All language subtitles for Solar.System.2024.S01E01.1080p.BluRay.x264-DRCOX_track3_[eng]

So far, we've set foot on
one world beyond our own.

We discovered
a desolate, barren rock...

..an ancient, unchanging
cratered world.

And the footprints
we left there

could last
for millions of years.

Our only direct
personal experience

of an alien world
is of our Moon -

beautiful, but a dead, inactive
world, frozen in time -

whereas our planet
is active and alive.

If you come to the right places
on Earth,

it's literally seething
with energy beneath our feet.

For a long time, we wondered
if all this activity

is unique to our planet.

But now, thanks to a fleet
of spacecraft,

we know our world is not alone.

We currently have
over 40 probes

exploring the solar system...

.. relaying a stream
of information to Earth...

...allowing us to see
our sister worlds

in unprecedented detail.

They're revealing planets and
moons covered with volcanoes,

dwarfing anything
seen on our planet.

Alien landscapes
bursting with fire...

...and ice.

Eruptions so violent,
they reach into space.

So, why are some worlds
vibrant and alive...

...while others are cold
and dead?

Now, that question is deeper
than it first sounds,

because answering it will have
profound implications

for our understanding
of our place in the universe.

See, geological activity,

the flow of energy from the
interior of a world outwards,

is necessary
for the origin of life.

And that's why finding and
understanding those worlds

is a necessary first step

in the search for life
beyond Earth.

(CRASHING AND RUMBLING)

Let's begin a journey
to the volcano worlds...

... by leaving Earth...

.. heading away from the sun...

..and setting a course
to the planet next door -

the most visited of them all.

For almost two decades...

... the Mars Reconnaissance
Orbiter has pointed its cameras

at the Red Planet.

And the images it has sent back

have revealed volcanoes
on a staggering scale.

One So wide...

..[t would span the UK.

And one so fall...

../t rises up through
Mars's atmosphere,

almost to the edge of space.

Over time, these mega volcanoes

have flooded
the Martian surface

with a billion billion tonnes
of lava...

...so much that they've tipped
the entire planet over

by 20 degrees.

So, what drives
a planet's volcanism?

Iceland's one of the most
volcanically active

places on Earth.

This is the Icelandic
Met Office,

so this is the weather
forecasting site.

But it also gives you
a real-time update

on earthquakes,

and earthquakes are precursors
for volcanic eruptions.

These dots are all earthquakes
that have happened

in the last few hours,
actually.

And we, at the moment,
are driving along a road...

(LAUGHS) ...in there!
So, there's...

Is that OK, by the way?

- Oh, yeah, that's normal.
- It's normal?

- Yeah.
- Yeah?

KARL:
When you have a collection

of earthquakes like this,

a lot in the same place,
at the same time,

it's called the Jardéfreedingur.

- Jar6...?
- ...freedingur

...reedingur.

Yeah, so it's basically
stirring the Earth.

- Stirring the Earth.
- Yeah, yeah.

But recently, the land here
did more than stir.

Just last year, over ten
million Cubic metres of lava

flowed out down this valley,

creating brand-new land.

This is planet-building
in action.

Activity so recent,

you can still see
the afterglow.

So, there's the old volcano
in the distance,

which is old and cold,

and then there's
all this new land.

And look, it's glowing!

To drive volcanism
on this scale

takes an enormous amount
of energy.

So, where does it all
come from?

Think about
what was happening here

about 4.5 billion years ago.

So, this would have been

a cloud of gas and dust
and rocks,

and all those rocks

falling together under
the influence of gravity

ultimately to form
the primordial Earth.

During our planet's formation,

that gravitational energy
was transformed into heat...

...adding to the heat released

by the decay
of radioactive elements.

Heat is a form of energy.

Now, there's a law of physics,
a law of thermodynamics -

it's called the first law
of thermodynamics -

and it says that energy is
neither created nor destroyed.

