A soaring quest through the Solar System's exotic and hidden water realms, from the deep seas below the icy crust of Europa to the vast prehistoric oceans that once existed on Mars billions of years ago.
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LearningTranscript
00:00The oceans define the Earth.
00:11They're crucial to life.
00:15In fact, without the oceans, there would be no life.
00:21We once thought they were unique to our planet.
00:25But we were wrong.
00:30We've recently discovered oceans all over our solar system, and they're very similar to our own.
00:37Imagine this at the bottom of Enceladus' ocean.
00:42Now, scientists are going on an epic journey in search of new life in places that never seemed possible.
00:49Life has got this amazing ability to, you know, just keep surprising us.
00:54I want to get data back from a probe and be able to say, it's life, Jim, but not as we know it.
01:04The hunt for oceans in space marks the new dawn of an era in the search for alien life.
01:10Nearly two centuries ago, Charles Darwin set out on a journey across the world's oceans to uncover the secrets of life.
01:35What he came to understand was that the answer to the mystery of where we came from lay beneath the hull of his ship, the beagle.
01:46As he filled his notebooks with beautiful sketches of the birds and animals he came across, he began to formulate an idea that life might actually have started in water.
02:00Darwin's important for the whole story of the evolution of life, the natural selection, where we all came from, how life ultimately started as well.
02:10A lot of that goes back to Darwin. He had ideas, not very well publicized ideas, not in the origin of species, but on how life started in a small, warm pond.
02:19So Darwin had put his finger on the importance of water in the origin and evolution of life very early on.
02:26Water is so essential that it's dictated where scientists look in the search for life in our solar system.
02:34Life needs water. We look at all life forms on Earth. The one requirement they all have in common is water.
02:40An ocean may be a good place to incubate life, and not surprisingly, an ocean has got what life needs to survive.
02:47Everywhere where we look on Earth, whether it's frozen or boiling hot, wherever we find water, we find life.
02:54Water is our working fluid. You're mostly made up of water. I'm mostly made up of water.
02:58The search criteria was simple. To find life, first, find a liquid ocean.
03:06Only beyond Earth, there didn't seem to appear to be any in our solar system.
03:11There used to be the idea of the Goldilocks zone, where everything was just right for water to be in the liquid state on the surface of a planet.
03:18And Earth was a slap-bang in it. Venus was too close to the Sun, too hot, really, for liquid water on the surface.
03:26Mars thought to be a little bit too far away.
03:28But is finding liquid water and life on Mars impossible?
03:39We have been sending increasingly more complex and sophisticated spacecraft to the Red Planet for decades,
03:46and we now know more about it than we ever did.
03:49Unfortunately, all the scientific evidence gathered so far points to Mars being dry, cold, and seemingly lifeless.
03:59But has it always been that way?
04:02It's a question that's intrigued scientists and astronomers like Geronimo Villanueva for years.
04:09Ironically, the search for evidence of an ancient Martian ocean is being conducted from one of the driest places on Earth,
04:16the Atacama Desert in Chile.
04:19So there's a strong relationship between Mars and Atacama, because Mars is a very dry place,
04:25and Atacama is one of the driest places on the planet.
04:27Actually, the relative humidity measured by Curiosity rover on Mars is practically the same as we are right now here on this desert.
04:35Fittingly, it's that lack of water that makes the Atacama the perfect place to build one of the biggest telescopes in the world,
04:43because water in the atmosphere here would drastically limit the telescope's ability to find water
04:49anywhere else.
04:50Water and many other things like organics are what we're looking for.
04:54So we come to a place which is devoid of those things, like a desert.
04:57So we don't get the contamination from those things when we observe through the atmosphere.
05:02So when you come to a place like this, you're looking for, you're looking, trying to look through the water in our own atmosphere.
05:07What's immediately obvious to anyone with even an ordinary telescope is that there is water on Mars, but today it's frozen solid at the poles.
05:19Yet the Martian landscape looks strangely as though it was carved and shaped by liquid water.
05:25Planets show all this morphology, geomorphology driven by water, a huge amount of water.
05:31So the estimates of how much it was on the planet vary a lot, because we didn't know.
05:35I mean, we see all this carving, all these big valleys, and so how much water was there was a big question.
05:40Answering that question was pretty much impossible until scientists got lucky in 1984 in another desert, this time in the coldest place on Earth, Antarctica.
05:59Here they found a remarkable meteorite.
