What Saturn's most mysterious moon could teach us about the origins of life | Elizabeth Turtle

77,622 views

2020-09-17 ・ TED


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What Saturn's most mysterious moon could teach us about the origins of life | Elizabeth Turtle

77,622 views ・ 2020-09-17

TED


Please double-click on the English subtitles below to play the video.

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Picture a world with a variety of landforms.
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It has a dense atmosphere
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within which winds sweep across its surface
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and rain falls.
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It has mountains and plains,
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rivers, lakes and seas,
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sand dunes and some impact craters.
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Sounds like Earth, right?
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This is Titan.
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In August 1981,
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Voyager 2 captured this image of Saturn's largest moon.
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The Voyager missions have traveled farther than ever before,
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making the solar system and beyond
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part of our geography.
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But this image, this hazy moon
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was a stark reminder of just how much mystery remained.
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We learned an exponential amount as the Voyagers flew by it,
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and yet we had no idea what lay beneath this atmospheric blanket.
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Was there an icy surface with landforms like those of the other moons
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that had been observed at Saturn and Jupiter?
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Or perhaps simply a vast global ocean of liquid methane?
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Shrouded by the obscuring haze,
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Titan's surface was a huge, outstanding mystery
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that Cassini-Huygens, an orbiter lander pair launched in 1997,
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was designed to solve.
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After arrival in 2004,
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the early images Cassini sent back of Titan's surface
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only heightened the allure.
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It took months for us to understand what we were seeing on the surface,
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to determine, for example,
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that the dark stripes,
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which were initially so unrecognizable that we referred to them as cat scratches,
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were actually dunes made of organic sand.
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Over the course of the 13 years Cassini spent studying Saturn
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and its rings and moons,
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we had the privilege
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of going from knowing almost nothing about the surface of Titan
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to understanding its geology,
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the role the atmosphere plays in shaping its surface,
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and even hints of what lies deep beneath that surface.
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Indeed, Titan is one of several ocean worlds,
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moons in the cold outer solar system
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beyond the orbits of Mars and the asteroid belt
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with immense liquid water oceans beneath their surfaces.
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Titan's interior ocean may have more than 10 times as much liquid water
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as all of the Earth's rivers, lakes, seas and oceans combined.
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And at Titan, there are also exotic lakes and seas
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of liquid methane and ethane on the surface.
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Ocean worlds are some of the most fascinating places
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in the solar system,
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and we have only just begun to explore them.
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This is Dragonfly.
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At the Johns Hopkins Applied Physics Laboratory,
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we're building this mission for NASA's new Frontiers program.
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Scheduled to launch in 2026 and reach Titan in 2034,
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Dragonfly is a rotorcraft lander,
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similar in size to the Mars rovers or about the size of a small car.
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Titan's dense atmosphere, combined with its low gravity,
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make it a great place to fly,
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and that's exactly what Dragonfly is designed to do.
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Technically an octocopter,
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Dragonfly is a mobile laboratory that can fly from place to place
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taking all of its scientific instruments with it.
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Dragonfly will investigate Titan in a truly unique way,
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studying details of its weather and geology,
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and even picking up samples from the surface
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to learn what they're made of.
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All told, Dragonfly will spend about three years exploring Titan,
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measuring its detailed chemistry,
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observing the atmosphere and how it interacts with the surface,
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and even listening for earthquakes,
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or technically titanquakes, in Titan's crust.
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The Dragonfly team,
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hundreds of people across North America and around the world,
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is hard at work on the design for this mission,
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developing the rotorcraft, its autonomous navigation system
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and its instrumentation,
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all of which will need to work together to make science measurements
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on the surface of Titan.
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Dragonfly is the next step in our exploration
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of this fascinating natural laboratory.
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In flying by, Voyager hinted at the possibilities.
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In orbiting Saturn for over a decade
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and descending through Titan's atmosphere,
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Cassini and Huygens pulled Titan's veil back a bit further.
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Dragonfly will live in the Titan environment,
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where, so far, our only close-up view
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is this image the Huygens probe took in January 2005.
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In many ways, Titan is the closest known analogue we have to the early Earth,
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the Earth before life developed here.
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From Cassini-Huygens' measurements,
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we know that the ingredients for life,
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at least life as we know it,
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have existed on Titan,
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and Dragonfly will be fully immersed within this alien environment,
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looking for compounds similar to those
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that might have supported the development of life here on Earth
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and teaching us about the habitability of other worlds.
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Habitability is a fascinating concept.
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What's necessary to make an environment suitable to host life,
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whether life as we know it here on Earth,
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or perhaps exotic life that has developed under very different conditions?
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The possibility of life elsewhere
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has inspired human imagination and exploration throughout history.
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On a grand scale,
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it's why the ocean worlds in the outer solar system
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have become such important targets for study.
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It's the "what if" that drives human exploration.
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We don't know how chemistry took the step to biology here on Earth,
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but similar chemical processes may have happened on Titan,
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where organic molecules have had the opportunity
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to mix with liquid water at the surface.
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Has organic synthesis progressed under these conditions?
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And if so, how far?
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We don't know ... yet.
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What we will learn from Dragonfly, this fundamentally human endeavor,
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is tantalizing.
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It's a search for building blocks, foundations, chemical steps
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like those that ultimately led to life on Earth.
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We're not sure exactly what we will find when we get to Titan,
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but that's exactly why we're going.
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In 1994, Carl Sagan wrote,
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"On Titan, the molecules that have been raining down
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like manna from heaven for the last four billion years
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might still be there,
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largely unaltered, deep-frozen, awaiting the chemists from Earth."
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We are those chemists.
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Dragonfly is a search for greater understanding,
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not just of Titan and the mysteries of our solar system,
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but of our own origins.
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Thank you.
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