Documental Vida en el espacio exterior- El sistema solar
La comunidad científica está convencida de que, en las próximas décadas, el ser humano finalmente habrá desvelado uno de los mayores misterios del universo, ¿hay vida más allá de nuestro planeta?. Los últimos descubrimientos nos llevan a pensar que en entornos aparentemente extremos de nuestro sistema solar hay vida ahora o pudo haberla en el pasado.Podríamos encontrar alguna forma de vida en los extraños lagos de metano de Titán, en el océano oculta bajo la oculta capa de hielo de Europa, en los gigantes geiseres de Encélado o incluso en las desérticas llanuras de Marte.
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00:00Is life an extraordinary exclusive phenomenon on our planet?
00:12Is there life outside the Earth?
00:19Humanity has always asked this question.
00:27But so far, no answer has been found.
00:35However, thanks to the latest advances in astronomy,
00:40it seems that we are closer to solving this mystery.
00:47The latest generation space probes explore the planets and moons of our solar system,
00:53while sophisticated telescopes search the universe for answers.
00:58The results are surprising.
01:01One of the great triumphs is to have demonstrated that most stars have planets.
01:07There are planets everywhere. There are more planets than stars.
01:14These discoveries have been possible thanks to the Kepler space probe.
01:19Launched in 2009, it has set a milestone in the search for life beyond the limits of our solar system.
01:30Now we know that only in our galaxy there are billions of exoplanets similar to Earth.
01:39Given the immensity of our universe, with more than 100 billion galaxies,
01:44it is difficult to think that somewhere there is not a planet like Earth capable of housing life.
01:52Finding it is only a matter of time.
01:58It has revolutionized our way of thinking about the possibility of life on another planet.
02:04Exoplanets and extremophiles are two revolutionary milestones.
02:10All this leads us to think that in apparently extreme environments of our solar system,
02:16there is life now or could have been in the past.
02:21We could find some form of life in the strange lakes of titanium methane,
02:28in the hidden ocean under the mysterious layer of ice in Europe,
02:34in the gigantic geysers of Enceladus,
02:40or in the desert plains of Mars.
02:45A second genesis within the solar system would imply that life at its origin is a probable fact.
02:52We do not know if the discovery of life will take place first on one of those moons or planets of our solar system,
03:01or on an exoplanet similar to Earth.
03:06But what we do know is that we are closer than ever to unveiling one of the great mysteries of nature.
03:13Is there life in outer space?
03:17Is there life in outer space?
03:21Life in outer space.
03:25The solar system.
03:30Life.
03:32A combination of amazingly perfect elements capable of creating living matter.
03:41It is possibly the greatest mystery of nature.
03:48A combination of matter that has certain attributes
03:53including the ability to respond, growth, metabolism, energy transformation and reproduction.
04:00We do not yet know exactly what life is.
04:05My preferred definition of life is that life is a sort of chemical entity
04:12that itself can evolve and escape from Darwinian evolution by natural selection.
04:19Some studies claim that life could have appeared on Earth 4,100 million years ago.
04:26So life would be just a little younger than Earth.
04:31Immediately a question arises.
04:35Is life an exclusive phenomenon of Earth?
04:39There is no easy answer to that question.
04:48The chemistry of life began shortly after the Big Bang, 13,800 million years ago,
04:54during a habitable era in which the universe was between 10 and 17 million years old.
05:01Life could appear independently in many places in the universe.
05:06Or life could form somewhere and then spread by meteoroids or comets between usual planets,
05:13according to the theory of panspermia.
05:18In any case, the complex organic molecules could form in the gas protoplanetary disk
05:24and dust particles that surrounded the Sun before the formation of the Earth.
05:32According to these hypotheses, the process could take place far away from the Earth.
05:38But there is no clear answer to this question.
05:44According to these hypotheses, the process could take place far away from the Earth,
05:49on several planets and moons of the solar system,
05:53and on planets of other stars, the so-called exoplanets.
05:59Since ancient times, humanity has wondered if we are alone in the universe
06:04and if there is life outside the Earth.
06:09Perhaps these are not easy questions to answer.
06:13However, we have always been fascinated.
06:18Astronomers have been interested in life beyond Earth.
06:24We could go back to the writings of the ancient Greeks, Romans and Chinese
06:29who speculated about the existence of life outside the Earth.
