All language subtitles for Solar.System.2024.S01E03.1080p.BluRay.x264-DRCOX_track3_[eng]

There's something
out there in the darkness.

A world with no name.

Its surface is ancient...

..and probably pink.

We don't know
where it came from

or how long it's been there.

But we do know it's not alone.

It's a dwarf planet,
only discovered in 2018.

Now, you might reasonably ask,

how could thousands
of astronomers,

both amateur and professional,

miss a world that is pink
and 400km across?

Well, the answer
might lie in its nickname,

which is FarFarOut,

because it really is
far, far out.

You might have thought
of the solar system as the sun,

and then all the planets lined
up, all the way out to Pluto,

but we now know that that's
just the tip of the iceberg.

This is a journey to
the least explored regions

of our solar system...

...asS we probe the mysteries
of the asteroid belt...

... Visit frozen worlds

that we're discovering
beyond Pluto...

..and reveal
a vast hidden kingdom

that even our most powerful
telescopes can't see...

...lost...

...In the dark.

It was the sound
that most people noticed.

(RUMBLING BOOM)

A sonic boom in the night.

Travelling at almost
50,000km per hour,

a rock tore through
the atmosphere...

... broke apart...

...and rained down
across Winchcombe.

A visitor from a distant realm.

On 28th February 2021,
a rock from space landed there,

on this driveway,

and it shattered
into hundreds of pieces.

Most of it went onto the lawn,

bits of it went onto
the neighbour's driveway,

and the indentation
in the driveway that was here

is now in
the Natural History Museum.

And here is a piece
of that rock.

And you see that it's
very dark. It's almost black,

very different to the rocks

that you find naturally
around here.

So the question is, other than
the rather nonspecific

"it came from space",

what exactly is this and where
exactly did it come from?

The cows werent the only ones
watching that night.

Doorbell and CCTV cameras
never sleep.

A network of specialist meteor
cameras also captured it.

And that meant it was possible
to calculate its trajectory...

...back over the skies
of England...

...out of Earth's atmosphere...

... past Mars...

...and into the darkness.

In between Mars and Jupiter...

.. lies a realm
of rocky worlds.

This is where
that rock came from.

The asteroid belt.

Asteroids are rubble
left over from the formation

of the solar system.

The remnants of planets
that never were.

It's thought there are at least
a million out here,

so dark they're incredibly
difficult to see.

But asteroids don't always stay
in the asteroid belt.

(RUMBLING EXPLOSION)

Every now and then,
two asteroids collide...

... causing fragments,
big and small,

to be lost from the belt.

This can create havoc
for neighbouring planets...

...[ncluding...our own.

We've flown several spacecraft

Straight through
the asteroid belt...

...but only one has stayed
to explore the region itself.

Most asteroids are like
misshapen boulders...

...but one stands out
from the rest...

...much bigger than the others

and almost perfectly spherical.

Dawn's target world.

At first, Ceres appears dark
and heavily cratered,

like its fellow asteroids.

But Dawn has discovered
that it's different.

Its surface is peppered
with bright white crystals.

So what are they?

Now, there is another world
in the solar system

where white crystals form
on the surface.

It's here, it's Earth.

This is a mountain composed
almost entirely of salt.

It's mainly sodium chloride -
actually, table salt -

although there's a bit
of magnesium

and potassium in there,

which gives it
those pinky colours.

This is enormous.

It extends hundreds of metres
down into the ground.

Now, it formed because,

around 40 million years ago
Or SO,

this was the Atlantic Ocean.

And then, as the climate
changed, the oceans receded,

evaporated away,
and left the salt behind.

And then plate tectonics
raised the ground up

to form salt mountains.

Now, salt crystals like this

only form in the presence
of liquid water.

In this case,
it was the Atlantic Ocean.

That raises
an intriguing question.

Are those crystal deposits
on the surface of Ceres salt?

And, if so, does that imply

there was once an ocean
on Ceres?

Dawn entered
into a close orbit.

