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00:00the question is no longer if but when looking for life beyond earth has been a human obsession for
00:16centuries but it was brought into sharp relief not by scientists but by creative spirits more
00:22than 100 years ago HG Wells became a household name with imaginative works like the time machine
00:29and especially the war of the worlds French pioneering filmmakers of me yes took things
00:37a stage further in 1902 with his hugely popular fantasy why I don't know or a trip to the moon
00:47Wells was by no means the first to suggest alien eyes are upon us some of his predecessors were
00:55after all burned alive for even suggesting the possibility of life on other planets but Wells's
01:02sustained invention was the game changer the radio play based on his work caused widespread panic in
01:08the USA when listeners mistook what they heard for an actual alert two-time British Prime Minister Sir
01:15Winston Churchill a Nobel Prize winning man of words penned an article in 1939 whose title was are we
01:23alone in the universe I for one wrote Churchill I'm not so immensely impressed by the success we are
01:29making of our civilization here that I am prepared to think we are the only spot in this immense universe
01:35which contains living thinking creatures film and then television milked the idea of aliens for decades
01:42alas it all amounts to nothing except a billion dollar entertainment industry what if instead of waiting
01:50for aliens to come to us we went in search of life beyond the world we know science is overtaking those
02:02visions we keep looking and we're getting better at it science and fiction are about to meet in the
02:09middle when not if we come across life beyond Earth we have only one reference point our planet and the life on it
02:36the complex DNA based carbon life form that has infiltrated every nook and cranny of the
02:42environment on this planet including its most hostile places volcanic vents on its ocean beds its highest
02:49mountains and its coldest regions
02:52the assumption that organic compounds might be difficult to find in the cold dark vastness of
03:04space is quite wrong space is full of them as we have discovered in our exploration of our solar system
03:11asteroids comets and meteorites do indeed to carry the carbon compounds needed for life
03:17we discovered that these carbon was actually a very complex material very complex carbon very
03:28different from the simple molecules that we would expect to find there so we don't see amino acids or
03:34alcohol or this kind of molecules which is observed in the gas but we see something much more complex and
03:40very rich in carbon and pouring nitrogen or hydrogen compared to these other materials it appears the
03:51fundamental assets to make life are distributed throughout the solar system a function of the
03:56evolution of planets what at first glance appears a simple question where can life be rapidly spirals into a
04:07complex conundrum the complexity of DNA here on earth and what other environments could facilitate such
04:15growth in complexity and biological life even get started in the harsh conditions of the solar system until
04:27concrete evidence is available the question is polarizing I can't say for sure because we've only got the one
04:36example of life on earth to work with so far but all the ingredients are out there solar systems make
04:44everything you need for for life insofar as we know so it could be that matter naturally organizes itself into into life
04:55my answer to the question of whether there's life out there in the universe is I'm afraid I don't know the great
05:01thing about being a scientist and not a politician is that I'm not required to have an opinion on anything I'm
05:07only required to be able to tell you what the facts tell us and what the evidence is that we don't know we
05:14don't know how life on earth got started in detail we don't know how long it took we don't know what the
05:19preconditions were and so life could be incredibly common because there are lots of planets out there or it could be an
05:29incredibly rare event that only happens you know on one in a billion planets in a galaxy
05:36you want to have fluids available
05:57so water in so far as we know is necessary it's necessary for biogeochemistry on earth so you would
06:06expect that anywhere you have liquid water or liquid organics would be good places to look for life
06:14another question for scientists the environment that hosts life now may not be the originating location
06:22for that life life now occupies almost every imaginable niche you know most rainstorms are seeded on
06:32bacteria that float around in the water vapor and then they start to nucleate water droplets and down
06:37they come so you know life is just everywhere and it's in Antarctic ice caps and then snow patches and so
06:45it's everywhere at the moment and it can survive for unbelievably long periods under harsh conditions
06:50but are those the conditions you need to make life those are kind of two steps we've got to almost
06:57attach our minds from in two different kind of views so that whole idea about you know where do you start
07:05life because the most primitive organism is already an unbelievably complex piece of machinery you know
07:12it's got a membrane that isolates an interior component that's different chemistry from the
07:18outside it's got a mechanism for mobility it's got this incredibly complex molecule inside so those are
07:24almost like different pieces of a puzzle put together into something that works and can then self-replicate and
07:30and such so you know even before you get to that stage you have this immense series of events that
07:36we can't even really begin to understand yet we're starting to but how do you get to that stage so you
07:42almost have to detach yourself from life where can it live now to the building blocks of life
07:47life as we know it is a complex mechanism capable of self-replication and great diversity but what
07:59actually is it how do you go from a puddle of organic chemical broth exposed to some form of energy
08:06энd then turn into this
08:08okay
08:08and turn into this
08:10oh
08:15okay
08:18and
08:19.
