Professor Brian Cox journeys to the volcano worlds of the Solar System and explore alien landscapes bursting with fire and ice. There are planets and moons covered in volcanoes, with eruptions so violent they reach into space. Understanding what makes these worlds active is critical in the search for life beyond Earth.
Thanks for watching. Follow for more videos.
#cosmosspacescience
#solarsystem
#season1
#episode1
#cosmology
#astronomy
#spacetime
#spacescience
#space
#nasa
#spacedocumentary
#volcano
#iomoon
#volcanoworlds
#briancox
Thanks for watching. Follow for more videos.
#cosmosspacescience
#solarsystem
#season1
#episode1
#cosmology
#astronomy
#spacetime
#spacescience
#space
#nasa
#spacedocumentary
#volcano
#iomoon
#volcanoworlds
#briancox
Category
📚
LearningTranscript
00:00So far, we've set foot on one world beyond our own.
00:15We discovered a desolate, barren rock.
00:20An ancient, unchanging, cratered world.
00:23And the footprints we left there could last for millions of years.
00:34Our only direct personal experience of an alien world is of our moon.
00:39Beautiful, but a dead, inactive world, frozen in time.
00:44Whereas our planet is active and alive.
00:47If you come to the right places on Earth, it's literally seething with energy beneath our feet.
01:06For a long time, we wondered if all this activity is unique to our planet.
01:11But now, thanks to a fleet of spacecraft, we know our world is not alone.
01:27We currently have over 40 probes exploring the solar system.
01:31Relaying a stream of information to Earth.
01:34Allowing us to see our sister worlds in unprecedented detail.
01:49They're revealing planets and moons covered with volcanoes.
01:53Dwarfing anything seen on our planet.
01:55Alien landscapes bursting with fire.
02:04And ice.
02:08Eruptions so violent, they reach into space.
02:14So why are some worlds vibrant and alive?
02:16While others are cold and dead?
02:30Now that question is deeper than it first sounds.
02:35Because answering it will have profound implications for our understanding of our place in the universe.
02:40See, geological activity, the flow of energy from the interior of a world outwards, is necessary for the origin of life.
02:50And that's why finding and understanding those worlds is a necessary first step in the search for life beyond Earth.
02:58Let's begin a journey to the volcano world.
02:59Let's begin a journey to the volcano world.
03:28the prophets.
03:30By leaving Earth.
03:31Heading away from the sun.
03:35And setting a course to the planet next door.
03:42The most visited of them all.
03:58For almost two decades the Mars Reconnaissance Orbiter has pointed its cameras at the red planet.
04:19And the images it has sent back have revealed volcanoes on a staggering scale.
04:28One so wide, it would span the UK.
04:41And one so tall, it rises up through Mars' atmosphere, almost to the edge of space.
04:59Over time, these mega-volcanoes have flooded the Martian surface with a billion, billion tonnes of lava.
05:06So much that they've tipped the entire planet over by 20 degrees.
05:18So what drives a planet's volcanism?
05:30Iceland's one of the most volcanically active places on Earth.
05:36This is the Icelandic Met Office, so this is the weather forecasting site.
05:40But it also gives you a real-time update on earthquakes, and earthquakes are precursors for volcanic eruptions.
05:53These dots are all earthquakes that have happened in the last few hours, actually.
05:57And we, at the moment, are driving along a road in there.
06:03So, is that okay, by the way?
06:04Oh, yeah, that's normal.
06:05It's normal?
06:06Yeah.
06:07Yeah.
06:08When you have a collection of earthquakes like this, are locked in the same place at the same time.
06:13It's called the Jarrairingall.
06:22Jarrairingall.
06:23Jarraircker?
06:24Jarrairingall.
06:25Yeah.
06:27So it's basically stirring the earth.
06:38Stirring the earth.
06:39Yeah.
06:40Yeah.
06:41But recently, the land here did more than stir.
06:50Just last year, over 10 million cubic metres of lava flowed out down this valley, creating
07:15brand new land.
07:16This is planet building in action.
07:20Activity so recent, you can still see the afterglow.
07:40So there's the old volcano in the distance, which is old and cold, and then there's all
07:46this new land.
07:51And look, it's glowing.
07:54To drive volcanism on this scale takes an enormous amount of energy.
07:58So where does it all come from?
08:05Think about what was happening here about four and a half billion years ago.