And by measuring sunlight

reflected off
the crystal deposits,

it could determine
what they're made of.

Sodium carbonate.

A common type of salt.

A tantalising sign that Ceres
had an ocean in its past.

Orbiting just 35km
from the surface,

Dawn found another clue

that suggests an ocean
may still be there today.

It detected a different type
of salt crystal

that's only been found
in one other place

in the solar system.

When saltwater evaporates,

then it leaves these things
behind -

salt crystals - essentially
sodium and chlorine ions

bonded together
into a crystal lattice.

But under the right conditions,
when it's very cold,

then a different sort
of crystal can form

when sea water freezes.

It's called a hydrohalite.

Essentially, water molecules
are incorporated

into the crystal lattice.

Now, we see hydrohalites
here on Earth.

But the fact that we also
see them on Ceres

presents a mystery,

because hydrohalites
are unstable in a vacuum.

It's been calculated

they should only last
around 100 years

on the surface of Ceres

before the water escapes
out into space.

So the fact that we find them

implies that they must be
constantly forming,

and that, in turn,

must imply that,
below the surface of Ceres,

there is a reservoir
of saltwater today.

(BUBBLING)

Ceres is a world of water.

It's thought salty
subterranean lakes 40km deep

exist beneath the surface
today.

But how did the salt end up
on the surface?

The answer lies
in Ceres’ location.

Incoming asteroids
can punch straight through

to the lakes below.

Exposed to the vacuum of space,

the water vaporises
instantly...

... leaving its cargo of salt
behind,

and peppering Ceres
with bright white spots.

The discovery of water
beneath the surface

means this asteroid
is Now a candidate

in the search for life.

(WIND WHISTLES)

The more we've explored
the asteroid belt,

the more we've come fo realise

that it's not just
a band of rubble.

The dark worlds hiding here

are worthy of exploration
in their own right.

And the asteroids
that leave the belt

can transform
the planets nearby.

Mars orbits closer
to the asteroid belt

than any other planet.

And around
100 fresh impact sites

appear on Mars every year.

NASA's rovers have found
some spectacular meteorites...

... scattered
across its surface.

And one even spotted

what looks like an asteroid
in the sky...

.. floating
in front of the sun.

But it's actually
one of Mars's two moons.

Phobos isn't spherical,
like Our moon.

It's kind of a strange,
irregular shape.

So, there's a theory,
a simple theory -

maybe Phobos is an asteroid

that came in
from the asteroid belt

and was captured
by Mars's gravity.

Well, actually, wonderfully,

it turns out
things aren't that simple.

The European Space Agency
has a probe in orbit,

busily surveying
the Red Planet.

Mars Express orbits Mars
three times every day,

regularly passing
beneath Phobos.

Its high-resolution cameras
captured the most detailed

images of the moon ever seen...

... showing a surface covered
in strange grooves.

Phobos looks like someone's
ridden a bike all over it.

But perhaps more intriguing

were the measurements
Mars Express made

of the tiny moon's mass.

It's pretty hard, actually,

to measure the mass
of a small moon,

but the way it was done

was to measure how the path
of the Mars Express spacecraft

was deflected by the weak pull
of Phobos's gravity.

Now, once you have the mass,

and we have a reasonable idea
of the volume,

we calculate the density.

And that came as a surprise

because it turned out
that Phobos is more like...

...Kind of a gravel pile
weakly held together.

It's not very dense at all.

And that does support
the theory that maybe Phobos

was formed from the debris
of some kind of collision.

So it's possible that Phobos

is not a captured asteroid
after all...

...Dut was, in fact, formed

after a massive asteroid
hit Mars.

But there's still something
about Phobos

that neither theory
can explain.

Its strange grooves.

This landscape was sculpted
by the elements,

by the wind and the rain,

but on Phobos,
there is no wind and rain,

and so the landscape is
sculpted by something else.

It's actually sculpted
by gravity.

When you've got a planet anda
moon orbiting around each other

and spinning on their axes,

very complex gravitational
forces come into play -

they're called tidal forces -

and they act to deform the moon

and also actually
slightly deform the planet,

and they also act to change
the orbits.