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28:23from studies on Earth.
28:29I really hope that we do find fossilized microorganisms on Mars.
28:33That would be a triumph for science and for humanity.
28:38I'm not holding my breath, though.
28:41It could be a long journey to try to find a record there,
28:46but it's probably our best hope in the solar system.
28:50There is another consideration when looking for alien life,
28:53in particular on Mars, contamination.
28:56Earthly bacteria can easily ride the rocket through space
29:00and land on Mars with the probe,
29:02leaving the distinct possibility of contaminating
29:05and possibly destroying the very thing we are looking for.
29:12Yeah, look, this is a real possibility.
29:14And there's a group in NASA,
29:17and I'm sure that other agencies have them as well,
29:20called Planetary Protection Officers,
29:22who take the most careful steps imaginable
29:25to try and protect a planet from seeding
29:28with our own sort of, you know, bacteria community
29:31that we bring in with us everywhere.
29:33And so that's the main reason why the Mars 2020 mission
29:39is not going to look for active, like, existing life.
29:43Because no, there's water flowing on Mars.
29:45It's coming out from the subsurface,
29:46but we know that can live on Earth, no problem.
29:49But they're not going there because they're worried
29:51that if they put in a sampler,
29:53they might introduce bacteria that ride on spaceships,
29:56and we know it can survive in space.
29:58So they're avoiding that altogether
30:00and going for the ancient life in rocks
30:03where there's not the possibility of contaminating
30:06an existing water body.
30:08So, yeah, there's great care being taken by,
30:10at least by some groups.
30:12Beyond Mars, the next outposts in our solar system
30:26to be potential habitats for life
30:28are the ice moons of Jupiter and Saturn.
30:35Dr. Helen Maynard Casely has been studying
30:38the planetary conditions of these icy worlds
30:41in the laboratory.
30:42So, as I said, my expertise is sort of recreating
30:46those surface and interior conditions of the icy moons
30:50in order to sort of understand what the materials are doing
30:53and how they interact there.
30:55But from the various space missions
30:58that we've sent out to Europa and Ancelas,
31:00we know, or at least infer, quite a lot about their structures.
31:04So, Europa, everybody gets very excited about
31:08because we believe that it has got quite a thick,
31:10ice crust or thin or thick.
31:12Again, we're not entirely sure how much,
31:15but there's a global ocean underneath that ice
31:19and that should boundary straight onto a rock mantle,
31:24a rock inner core.
31:25So, at that interface, you've got rock and water quite warm,
31:30like probably more than room temperature.
31:33So, you've got potential for that water to pluck out minerals,
31:36nutrients, and then, of course, that whole ocean is shielded
31:41from the intense radiation of Jupiter.
31:44So, it's a rather snug little place to be.
31:48So, I think, you know, that the community is fascinated by the fact
31:59that there's water, known water and liquid water,
32:03in these very far off moons of Jupiter and Saturn.
32:07But this gets back to the origin of life, right?
32:11So, we have life occupying these chemical hot springs down deep in the oceans,
32:19and they're some of the most primitive organisms, no doubt.
32:22But it gets back to that question of,
32:24how do you make something that's as complex of life
32:28from very simple building blocks?
32:30If you can't do it in the oceans,
32:32then I would say you're wasting your time going to Europa and Enceladies,
32:39because those deep oceans would never have the wetting drying cycles.
32:43So, they probably and very likely have the kind of elements
32:47we see in the deep oceans on Earth.
32:49They may have hot smokers,
32:50they may have mineralized water-rock interactions,
32:53but from our group's perspective,
32:56if you never had an exposed land surface,
32:59you probably never got life.
33:01And so, without that,
33:03yeah, we'd really question whether it's worth going.
33:08Perhaps meteors punch through the ice crust
33:11to deliver the additional organic chemistry required.
33:20Potentially, yes.
33:21I've seen that there's a big change in the craters.
33:25So, there are craters on the surface of Europa, let's talk here.
33:28The surface of Europa is very young,
33:30geologically.
33:31It's at most 100 million years old,
33:33which is why a lot of people get excited about the potential of activity.
33:37Craters up to about 30 kilometers are pretty normal.
33:41They compare normal for an icy satellite.
33:44They compare quite well with the similar sized craters,
33:47adjusted for gravity on Ganymede and on Callisto.
33:50Now, once you get above 30 kilometers,
33:53they change very dramatically in morphology.
33:56You don't get the sort of big crater.
33:58You don't get such the crater shape.
33:59You get a sort of ring-like structure.
34:01Now, again, the modeling of that is not complete,
34:05but you could imagine that that's happened because something's actually punched all the way through
34:10and then water is sort of squished through and it would maybe form that.