08:10So this would have been a cloud of gas and dust and rocks, and all those rocks falling together
08:21under the influence of gravity, ultimately to form the primordial Earth.
08:26During our planet's formation, that gravitational energy was transformed into heat, adding to
08:39the heat released by the decay of radioactive elements.
08:45Heat is a form of energy.
08:46Now, there's a law of physics, a law of thermodynamics, called the first law of thermodynamics.
08:52And it says that energy is neither created nor destroyed.
08:56But all the energy released when all those rocks were smashing together to form the primordial Earth is still here.
09:04It's stored, trapped, ever since.
09:13Just below the surface there, down in that crack, it's just glowing hot.
09:26Mars formed at the same time, and in the same way, the planet trapping enough heat to raise
09:35the largest volcanoes in the solar system.
09:46But unlike the Earth, these giant volcanoes fell silent, millions of years ago.
09:56Something happened to Mars's inner heat.
10:17And in the north of the planet, Mars Reconnaissance Orbiter spotted a clue.
10:26An impact crater, whose walls appear to be built from an intricate array of pillars.
10:47So perfect, they look almost engineered.
10:50They aren't, of course, the work of Martian sculptors.
11:00They're also found here on Earth.
11:09Just look at these beautiful geometric shapes.
11:12They look almost carved into the rock.
11:14They are a beautiful example of one of, actually, perhaps, in some sense, the most fundamental law of nature in action, the second law of thermodynamics.
11:30The second law of thermodynamics, put really simply, is that if you get a hot thing, high temperature, and bring it into contact with a cold thing, low temperature, then it is inevitable that energy will be transferred from the hot thing to the cold thing until they reach the same temperature.
11:51That's absolutely fundamental.
11:53That's what's happened here.
11:56That's what's happened here.
11:57The hot lava has come out from underneath the ground, that inner heat.
12:01It's met the cold atmosphere, and it's cooled down.
12:05It's lost energy.
12:06And what's true here on Earth is also true on Mars.
12:10On both planets, the pillars started life as hot, molten rock.
12:23As the lava cooled, it contracted, causing cracks to form on the surface that then grew downwards, creating the symmetrical columns.
12:37They are a direct consequence of the second law in action, as the lava released enormous amounts of heat, ultimately, out into space.
12:52But the pillars on Mars are likely millions of years older.
12:58The flows that built them died, just as Mars' volcanoes did.
13:03Mars lost its inner heat far faster than Earth.
13:08The question is, why?
13:13God, it's the single simplest invention in human history.
13:29If I'd have been the cavemen, we wouldn't have even domesticated animals.
13:37Ah!
13:39Success!
13:44Take one Earth-sized rock, add a smaller Mars-sized one, then roast for 30 minutes.
13:52So these two rocks have been in the fire, they've been heating up, and I've just got them out of the fire at the moment.
14:07They're at the same temperature.
14:08You can see there, they're both about 200 degrees.
14:10But now I've removed them from the fire, in accord with the second law of thermodynamics.
14:13They're going to start losing energy.
14:30But now I've removed them from the fire in accord with the second law of thermodynamics,
14:35well, they're going to start losing energy.
14:39So if we wait, then the rocks will cool down.
14:53Well, now these two rocks have been out of the fire for about 20 minutes or so,
14:57and not surprisingly, they've cooled down because they're in contact with a colder environment.
15:03The big one has cooled down to about 150, 155 degrees or so.
15:13But the little rock has cooled down way more.
15:16It's now only at a temperature of about 50 degrees or so.
15:20I can pretty much touch it with my finger.
15:22And that's because the small one is small, to be more specific.
15:30These rocks are losing heat to the environment through their surface area.
15:34And the small one has got much more surface area in relation to its volume than the large one.
15:42That means that it loses heat more quickly, cools down.
15:47And this is exactly what's happened to Earth and Mars.
15:58Earth is large enough to have held on to much of its internal heat.
16:03But Mars' radius is about half that of Earth's.
16:10So since the glory days, when its volcanoes were raised on a scale seen nowhere else,
16:20Mars' inner heat has escaped, lost to the cold of space,
16:25bringing the grandest volcanism the solar system has ever seen to an end.
16:45Size, then, sets a powerful limit on volcanic activity.
16:49Yet the next volcano world seems to break this rule.