06:34The main problem to find life in outer space
06:39is to establish what are the essential conditions for life.
06:44A source of life is the Earth.
06:49A source of energy, like that of a nearby star,
06:54is necessary to produce an endothermic reaction or reactions that absorb energy.
06:59Basic elements, predominantly carbon,
07:04are essential to build and form organic molecules.
07:09The essential elements of life on Earth
07:14are oxygen, hydrogen, nitrogen and others.
07:19They are what we are looking for on other planets
07:24to find life as we know it.
07:29Those essential elements of life, at least as we know them, are ubiquitous.
07:34It is also essential to have a liquid or a very dense gas
07:39that acts as a solvent for biochemical reactions to occur quickly and stably.
07:44Water in a liquid state,
07:49the universal solvent that sustains life, at least on Earth,
07:54requires adequate temperature and atmospheric composition.
07:59In order to have an habitable environment,
08:04you need three things.
08:09You need water in a liquid state, organic material and energy.
08:14And there are some places in the solar system
08:19where those three things are thought to exist.
08:24Now that we know the necessary conditions for the appearance of life,
08:29planets and moons of our solar system meet those conditions.
08:34Considering that one of the key prerequisites for extraterrestrial life
08:39is the existence of water in a liquid state,
08:44there are three candidates in our solar system that have liquid water on their surface.
08:49The planet Mars,
08:54the Soviet Union,
08:59and the moon of Saturn, Enceladus.
09:04In addition to Mars, Europe and Enceladus,
09:09which could have water in a liquid state on their surfaces,
09:14there is another candidate to house life in our solar system,
09:19Titan.
09:24Until 2004, Titan was still a great mystery to astronomers,
09:29as dense and opaque fog prevented them from studying its surface.
09:34In 2004, the spacecraft Cassini reached Titan
09:39and sent a small probe called Huygens.
09:44That probe would change everything.
09:49These are images recorded by the Huygens camera
09:54as it descends through the fog.
09:59The landscape of Titan is very similar to that of Earth,
10:04with mountains, valleys and plains.
10:09When the probe hovered on the surface, it revealed something that no one expected.
10:14There were guillotines everywhere,
10:19similar to those found in the riverbeds of the Earth.
10:24When you look at those guillotines, yes, they are guillotines
10:29that have undergone the erosion of the torrents and the streams,
10:34but they are actually other ice, so hard that it looks like rock.
10:43How were those rocks eroded?
10:48Is there water in a liquid state on the surface of Titan?
10:53If there was, at minus 180 degrees Celsius,
10:58the water should be completely frozen and solidified.
11:03Cassini found the answer.
11:08He showed us that the surface of Titan is covered by hundreds of lakes.
11:13But the big difference is that they are not formed by liquid water,
11:18but by methane and ethane liquids.
11:23On Earth, those two hydrocarbons are volatile gases,
11:28and all their icy temperatures are liquid.
11:33The atmosphere of Titan has methane and ethane and other organic materials
11:38that provide a very different kind of chemistry,
11:43but it is a kind of chemistry that is reminiscent of what the Earth was before it proliferated.
11:48All those worlds are very far from the heat of the sun.
11:53They are extremely cold and some are exposed to high levels of radiation
11:58because their atmosphere is very thin.
12:03That is why their surroundings are quite hostile to life.
12:08However, life could have found its way there.
12:13We also know that there are extremophiles,
12:18and we know that life could not exist.
12:23That's what they told me when I was a student.
12:28It's too hard, it's too cold, it's too acidic, it's too basic,
12:33there's too much pressure, too much radiation.
12:38But those organisms evolved to proliferate under those conditions.
12:43That's our way of thinking about the possibility of life somewhere else.
12:52Extremophiles, like the bacteria that live at great depths and high temperatures
12:57around the terrestrial hydrothermal ocean fumaroles,
13:02offer us a vision of life that could have developed on other planets,
13:07with extreme conditions and inhospitable environments
13:12that could include freezing temperatures and minimal sun exposure.
13:17This gave us such a different vision of what actually is necessary for life to survive.
13:24And all of a sudden, the solar system blew its flow
13:29into what we call stellar habitability.
13:33The habitable environment expanded enormously in a way that we would never have imagined.
13:39The possibilities of finding life in one of those remote worlds of the solar system
13:44are now much higher.