So, all the energy released
when all those rocks

were smashing together to form
the primordial Earth

is still here.

It's stored - trapped -
ever since.

Just below the surface there,
down in that crack,

it's just glowing hot!

Mars formed at the same time,
and in the same way -

the planet trapping enough heat
to raise the largest volcanoes

in the solar system.

But unlike the Earth,

these giant volcanoes fell
silent millions of years ago.

Something happened
to Mars's inner heat.

And in the north
of the planet...

... Mars Reconnaissance Orbiter

spotted a clue.

An impact crater...

...Whose walls appear
to be built

from an intricate array
Of pillars...

...SO perfect they look
almost engineered.

They aren't, of course,
the work of Martian sculptors.

They're also found
here on Earth.

Just look at these beautiful
geometric shapes.

They look almost carved
into the rock.

They 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.

The 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.

That's absolutely fundamental.

That's what's happened here.

The hot lava has come out
from underneath the ground,

that inner heat.

It's met the cold atmosphere,

and it's cooled down,
it's lost energy.

And what's true here on Earth
is also true on Mars.

On both planets,

the pillars started life
as hot molten rock.

As the lava cooled,
it contracted,

causing cracks to form
on the surface

that then grew downwards...

.. creating
the symmetrical columns.

They're a direct consequence
of the second law in action,

as the lava released enormous
amounts of heat

ultimately out into space.

But the pillars on Mars are
likely millions of years older.

The flows that built them died,

just as Mars's volcanoes did.

Mars lost its inner heat
far faster than Earth.

The question is, why?

God, it's... (LAUGHS)

It's the single simplest
invention in human history.

If I'd have been the cavemen,

we wouldn't have
even domesticated animals.

Ah!

Success!

Take one Earth-sized rock,

add a smaller Mars-sized one,

and roast for 30 minutes.

So, 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, they're at...

...the same temperature.
You can see there,

they're both about 200 degrees.

But now I've removed them
from the fire,

in accord with the second law
of thermodynamics, well,

they're going to start
losing energy.

So, if we wait...

.. then the rocks
will cool down.

Well, now these two rocks
have been out of the fire

for about 20 minutes or so,

and, not surprisingly,
they've cooled down,

cos they're in contact
with a colder environment.

The big one has cooled down
to about...

...about 150,
155 degrees or so.

But the little rock
has cooled down way more.

It's now only at a temperature
of about 50 degrees or so.

| can pretty much touch it
with my finger.

And that's because
the small one is small.

To be more specific,
these rocks are losing heat

to the environment
through their surface area,

and the small one has got
much more surface area

in relation to its volume

than the large one.

That means that it loses heat
more quickly, cools down.

And this is exactly what's
happened to Earth and Mars.

Earth is large enough

to have held on to
much of its internal heat.

But Mars's radius
is about half that of Earth's.

So, since the glory days,

when its volcanoes were raised
on a scale seen nowhere else...

...Mars's inner heat
has escaped,

lost to the cold of space...

... bringing the grandest
volcanism

the solar system
has ever seen...

...to an end.

Size, then, sets a powerful
limit on volcanic activity.

Yet the next volcano world
seems to break this rule.

Out beyond the asteroid belt

lies the first
of the gas giants.

Jupiter commands
its own system of moons -

over 90 at the last count...

..ncluding one
that is truly unique.

lo.

NASA's Juno probe has been
circling Jupiter since 2016...

. Its orbit taking it
ever closer to lo.

Its infrared camera saw a world
consumed by fire...

..e@ach bright patch
a volcanic eruption.

Right now, rivers of lava
are pouring

across its tortured surface.

In places, the volcanic
eruptions are so violent...

... they throw columns of gas
and dust far out into space.

lo is the most volcanically
active world

in the solar system...

.. yet its radius is just over
half that of Mars.

You remember that scene
in Alien,

where John Hurt
and all the astronauts

descend into the cave?