17:03Out beyond the asteroid belt lies the first of the gas giants.
17:08Jupiter commands its own system of moons.
17:23Over 90 at the last count.
17:29Including one that is truly unique.
17:38NASA's Juno probe has been circling Jupiter since 2016.
18:01Its orbit taking it ever closer to Io.
18:17Its infrared camera saw a world consumed by fire.
18:22Each bright patch a volcanic eruption.
18:25Right now, rivers of lava are pouring across its tortured surface.
18:42In places, the volcanic eruptions are so violent.
18:49They throw columns of gas and dust far out into space.
18:53Io is the most volcanically active world in the solar system.
19:08Yet its radius is just over half that of Mars.
19:11Remember that scene in Alien?
19:12Where John Hurt and all the astronauts descend into the cave.
19:14And remember what happens to them.
19:18It's a bit of that feel.
19:19It's a bit of that feel.
19:51The fact that the planet of Io is hard to comprehend, to visualize.
19:54Until you come to a place like this.
19:58Here's a photograph of the surface of Io.
20:01And you see all those colors, all those beautiful yellows and oranges.
20:05Now look at the walls of this cave.
20:08Same colors.
20:09And that's because these are the same chemical elements.
20:12It's elements like sulfur.
20:13Now in this case, they were deposited on the walls of the cave when the magma seeped away around 5,000 years ago.
20:21But here, on the surface of Io, they've been constantly replenished.
20:26Just look at the scale of it.
20:28Imagine that.
20:29All on a small world, no bigger than our moon.
20:32Its small size means that Io's heat of formation has long gone.
20:42Something else is fueling these fires.
20:49The giant planet that looms so large in its skies.
21:03Io orbits around Jupiter.
21:07And Jupiter, being a very massive planet, raises tides on Io.
21:11And that's pretty much the same mechanism by which the moon raises the tides on Earth.
21:15But Jupiter is extremely massive.
21:19And so the tides on Io are extremely violent.
21:23It actually raises the tides in the rock of something like 100 meters.
21:28It's not in water, it's in rock.
21:30It's about the height of this cavern.
21:34But Io's orbit is not circular.
21:38It's elliptical.
21:40So that means that the moon comes close to Jupiter and far away.
21:45Close and far away.
21:47Once every 42 hours.
21:50So that 100-meter rock tide is going up and down and up and down every 42 hours as Io goes around Jupiter.
22:00So imagine the friction as that rock tide rises and falls and rises and falls.
22:07That introduces immense amounts of heat into the moon.
22:10It's actually about half the energy that we know is needed to power the volcanoes.
22:20But it's only about half.
22:22So where does the other half come from?
22:23Well that's where it gets really cool.
22:24So let's say Jupiter is there.
22:34And let's say that Io is orbiting around Jupiter.
22:38I'm going to exaggerate it a lot.
22:42Orbiting around Jupiter in an elliptical orbit.
22:47So Io is moving around like this.
22:51In an elliptical orbit there are two foci.
22:56The cross out here in empty space which we call the empty focus.
23:01And the other centered on the planet.
23:03And it turns out that Io, it can be shown that.
23:09That's what you say when I'm not going to show it because it's a load of mathematics.
23:13But it can be shown that Io is locked to the empty focus of the ellipse.
23:21The other focus, not the planet.
23:24But the tide is raised by Jupiter's gravity.
23:30So that big sort of huge towering tide in the rock always points towards the planet.
23:37As Io goes around, that tide is dragged backwards and forwards across the face of the moon.
23:46So not only have you got this big hundred meter tide in the rock going up and down as it goes around.
23:51It's going side to side, being dragged backwards and forwards across the face of the moon.
23:57That also injects a tremendous amount of energy into the moon.
24:02And that's the other half of the energy that's required to power Io's volcanoes.
24:07These colossal tides are what enabled Io, despite its size, to become so violently volcanic.
24:21The friction may even have melted so much of the moon that there's a global ocean of magma just below the surface.
24:32But there's another twist to Io's tale.
24:45This is a series of photographs of Io taken a few months ago now, over a period of several weeks.
24:58And you see the volcanoes, you see all that activity, the hotspots switching on and switching off.
25:03This is an infrared photograph. So what you're seeing here is heat, which is of useless energy being radiated off into space.
25:12Energy is being removed from Io's orbit.