13:48To do it alone is a matter of time.
13:57Among the 160 planets and moons of the solar system,
14:02Mars is the one that has most interested astrobiologists so far.
14:08There are many indications that show that at a very early stage in its history,
14:13Mars looked a lot like Earth, with large areas covered with liquid water,
14:18a dense atmosphere and abundant sources of energy for life,
14:23as well as a good amount of organic molecules.
14:28In fact, I would like to say that when you compare the two planets,
14:33you don't have to invent words to describe Mars.
14:36There are mountains, canyons, polar caps, dunes.
14:43There is evidence that Mars had a warmer and drier past.
14:48Dry riverbeds,
14:53large canyons dug by epic floods,
14:58valleys carved by rivers,
15:03polar caps,
15:06volcanoes,
15:09and also found minerals that can only be formed in the presence of water.
15:15There is a lot of evidence of water at the beginning of the history of the planet,
15:19very early, about 4 billion years ago.
15:23Maybe there were water courses then.
15:28But the evidence indicates that all that water disappeared from the surface
15:33billions of years ago, when Mars cooled down and lost its atmosphere.
15:41Was there ever life on the planet?
15:46As we are looking for evidence of life on Mars in the past,
15:51some people believe that we already have proof of the arrival of life on our own planet.
15:59And the best example of that is the Alan Hills meteorite.
16:07We had a piece of Mars here in the laboratory, and we still have it.
16:12Alan Hills 84001.
16:17It is a fragment of rock that came off Mars by an impact millions of years ago,
16:24and ended up landing on the Antarctic ice sheet.
16:31During the spring collection season in 1994, when the ice melts,
16:37those black rocks were collected in the natural pools that are formed with the thaw.
16:44And then we realized, due to the gases contained in that fragment of rock,
16:49that it was a piece of Mars.
16:52When we studied it on a microscopic scale, there was a great scientific controversy.
16:57Some scientists claimed that there were clues in that rock
17:02that only biology could have produced.
17:05While other scientists said, no, it can be a work of geology.
17:14The search for life on the red planet began decades ago.
17:21In 1976, for the first time in history, the search for microorganisms on Mars began.
17:31Two decades later, in 1997, the Mars Pathfinder mission
17:36took a new step forward in the adventure of the search for life.
17:40It found magnesium, aluminum, iron and phosphate on the ground of Mars,
17:45all essential materials for the appearance of life.
17:51In 2008, the Phoenix space probe explored the north pole of Mars.
18:03After escaping a few centimeters, it found a white material that evaporated a few days later.
18:11The analysis of that material revealed that it was water ice.
18:19The satellites explored the two polar caps and discovered
18:24that there was a large mass of water ice under a layer of carbon dioxide ice.
18:30If all that ice ever melted,
18:33a sea of 25 meters deep would be formed that would cover the entire planet.
18:41The same satellites also discovered that there was ice buried
18:45under the entire surface of the desert plains.
18:50It was a shocking discovery.
18:54On Mars, there were huge amounts of water ice everywhere.
18:59But could life have existed in that buried ice?
19:04Now we know that there are extremophile microorganisms
19:08capable of living in similar environments in the dry valleys of Antarctica,
19:12here on Earth.
19:15Now Mars is very dry and very cold.
19:18It's like some regions in Antarctica.
19:21And it's very similar to a cold desert.
19:24So the liquid water would not be stable.
19:28It is so dry that if you opened a container of water,
19:32it would evaporate immediately due to the dryness.
19:37The buried ice was under a layer of dry dust, just like on Mars.
19:42At the exact point where the dust comes into contact with the ice,
19:46there was a very thin layer of water,
19:49in which the extremophiles could have developed,
19:52although only for a short period.
19:55These microorganisms remain frozen and inactive
19:58for much of the year,
20:00and only activate for a few weeks in summer.
20:04Today, adapted microbes could continue to live some depth
20:08thanks to the presence of a thin layer of water or more liquid water.
20:12The deeper you go,
20:14the more likely it is that the water can be liquid.
20:20On Mars, during the summer,
20:22it is common to reach 20 degrees in Ecuador,
20:25so the underground ice would melt,
20:28creating conditions very similar to those we find today
20:31in the dry valleys of Antarctica.
20:34Any microbe that would have been there
20:37would probably continue to live inside the rocks
20:40or under the rocky surface.