And remember what happens
to 'em?

This has a bit of that feel.

(CREAKING)

The scale of volcanism on lo
is hard to comprehend,

to visualise,

until you come to a place
like this.

Here's a photograph
of the surface of lo.

Can you see all those colours?

All those beautiful yellows
and oranges?

Now look at the walls
of this cave.

Same colours.

And that's because these are
the same chemical elements.

It's elements like sulphur.

Now, in this case,
they were deposited

on the walls of the cave
when the magma seeped away

around 5,000 years ago.

But here, on the surface of lo,

they're being constantly
replenished.

Just look at the scale of it!

Imagine that,
all on a small world

no bigger than our moon.

Its small size means
that lo's heat of formation

has long gone.

Something else
is fuelling these fires.

The giant planet that looms
so large in its skies.

lo orbits around Jupiter,

and Jupiter,
being a very massive planet,

raises tides on lo.

And that's pretty much
the same mechanism

by which the moon raises
the tides on Earth.

But Jupiter
is extremely massive,

and so the tides on lo...
(LAUGHS)

...are extremely violent.

It actually raises the tides
in the rock

of something like 100 metres.

It's not in water -
it's in rock!

And it's about the height
of this cavern!

But lo's orbit is not circular.

It's elliptical.

So that means that the moon
comes close to Jupiter

and far away,

close and far away,

once every 42 hours.

So, that 100-metre rock tide
IS going up and down

and up and down every 42 hours

as lo goes around Jupiter.

So, imagine the friction as
that rock tide rises and falls,

and rises and falls.

That introduces immense amounts
of heat into the moon.

It's actually about
half the energy

that we know is needed
to power the volcanoes.

But it's only about half.

So, where does the other half
come from?

Well, that's where
it gets really cool.

So, let's say Jupiter...

...1S there,

and let's say that lo...

..1S orbiting around
Jupiter...

I'm going to exaggerate it
a lot.

...orbiting around Jupiter
in an elliptical orbit.

So lo is moving around
like this.

In an elliptical orbit,
there are two foci.

The cross,
out here in empty space,

which we call the empty focus,

and the other centred
on the planet.

And it turns out that lo...

"It can be shown that..."
That's what you say.

I'm not going to show it,
cos it's a load of mathematics.

But it can be shown that

lo is locked

to the empty focus
of the ellipse -

the other focus,
not the planet.

But the tide is raised
by Jupiter's gravity.

So, that big, sort of huge,

towering tide in the rock

always points
towards the planet.

As lo goes around,

that tide is dragged
backwards and forwards

across the face of the moon.

So not only have you got this
big 100-metre tide in the rock

going up and down
as it goes around,

it's going side to side,

being dragged backwards
and forwards

across the face of the moon.

That also injects a tremendous
amount of energy

into the moon,

and that's the other half
of the energy

that's required to power
lo's volcanoes.

These colossal tides are what
enabled lo, despite its size,

to become so violently
volcanic.

The friction may even have
melted so much of the moon...

...that there's a global ocean
of magma

just below the surface.

But there's another twist
to lo's tale.

This is a series of photographs
of lo taken -

it's only a few months ago
now -

over a period of several weeks.

And you see the volcanoes,
you see all that activity,

the hot spots switching on
and switching off.

This is an infrared photograph,

so what you're seeing here
is heat,

which is useless energy
being radiated off into space.

Energy is being removed
from lo's orbit.

Now, if you remove energy
from an elliptical orbit,

it gets more and more circular.

And if the orbit was circular,

then the tidal heating
would die away

and the volcanoes
would fall silent.

So, if all there was
was Jupiter and lo,

then lo would not
look like that.

lo's extreme activity should
have killed off the tides

that create its internal heat.

So there must be something else

beyond the squeezing
of the moon

keeping its fires alive.

lo is not alone in orbit
around Jupiter.

It's one of the four big moons

known as
the Galilean satellites.

