</a>.</p>
<figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/132757/original/image-20160802-17187-1swnp9i.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/132757/original/image-20160802-17187-1swnp9i.png?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=874&fit=crop&dpr=1 600w, https://images.theconversation.com/files/132757/original/image-20160802-17187-1swnp9i.png?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=874&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/132757/original/image-20160802-17187-1swnp9i.png?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=874&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/132757/original/image-20160802-17187-1swnp9i.png?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=1098&fit=crop&dpr=1 754w, https://images.theconversation.com/files/132757/original/image-20160802-17187-1swnp9i.png?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=1098&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/132757/original/image-20160802-17187-1swnp9i.png?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=1098&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
<figcaption>
<span class="caption">Travel to Europa.</span>
<span class="attribution"><span class="source">NASA/JPL</span></span>
</figcaption>
</figure>
<p>However, getting a submarine through at least 5km of ice makes putting a submarine on Titan look very easy. Cryobots – robotic devices that penetrate ice by <a href="http://www.jpl.nasa.gov/releases/2002/release_2002_6.html">melting it, allowing gravity to pull the robot downwards</a> – have been proposed as a way to <a href="http://www.jpl.nasa.gov/news/news.php?release=2013-077">deliver a submarine</a> into Europa’s oceans.</p>
<p>But energy is needed both to heat up the ice and then melt it -– a typical power station would be able to provide this in about five minutes. But it’s not going to be practical to send a power station to Europa. And with the amount of power available to most spacecraft, it would take a cryobot about eight years to get through the ice.</p>
<p>One way this problem can be solved is to use a compact nuclear fission reactor, which will do the job in about six weeks. But such a nuclear reactor wouldn’t fit into the cryobot. One problem solved, another is created. To get around this, <a href="http://www.igsoc.org:8080/annals/55/65/a65A200.pdf">one idea</a> involves leaving the reactor on the surface and sending the electrical power to the descending cryobot as light along a fibre-optic cable. Once the cryobot has reached the ocean it would deploy a submarine to take measurements. Communications with the cryobot could be achieved by sound waves in the ocean (think whales talking to each other) and then sent back up the connection to the surface vehicle for transmission to Earth.</p>
<p>Amazingly, these ideas have actually been <a href="https://www.newscientist.com/article/dn1786-ice-melting-robot-passes-arctic-test/">tested in Antarctica</a>. But one significant challenge is that, as the water melts, sediments build up ahead of the probe. Another is that the cryobot and submarine would have to undergo expensive extreme <a href="https://planetaryprotection.arc.nasa.gov/about">sterilisation</a> to avoid introducing any contamination to an environment that may harbour life.</p>
<p>So there are big hurdles to clear. But NASA does appear committed. It’s mission concept could possibly executed in the mid 2040s. And after Titan, who knows, we may even be hunting for <a href="https://en.wikipedia.org/wiki/Hydrothermal_vent">hydrothermal vents</a> on Europa.</p><img src="https://counter.theconversation.com/content/63417/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Chris Arridge receives funding from the Science and Technology Facilities Council (STFC), the Royal Society and the Royal Astronomical Society. He also provides scientific advice to STFC and the UK Space Agency on solar system exploration.</span></em></p>We could be exploring the oceans of Jupiter’s and Saturn’s icy moons in a couple of decades. Here’s what we need to work out.Chris Arridge, Research Fellow/Lecturer, Lancaster UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/630142016-07-27T09:37:06Z2016-07-27T09:37:06ZWhat does the solar system sound like?<figure><img src="https://images.theconversation.com/files/132048/original/image-20160726-7028-ro9h9q.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption">We will soon get to hear the winds on Mars.</span> <span class="attribution"><span class="source">NASA/JPL-Caltech/MSSS</span></span></figcaption></figure><p>“In space, no one can hear you scream” was the tagline of the 1979 box office film success <a href="http://www.imdb.com/title/tt0078748/">Alien</a>. And it’s true. Sound waves propagate mechanically as a vibration and therefore need a medium – solid, liquid or gas – to travel through. Although interplanetary (and interstellar) space is not completely empty, gas molecules and dust grains are so sparsely distributed that they do not form a continuous medium that would enable sound waves to be transmitted directly. </p>