25:15Now, if you remove energy from an elliptical orbit, it gets more and more circular.
25:22And if the orbit was circular, then the tidal heating would die away and the volcanoes would fall silent.
25:28So if all there was was Jupiter and Io, then Io would not look like that.
25:41Io's extreme activity should have killed off the tides that create its internal heat.
25:49So there must be something else beyond the squeezing of the moon, keeping its fires alive.
25:59Io is not alone in orbits around Jupiter.
26:03It's one of the four big moons known as the Galilean satellites.
26:07And Io orbits in what's called an orbital resonance with two of them, Europa and Ganymede.
26:13So here's Jupiter.
26:15And for every four orbits of Io, Europa goes around twice.
26:22And Ganymede goes around exactly once.
26:28That means on every fourth orbit, the moons line up and they give a gravitational kick to Io.
26:35They put energy into the orbit, which keeps the orbit elliptical.
26:41And so, whereas here on Earth, the volcanoes are driven by the primordial heat.
26:47And at the Earth's core, Io's volcanoes ultimately are driven by gravity.
26:51This bizarre volcanic moon,
27:05locked in a seemingly endless cycle of eruptions by its sister moons,
27:13is the furthest world from the sun where we've seen molten rock erupting onto the surface.
27:21But beyond Jupiter, another mission has encountered an entirely different type of volcano.
27:38Crossing the great gulf of space, we encounter the next planet.
27:52Saturn's rings loop for hundreds of thousands of kilometres through space.
28:11And just beyond them lies a glittering gem.
28:23A frozen moon, perhaps the last place you'd expect to find a volcano.
28:28Enceladus' surface is a hard mantle of frozen water.
28:46That's a deathly minus 200 degrees Celsius.
28:49On such a cold world, everything should be frigid, unchanging.
29:05Yet in 2005, the Cassini probe witnessed an extraordinary sight.
29:11Explosive jets roar from the surface.
29:30Reaching hundreds of kilometres into space.
29:32The largest volcanic plumes in the solar system.
29:47How are such epic eruptions possible on a tiny frozen moon?
29:52Even on Earth, eruptions don't happen.
29:53Even on Earth, eruptions don't happen.
29:54have to be molten rock.
29:55Even on Earth, eruptions don't have to be molten rock.
29:59The surface is the water.
30:17Even on Earth, eruptions don't have to be molten rock.
30:20Even on Earth, eruptions don't have to be molten rock.
30:37The geothermal activity so close to the surface here in Iceland,
30:41it's kind of a double-edged sword.
30:44I mean, on the one hand, it can be dangerous.
30:47But here, that geothermal activity is also used
30:52for the benefit of the population of Iceland.
30:55I mean, here you see thermodynamics in action.
30:59This is a power station.
31:01These two power stations in this region
31:04provide over 400 megawatts of power.
31:07It's enough to power Reykjavik and also half its hot water.
31:11And so you can feel the energy, that primordial energy of the Earth,
31:17rising to the surface, heading off into the cold of the atmosphere.
31:21And this is precisely what's happening out there on Enceladus.
31:28You do get a sense of the raw power just sitting just a few...
31:38Not far, in this case, below our feet, actually.
31:41But this is nothing compared to Enceladus.
31:54Where over 300 kilograms of water vapour and ice
32:00erupts every second from giant cryovolcanoes.
32:05It was Cassini that first spotted something odd
32:30about the motion of Enceladus.
32:33As it orbits Saturn, it wobbles on its axis.
32:39By a very small, but it turns out very significant, 0.12 degrees.
32:51Consider an egg.
32:56Now, when you spin an object, so when an object spins on its axis,
33:00it rotates around what's called its centre of mass.
33:04And for solid objects, like this hard-boiled egg,
33:06if I spin it, it spins nice and evenly.
33:12Uniformly.
33:14But now, look what happens if I take an egg that hasn't been hard-boiled,
33:18so it's filled with fluid.
33:19If I spin this, it wobbles all over the place, because the fluid inside is sloshing around.
33:32Because this egg is raw, the shell and liquid inside move independently of each other when spun,
33:36making the egg wobble.
33:37So the reason that Enceladus wobbles is because it's not completely solid.
33:51And we now think, by high-precision measurements and simulations of exactly how Enceladus wobbles,
33:58that there is a global liquid ocean beneath the frozen icy surface of Enceladus.