20:42It is one of the places where microbes have been found under the surface,
20:46because that would also be viable on Mars.
20:52A future mission could finally prove
20:55whether this hypothesis is correct or not.
21:01But there is another possibility that there is liquid water
21:04under the surface of Mars.
21:11The huge volcanoes of Mars, like Mount Olympus,
21:14could generate the necessary internal heat
21:17to keep the water in liquid state underground.
21:20That would imply that on Mars there could also be hydrothermal smoke waves
21:24and that, therefore, it would be equally possible
21:27the existence of extremophiles,
21:29similar to those that proliferate in the terrestrial hydrothermal chimneys.
21:35However, it is quite unlikely.
21:44Everything would change if we were able to find water
21:47in liquid state on the surface.
21:53In September 2015,
21:55the NASA reconnaissance orbiter made an incredible discovery.
22:02This space probe provided the most solid evidence
22:05that water flows intermittently in liquid state
22:08on the surface of Mars.
22:12It's not pure crystalline water.
22:14It's very dark water, with a lot of salt,
22:17which gives it stability for a short period on the surface of the planet,
22:21because the pressure on the surface of Mars is very, very weak.
22:29Using an image spectrometer,
22:31the researchers detected signs of hydrated minerals
22:34on the slopes of the red planet,
22:37where some mysterious veins had been observed.
22:41The veins darkened and seemed to flow down the slope
22:44during the warm seasons,
22:47fading in the cold seasons.
22:50This discovery showed what anyone could have imagined.
22:54On the surface of Mars there is currently water in liquid state.
23:00Perhaps, in some of those ephemeral courses of water in liquid state,
23:04microbial life has managed to emerge.
23:12We will have to wait for future missions with space probes
23:15to confirm this hypothesis.
23:25What will really change our vision of the red planet
23:28will be the NASA and ESA missions.
23:31Both are part of the Mars Exploration Program.
23:36Since 2007, the main objective of space missions to Mars
23:40was not only to find water, both in liquid and ice form,
23:43but to explore its habitability
23:46and, above all, to look for signs of life.
23:53The more we investigate Mars,
23:56the more evidence we have that in ancient times,
23:59Mars undoubtedly welcomed life.
24:02The final step would be if that life managed to evolve,
24:05and if it did, where did it evolve,
24:08and how many species exist today,
24:11because that happened a long time ago.
24:15The final objective of the missions to Mars
24:18is to prepare a human expedition.
24:21Would it really be a giant step for humanity?
24:27The first step in this ambitious exploration program
24:30is the ExoMars program, created by ESA,
24:33the European Space Agency,
24:36in collaboration with the Russian space agency Roscosmos
24:39and the participation of NASA.
24:45Its main objective will be to look for possible bio-signs on Mars,
24:48both past and present.
24:54ExoMars is a multi-probe space program.
24:57The first ExoMars mission in 2016
25:00is the so-called Trace Gas Orbiter, TGO.
25:07The objective of this probe is to study the atmosphere of Mars
25:10and look for methane and other gases,
25:13gases that could be related to some biological processes.
25:20The second mission of the ExoMars program
25:23is the rover and the ExoMars 2018 surface platform.
25:28The rover, with a drill of two meters,
25:31takes samples at various depths
25:34in places where there could be water in a liquid state.
25:40The drill should be able to drill
25:43the first couple of meters of sediments.
25:46In this way it is even more likely
25:49to find evidence of viable cells.
25:54The third step in this fascinating exploration program on Mars
25:57is the NASA Mars 2020 mission.
26:01The objective of the rover Mars 2020
26:04is to study different rocks and soils
26:07to understand the past conditions of habitability on Mars
26:10and look for remains of ancient microbial life.
26:16One of its functions is to study the climate and dust of the atmosphere of Mars
26:19and test its ability to extract oxygen from the carbon dioxide
26:22of the atmosphere of the red planet
26:25to prepare future human expeditions.
26:31Any of these innovative missions
26:34could solve the enigma of the existence of life on Mars,
26:37both past and present.
26:43Farther than Mars,
26:46there is another unique world that could house life.
26:54Our next destination in the search for life
26:57is Europe,
27:00one of the most fascinating Jovian moons.
27:06Europe is one of the four largest moons of Jupiter.