06:02Analysis confirmed it was Martian in origin, and that they had discovered the key that would unlock the mystery of Mars' watery past.
06:13So once you identify when in the history of our solar system where it came, then say, okay, this rock is dated there, and it came from Mars.
06:20So you have a good reference point in time and in place of that rock.
06:25Careful analysis revealed that this meteorite was four and a half billion years old.
06:32The meteorite also carried crucial chemical information, an isotopic signature fixed by the amount of water on Mars four and a half billion years ago.
06:43On its own, this signature was worthless, but by measuring the amount of water on Mars today,
06:49then comparing the signatures of recent rocks against the ancient meteorite, all would be revealed.
06:56And that's where the huge telescope comes in.
06:58It's so powerful, it can detect water molecules on the surface of the planet.
07:08Armed with a precise measurement of the amount of water on Mars today,
07:12Geronimo was able to make an astonishing calculation.
07:15We extrapolated back in time and we inferred that there was almost seven times more water than it's right now.
07:28What happened, Mars, topographically speaking, has very low plains in the north and a very high altitude place on the south.
07:35So if you throw water, it will tend to flow into the lower topography, which is going to be the northern plains.
07:41So one of the things we did is, okay, so we have this volume of water and so what do we do with this?
07:45So one trick we said, okay, was just throw it on the planet and let's see where it falls.
07:50And we just did like, you know, follow the rivers and everything and it formed an ocean on the northern plains of the planet.
08:04NASA's Planetary Models
08:13Four and a half billion years ago, Martian Ocean covered 19% of the planet and was as deep as the Mediterranean.
08:21In fact, NASA's planetary models reveal a Mars at its warmest, complete with an Earth-like atmosphere.
08:29If you were in an alien spacecraft randomly coming to Earth, the chances are better than even that
08:38you're going to land up in water. So bring a boat. And it's the same on early Mars. And that's a
08:44fundamental point that Mars was a water world. It would have been better to characterize it as a
08:49water world, whereas now, of course, it's a desert world. But it's that water world that's interesting.
08:54That's the world that may have had life. And that's the world we want to investigate.
09:05It even had waves. The reduced gravity on Mars meant that these waves would have been twice as
09:12tall as those on Earth, a surfer's paradise. But according to NASA's scientists,
09:19most of the time, you'd have to be pretty tough to catch a Martian wave.
09:23If we think back to early Mars, we would expect it to be an Earth-like environment if it had water
09:31and a thicker atmosphere and was warmer. The one big difference, I think, would be that it would be
09:37more like the Arctic Ocean. It would be an ice-choked, ice-covered ocean. So if you imagine
09:43standing on the north shore of Greenland, looking out at the ice packs moving, I think you'd get a good
09:49imagination of what early Mars might have been like. It may have been cold. Mars is much further
09:57away from the Sun than the Earth. But four and a half billion years ago, life on Mars would have
10:03been technically possible. This is the time when Mars was the most habitable time. When the planet
10:09was formed, actually, planet Earth and Mars were similar in some aspects. It had a thicker atmosphere.
10:14Maybe there was a big ocean there. So habitability of the two planets were similar. And interestingly,
10:19the time that we think this ocean was there was the time that life started on our planet.
10:24So, you know, if the conditions were favorable for life here to start life, you know, what could be
10:29the conditions on the planet Mars? Sadly, however habitable that early ocean was, it didn't last.
10:38Scientists think that the early Martian atmosphere was vulnerable to solar radiation. And over the course
10:44of one and a half billion years, it evaporated away, leaving just 13% frozen at the poles.
10:51But if Martian life was theoretically possible in that ocean millions of years ago, is it possible
10:58that anything could have survived until now? I think the possibility of finding life on Mars now
11:06traces directly to the possibility of finding liquid water on Mars that's relatively fresh.
11:16And finding water has been a large part of the Curiosity rover's mission.
11:21Curiosity has been rolling around Mars since 2012, and the images it's been sending back have been stunning.
11:30Sequences like this blue sunset are starting to change our understanding of the planet.
11:36But it's the pictures from the Mars Reconnaissance Orbiter of a region called the Newton Crater that are
11:42helping to shed new light on the amount of liquid water left on Mars.
11:46This is a time-lapse sequence showing streaks on the crater wall, apparently growing and getting darker.
11:54Scientists think that they might be caused by water.