34:05And we can infer that because the laws of physics that apply to eggs here on Earth
34:11also apply to moons.
34:14I mean, Enceladus isn't going to do that.
34:32So Enceladus has an outer shell of ice
34:36sitting on top of a global ocean of water.
34:45But how is that water managing to force its way through five kilometres of solid ice?
34:55To find out, Cassini took a much closer look at the moon's south pole.
35:00Oh, wow. That's changed, hasn't it?
35:14It's changed. I don't know if it's changed for good or bad.
35:17Crikey.
35:21We found a really nice, relaxing place to explain some complicated physics.
35:26Now, here, about two kilometres down below my feet, there's a hot reservoir of water that's under pressure.
35:35Now, in the normal circumstances, that couldn't escape, but you'd build a borehole.
35:41And the moment that that borehole is present, then those pressure and temperature differences will equalise.
35:47And in this case, the water comes out of the borehole as superheated steam.
35:55Now, here is a photograph of Enceladus's south pole from Cassini.
35:59And you can immediately see there's something interesting here,
36:03interesting geology, cracks in the thin ice of the south pole.
36:07These things became known as the tiger stripes.
36:09They are revealed most clearly by Cassini's infrared instruments.
36:23The red shows freshly deposited ice crystals.
36:29Hints of activity along the entire length of the cracks.
36:32But the real insight comes when you measure their temperature.
36:41Because those tiger stripes are hot, really hot, compared to the surface.
36:47The surface of Enceladus is at minus 200, maybe minus 220 degrees Celsius.
36:53These tiger stripes are at minus 80 degrees Celsius.
36:56You might say, well, it's still cold.
36:59It is cold, but it's a lot hotter than the surface surrounding those structures.
37:05And so, what you can see here is high temperature, high pressure ocean beneath the surface.
37:11And there's a cold, low pressure environment of space above.
37:16And there's a weakness here in the surface.
37:20That allows that gradient to equalise.
37:22It's exactly what you see there.
37:24Other than there, someone has drilled a hole down into the deep underneath the earth.
37:30Whereas here, the ice happens to be thinner.
37:38We're not really sure why, actually.
37:41It could have been that there was some kind of impact here.
37:43But the upshot is the same.
37:44You get plumes of water, ice in this case, erupting out into space.
38:00The tiger stripes also create a window into Enceladus' interior.
38:05As Cassini flew through the plumes, it detected traces of molecular hydrogen and silicon dioxide.
38:16Chemistry that most likely comes from ocean water interacting with hot volcanic rock.
38:23This suggests that the ocean beneath Enceladus' icy shell has something that on Earth we call hydrothermal vents.
38:35The discovery of active geology on Enceladus took everybody by surprise.
38:54Nobody expected to see it on such a small world.
38:57But there might be more to Enceladus than just geology.
39:00See, hydrothermal vents of the kind we think might be present on Enceladus are one of the prime candidates for the cradle of life on Earth.
39:12The reason is that if you think about what the origin of life has to be, it has to be, in a sense, a transition from geochemistry to biochemistry.
39:22From active geology to active biology.
39:24So all the conditions seem to be present on Enceladus for the origin of life.
39:30And we don't even need to land or find some way of getting into that ocean to test that hypothesis.
39:36Because Enceladus is throwing the evidence potentially out into space.
39:41All we need to do is fly a spacecraft through those plumes.
39:44So Enceladus has to be one of the prime candidates for exploration in the solar system to search for the origin of life beyond Earth.
39:55Enceladus is not the only world with cryovolcanoes.
40:04Even at the furthest planet from the sun, we found evidence of them.
40:22Only one ship has ever made the journey.
40:39It was on one of Neptune's frozen moons that Voyager 2 caught a glimpse of recent activity.
40:46Its camera sent back images of dark smudges on Triton's face.
41:03Trails left by plumes erupting from its surface.
41:24Making Triton the most distant of the active volcanic worlds that we've witnessed.
41:30It seemed that the inventory of the solar system's active volcano worlds was complete.
41:50But recently, we found something we'd missed far closer to home.
41:59Venus is shrouded in thick clouds of sulphur dioxide.
42:06Making it very difficult to see the surface.
42:12So the spacecraft deployed here use radar to peer through the dense atmosphere.
42:25Magellan's radar imagery revealed Venus to be a hellish world.