27:09It is only a little smaller than our moon
27:12and its frozen surface is at minus 160 degrees Celsius.
27:18Virtually everything we know about Europe
27:21is thanks to Galileo,
27:24a NASA crew member who flew over Europe 12 times.
27:32These are the first images he captured.
27:36Europe is covered by a soft layer of water ice.
27:39In fact, it has the smoothest surface
27:42of all solid objects known to the solar system.
27:46The surface of Europe is unique in the solar system.
27:49It has very few craters,
27:52which tells us that its surface has been processed frequently.
27:57In some parts, separate blocks of ice appear,
28:00but they seem to fit like pieces of a puzzle.
28:03Those icebergs could have been modeled
28:06by the groundwater in a liquid or semi-solid state.
28:10There are cracks that probably extend to the bottom of the ocean
28:13and through which, at some points,
28:16the water could be filtered.
28:19This unique landscape is very similar
28:22to that of the terrestrial banquets.
28:28Thanks to everything revealed by Galileo,
28:31added to our vision,
28:34we now know that Europe has a liquid ocean under its surface.
28:39In 1996, the Galileo space probe
28:42detected a magnetic field on the surface of the planet
28:45that suggests that there must be
28:48some kind of electric field,
28:51possibly caused by a salty ocean
28:54that could be about 100 kilometers deep.
28:58Studies, observations and measurements
29:01made in recent decades
29:04seem to coincide very clearly
29:07with the presence of an ocean
29:10under the surface of the ice.
29:14We now have the first key ingredient in life,
29:17water in a liquid state.
29:21But how can water remain in a liquid state
29:24at a temperature of minus 160 degrees Celsius?
29:30Some kind of mysterious internal heat
29:33must be melting its layer of ice.
29:36Jupiter is the key.
29:39The warming of the sea produced by the freezing of the ice
29:42due to the eccentricity of Europe
29:45in its orbit around Jupiter
29:48is one of the hypotheses.
29:51The ice on the surface of Europe is cracked.
29:54It is not completely sealed.
29:57You can see the gravitational force.
30:00There is this friction
30:03as Europe moves around Jupiter.
30:06And we can imagine that all that friction
30:09produces a lot of energy, a lot of heat.
30:12So we have good reasons to think
30:15that there is a hydrothermal base,
30:18a base through which that process heats the water.
30:24Volcanoes of depth
30:27could originate hydrothermal chimneys
30:30that would provide a source of energy
30:33that would heat the water and keep it in a liquid state.
30:36There are three necessary conditions for life to exist.
30:39A liquid, water in a liquid state,
30:42and a source of energy, internal heat.
30:45We only need an organic compound
30:48and the chances that life would appear
30:51would skyrocket.
30:54The Galilean probe observed
30:57that the ice of Europe contains carbon dioxide.
31:00When that carbon dioxide is reached
31:03by the intense radiation of Jupiter,
31:06it can produce simple organic molecules
31:09such as formaldehyde,
31:12which is a step towards life.
31:15The already mentioned tides of Europe
31:18could also mix in the ocean
31:21life-provoking substances,
31:24but it has not yet been proven.
31:27In 2013, NASA announced
31:30a surprising discovery in the ice layer of Europe.
31:33They had discovered some clay-like materials,
31:36specifically phyllosilicates.
31:42Phyllosilicates means that there are layers of silicates.
31:45It's a nice name for clay.
31:48Clay is a type of mineral
31:51that is formed in water and earth.
31:54According to some theories,
31:57the presence of these minerals
32:00associated with organisms
32:03could be the result of a collision
32:06with an asteroid or comet.
32:18With water in a liquid state,
32:21a source of energy and the necessary chemical elements
32:24perhaps carried by comets or asteroids,
32:27Europe opens the possibility
32:30that life can exist in places we never imagined.
32:39At 3,500 meters below the Arctic basin,
32:42in the absolute darkness,
32:45there are hydrothermal chimneys
32:48that spit water at very high temperatures
32:52Scientists believe that chimneys like these
32:55could also exist in the oceanic background of Europe.
32:58We believe that the potential source of energy
33:01for ocean activity in Europe
33:04would be volcanic activity.
33:07It has recently been discovered
33:10that micro-organisms live around the chimneys
33:13that cover kilometers of the Arctic Ocean.
33:16The discovery of life there
33:19really raises the possibility
33:22that there is life in Europe.