11:58The small amounts of water, compared to an ocean on Earth or even an ocean on early Mars, they're
12:05insignificant. But as an indicator of Mars still being active, as still having liquid phases,
12:12and maybe a hint of bigger and better things elsewhere, then I think it's very important.
12:19What appears to be happening is that the moisture in the soil is evaporating during
12:23the relative warmth of the day and condensing back at night when it's colder.
12:28So Mars still has a heartbeat, it's a faint one, if we measure its heartbeat in terms of the presence of water.
12:35At one time it was huge, it was an ocean, and now there's just a faint glimmer of it.
12:39The problem is that these small amounts of water are exceptionally salty.
12:46The Curiosity rover has identified in the Martian soil a salt called calcium perchlorate.
12:52It's this salt that absorbs the Martian dew as it condenses onto the cold surface each day.
12:58The salt also lowers the water's freezing point, keeping it a liquid even at sub-zero temperatures.
13:10But it also makes these faint traces of brine so concentrated,
13:15they would be toxic to conventional life forms. So could they support life on Mars?
13:28There may be clues in the saltiest parts of the Earth, like the Bonneville salt flats in Utah.
13:35It's famous for land speed records, but it's fascinating for astrobiologists,
13:40because the salty surface here not only mimics that found on Mars, it also contains life.
13:48Even though this looks dead, we could probably take some of these crystals right here and get bacteria to grow.
13:56I know it seems ridiculous, but, you know, as a microbiologist, one of the things that we've
14:03come to appreciate is if there's any liquid water present, you're typically going to find life.
14:10So life has got this amazing ability to, you know, just keep surprising us.
14:17Unfortunately, Mars is way colder than the Bonneville salt flats.
14:21The average temperature of minus 58 Fahrenheit is a huge challenge for anything living on the surface of the red planet.
14:32And it's partly to do with the angle of its axis.
14:36Earth spins on an axis of 23 degrees, which should make the planet unstable, but it isn't.
14:43Earth's axis is stabilized by the moon. It's sort of like an outrigger, a gravitational outrigger that keeps the Earth stable.
14:50Mars doesn't have a large moon, and so, and it's also closer to Jupiter.
14:54As a result, its axis wobbles significantly, much, much more than Earth's, more than double the wobble of Earth.
15:02Over 100,000 years, Mars' tilt wobbles by as much as 10 degrees, causing huge climate change,
15:09similar but more extreme than the Earth's ice ages.
15:13At the peaks of that cycle, the surface of Mars is briefly warm enough to support life,
15:19but to survive 100,000 years of cold between these peaks would demand a strategy of extreme hibernation.
15:29For microorganisms, this strategy of living when it's warm and then sleeping when it's freezing cold is a good one.
15:36Those organisms can be frozen and thawed without any damage at all.
15:40Every once in a while, when the tilt is right, you get a few thousand years of time to have a go at it,
15:46and then you go back to deep-free sleep.
15:52That all sounds fine in theory, but could any living thing possibly hibernate for up to 100,000 years?
16:00The answer lies in the salt.
16:07The salt crystals form in cubes, and as they form, you'll have pockets of liquid that become entrapped as
16:17the solid salt is forming. And the microorganisms that are present become trapped in those fluid inclusions,
16:26those little pockets of fluid. How long then could a single bacteria survive trapped in a salt crystal?
16:34Melanie took a crystal dated at 97,000 years old and drilled into its core. She extracted the fluid,
16:43placed it in a nutrient-rich dish, and walked away. When she came back a week later, something
16:50astonishing had happened. 97,000-year-old bacteria were flourishing in the dish.
17:00It was pretty amazing, you know, to be able to have such strong evidence. I mean,
17:11taking that fluid inclusion up and using it to inoculate the media, you know, and then having
17:18something to grow, that's pretty, pretty powerful stuff.
17:23So, right here on Earth, these bacteria have developed a hibernation strategy extreme enough
17:36to cope with the length of the Martian Ice Age. But even at its warmest, Mars is much colder than
17:42the Bonneville salt flats. Extreme endurance alone wouldn't be enough.
17:47So, is there any life form capable of hibernating through extreme cold?
18:09This doesn't look like the place to answer the question, what life forms might be able to
18:14hibernate through extreme cold? But biologists Carl Johansson and Byron Adams aren't here just to
18:20drink in the obvious beauty of the Bridal Veil Falls in Utah.