42:40Its landscapes dominated by volcanoes.
42:44Over 85,000 at the last count.
43:00The moon's radar.
43:02Including truly bizarre examples.
43:05With deeply rutted sides.
43:10And lines of flattened volcanic domes like chains of pancakes.
43:15But with only snapshots from orbit to go on, no one knew if any of these volcanoes were active.
43:30Until, in 2023, a new analysis of the Magellan data revealed on a volcano the size of Mount Everest.
43:40An eruption along its northern flank.
43:48Proof, after all, that there's activity on the most volcano-ridden planet in the solar system.
43:55So why does Venus have such strange and diverse volcanoes littered across its surface?
44:08A clue can be found in Iceland's remote volcanic interior.
44:24In 1783, for a period of eight months, one of the most catastrophic volcanic eruptions in human history happened here.
44:4015 cubic kilometers of lava emerge from these eruptions.
44:47You see this, it's a remarkable landscape.
44:53The line of volcanoes.
44:55And they're really classic volcanoes.
44:59Like a child has drawn a volcano.
45:02And then everywhere else that you look across this valley, it's just lava.
45:11The fact that such a violent eruption happened here is not down to chance.
45:16If I take a map of the Earth and draw all the volcanoes, then they form a very distinct pattern.
45:32So there's a line all the way down North and South America on the Pacific coast.
45:38And then the other side of the Pacific, there's another line of volcanoes through places like Indonesia.
45:46Down here in the Rift Valley, Tanzania and Ethiopia.
45:50And then there's a line of volcanoes through Iceland and actually under the ocean,
45:56down the middle of the North and South Atlantic.
45:59So there's a very distinct pattern here.
46:02And that's because the surface of the Earth is not just one big slab.
46:06It's carved up into plates.
46:09The Earth has what's known as plate tectonics.
46:12So here, for example, down the Pacific coast of North and South America,
46:17the Pacific Ocean crust, the floor of the Pacific,
46:21is moving down this way underneath the continent.
46:26And you get eruptions, you get volcanoes.
46:29In the Atlantic, here, through Iceland, the opposite is happening.
46:35The Earth's crust is spreading.
46:37You can see it, actually. I'm sat on it.
46:40So over there in the west is North America, the North American plate.
46:46And over there in the east is the Eurasian plate.
46:49They're spreading apart here, literally here.
46:52And that's why there's a line of volcanoes moving down through here
46:57and straight onwards down into the South Atlantic.
47:01So Earth's pattern of volcanoes is telling us
47:04that there's what's called plate tectonics on the Earth.
47:08Now look at a map of the volcanoes on Venus. Look at that.
47:15It's absolutely covered completely randomly
47:19in pretty much every kind of volcano you can imagine,
47:23scattered across the entire face of the planet.
47:26And the reason for that is that there are no plate tectonics on Venus.
47:32We don't fully understand why Venus and Earth are so different.
47:47Why Earth developed plate tectonics and Venus didn't.
47:53But we do know that Venus's outer crust is much thinner.
48:06The planets Venus and Earth are roughly the same size.
48:09They've probably started life with about the same amount of internal heat.
48:13But it's how the heat escapes that makes all the difference.
48:17So here on Earth, it escapes mainly at those boundaries between the plates.
48:22But Venus has a much softer and thinner crust lithosphere than Earth.
48:28And so the heat can escape anywhere.
48:30And that's why you see this surface covered in a plethora of volcanoes.
48:36With less of a barrier, Venus's inner heat has built vast lava flows
48:48that run for thousands of kilometres.
48:58Can we now think that at least one of its volcanoes,
49:01we suspect many more remain active to this day.
49:13But only further missions will reveal just how alive
49:17volcanoes on our sister planet really are.
49:31Our exploration of the solar system has shown us that there's active geology
49:54in the strangest and most unexpected of places.
49:57The ice fountains of Enceladus.
50:00The Galilean moons of Jupiter.
50:03Even the frozen outer moon of the solar system, Triton.
50:09But amongst all those geologically active worlds scattered across the solar system,
50:14it still remains the case that there's only one place where we know for certain
50:19that the active geology became biology.
50:22And that's here on Earth.
50:24And if that really is the case, if we're alone here on Earth,
50:28then I think that raises a deep and very profound question.
50:31It's why?
50:33What is so special, possibly, about this place?