33:37Now the challenge lies in proving
33:40that life could appear in such a strange environment.
33:43NASA and ESA have planned
33:46two different missions to Europe
33:49in the coming years to investigate its habitability.
33:54In 2015, NASA approved
33:57a new mission to travel to Europe
34:00and investigate its environment,
34:03especially its habitability conditions.
34:06The European Overflight NASA mission
34:09is a probe that will be launched in 2020.
34:12The ship is technically very sophisticated
34:15and resistant to radiation
34:18and will carry out flights close to the ice surface of ESA Luna.
34:23We will also look under the surface
34:26to learn more about the structure of the ice layer
34:29and the structure of the ocean under that layer
34:32using radars, magnetic detectors and other instruments.
34:39ESA develops its own mission in parallel
34:42with the mission of Jupiter,
34:45also known as the JUS mission,
34:48which will be launched in 2022 and will reach Jupiter in 2030.
34:53This space probe will spend at least three years
34:56making detailed observations not only of Europe,
34:59but also of Jupiter, the gigantic gaseous planet
35:02and two of its largest moons, Ganymede and Callisto.
35:06We will have to wait until the next decade
35:09to confirm whether there is life or not in Europe.
35:20Europe is not the only fascinating place
35:23in the solar system at that distance.
35:26Similar conditions could occur
35:29on other moons orbiting the sun.
35:32Orbiting around Saturn,
35:35there is a small and mysterious moon
35:38that is completely different
35:41from the rest of its more than 60 moons.
35:44This small moon, covered with ice
35:47of only 550 km in diameter, is encased.
35:50In recent years, it has become
35:53the main objective of the exoviolation mission.
35:57Almost everything we know about Enceladus
36:00is thanks to the Cassini mission.
36:03It is a mission that has lasted many years.
36:06It is a probe that has been studying
36:09the entire system of Saturn and its different moons,
36:12but paying special attention to Enceladus.
36:15It is a probe that has been studying
36:18the entire system of Saturn and its different moons,
36:21but paying special attention to Enceladus.
36:24The Cassini mission provided us
36:27with a first glimpse of this remote world
36:30for the first time in history.
36:37These were the first images it sent.
36:40The surface is white and shiny
36:43and is full of cracks, ridges and cracks.
36:46In the south pole, Cassini made
36:49a surprising discovery.
36:52It photographed some long and strange cracks
36:55that we see here in blue.
36:58They are four parallel grooves
37:01that scientists called tiger stripes.
37:04They are 120 km long
37:07and hundreds of meters deep.
37:10They look a lot like terrestrial faults.
37:16After several reconnaissance flights,
37:19the Cassini thermal radar
37:22made an unexpected discovery.
37:25The tiger stripes should be colder
37:28than the rest of the moon,
37:31since they are in the south pole.
37:34However, they radiated heat.
37:37The cracks were at minus 80 degrees
37:40when the rest of the moon
37:43was at minus 200 degrees Celsius.
37:49It is definitely a place
37:52where we see that something deep
37:55happens in terms of potential
37:58for a habitable environment.
38:01But the most surprising discovery
38:04was yet to come.
38:07While he was reorienting,
38:10Cassini captured an amazing image.
38:13Eruptions of large ice jets rising in space.
38:17The camera was able to capture
38:20images of plumes of water, vapor,
38:23and ice crystals
38:26emerging from the south pole of Enceladus.
38:30The plumes launched ice particles
38:33at hundreds of kilometers high
38:36at the speed of the tiger stripes.
38:39Those materials are being ejected
38:42through those fractures
38:46But how can this small moon
38:49generate enough heat to maintain
38:52that intense geothermal activity?
38:55Scientists believe that Enceladus
38:58could have an internal energy source
39:01like Europe.
39:04When it orbits around the gigantic Saturn,
39:07the friction produced by the gravitational process
39:10causes its warming, melting the ice
39:13in a way similar to what happens
39:16in the hot spots of the Earth.
39:19Cassini actually has a detector
39:22that can fly through a plume,
39:25pick up some of the particles
39:28and analyze them chemically.
39:31And when that detector did its work,
39:34it found that some of the particles
39:37were salt, and the only way
39:40for the salt to incorporate into a particle
39:43is by evaporating directly from a liquid.