18:25What we want to try and target is that base there where the upper falls are kind of falling down.
18:29Just right below the main part of the fall, you can see all the moss beds that are in there.
18:33That's all going to be good stuff. You get in there. It's nice and slick.
18:38All right, let's go.
18:44They're looking for a creature with an unusual ability, one that might prove crucial in the
18:50search for alien life. Not surprisingly, it loves water, and there's plenty of that here.
18:58Yeah, this looks good. There's a good way around this way, I think.
19:03It's a good spot. Watch your step, man. It's slippery, bro. Yeah, this looks really good here, man.
19:09Yo, Carl. Bag me, bro.
19:13This creature is so small that it's almost impossible to see with the naked eye.
19:19Being small doesn't mean it's insignificant. It just means they have to collect lots of very
19:25damp moss to make sure they wrangle one. Bag them and tag them. He's got it.
19:35Dude, I'm taking it right here, bro. It's like raining on me.
19:39I know it. That's why I got a hose.
19:42It's only when they get back to their lab at Brigham Young University that they can see what they've got.
19:47So when we look at the slide that Byron bought us, we start looking through,
19:56we can see some movement right here of an animal. This is the tardigrade. Tardigrade
20:03means this Latin name, slow stepper. Tardigrade means slow. In grade, it refers to foot. And you can
20:09start to see he's got long thin filaments coming off his body and some actual more almost look like
20:16horns coming off his head that he uses in feeding. Tardigrades are aquatic, so you'd expect them to
20:23die if they weren't in water. But they have a very special ability.
20:28As that sample jar starts to dry out, as that specimen starts to dry out,
20:32what's cool about these guys is they can survive that extreme desiccation,
20:36drying down to like a crispy little booger. It's called a ton. They roll up into a special
20:44tight ball essentially, like a roly-poly bug almost, and then go through a series of radical
20:51chemical changes in the cells in their bodies to deal with this loss of water.
20:57It looks like it's dead. But when they add water, it springs back to life.
21:08As well as surviving extreme cold, tardigrades have another trick up their sleeve. In 2007,
21:14the European Space Agency sent a sample of tardigrades up to the International Space Station
21:20for an astonishing experiment. Took them into space, put them on a satellite, opened up the door,
21:27set them outside, exposed them to extreme temperatures, vacuum, right? Hot, cold.
21:34Huge radiation. And then when they brought them back to Earth, they did what you're seeing here,
21:38they dumped some water on them, see if they actually reanimated.
21:41What happened? Voila. They take the water up, man, and they start, right? They swap out the molecules
21:49and like a machine, man. You add the water to it, they take them up, cells start to do their thing
21:55again, and they come back alive. It always blows my mind. Look, I'm an old, fat dude, and I've looked
22:00at these a hundred times. Thousands of times. Millions, maybe. Man, well, and then when I actually
22:07look at them under the microscope every single time, I'm like, dang, that's cool, man.
22:13So the remarkable tardigrade can survive the extremes of space and the killing cold of Antarctica,
22:20conditions similar to modern-day Mars. And of course, life can also survive for tens of thousands
22:28of years locked away in a salt crystal. So there could possibly be life on Mars.
22:36It used to have an ocean, and there might still be traces of that ocean left today.
22:42But what about the rest of our solar system?
22:58From the early 1960s, scientists have been sending probes out into the furthest reaches of our solar
23:05system, looking in part for liquid water. But everything appeared largely frozen, dry, and lifeless.
23:18Most of our solar system was colder than anywhere on Earth, even the icy wastes of the high Atacama desert.
23:28But in these remote mountains, scientists have uncovered tantalizing clues that could help answer the
23:34question, are Earth's rich and flourishing oceans unique or ubiquitous?
23:44And the Voyager probe launched by NASA in 1977 pointed the way.
23:48In 1980, it photographed a small moon of Saturn called Enceladus.
23:56It's tiny, about the same size as the United Kingdom, and at first, it looked insignificant.
24:02Enceladus is this bizarre little moon that the Voyager spacecraft took a few snapshots of.
24:11The surface could be seen to be cratered in the north, a lot of craters on its icy surface.
24:17Now, to a planetary scientist and astronomer, that means old ice. But in the south, and in particular,
24:25down near the south pole, what was seen was a fresh ice surface, very few craters.
24:32If the ice was fresh, then where had it come from?
24:39Scientists had to wait for years before they got an answer.