34:15There's a big debate as to how thick or thin the Europa crust is,
34:19but I believe that from the cratering record people see,
34:23it points to it more being in the 20 kilometers range.
34:27That's good because it would definitely protect anybody down there.
34:32It's bad because it's very difficult for us to get down there and actually go and find them.
34:37So, we'll still see.
34:57Enceladus, though, which is one of the moons of Saturn,
35:01is, I believe, quite a surprise.
35:04It's absolutely tiny and so when Cassini got there and saw these massive gazes coming out,
35:09the first big question is where is all the heat coming from?
35:12And it's something that there's potential that it's tidal friction or is it radiogenic heating
35:18and there's still not a sort of definite, right, it's definitely this,
35:22but we know there is a lot of heat coming out of Enceladus and it is very, very small.
35:27And now we know that from Cassini, the way it sort of passed by Enceladus,
35:32we know that there is an ocean underneath the South Pole.
35:35So, again, the other potential is there.
35:38But whether that ocean is trapped in ice or actually goes all the way down to the rock,
35:42we're not sure yet.
35:43So, certainly the ingredients seem to be there.
35:47I mean, or we infer the ingredients there.
35:49If the water, the ocean goes all the way down to that rock crust and you've got water-rock interactions,
35:57then there is also the potential that if it's too deep, the pressure of the water can go so high
36:04that you actually solidify the water. It's become solid ice.
36:09So, Europa's one moon, but it has a much bigger sister, Ganymede.
36:15And it was thought that Ganymede could, would have an internal ocean.
36:20In fact, actually, internal oceans are sort of seen as a must-have for most icy moons now.
36:26And the reason why people got less excited about Ganymede was thought that the ocean would be so deep
36:31that the water would then freeze and isolate anything, everything from the rock,
36:36and so you couldn't get these interactions.
36:38However, there's been more work that looked at the interactions of the dirty stuff,
36:43the potential salt in Ganymede's ocean.
36:46And actually, it could cause layers, so you could potentially get a solid, liquid, solid, liquid, solid, liquid ocean.
36:54And a few of the models worked out that you could get liquid in contact with the rock.
36:59So, I think there's a lot of justification in doing a lot more study in the potential of, you know,
37:05taking those ingredients that could be in the bottom of Europa and Ganymede and potentially Callisto,
37:11because there's a lot of environments that we think like that in the solar system
37:16and to find out a bit more about how the biology might work down there.
37:34Discovering geysers emanating from the moon, Cassini was re-tasked to fly through the plumes
37:40and make close-up observations.
37:45So they managed to detect, I think, at least CO2 and methane, for instance,
37:49but really what they want to look for is the potential of amino acids, the building blocks, proteins.
37:57And so that's why there's now a proposal to send another mission there,
38:01and it's called ELF or Enceladus Life Finder.
38:04They would fly a better, more sensitive mass spectrometer that would be able to directly detect the potential of amino acids.
38:12Now, amino acids don't necessarily mean life, and I know that the ELF and science team have come up with a sort of cube matrix of observations,
38:22and amino acids is just one of those, and there's a number of other things, parameters in that sort of cube.
38:27What could they detect for in order to say that there's actually something in there?
38:34Titan, the moon of Saturn, has always drawn attention to itself.
38:38A mysterious satellite with a dense and cloudy atmosphere, liquid oceans, rocky terrain and abundant carbon organics.
38:46So Titan is the first planetary body, apart from our own Earth, to see liquid on the surface,
38:53and that's these big lakes and seas that are ethane and methane, and it's got very thick atmosphere,
39:01much thicker than our own atmosphere.
39:03And because of that, it controls the temperature very well on the surface,
39:08so globally around minus 180 degrees C, and it hardly varies, hardly varies from that value.
39:17So if you want to study the surface of Titan, from my point of view, it makes it very easy.
39:22All I have to do is drive to 90 Kelvin and just sit around there.
39:27So you've got those conditions, you've got very thick nitrogen, but there's also methane in the atmosphere.
39:33Now that methane was always a bit of a mystery.
39:37It was actually first discovered by Gerald Kuiper back in 1944,
39:42and it got everybody a bit interested because methane shouldn't really be held onto by Titan.
39:50It's quite small, doesn't have quite the gravitational field.
39:52Methane should have escaped into space.
39:54And so automatically there was like, well, where's that methane coming from?
39:58That starts to get Titan a little bit more interesting.
40:01But then, of course, you've got this methane, you've got this nitrogen,
40:04and you've got this atmosphere that isn't well protected, doesn't have a magnetic field like we do on Earth.
40:09And so you've got all this cosmic and solar radiation that causes interactions to happen.
40:16And you see interactions into bigger organics, things like benzene, acrylonitrile,
40:22anything with C, H and N, pretty much, there's a pathway that potentially could form.