But in the case
of Mars and Phobos,

what's changing is that Phobos
is descending towards Mars

in its orbit,

so it's only about 6,000km
above the surface now.

And, ultimately, over time,
Phobos gets closer to Mars,

and that means the tidal forces
get stronger and stronger.

The grooves on the surface

are stretch marks
and fractures.

(RUMBLING AND CRACKING)

Mars's gravity is tearing
Phobos apart.

Eventually,
Phobos will drift so close

that Mars's gravity
will destroy it.

But from this destruction,

something beautiful
will emerge.

As Phobos
begins to break apart...

...most of the debris will fall
to the surface of Mars.

But the rest
will remain in close orbit,

spreading out to encircle
the entire planet...

... leaving Mars with
a spectacular set of rings.

So what is Phobos?

The truth is,
and | think this is wonderful,

we still don't Know the full
story of the origin of Phobos.

But what we can say
is that this little moon

is a wonderful place...

...because in the future it's
going to turn the Red Planet

into a ringed world.

Leaving the asteroid belt
behind, we travel out,

further into the darkness.

Beyond Jupiter,

the gaps between the planets
get ever wider...

..and the temperature
plummets.

We push on, through millions
of kilometres of empty space...

...Uuntil we reach the furthest
planet from the sun.

Neptune is wrapped
in a dense blue blanket...

...clouds of methane
and ammonia

thousands of kilometres thick,

beneath which there is
no detectable surface.

But there are worlds out here
that you could stand on.

Neptune has at least 16 moons.

And one of them
is very unusual.

Triton's surface is coated
with pale nitrogen ice.

But unlike the other moons,
which are frozen to the core,

Triton is an active world.

Geyser-like plumes of gas
and dust 8km high

stretch into Triton's
upper atmosphere,

which flattens them abruptly
at 90 degrees...

... creating a vista
so Strange...

...It's hard to believe
it's real.

How did a moon,

4.5 billion kilometres
from the sun...

...become so active?

In the 10th century,

monks built a chapel
on this hillside.

It's an astonishing
achievement.

They carried all the stones
up by hand,

and when they'd finished,
a solitary monk...

...a hermit, lived here,

contemplating the great
mysteries of existence.

And every morning,

he would have seen the sun
rise in the east.

Now we know the reason
for that.

It's because the Earth's
spinning on its axis.

And, in fact, everything
spins in the solar system,

and almost everything
spins in the same direction.

Now, it's a fundamental
property of nature

that once things are spinning,
they continue to spin,

and continue to spin
in the same direction,

unless something happens.

Triton doesn't spin
in the same direction

as almost everything else.

It goes
in the opposite direction

in its orbit around Neptune,

so there must be a reason
for that.

Triton's unusual orbit,

which takes it around Neptune
in the opposite direction

to the inner moons...

.. suggests that Triton didn't
form alongside Neptune.

It came from somewhere else.

Sometimes in science,
things are quite simple.

There are sort of
rules of thumb that apply

and are useful.

And one of them
in the solar system

is that planets and moons
that form in the same region

around the sun, the same
distance from the star,

are made of the same stuff.

So, for example,
here's Neptune,

which is mainly made
of hydrogen,

helium and a bit of methane.

And there is Uranus,

which is made of hydrogen,
helium and a bit of methane,

cos they formed in the same
icy region far from the sun.

Here's Mars,
formed much closer in,

and it's silicates
and iron oxides,

aluminium, magnesium,
things like that.

And there's the Earth,

roughly the same place,
same stuff again.

Here is Pluto,

made of water ice,

nitrogen ices,

methane ices,
carbon monoxide.

And here is Triton.

The same.

So, we have a hypothesis,

which is a guess, | Suppose,
that we could test.

The hypothesis is that
maybe Triton and Pluto

formed in the same place.

To understand Triton,

we have to look deeper
into the darkness.