And lo orbits in what's called
an orbital resonance

with two of them -
Europa and Ganymede.

So, here's Jupiter,

and for every four orbits
of lo,

Europa goes around twice,

and Ganymede goes around
exactly once.

That means, on every fourth
orbit, the moons line up,

and they give
a gravitational kick to lo.

They put energy into the orbit,

which keeps the orbit
elliptical.

And so, whereas here on Earth,
the volcanoes are driven

by the primordial heat
down at the Earth's core,

lo's volcanoes, ultimately,
are driven by gravity.

This bizarre volcanic moon...

... locked in a seemingly
endless cycle

of eruptions
by its sister moons...

...1S the furthest world
from the sun

where we've seen molten rock
erupting onto the surface.

But, beyond Jupiter,

another mission has encountered
an entirely different

type of volcano.

Crossing the great gulf
of space,

we encounter the next planet.

Saturn's rings loop

for hundreds of thousands
of kilometres through space.

And just beyond them
lies a glittering gem.

A frozen moon -

perhaps the last place
you'd expect to find a volcano.

Enceladus's surface is
a hard mantle of frozen water

that's a deathly
minus 200 degrees Celsius.

On such a cold world,

everything should be frigid,
unchanging.

Yet, in 2005,

the Cassini probe witnessed
an extraordinary sight.

Explosive jets roar
from the surface...

... reaching hundreds
of kilometres into space.

The largest volcanic plumes
in the solar system.

How are such epic eruptions
possible

on a tiny frozen moon?

Even on Earth, eruptions
don't have to be molten rock.

The geothermal activity
so close to the surface

here in Iceland is kind of
a double-edged sword.

| mean, on the one hand,
it can be dangerous.

But here, that geothermal
activity is also used

for the benefit of
the population of Iceland.

| mean, here you see
thermodynamics in action.

This is a power station.

These two power stations
in this region

provide over 400 megawatts
of power.

It's enough to power Reykjavik,
and also half its hot water.

And so,
you can feel the energy,

that primordial energy
of the Earth,

rising to the surface,

and heading off into the cold
of the atmosphere.

This is precisely
what's happening

out there on Enceladus.

It's just... (LAUGHS)

...you get... You do get
a sense of the raw power

just sitting just a few...

Not far, in this case -
below our feet, actually!

(LAUGHS)

But this is nothing
compared to Enceladus...

...where over 300kg
of water vapour and ice

erupts every second

from giant cryovolcanoes.

It was Cassini that first
spotted something odd

about the motion of Enceladus.

As it orbits Saturn,
it wobbles on its axis...

.. DY a very small

but, it turns out, very
significant 0.12 degrees.

- Consider an egg...
- (EGG CRACKS)

(CREW LAUGHS)

- (BEEP)
- Now, when you spin an object,

so when an object spins
on its axis,

it rotates around what's called
its centre of mass.

And for solid object
like this hardboiled egg,

If | spin it,
it spins nice and evenly.

Uniformly.

But now...

... look what happens if | take

an egg that hasn't been
hardboiled,

so It's filled with fluid.

If | spin this...

...It wobbles
all over the place

because the fluid inside
is sloshing around.

Because this egg is raw,

the shell and liquid inside
move independently

of each other when spun,
making the egg wobble.

So the reason
that Enceladus wobbles

is because it's not
completely solid.

And we now think,

by high-precision measurements
and simulations

of exactly how Enceladus
wobbles,

that there is a global
liquid ocean

beneath the frozen, icy surface
of Enceladus.

We can infer that

because the laws of physics

that apply to eggs
here on Earth

also apply to moons.

| mean, Enceladus isn't
going to do that. (LAUGHS)

So, Enceladus
has an outer shell of ice

sitting on top a global ocean
of water.

But how is that water
managing to force its way

through 5km of solid ice?

To find out, Cassini took
a much closer look

at the moon's south pole.