<p>But there are many locations in the solar system where it might actually be quite noisy. Such places will have a medium through which sound waves can be transmitted – for example, an atmosphere or an ocean. And we have only started to explore what they sound like.</p>
<p>NASA announced that its next mission to Mars, <a href="http://www.jpl.nasa.gov/missions/mars-2020/">the Mars 2020 lander</a>, will carry a microphone so that the soundscape of the planet can be recorded. This is not the first time that a microphone has been sent to Mars – the US Planetary Society <a href="http://www.planetary.org/explore/projects/microphones/history.html">sponsored a microphone on the Mars Polar Lander mission</a> in 1999. Unfortunately, the spacecraft crashed before any recordings could be transmitted. A microphone was also part of one of the instruments on the <a href="http://phoenix.lpl.arizona.edu/">Phoenix Lander of 2008</a>, but because of concerns about an interface problem with the landing system, the instrument was not switched on. </p>
<h2>The tantalising sounds of Titan and comet 67P</h2>
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<img alt="" src="https://images.theconversation.com/files/132050/original/image-20160726-7028-mdj6pw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=237&fit=clip" srcset="https://images.theconversation.com/files/132050/original/image-20160726-7028-mdj6pw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=600&fit=crop&dpr=1 600w, https://images.theconversation.com/files/132050/original/image-20160726-7028-mdj6pw.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=600&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/132050/original/image-20160726-7028-mdj6pw.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=600&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/132050/original/image-20160726-7028-mdj6pw.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=754&fit=crop&dpr=1 754w, https://images.theconversation.com/files/132050/original/image-20160726-7028-mdj6pw.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=754&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/132050/original/image-20160726-7028-mdj6pw.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">
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<span class="caption">Titan in true color.</span>
<span class="attribution"><span class="source">NASA</span></span>
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<p>We do have some recordings of space sound already – when the European Space Agency’s (ESA) <a href="http://sci.esa.int/cassini-huygens/">Huygens spacecraft</a> landed on Saturn’s giant moon Titan in January 2005, the probe recorded its journey down through Titan’s atmosphere. When you <a href="http://www.esa.int/Our_Activities/Space_Science/Cassini-Huygens/Sounds_of_an_alien_world">listen to the recording</a>, you get a real impression of the capsule being buffeted by winds as it floated to the surface. </p>
<p>The point of an experiment like this is to use the sound to infer how the pressure of Titan’s atmosphere changes with depth. This can then be used to build a circulation model for Titan, similar to the ones we use on Earth to forecast the weather and understand changes in climate.</p>
<p><audio preload="metadata" controls="controls" data-duration="102" data-image="" data-title="Speeding through Titan's haze" data-size="453924" data-source="ESA" data-source-url="http://www.esa.int/Our_Activities/Space_Science/Cassini-Huygens/Sounds_of_an_alien_world" data-license="" data-license-url="">
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Speeding through Titan’s haze.
<span class="attribution"><a class="source" rel="nofollow" href="http://www.esa.int/Our_Activities/Space_Science/Cassini-Huygens/Sounds_of_an_alien_world">ESA</a><span class="download"><span>443 KB</span> <a target="_blank" href="https://cdn.theconversation.com/audio/456/huygens-alien-winds-descent.mp3">(download)</a></span></span>
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<p>And, at a time when <a href="http://www.esa.int/Our_Activities/Space_Science/Rosetta">ESA’s Rosetta mission</a> is drawing to a close, we should remember that its target comet, 67P Churyumov-Gerasimenko, <a href="https://soundcloud.com/esaops/a-singing-comet">was singing out</a> into the void as it approached the sun. We also heard <a href="https://soundcloud.com/esaops/philae-touchdown-thud#t=0:00">the thud of the comet lander Philae’s arrival</a> when it touched down on the comet in November 2014.</p>
<p>There are soundscapes of other solar system bodies including Jupiter and the rings of Saturn. But these are not direct audio recordings – they are a conversion of electromagnetic vibrations into audio signals. They sound pretty weird.</p>
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<iframe width="440" height="260" src="https://www.youtube.com/embed/-MmWeZHsQzs?wmode=transparent&start=0" frameborder="0" allowfullscreen=""></iframe>
<figcaption><span class="caption">Sounds of the planets.</span></figcaption>
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<h2>Music of Mars</h2>