Neptune might be the furthest
planet from the sun,

but it's not the edge
of the solar system.

Not even close.

Over a billion kilometres
further out lies Pluto.

And it's not alone.

There are hundreds of thousands
of other worlds out here.

This is the Kuiper belt...

...a Vast frozen realm
billions of kilometres wide.

It's home to an exotic
collection of icy worlds...

.. Including
some 200 dwarf planets.

Some have rings and moons.

Others are bizarre
and misshapen.

But they all share
one thing in common.

They're made of
similar material to Triton.

It seems, then,
that the Kuiper belt

is where Triton belongs.

So how did it end up
in orbit around Neptune?

The answer might lie
in the strange geography

of the Kuiper belt itself.

In one region,

everything orbits the sun
in pretty much circular orbits,

like almost everything
else in the solar system,

but there's another region
where things orbit in ellipses.

It's almost as if something

ploughed through the
Kuiper belt and disturbed it.

There is one prime suspect.

Neptune.

It's thought Neptune formed
much closer to the sun...

...then slowly drifted out.

Its gravity disrupted
the Kuiper belt

and scattered
the icy worlds...

...but Triton was unable
to escape.

To this day,

Triton is trapped in a
backwards orbit around Neptune.

And being this close to
a giant has consequences.

Just as our moon raises
tides on the Earth,

Neptune raises tides
on Triton...

... Stretching
and squashing it...

(CRACKING AND RUMBLING)

... heating up its rock and ice.

It's thought that this is what
melts its frozen interior...

..and powers
the spectacular plumes.

So here is
the wonderful hypothesis

of what might have
happened

to explain
what we see on Triton.

So, as Neptune ploughed through
the Kuiper belt,

in the ensuing
gravitational chaos,

Triton got captured
into its reverse orbit.

And even to this day,

that orbit is ejecting energy
into the moon

by the tides raised upon it
by Neptune's gravity,

and that's driving the geology.

And isn't that
a wonderful example

of how you build
a hypothesis in science?

You put together the clues.

So we have
the composition of Triton

being the same as Pluto,

we have the strange geography
of the Kuiper belt,

and we know that gas giants
can change their orbits.

Put those together
and we have a hypothesis

of why Triton is the strange,
magical, twilight world

that we see today.

Leaving Triton behind,
we travel into the Kuiper belt.

We know very little
about the worlds out here.

They're so far away, we can't
make them out in much detail.

But we have sent
one spacecratt...

...to explore this region.

It took over nine years
for New Horizons to get here

and hone in on
its primary target.

The spacecraft captured
the first close-up images

of a Kuiper belt world
ever seen...

... revealing mountains on Pluto
as high as the Alps...

...made from water...
frozen hard as granite.

But there's something else
here.

Another world...

... hanging uncomfortably
close in the sky.

Charon doesn't rise or set,

and it's only visible
from one side of Pluto.

Understanding why these two
are so close together...

... reveals something unique

about this dark
and distant realm.

When Charon
was first discovered in 1978,

we just assumed that
it was a moon, Pluto's moon.

But the more we've learned
about Charon and, crucially,

the more we've learned about
the Pluto-Charon system,

the more we've come to realise
that there's more to it.

All large moons in the solar
system, including our own,

have something in common.

They only show one face
to their parent planet.

And the fact that all moons
do this is not a coincidence.

It's to do with
the complexity of orbits.

So let's say this is the Earth,
and I'm the moon.

We tend to think of the moon
just orbiting around the Earth

and the Earth sitting still.
That's not what happens.

Actually, both moon and Earth
orbit around what's called

the common centre of mass
of the Earth-Moon system.

It's just that, because
the Earth is way more massive

than the moon,
the centre of mass

is actually inside the Earth,

so the Earth is
kind of doing that.

- Let me show you what | mean.
- Bueno.

So here's the Earth,
spinning on its axis

once every 24 hours -
that's one day.

And there is the moon
orbiting around the Earth,

once every 27 and a bit days.

The gravitational interactions
between Earth and moon

cause their orbits
to synchronise.