24:44And it was provided by the Cassini probe, which spanned past Enceladus in 2005.
24:50And what Cassini saw shocked scientists.
24:56Plumes of water vapor pouring out from the surface of the little moon's south pole.
25:00So when Cassini returned these images of the plumes, the community just went nuts.
25:08This was astounding to see these jets of water erupting out of this bizarre little moon.
25:13Enceladus is just 500 kilometers in diameter. That's about the width of the United Kingdom.
25:19And to see these jets erupting was phenomenal.
25:24As Cassini got closer to Enceladus, it revealed the plumes were spewing not just from one crack,
25:31but from four huge fractures in the ice.
25:36Each of them was about 81 miles long, one and a half miles wide, and about 1600 feet deep,
25:45with water vapor pouring out of them. That amount of water could only mean one thing.
25:52Enceladus had to have a liquid ocean beneath its frozen surface.
25:56But this dark subterranean ocean would be lacking in something that's crucial for life on Earth.
26:05Life as we know it needs not only liquid water.
26:09It also requires the elemental building blocks for life, the carbon, the hydrogen, the oxygen,
26:15a smattering of the elements across the periodic table.
26:19In the darkness of Enceladus' hidden oceans, there could be no photosynthesis to capture the sun's energy.
26:41Yet the possibility of finding life there isn't entirely hopeless.
26:46It's a massive geyser field.
26:53It sits over two and a half miles above sea level.
26:57high in the Atacama desert, and it's a flurry of hydrothermal activity.
27:06And there's something bubbling up here that makes the prospect of life on the distant moon of Enceladus just a little more feasible.
27:15And there's something bubbling up here that makes the prospect of life on the distant moon of Enceladus just a little more feasible.
27:28Well, the clue is what we find here on Earth.
27:32If we look alongside of this geyser, we see these geyser pearls.
27:39This is silica, SIO2, that has sintered out of this geyser water.
27:46And the cosmic dust analyzer on the Cassini spacecraft has captured grains like this, except much, much smaller.
27:59And the fact that those grains are found in the plume of Enceladus leads us back to the water-rock interaction,
28:07where that silica in the plumes of Enceladus could only be there if the ocean of Enceladus is cycling with an active, rocky, potentially hot seafloor.
28:22Cassini's measurements indicated that deep in the oceans of Enceladus, a process very similar to the geysers of El Tatio must be underway.
28:31If you simply remove the water and have dry surfaces, everything would remain stuck in its place on the surface,
28:38and there'd be no movement to bring things together to react.
28:41So I suppose water is the universal lubricant that makes things happen.
28:48And the evidence for that can be found throughout this seemingly inhospitable environment.
28:53But at the most basic level, biology is a layer on geology.
29:02Biology is harnessing some of the stored chemical energy that exists in chemically rich waters interacting with rocks.
29:11And right here we've got a beautiful example of exactly that kind of biology being a layer on geology.
29:18Everything that you see here, the red that you see, those are microbes utilizing the rich chemistry of the geyser water.
29:30The presence of these extreme life forms thriving in almost alien chemistries raises real hope for scientists,
29:38not just in the search for life, but in answering one of biology's most fundamental questions.
29:44Is there a second independent origin of life elsewhere within our own solar system?
29:51And if there is, then that tells us that life arises wherever the conditions are right,
29:57and we live in a biological universe.
30:01If we don't find life within these worlds, then that may be an indication that the origin of life is hard,
30:07and that life is quite rare within our solar system and beyond.
30:14Both outcomes are equally profound.
30:16Both outcomes are equally profound.
30:36Is there really only one way to cook up life?
30:40Could life form from a different set of ingredients?
30:43Science fiction writers have speculated wildly about alternative life forms.
30:49But in the cold, hard world of science, we only have proof of life as we know it.
30:55But if an ocean really is critical, does it have to be an ocean of water?
31:00That's a question that drives NASA's Chris McKay.
31:03What I'm really interested in finding is what I call a second genesis of life.
31:09Organisms that are clearly not related to any life on Earth.
31:13All life on Earth is related to itself, forms a single tree.
31:17You can call that life one.
31:19What I'm looking for is life two, something that's not related.
31:23It doesn't have to be profoundly different, but it has to be different enough that we can
31:27say with very high confidence that they are not related to us, we do not have a common ancestor.
31:36Where such a life form could feasibly emerge was anyone's guess.