<p>You only have to imagine being in a desert to realise the variety of sounds a microphone on the surface of Mars could record – and how they can be interpreted. First of all, the wind, whistling across the planetary landscape – how fast is it travelling? How often does it vary in speed or direction? What does a dust devil sound like? Or a dust storm? What about the crack of thunder associated with a lightning bolt? Or the variation in pressure during an electric storm? Once the wind drops, the gentle sounds that break the silence can be heard: the settling of dust grains disturbed by the wind. </p>
<p>There are <a href="http://www.hou.usra.edu/meetings/lpsc2016/pdf/3044.pdf">several engineering advantages</a> to having a microphone carried by a rover on Mars. As the vehicle trundles across the landscape, we might hear the noise of crashing gears, and realise that sand had clogged the wheels. This would allow engineers to diagnose problems more efficiently, and work out strategies to ameliorate or avoid them. </p>
<p>We have heard some sounds of a rover on Mars already: NASA released audio from the Opportunity rover’s 11-year marathon. But like the sounds of Jupiter and Saturn’s rings, these sounds were not recorded directly – they are a conversion of the vibrations of the rover into audio as it travelled across the surface. The microphone on the Mars 2020 mission will be the first to pick up the sounds of Mars directly and transmit them to Earth.</p>
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<figcaption><span class="caption">Rover sounds.</span></figcaption>
</figure>
<p>What is interesting about the proposal for the microphone is the instrument into which it will be incorporated. It’s not an accelerometer, as on Titan and the previous Mars microphones, but on an instrument that is designed to measure the chemical composition of the rocks and soil by vapourising them: a Laser-Induced Breakdown Spectrometer. This works by firing a laser at a target, which “explodes” as a plasma and creates a very sharp pressure wave – the acoustic signal of which is proportional to the mass of sample being destroyed. Using the microphone to set up, calibrate and focus the laser will help improve the instrument. But at the same time, a whole raft of new sounds from the surface of the Red Planet will be picked up.</p>
<p>So where else might it be interesting to listen? I’d like to hear Europa or Enceladus, the respective moons of Jupiter and Saturn. They both have an ice-covered surface, below which is a deep ocean. Imagine what a microphone might pick up as a spacecraft penetrated the ice. The groaning of the icebergs as they moved against each other. The suck and pluck of more mushy ice as it percolated up through the cracks. The sudden whoosh of an ice geyser. And then into the ocean below. Waves slapping against the base of the icesheet. Water of different temperatures mixing – what does that sound like? Will there be bubbles? And perhaps as the penetrator settles onto the ocean floor, we might hear an unexpected crab scuttle past.</p><img src="https://counter.theconversation.com/content/63014/count.gif" alt="The Conversation" width="1" height="1" />
<p class="fine-print"><em><span>Monica Grady is a Trustee of Lunar Mission One and receives funding from the STFC and the EU.</span></em></p>Scientists are excited about sending a microphone to Mars for the very first time.Monica Grady, Professor of Planetary and Space Sciences, The Open UniversityLicensed as Creative Commons – attribution, no derivatives.tag:theconversation.com,2011:article/214562013-12-12T23:25:24Z2013-12-12T23:25:24ZCassini spots mosaic of Titanic extraterrestrial seas<figure><img src="https://images.theconversation.com/files/37626/original/zntypj24-1386889799.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=496&fit=clip" /><figcaption><span class="caption"></span> <span class="attribution"><span class="source">NASA-ESA</span></span></figcaption></figure><figure class="align-center ">
<img alt="" src="https://images.theconversation.com/files/37626/original/zntypj24-1386889799.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&fit=clip" srcset="https://images.theconversation.com/files/37626/original/zntypj24-1386889799.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=600&h=575&fit=crop&dpr=1 600w, https://images.theconversation.com/files/37626/original/zntypj24-1386889799.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=600&h=575&fit=crop&dpr=2 1200w, https://images.theconversation.com/files/37626/original/zntypj24-1386889799.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=600&h=575&fit=crop&dpr=3 1800w, https://images.theconversation.com/files/37626/original/zntypj24-1386889799.jpg?ixlib=rb-1.1.0&q=45&auto=format&w=754&h=722&fit=crop&dpr=1 754w, https://images.theconversation.com/files/37626/original/zntypj24-1386889799.jpg?ixlib=rb-1.1.0&q=30&auto=format&w=754&h=722&fit=crop&dpr=2 1508w, https://images.theconversation.com/files/37626/original/zntypj24-1386889799.jpg?ixlib=rb-1.1.0&q=15&auto=format&w=754&h=722&fit=crop&dpr=3 2262w" sizes="(min-width: 1466px) 754px, (max-width: 599px) 100vw, (min-width: 600px) 600px, 237px">
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<span class="attribution"><span class="source">NASA-ESA</span></span>