The moon rotates on its axis
exactly once

for each lap it makes
around the Earth...

...with the result that
the same face of the moon

always points to the Earth.

But in the case of Pluto
and Charon,

the centre of mass
of the system

is outside of both bodies,

and so they both orbit
around the centre of mass,

which is somewhere in space.

It's where I'm standing.

Now, Pluto orbits once every
six and a half Earth days or so

and spins on its axis

once every six and a half days
or SO.

And Charon also orbits once
every six and a half days or so

and spins on its axis

once every six and a half days
or SO.

And the result of all that is

that Charon always presents
the same face to Pluto...

...and Pluto always presents
the same face to Charon.

Both worlds face each other
in a synchronous dance.

Now, this might seem really
strange and unusual. It isn't.

It's a consequence
of all those forces acting.

This is what would happen
to our Earth and moon,

given enough time,

but enough time would be

many times the current age
of the universe.

The difference here
is that this is not a moon

orbiting around a planet.

It really should be thought of
as two objects of similar mass

orbiting around each other.

Thank you.

Pluto and Charon are
a double planetary system...

..also known as a binary pair.

Just 20,000km apart,

they gaze at each other
without ever turning away.

This ts the first
double planetary system

we've observed,

but we think
there could be many more.

New Horizons is still
out there today,

searching for
more Kuiper belt worlds.

So far,
it's encountered just one.

Arrokoth is formed
from another pair,

now so close
they're touching.

So why do the worlds out here
in the Kuiper belt

form these rare partnerships?

The further from the sun
planets are,

the slower they move.

And way out here,
they move very slowly indeed.

But, occasionally,
collisions do occur.

It's thought that in the past

Pluto and Charon
crossed paths...

...but their glacial movement

meant that this was
less of an impact

and more of an embrace.

Instead of destruction,

the pair became partners
for life.

Now,
we've only actually visited

three worlds
in the Kuiper belt -

Pluto, Charon and Arrokoth -

but we have seen more using
the Hubble Space Telescope.

And what's interesting is that,
when we zoom in on those

what look like single pixels
of light,

many of them aren't
single pixels.

They're binaries,
just like Pluto and Charon.

So this is a pair of worlds
called Typhon and Echidna,

and it's a binary.

And this is another pair
of worlds, Vanth and Orcus.

And, again, you can see them
orbiting around each other,

orbiting around their
common centre of mass.

And this complex gravitational
dance, far from the sun,

means that the Kuiper belt
has a very complex structure

we don't really understand.

So the Kuiper belt does,
in a very real sense, represent

the frontier of our Knowledge

about the solar system...

...almost.

Past the Kuiper belt,

we enter a realm
of true darkness.

All we see are the bright stars
of the Milky Way.

Even our most powerful
telescopes struggle to see

anything in the solar system
out here.

But every now and then,

things do show up
in the darkness.

In 2018, a faint point of light
was detected...

...10 billion kilometres
beyond the Kuiper belt.

It's a dwarf planet...

...nicknamed FarFarOut.

But we think there's more
out there.

A lot more.

There's another realm
of our solar system,

far beyond the reaches

of any spacecraft or telescope
we've ever built...

...SO vast, so strange

and so deep
into the darkness...

.. It's almost impossible
to imagine.

Imagine that pinnacle
is the sun,

and I'm standing somewhere
around the orbit of Neptune,

and let's head out
to the Kuiper belt.

Now, Neptune is about 30 metres
away from the sun

so, on our scale,

that means that the Earth
would be one metre away.

One metre. That's called
one astronomical unit -

the distance of the Earth
from the sun.

It's about
150 million kilometres.

Now I'm inside the Kuiper belt,

traversing through that realm
of icy worlds,

and | reach Pluto, the furthest
extent of its orbit

at the edge
of the Kuiper belt -

50 astronomical units -
so 50 metres away.

And then, to the most distant
object we can see...

Well, we have to get a move on

because it's a long way away.

It is, of course, FarFarOut.