Oh, wow.
That's changed, hasn't it?

It's changed.

| don't know whether
it's changed for good or bad.

Crikey!

(CHUCKLES)

We've found
a really nice, relaxing place

to explain
some complicated physics!

Now, here, about 2km
down below my feet,

there's a hot reservoir of
water that's under pressure.

Now, under normal
circumstances,

that couldn't escape,
but we've drilled a borehole,

and the moment that
that borehole is present,

then those pressure and
temperature differences

will equalise,
and, in this case,

the water comes out of the
borehole as superheated steam.

Now, here is a photograph
of Enceladus's south pole

from Cassini, and you can
immediately see

there's something interesting
here - interesting geology.

Cracks in the thin ice
of the south pole -

these things became known
as the tiger stripes.

They are revealed most clearly

by Cassini's
infrared instruments.

The red shows freshly
deposited ice crystals...

. hints of activity

along the entire length
of the cracks.

But the real insight comes

when you measure
their temperature.

Because those tiger stripes
are hot, really hot,

compared to the surface.

The surface of Enceladus
is minus 200,

maybe
minus 220 degrees Celsius.

These tiger stripes are
at minus 80 degrees Celsius.

You might say,
"Well, it's still cold."

It is cold,

but it's a lot hotter
than the surface

surrounding those structures.

And so, what you can see
here is high-temperature,

high-pressure ocean
beneath the surface,

and there's a cold,
low-pressure environment

of space above,

and there's a weakness
here in the surface.

That allows that gradient
to equalise.

It's exactly
what you see there,

other than there,
someone has drilled a hole down

into the deep,
underneath the Earth,

whereas, here,
the ice happened to be thinner.

We're not really sure why,
actually.

It could have been that there
was some kind of impact here.

But the upshot is the same.

You get plumes of water,

ice in this case,

erupting out into space.

The tiger stripes also create

a window
into Enceladus's interior.

As Cassini flew
through the plumes,

it detected traces of molecular
hydrogen and silicon dioxide...

...chemistry that most likely
comes from ocean water

interacting
with hot, volcanic rock.

This suggests that the ocean
beneath Enceladus's icy shell

has something that, on Earth,
we call hydrothermal vents.

The discovery of active
geology on Enceladus

took everybody by surprise.

Nobody expected to see it
on such a small world.

But there might be more to
Enceladus than just geology.

See, 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.

The 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, from active
geology to active biology.

So, all the conditions seem
to be present on Enceladus

for the origin of life,
and we don't even need to land

or find some way
of getting into that ocean

to test that hypothesis,
because Enceladus

is throwing the evidence,
potentially, out into space.

All we need to do

is fly a spacecraft
through those plumes.

So Enceladus has to be

one of the prime candidates
for exploration

in the solar system

to search for the origin
of life beyond Earth.

Enceladus is not the only
world with cryovolcanoes.

Even at the furthest planet
from the sun...

...we've found evidence
of them.

Only one ship
has ever made the journey.

It was on one of Neptune's
frozen moons

that Voyager 2 caught
a glimpse of recent activity.

Its camera sent back images
of dark smudges

on Triton's face...

...trails left by plumes
erupting from its surface...

...Making Triton
the most distant

of the active volcanic worlds
that we've witnessed.

It seemed that the inventory

of the solar system's
active volcano worlds

was complete.

But recently,

we found something we'd missed
far closer to home.

Venus Is shrouded in thick
clouds of sulphur dioxide...

...Making it very difficult
to see the surface.

So the spacecraft deployed here
use radar

to peer through
the dense atmosphere.

Magellan's radar imagery
revealed Venus to be

a hellish world...

.. Its landscapes dominated
by volcanoes.

Over 85,000
at the last count...

...ncluding truly bizarre
examples,

with deeply rutted sides...

...and lines of flattened
volcanic domes

like chains of pancakes.