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<p>The joint NASA-ESA <a href="http://www.nasa.gov/cassini">Cassini space probe</a>, exploring Saturn and her moons, has revealed extraordinary lakes and seas of liquid methane around the north pole of Titan. Scientists associated with the Cassini mission described a strange rectangular area of large seas, picked out by imaging instruments aboard the probe.</p>
<p>Elongated lakes and seas connected by long skinny peninsulas characterise the two seas picked out in the new image. Reminiscent of the topographic depressions in the basin and range province of USA, shaped by the movements of tectonic plates on America’s western fringe, there are suggestions that the large lakes seen on Titan may be tectonically shaped-seas.</p>
<p>“Scientists have been wondering why Titan’s lakes are where they are. These images show us that the bedrock and geology must be creating a particularly inviting environment for lakes,” said Randolph Kirk, a Cassini RADAR team member at the US Geological Survey. “We think it may be something like the formation of the prehistoric lake called Lake Lahontan near Lake Tahoe in Nevada and California, where deformation of the crust created fissures that could be filled up with liquid.”</p>
<p>Scientists described the observations of huge polar lakes called Ligeia and Kraken on Titan, at the meeting of the <a href="http://fallmeeting.agu.org/2013/">American Geophysical Union</a> here in San Francisco today, the world’s largest gathering of Earth scientists.</p>
<p>Alongside the two large liquid bodies picked out so clearly, there is a myriad of smaller lakes that are seen scattered around the pole of Titan. Their origins are unclear, with speculations ranging from volcanic crater lakes to giant sinkholes formed in dissolved Titan crust.</p>
<p>Marco Mastrogiuseppe from Sapienza University, Rome, described the results from RADAR imaging of the fluid bodies at Titan’s surface. “For the first time we were able to observe the topography of the subsurface of an extraterrestrial sea”, he explained. </p>
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<figcaption><span class="caption">Cassini soaring over Titan.</span></figcaption>
</figure>
<p>Cassini’s RADAR has charted the areas of the lakes and seas near the pole, but has also bounced signals off the lake beds in the first depth soundings of an extraterrestrial sea. </p>
<p>“Ligeia Mare turned out to be just the right depth for radar to detect a signal back from the sea floor, which is a signal we didn’t think we’d be able to get,” said Mastrogiuseppe. A maximum depth of around 170 meters, similar to Lake Michigan, was found, and the lake was crystal clear to RADAR eyes.</p>
<p>The total volume of Ligeia is put at 9000 cubic kilometres and it is filled not with water, but with hydrocarbon fluids. The total volume of the hydrocarbon Titanic seas corresponds to around 300 times that of Earth’s oil reserves, in a celestial body smaller than Earth.</p>
<p>The RADAR reflectivity suggests that the lakes are mainly filled with methane alongside a few other heavier hydrocarbon fluids. These include ethane and nitrogen. Alongside Ligiea sits another sea, Kraken. Comparable in size to the Caspian Sea here on Earth, Kraken is four or more times the area of Ligeia. Cassini will return to carry out bathometry of it in August 2014.</p>
<p>Jeffrey Kargel, from the University of Arizona Tucson, pointed out that the presence of extensive methane seas and lakes at Titan’s north pole makes worse a long acknowledged deficiency of heavier hydrocarbons expected from models of Titan’s chemistry. Among them are ethane, ethylene, propylene, acetylene and benzene - heavy hydrocarbons generated as sunlight causes chemical reactions in Titan’s soup of natural gas. Using visual imaging instruments Cassini has revealed that Titan has a northern polar cap larger than Greenland.</p>
<p>Bright deposits around the lakes show the nature of the solid surface. In a world that is difficult to imagine, crystallised heavy hydrocarbons form Titan’s crust, with suggestions of huge dune fields of solid hydrocarbon sand around the equator. While these equatorial “rocks” are saturated in ethane the polar regions appear to be made of methane.</p>
<p>We are now close to summer solstice on Saturn, and Titan has weather that changes with the seasons. Giant storms arise on Saturn, with jets of gas seen shooting from the south pole of cousin moon, Enceladus. A fly-by is planned in 2015 in which Cassini will fly through these plumes and take a closer look at Enceladus’ north pole.</p>
<p>Cassini is now in a set of intricate complicated orbits. Only 4% of its propulsion is left, and future fly-bys are largely powered by the gravitational fields of Saturn and its moons. The probe’s final journey, planned for September 2017 will skirt Saturn’s innermost ring and touch her atmosphere before finally succumbing to the giant planet’s grasp.</p><img src="https://counter.theconversation.com/content/21456/count.gif" alt="The Conversation" width="1" height="1" />
The joint NASA-ESA Cassini space probe, exploring Saturn and her moons, has revealed extraordinary lakes and seas of liquid methane around the north pole of Titan. Scientists associated with the Cassini…Simon Redfern, Professor in Earth Sciences, University of CambridgeLicensed as Creative Commons – attribution, no derivatives.