39:46So that was yet another indication
39:49that there is liquid under the surface of Enceladus,
39:52from where those plumes are emanating.
39:55But would that prove that under the layer of ice
39:58there is an underground ocean like in Europe?
40:04We needed even more evidence.
40:07The next evidence came
40:10when Cassini was flying over Enceladus,
40:13just carefully analyzing its trajectory
40:16to directly measure how Enceladus
40:19and its gravity were pulling from the spacecraft.
40:22And when that analysis was done,
40:25it found a density normalization
40:28under the whole South Pole,
40:31indicating that there was a primordial ocean of water
40:35Those plumes could be connected
40:38with active hydrothermal chimneys
40:41at the bottom of the ocean,
40:44where the lunar ocean comes into contact
40:47with the underlying rock,
40:50a potentially perfect habitat for life.
40:53But there was still nothing that could prove
40:56the existence of life under that layer of ice.
41:04The spectrometers of the probe
41:07detected something really extraordinary.
41:10They found in the plumes
41:13the essential chemical parts of the building of life.
41:16Enceladus is fascinating because,
41:19from what we know,
41:22it contains the three basic ingredients for life.
41:25Liquid water, nutrients, and organic compounds.
41:28But is there really life
41:31in this strange and unknown world?
41:34The geysers could provide
41:37easy access to take samples
41:40of the hidden lunar ocean.
41:43And if there was microbial life,
41:46the ice particles emanating from the sea
41:49could contain the evidence
41:52that astrobiologists need.
41:55There are two exploration missions
41:58to Enceladus proposed by NASA
42:01that, in the near future,
42:04could try to find evidence of life
42:07in the small moon of ice.
42:10The first is the mission
42:13Travel to Enceladus and Titan.
42:16It is an astrobiological mission
42:19to evaluate the potential
42:23The second, which is still waiting for approval and financing,
42:26is the mission
42:29Life Research in Enceladus.
42:32Its objective would be to capture
42:35ice particles from the moon of Saturn, Enceladus,
42:38and return to Earth,
42:41where they could study in detail
42:44to find signs of life, such as biomolecules.
42:47It is relatively simple to send a probe to Enceladus
42:50to capture those ice particles in the feathers
42:53and analyze them in situ or bring them to Earth
42:56for a detailed analysis in the laboratory.
42:59Unfortunately, none of these missions
43:02has been approved yet.
43:05So we will have to wait
43:08to reveal the mystery of the existence or not
43:11of life in that tiny and fascinating moon of Saturn.
43:14Very close to Enceladus
43:17is the last of the great candidates
43:20to host life in the solar system.
43:23Titan.
43:26Titan is the largest moon of Saturn.
43:29It is one of the largest moons in the solar system.
43:32And it is also the only moon
43:35that we know has a dense atmosphere.
43:38Data from the Cassini-Huygens mission,
43:41which flew over Titan in 2004,
43:44showed the existence of hydrocarbons lakes.
43:50Titan is a fascinating world.
43:53It is the strangest place in the solar system
43:56because, in fact, apart from the Earth,
43:59it is the only place we know
44:02that has liquid seas on its surface.
44:05But those seas are not made of water.
44:08There are no waves in those seas and lakes.
44:11Because they are made of methane and ethane,
44:14which are much denser than liquid water.
44:19Those two hydrocarbons are volatile gases on Earth.
44:24But in Titan,
44:27at a temperature of minus 180 degrees Celsius,
44:30they are liquid.
44:33The landscape of Titan is very similar to that of Earth.
44:36There are seas, lakes, erosional rocks
44:39on the riverbeds, mountains, valleys, canyons.
44:42But these mountains and gorges
44:45are not formed by rocks like on Earth,
44:48but by water ice,
44:51frozen by the minus 180 degrees Celsius
44:54of the icy surface of Titan, which looks like rock.
45:01The images of the Cassini spacecraft radar
45:04showed that liquid methane forms clouds and storms
45:07and that it even precipitates in the form of rain.
45:11Methane in the atmosphere
45:14also plays a role similar to water in the atmosphere.
45:17On Earth you have a water cycle.
45:20On Titan, methane plays a very similar role.
45:23It falls to the surface like rain or dew,
45:26and we see channels and rivers
45:29through which methane flows through the surface
45:32doing geological work
45:36Liquid methane has a cycle
45:39very similar to the water cycle on Earth.