40:28This bigger stuff starts forming and then starts raining down onto the surface.
40:33So you've got this very, whenever you see Titan, it's very orange and hazy,
40:37and that's what this organic haze is.
40:40And this is thought to have been going on for a very, very long time.
40:44So much so that any water ice that's on the surface of Titan has been buried completely.
40:50That there's actually just a massive carpet of organic material.
40:55Recently discovered vinyl cyanide, C2H3CN, is an organic molecule which helps form biological membranes in the atmosphere.
41:07These molecules have been recently discovered on Saturn's moon Titan.
41:11This is quite an exciting discovery because these molecules are the building blocks of what's needed for forming the cell membrane.
41:20And the cell membrane defines the barrier of a cell and protects the inside components of a cell from its outside environment
41:28so that the cell can metabolize and grow and divide.
41:34It's hypothesized that for the very earliest life forms, there were probably already naturally existing membranes in these hydrothermal vents
41:43that the bacteria are basically able to use to partition these chemical processes.
41:48And certainly in systems such as Titan, where there are also these membranes available,
41:54perhaps this could actually serve as a useful precursor for, again, these self-replicating chemical systems to evolve.
42:02It's not the only thing they will require, but it could certainly help and basically have these micro-environments developing for life to develop.
42:13The next possible habitat is the outer reaches of the solar system.
42:34A newly visited world showing a complex environment with the potential to harbor microscopic life.
42:41If you go in closer to the surface, you can see this type of really diverse terrain.
42:46So you have a very bright region. These are flat plains.
42:49I'm not entirely sure how they've formed yet, but there's a couple of leading theories.
42:53There's a huge range of mountains. There's all kinds of different aged surfaces.
42:57Some of them have lots of craters. Some of them have very few, which means they're younger.
43:02If you look in a lot of detail at some of the mountainous regions, you can see that actually they're a few kilometers high, but they're made of water ice.
43:10I mean, that's, on Pluto, it's so cold that water ice is the hardest thing. It's more like rock.
43:15And so the stuff that forms the softer material is actually nitrogen ice.
43:20One of the really fascinating things is some of the surface coloration you can see in these images actually shows that there are these compounds called tholins,
43:29which are a combination of elements, but they're related to prebiotic molecules.
43:36So they're kind of relevant to prebiotic chemistry.
43:39And I think the fact that they have been able to form on planetary surfaces very far out in the solar system at very cold temperatures really has implications for a lot of places.
43:49I mean, if you can imagine for star systems outside our own, where the star may be dim and the planets are quite far away,
43:56it's interesting to know that there are molecules that could be involved in supplying biotic material to processes that may one day lead to life or be involved in life or something like that,
44:09that they're actually forming way out in the solar system where no one really expected.
44:14We know that microbes can continue to have a very low but useful amount of metabolism in extremely cold and extremely dry environments.
44:25So for instance, in these Antarctic soils that we sampled, we're observing that microbes in there could very easily oxidize molecules such as hydrogen at temperatures as low as minus 20 degrees.
44:41And these were in incredibly dry soils.
44:43So I'd imagine that in certain planets where they have very low temperatures and are very dry,
44:50it would be possible if there is an energy source for at least a very, very low level of metabolism to occur.
44:56And according to all the, basically this comes down to thermodynamics.
45:01And with a warmer planet, then as long as it's not too warm, then metabolism will be more favorable.
45:09And this will have yield much faster evolutionary processes, but certainly in reasonably cold environments,
45:16maybe down to minus 80 degrees or so, you can still have microbes survive and do some very, very low level of metabolism to at least tick over,
45:27maybe not necessarily grow.
45:29Yeah.
45:30So listen, you know, organic molecules are extremely complex.
45:35So carbon is one of the most common elements in the universe.
45:39And we know that it's on comets.
45:41You know, there was that beautiful Rosetta mission that landed and sampled there,
45:45but they're very, very simple molecules.
45:48And so same with your organic molecules that have been found so far on Mars and the ones that are inferred on Pluto.
45:56They're very, very simple.
45:57Now, the exciting thing about Pluto is what we didn't know until we got closer up is that it's got a complex history.
46:03We can see different domains and that means there was activity there.
46:07And if there's activity like geological activity and organic molecules and a surface, then there's interesting stuff going on.
46:16So actually that looks like an interesting environment.
46:21The missing part of that equation in terms of thinking about complex life is the sun is so unbelievably faint at Pluto
46:29that you'd never have probably the possibility for photosynthesis,
46:33which is what allows oxygen to rise and allows for complex life like us and elephants to be around.
46:39That's a whole nother step away.
46:41So we wouldn't predict, you know, a complex advanced civilization on Pluto,
46:45Pluto, but maybe, maybe microbes.
46:48.
46:50.