31:41Until in 2005, the world's attention turned to Titan, the biggest of the moons which orbit around Saturn.
31:53At that time, all we knew of it was that it looked gassy, orange, and lifeless.
31:59We knew that Titan was a fuzzball from telescopes. Before spacecraft ever went to Titan,
32:04just looking at Titan with a telescope, we could tell that it had a thick atmosphere.
32:08We didn't know the composition of the atmosphere or the temperature of it, but we knew it had a thick atmosphere.
32:16But then in 2005, the Cassini-Huygens probe passed by revealing a surface that was unexpectedly Earth-like.
32:25It was dotted with huge bodies of water, bearing an uncanny geographical similarity to the Great Lakes.
32:37From a physical point of view, the presence of liquid creates all these other similarities.
32:42And so we realize that liquid on Earth, liquid on Titan, we're going to expect a lot of commonality,
32:48and we see it. And so visually, when we look at these images of the lakes, we see reflections of what
32:53we see in airplanes when we look down as we fly over the Great Lakes.
32:57There was one crucial difference, though. These weren't lakes of water. They were lakes of methane.
33:03And at minus 292 Fahrenheit, they're too cold for any life form with an Earth-like chemistry.
33:11I would contend that we don't understand the role of temperature directly in life.
33:15Now, on Earth, of course, we're used to living in a high-temperature liquid at high temperature.
33:21We're in the fast lane. We metabolize very rapidly because we're living at high temperature.
33:28Well, on Titan, the liquid that's there is cold, the temperatures are cold.
33:33If there's life there, it's obviously in the slow lane. It's metabolizing very slowly.
33:37But so what? What's the rush? There's not an absolute tempo that life must keep to.
33:51But is that possible? Can you have life using methane rather than water?
33:57With this in mind, scientists at the picturesque and very watery Cornell University in New York
34:03are trying to establish whether methane-based life is even theoretically possible.
34:10They took the chemical ingredients that exist on Titan and mixed them up.
34:18Not in a test tube, but inside a computer.
34:28The computer built a three-dimensional membrane.
34:31The outside wall of a cell.
34:37Except this alien membrane functions in methane, not water.
34:46It's not life yet. It's just a house.
34:49But the very first thing that you have to do is you have to have somewhere to shelter.
34:54A membrane is a way of keeping the outside to the outside.
34:59A small step, but this was groundbreaking science.
35:04For the first time, it opened up the possibility that there could be a second tree of life.
35:11We tend to think that life would look like us. You just have to look at the Star Trek movies.
35:15All the aliens kind of look like insects and things that we already know.
35:19But why not be something completely different?
35:22Something that we can't imagine, but something perfectly suited to the conditions that are on Titan.
35:28But if this extraordinary computer model is right, how would we know?
35:40Right now, we can't physically search for life on Titan.
35:43But that doesn't mean there wouldn't be other telltale signs that we can detect.
35:53The Star Trek movies are on Titan.
35:58The Star Trek movies are on Titan.
36:01The Star Trek movies are on Titan.
36:03In 2005, astronauts finally had an opportunity to test the hypothesis that hydrogen is the key to life,
36:09when the Cassini spacecraft sent down a probe called Huygens to land on Titan.
36:15The pictures the probe sent back were stunning.
36:18Unfortunately, there were no obvious signs of life.
36:22But Huygens was doing more than taking images of Titan.
36:26It was making detailed measurements of the mysterious atmosphere.
36:31As it turned out, the most important were the readings it took of hydrogen levels
36:35as it floated down from space to the surface.
36:38As the probe landed, scientists noticed something remarkable.
36:47The hydrogen levels dropped abruptly.
36:52When I heard about this result, for a couple minutes I was ecstatic, thinking,
36:56oh my God, this is just textbook science.
36:59Prediction, confirmation, you know, Nobel Prize comes next, right?
37:04But reality set in soon after, as I looked at the paper in detail,
37:08and considered how easy it is to jump to the answer you want.
37:13It's really a question of excluding other possibilities.
37:22On its own, Huygens' sensational measurement was inconclusive.
37:27What they needed was verification.
37:30So NASA put together a team of their best and brightest engineers to design a spacecraft capable
37:35of exploring the unique and technically challenging oceans of this liquid world.
37:45And after a number of false starts and dead ends, they came up with this.
37:51A submarine.
37:53I was reading 20,000 Leagues Under the Sea.