45:42The question is, does it behave like water on Earth?
45:45Like a liquid that allows
45:48organic molecules to dissolve and interact?
45:51There is no easy answer.
45:54The atmosphere of Titan also contains many organic gases
45:57such as methane, ethane and hydrocarbons.
46:00And it has conditions
46:04that resemble those of the Earth 4 billion years ago.
46:07The same conditions that allowed life to appear.
46:13In many ways, the atmosphere of Titan
46:16looks like the Earth in its youth,
46:19but in the fridge, much colder, much more.
46:22But the prebiotic chemistry, the same processes, are there.
46:25What we don't know is whether
46:28those prebiotic processes
46:31will become biological nature on the surface
46:34or in the underground of Titan.
46:37However, liquid methane and ethane
46:40are much colder than water in liquid state,
46:43around 200 degrees Celsius,
46:46and the biochemical reactions would occur
46:49at an extremely slow rate.
46:52These components are also less suitable
46:55as solvents compared to water.
46:58Therefore, it is more difficult for them to produce life.
47:01Water is also ruled out of this process
47:04due to the cold temperatures
47:07of less than 178 degrees Celsius.
47:10Some experiments have shown that
47:13with an atmosphere similar to that of Titan
47:16and the participation of ultraviolet radiations,
47:19complex molecules and natural polymers can be generated,
47:22substances that could be considered precursors of life.
47:28What? Where?
47:31Chemical physics? Maybe biology?
47:34Now we are trying to think
47:37how a biology based on methane would be.
47:40Apparently, it is not the ideal
47:43to provide a structure for biochemistry.
47:49The conclusion is that Titan is a world
47:52rich in organic matter,
47:55which is comparable to methane
47:58in terms of geological and atmospheric processes
48:01to the water cycle on Earth,
48:04so it is very likely that it houses life.
48:09In recent years, NASA and ESA
48:12have made joint efforts to develop
48:15a non-manned space mission
48:18to finally unveil all the mysteries of Titan.
48:22One of the most promising missions
48:25to unveil the secrets of the lakes of methane
48:28and ethane of Titan
48:31is NASA's submarine Titan mission.
48:34It would explore the depths of the Kraken Sea,
48:37the largest liquid mass known on its surface.
48:40The mission would measure the organic elements in Titan.
48:43It would be the first nautical exploration
48:46of an extraterrestrial sea to analyze its nature
48:49and possibly observe its coast.
48:55Like the rest of the missions to Titan,
48:58submarine Titan has not yet been approved.
49:01There are many ingenious options to explore Titan,
49:04but NASA has not yet selected any of them.
49:08To date, there is no space mission
49:11scheduled for Titan,
49:14but that could change if in the near future
49:17NASA makes a spectacular discovery.
49:23If those space missions will serve to finally reveal
49:26the existence of life on Mars,
49:29Europe,
49:32Enceladus or Titan,
49:35it is something that we do not know.
49:38But what we do know is that today we are much closer than ever
49:41to finally find an answer to the question
49:44of the origin of life on Earth.
49:52Just 50 years ago,
49:55the era of robotic exploration of our solar system was beginning.
50:02In July 1965,
50:05the Mariner 4 probe sent us the first close images of Mars.
50:08Those blurry images
50:11showed that Mars had no vegetation
50:14and much less channels crossing the planet,
50:17as the first generations of astronomers had imagined.
50:23At that time, the most widespread opinion was
50:26that Mars was not only the red planet,
50:29but also the dead planet.
50:32The chances that it housed some kind of life
50:35were infinitesimal.
50:42Things have changed radically since 1965
50:45thanks to the extraordinary technological advances
50:48that have allowed us to use increasingly sophisticated probes
50:51to explore our neighbors in the solar system.
50:58The three vital factors,
51:01energy,
51:04and the chemical pillars of life,
51:07are more widespread than we could ever imagine.
51:11Now it is not so unlikely to find life outside the Earth
51:14in our solar system.
51:17We cannot deny that a discovery of such importance,
51:20even if it were only microbial life,
51:23would be a real shock to humanity,
51:26as it would be the first step to accept
51:29that perhaps we are not completely alone in the universe.
51:35Then, the ideal conditions could also exist
51:38beyond the limits of our solar system,
51:44in the remote outer space.