50:37Wonderfully, at least part of the answer appears to be a consequence of plate tectonics.
50:51Volcanoes, when they erupt, emit huge amounts of greenhouse gases like carbon dioxide.
51:01And as we all know, greenhouse gases heat a planet up.
51:06Now, Earth has a natural regulatory system.
51:11When it rains, the carbon dioxide is dissolved in the water and falls on the ground.
51:18And the carbon dioxide reacts with the rock of the mountains to form minerals.
51:24Then, plate tectonics can take those rocks and send them back down into the Earth.
51:33So, there's a cycle from volcano to atmosphere to land and back into the interior of the planet.
51:42Over geological time, this wonderful relationship between volcanoes, plate tectonics and our atmosphere
51:56has kept Earth's climate in check.
51:59And that stability has helped sustain an unbroken chain of life that stretches back almost 4 billion years.
52:17It's only here on Earth that a range of geological processes,
52:21from volcanoes to plate tectonics and hydrothermal vents,
52:25have conspired together to produce an environment that not only allowed life to begin,
52:31but also was stable enough to allow life to flourish.
52:35From the simplest living organisms to the endless forms most beautiful that we see
52:40covering the surface of the Earth today.
52:43The question is, how special is Earth?
52:47Well, I think the answer might be found in this giant laboratory, the solar system,
52:53in exploring the eclectic and diverse collection of worlds that we find orbiting the Sun.
53:00The current velocity is 145 meters per second.
53:03The current velocity is 145 meters per second.
53:07The current velocity is 145 meters per second at an altitude of about 9.5 kilometers above
53:35the surface.
53:42In February 2021, an astonishing new piece of hardware arrived on the surface of Mars.
53:56Perseverance is looking for evidence of ancient life, which may have started on the planet,
54:02thanks in part to its giant volcanoes.
54:11Volcanism played such an important role in the history of our planet, but also in the
54:17origin of life and evolution of life.
54:24Mars is like Earth's cousin.
54:26Very early in their history, if they had these volcanic activity, we found evidence that
54:31Mars had liquid water on its surface, it had a thicker atmosphere.
54:36So, at that time, when life was emerging on Earth, Mars also was creating similar environments.
54:46So it's possible that there was the potential for life on Mars.
54:53Mars's volcanism faded away, and so did the water on its surface and the chance for life
55:00to flourish on the red planet.
55:05But if life did at least get started, crucial evidence could be locked in the Martian rocks,
55:11waiting to be discovered.
55:15Perseverance, or as the team members called it, Percy, went to Mars to a crater known Jezero,
55:24which used to be an ancient lake.
55:27And so Percy is looking for evidence about the habitability of this environment.
55:35We're looking for signatures that there was life on the planet, but it would be absolutely
55:41amazing if we actually found cells or something similar in these rocks that indicated that
55:47there is life on Mars today.
56:00As it makes its way across the dry lake bed, Perseverance leaves behind a series of small,
56:06carefully sealed rock samples.
56:10The plan is to analyse these in a lab here on Earth.
56:17But right now, they're stuck on the surface of Mars.
56:27Retreating our samples from Mars is not going to be any easy task.
56:32First, we have to land on the surface.
56:38Then we have to pick the samples up, make sure they're packed into the spacecraft, and make
56:45sure that the spacecraft gets back to Earth.
56:48So there's quite a bit of coordination that has to be done.
56:55The schedule is still uncertain.
57:03But NASA's hope is to return the canisters back to Earth in the mid-2030s.
57:12It's exciting to me because I study these rocks, and so this would be a unique opportunity to
57:21have samples directly collected from the surface that I could analyse.
57:26Being able to have samples from a planet is so much better than just having to look at a
57:31through a telescope or through data sent back by a spacecraft.
57:37So regardless of all the effort it's going to take to get the samples back from Mars, it's definitely
57:41going to be worth it.
57:45At that point in time, we'll have a piece of Mars in our hands.
57:58Next time, we venture to the hidden realms of our solar system.
58:06The dark worlds, where mysteries lurk in the shadows, and a distant hinterland sends unexpected
58:22visitors hurtling towards Earth.
58:36We'll be right back in time.
58:39We'll be right back after the disaster, and we'll see you next time.
58:47If you have any questions, please post our questions in the chat.
58:56Thank you, guys.
Comments