37:55I thought, you know, Titan has this wonderful groups of seas.
37:59What's underneath there?
38:01If we don't look there, we really haven't seen what's going on in Titan.
38:04So we came up with a fairly long, long submarine.
38:09As you see for terrestrial submarines, they're usually about 10 to 1 dimensions,
38:14length to the diameter.
38:15And the reason for this is it really reduces your drag.
38:18We are obviously a little power limited.
38:20We have a lot of communications to do.
38:21We have four thrusters in the back here, which is usually electrical energy.
38:25So we went with a very long submarine.
38:27If you can get below the surface of the sea and get all the way down to the bottom in certain areas
38:33and actually touch the silt that's on the bottom and sample it and learn what that's made of,
38:37it'll tell you so much about the environment that you're in.
38:39But if you have a boat that just drives on the surface, figuring out how to get a probe all
38:46the way down to the bottom, get that sample all the way back up to the surface and sample it,
38:51really becomes an intractable problem.
38:53There's so many things that could go wrong doing that.
38:56And instead, we said, if we can encapsulate everything together in a submarine,
38:59then we could go right down and do that sampling and come all the way back up to the surface.
39:12But sailing a large one tub sub around Titan's super cold methane rich seas isn't without its problems.
39:19Fortunately, NASA has the technology to replicate conditions on the freezing moon.
39:27And this is it.
39:29Inside this huge tank, scientists can safely and accurately mix up the highly volatile cocktail of
39:37chemicals that make up the atmosphere of the huge moon.
39:43As we design and build craft, we can basically use this facility to test
39:49problems or issues that come up for the submarine. So we can use this facility to basically
39:55create the seas of Titan, the coldness of Titan, the pressures of Titan.
40:00They have discovered that one of the biggest problems of Titan's methane seas
40:05is that they're rich in nitrogen, and that could make it very difficult to maneuver.
40:11There could be so much nitrogen dissolved in the sea that when the propellers turn on our jets,
40:17it might just make a lot of bubbles and not be able to push against the liquid.
40:20So we're doing analysis now and we hope to do some testing in the near future
40:24that shows us what happens if you spin a propeller in liquid methane and liquid ethane
40:30with lots of nitrogen dissolved in it. And can you get any thrust out or not?
40:34This is a really important question to answer. There's other ways to propel the submarine if that
40:38doesn't work. But the design that we came up with helps us get to that simple place in terms of space operations.
40:53The sub will be packed full of scientific instruments and teaming with cameras.
40:58But there's one thing the scientists feel will make the mission more than anything else.
41:07That first picture, are you kidding? That first picture from a submarine,
41:11from anybody's submarine on the surface of a sea on another planet in our solar system,
41:17changes the world. I mean, that's something that none of us had ever seen before.
41:21That is true discovery. That is why we do any of this. And that would be awesome.
41:26That first picture alone would make this entire mission worth it.
41:30Scientists aren't saying that the cameras of the Titan sub will definitely
41:34ping back pictures of living organisms. But they believe sending a sub to this strange moon
41:41gives them the best chance of finding a new form of life.
41:45I grew up when Star Trek was just coming out. And it was an inspiration to me. But the key moment
41:54was when I realized that the job I wanted was not Kirk's job, but Spock's job. He's the one with the
42:00tricorder. He's the one that's detecting life. And my favorite saying is, it's life, Jim, but not as we
42:07know it. That's what I want to be able to say. I want to get data back from a probe, Titan, Mars,
42:13and tell us wherever, and be able to say, it's life, Jim, but not as we know it.
42:20We used to think that the rest of our solar system was frozen and dead. But we now know
42:25that there are oceans of water and liquid in places we never thought possible. In 2015, the New
42:32Horizon mission to Pluto checked off the last of the great worlds to be explored in the solar system.
42:39But we're only at the beginning of the quest to find the holy grail of space science, life.
42:46We're through with the age of discovery. We've discovered all the planets. We know it's there.
42:51We've got a rough map of them all, a rough understanding of how they work. The next question,
42:56the question that I think should motivate and guide planetary science for the next 20 years,
43:01is, is there any life in these various and diverse oceans? Nearly two centuries ago,
43:09Charles Darwin set out on a voyage of discovery that changed the world. Perhaps NASA's Titan submarine
43:16will be a modern counterpart of Darwin's ship, the Beagle, and in the search for a new form of life,
43:23will boldly go where no one has gone before.
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