But with only snapshots
from orbit to go on,

no-one knew if any of these
volcanoes were active...

Until, in 2023,
a new analysis

of the Magellan data revealed,

on a volcano the size
of Mount Everest,

an eruption
along its northern flank.

Proof, after all,
that there's activity

on the most volcano-ridden
planet in the solar system.

So why does Venus
have such strange

and diverse volcanoes
littered across its surface?

A clue can be found

in Iceland's remote
volcanic interior.

In 1783,
for a period of eight months,

one of the most catastrophic
volcanic eruptions

in human history happened here.

15 cubic kilometres of lava
emerged from these eruptions.

You see this...

It's a remarkable landscape,
a line of volcanoes.

And they're really
classic volcanoes,

like a child has drawn
a volcano.

And then, everywhere else that
you look across this valley,

it's just lava.

The fact that such a violent
eruption happened here

is not down to chance.

If | take a map of the Earth

and draw all the volcanoes,

then they form
a very distinct pattern.

So, there's a line all the way
down North and South America

on the Pacific Coast.

And then the other side
of the Pacific,

there's another line
of volcanoes

through places like Indonesia.

Down here in the Rift Valley,
Tanzania and Ethiopia.

And then there's a line
of volcanoes through Iceland

and, actually, under the ocean,

down the middle of
the North and South Atlantic.

So there's a very distinct
pattern here.

And that's because
the surface of the Earth

is not just one big slab.
It's carved up into plates.

The Earth has what's
known as plate tectonics.

So, here, for example,

down the Pacific Coast
of North and South America,

the Pacific Ocean crust,

the floor of the Pacific,

is moving down, this way,

underneath the continent.

And you get eruptions,
you get volcanoes.

In the Atlantic, here,
through Iceland,

the opposite is happening.

The Earth's crust is spreading.

You can see it, actually.
I'm sat on it.

So, over there, in the west,
is North America,

the North American Plate,

and, over there, in the east,
is the Eurasian Plate.

They're spreading apart here,
literally here,

and that's why
there's a line of volcanoes

moving down through here

and straight onwards,
down into the South Atlantic.

So, Earth's pattern
of volcanoes is telling us

that there's what's called
plate tectonics on the Earth.

Now look...

..at a map of the volcanoes
on Venus. Look at that.

It's absolutely covered,

completely randomly,

in pretty much every kind
of volcano you can imagine,

scattered across the entire
face of the planet.

And the reason for that

is that there are no
plate tectonics on Venus.

We don't fully understand

why Venus and Earth
are so different...

...why Earth developed
plate tectonics

and Venus didn't.

But we do know that Venus's
outer crust is much thinner.

The planets Venus and Earth
are roughly the same size.

They probably started life

with about the same amount
of internal heat,

but it's how the heat escapes
that makes all the difference.

So, here on Earth,

it escapes mainly at those
boundaries between the plates.

But Venus has a much softer
and thinner crust -

a lithosphere - than Earth,

and so the heat can escape
anywhere.

And that's why you see
this surface

covered in a plethora
of volcanoes.

With less of a barrier,

Venus's inner heat has built

vast lava flows that run
for thousands of kilometres.

And we now think that
at least one of its volcanoes,

and we suspect many more,

remain active to this day.

But only further missions
will reveal just how alive

volcanoes on our sister planet
really are.

Our exploration of the solar
system has shown us

that there's active geology
in the strangest

and most unexpected of places.

The ice fountains of Enceladus,

the Galilean moons of Jupiter,

even the frozen outer moon
of the solar system Triton.

But amongst all those
geologically active worlds

scattered across
the solar system,

it still remains the case
that there's only one place

where we know for certain

that the active geology
became biology,

and that's here, on Earth.

And if that really is the case,
if we're alone here on Earth,

then | think that raises a deep
and very profound question.

It's why? What is so special,
possibly, about this place?

Wondertully,
at least part of the answer

appears to be a consequence
of plate tectonics.

