Solar System (2024) s01e01 Episode Script

1
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.
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
..it would span the UK.
And one so tall
..it 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
LAUGHTER
..in there!
So, there's
Is that OK, by the way?
Oh, yeah, that's normal.
- It's normal?
- Yeah.
Yeah?
When you have a collection
of earthquakes like this,
a lot in the same
place, at the same time,
it's called the jardfraedingur.
- Jard
- Fraedingur
..fraedingur?
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've 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 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 are 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
..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 remove 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
..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.
I 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.
Including one that is truly unique.
Io.
Nasa's Juno probe has been
circling Jupiter since 2016.
Its orbit taking it ever closer to Io.
Its infrared camera saw
a world consumed by fire,
each 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.
Io 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.
The scale of volcanism on
Io is hard to comprehend,
to visualise,
until you come to a place like this.
Here's a photograph
of the surface of Io.
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 Io,
they've been 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 Io's
heat of formation has long gone.
Something else is fuelling these fires.
The giant planet that looms
so large in its skies.
Io orbits around Jupiter -
and Jupiter,
being a very massive planet,
raises tides on Io.
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 Io
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 Io'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 hundred-metre rock
tide is going up and down
and up and down every 42 hours,
as Io 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
..is there,
and let's say that Io
..is orbiting around Jupiter
I'm going to exaggerate it a lot.
..orbiting around Jupiter
in an elliptical orbit.
So Io 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 Io
"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
Io 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 Io goes around,
that tide is dragged
backwards and forwards
across the face of the moon.
So not only have you got this big
hundred-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 Io's volcanoes.
These colossal tides are what
enabled Io, 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 Io's tale.
This is a series of
photographs of Io 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 Io'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 Io,
then Io would not look like that.
Io's extreme activity
should've 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.
Io is not alone in orbit around Jupiter.
It's one of the four big moons
known as the Galilean satellites.
And Io 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 Io,
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 Io.
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,
Io's volcanoes, ultimately,
are driven by gravity.
This bizarre volcanic moon
..locked in a seemingly endless cycle
of eruptions by its sister moons
..is 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 -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.
I 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.
I 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,
heading off into the
cold of the atmosphere.
This is precisely what's
happening out there on Enceladus.
It's just
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.
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
..by a very small but, it turns
out, very significant 0.12 degrees.
Consider an egg.
EGG CRACKS CREW LAUGH
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 a solid object -
like this hardboiled egg -
if I spin it, it spins nice and evenly.
Uniformly.
But now
..look what happens if I take an
egg that hasn't been hardboiled -
so it's filled with fluid.
If I 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.
I mean,
Enceladus isn't going to do that.
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 - I don't know whether
it's changed for good or bad.
Crikey!
HE 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 -200,
maybe -220 degrees Celsius.
These tiger stripes are
at -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.
Could've 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.
Including 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 I 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 I think that raises a deep
and very profound question.
It's why? What is so special,
possibly, about this place?
Wonderfully, 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, I 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.
Current velocity is 145 metres
per second, at an altitude
of about 9.5km above the surface.
In 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.
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.
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.
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.
Perseverance, or, as team members
called it, Percy, went to Mars,
to a crater known as Jezero,
which used to be an ancient lake.
And so Percy is looking for evidence
about the habitability
of this environment.
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.
As it makes its way across
the dry lakebed, Perseverance
leaves behind a series of small,
carefully sealed rock samples.
The plan is 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 an 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.
The schedule is still uncertain.
But Nasa's hope is to return
the cannisters back to Earth
..in the mid-2030s.
It's exciting to me,
because I study these rocks,
and so this would be a unique
opportunity to have samples
directly collected from the
surface that I could analyse.
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.
Next time, we venture to the
hidden realms of our solar system.
The dark worlds
..where mysteries lurk in the shadows
..and a distant hinterland
sends unexpected visitors
hurtling towards Earth.