Volcanoes, when they erupt,

emit huge amounts of greenhouse
gases, like carbon dioxide.

And as we all know,

greenhouse gases
heat a planet up.

Now, Earth has a natural
regulatory system.

When it rains,

the carbon dioxide
is dissolved in the water

and falls on the ground...

...and the carbon dioxide
reacts

with the rock of the mountains
to form minerals.

Then, plate tectonics
can take those rocks

and send them back down
into the Earth.

So there's a cycle from volcano
to atmosphere to land

and back into the interior
of the planet.

Over geological time,

this wonderful relationship

between volcanoes, plate
tectonics and our atmosphere

has kept Earth's climate
in check.

And that stability
has helped sustain

an unbroken chain of life

that stretches back
almost four billion years.

It's only here on Earth

that a range of geological
processes, from volcanoes

to plate tectonics
and hydrothermal vents,

have conspired together

to produce an environment

that not only
allowed life to begin,

but also was stable enough
to allow life to flourish,

from the simplest
living organisms

to the endless forms,
most beautiful, that we see

covering the surface
of the Earth today.

The question is,
how special is Earth?

Well, | think the answer
might be found

in this giant laboratory,

the solar system,

in exploring the eclectic and
diverse collection of worlds

that we find orbiting the sun.

COMMS: Current velocity
is 145 metres per second,

at an altitude of about 9.5km
above the surface.

PROF COX: /n February 2021,

an astonishing new piece
of hardware...

...arrived on the surface
of Mars.

Perseverance is looking
for evidence of ancient life

which may have started
on the planet,

thanks in part
to its giant volcanoes.

NEW SPEAKER: Volcanism
played such an important role

in the history of our planet,

but also in the origin
of life and evolution of life.

Mars is like Earth's cousin.

Very early in their history,

they had these
volcanic activities.

We found evidence that Mars had
liquid water on its surface,

it had a thicker atmosphere.

NEW SPEAKER: So, at that time,

when life was emerging
on Earth...

...Mars also was creating
similar environments.

So it's possible that there was

the potential for life on Mars.

PROFESSOR COx:
Mars's volcanism faded away,

and so did the water
on its surface,

and the chance for life
to flourish on the Red Planet.

But if life did at least
get started,

crucial evidence could be
locked in the Martian rocks,

waiting to be discovered.

DR NUNEZ: Perseverance or,
as team members call it, Percy,

went to Mars,
to a crater known...Jezero...

...which used to be
an ancient lake.

And so Percy is looking
for evidence

about the habitability
of this environment.

DR DOTTIN: We're looking
for signatures that

there was life on the planet,

but it would be
absolutely amazing

if we actually found cells,

or something similar,
in these rocks

that indicated that
there is life on Mars today.

PROF COx: As it makes
its way across the dry lakebed,

Perseverance leaves behind
a series of small,

carefully sealed rock samples.

The plan ts to analyse these
in a lab here on Earth.

But right now, they're stuck
on the surface of Mars.

Retrieving our samples
from Mars

is not going to be
any easy task.

First, we have to
land on the surface...

...then we have to
pick the samples up,

make sure they're packed
into the spacecraft...

...and make sure that the
spacecraft gets back to Earth.

So there's quite a bit
of coordination

that has to be done.

PROF COX: The schedule
is still uncertain.

But NASA's hope is to return
the cannisters back to Earth...

...In the mid-2030s.

DR DOTTIN: It's exciting to me,
because | study these rocks,

and so this would be
a unique opportunity

to have samples directly
collected from the surface

that | could analyse.

DR QUICK: Being able to have
samples from a planet

is so much better than
just having to look at a planet

through a telescope or through
data sent back by a spacecraft.

So, regardless of all
the effort it's going to take

to get the samples back
from Mars,

it's definitely going to be
worth it.

At that point in time,

we'll have a piece of Mars
in our hands.