That is the most distant object
we have ever seen.

And it is...

...well, 130 astronomical units
away,

130 metres.

But remarkably...

...we strongly believe
that there's another region,

another realm
to the solar system.

But to go to the edge of that,

we have to go
far, far, far away.

Here we are,
2km away from the sun.

That's
2,000 astronomical units.

And this is where we think
another realm begins.

And, astonishingly, to me,

we think
it extends 100km further.

100,000 astronomical units.

That's over a light year.

Just imagine how many
strange worlds that contains.

This distant realm is known
as the Oort cloud,

a mighty kingdom
at least a trillion strong...

...hidden in the dark.

Most are thought to be icy
objects the size of mountains.

But it's likely
some are made of rock.

And if we were able to go there
and visit them,

we'd discover
that they are pristine...

... barely changed...

... since the dawn
of the solar system.

Stretching out
into interstellar space...

..and held in place
by the sun's gravity...

...the Oort cloud is
our solar system's largest

and most mysterious realm.

Well, here's the thing.
No telescope has ever seen

anything in the Oort cloud,

and the most distant spacecraft
from Earth, Voyager 1,

is all the way back there.

It's just beyond FarFarOut.

It's travelling at
around a million miles a day

and it will take 300 years
to get here,

and 30,000 years
to cross the Oort cloud.

But science doesn't
deal in fairy stories.

It's not as if somebody
just said,

"Well, that'd be a good idea -
let's invent it."

So why are we So sure
that it's there?

For as long as we've been
looking into the night sky,

there have been signs
that the Oort cloud is real.

And this is one of them.

It's existed
for billions of years.

And for most of that time,

it's been locked
in a deep, frozen slumber.

But now it stirs.

As it nears the sun, warm rays
bathe its surface...

..and it begins to thaw.

(CRACKING AND RUMBLING)

So much material is torn
from the surface...

...It stretches out
to form a tail...

...20 million kilometres long.

It's a comet.

Comet Nishimura
was visible from Earth

for just a few weeks.

And it's by no means
the first of its kind.

Hale-Bopp...

..and NEOWISE lit up our skies

for weeks on end.

And when we followed
their trajectories back,

we discovered that they
all came from the same place...

...300 billion kilometres
from the sun.

Countless comets
throughout recent history

have orbits that started
in the Oort cloud.

And that's doubly surprising,

because comets
have a very short lifetime.

Many of them only last
a few orbits around the sun.

So that implies
that there must be

a vast reservoir of comets
out here,

and that is a central piece
of evidence for the existence

of the Oort cloud.

But what does the Oort cloud
look like?

Well,
here's a fascinating thing.

The comets all come
from different directions -

from over there and over there
and down and across,

from everywhere.

Now, if the Oort cloud
was flat, like the Kuiper belt,

you'd expect them to come
from similar directions...

...which implies
that the Oort cloud

is not a flat disc...

...but some kind of giant
sphere surrounding the sun.

Now, just imagine
the scale of the Oort cloud,

a giant sphere enveloping
the entire solar system,

stretching more than
a light year, every direction.

We tend to think of
the solar system as the sun

and all the planets
and moons.

But as technology's improved,
we've discovered more...

...and more.

Our exploration of the solar
system has only just begun.

We know that
we've only explored

the tip of the iceberg,

a fraction of what's out there.

Most of the solar system lies,
at least for now,

way beyond our reach.

But by just making
some observations

of a few comets and asteroids

and even captured moons
that have ventured inwards

from the outer solar system,
and by doing science,

we've been able
to build a picture

and tell a story
of our solar system.

And we've discovered that
it isn't just a few planets

orbiting close
to a lonely star.

It is a vast structure
that stretches outwards,

maybe halfway
to the nearest star.

NEW SPEAKER: There's a real
mystery surrounding Phobos,

which is, we don't really
know what it is.

It looks exactly like
an asteroid, but it orbits Mars

in a very circular orbit
around its equator,

which is not
what you would expect.

NEW SPEAKER: Phobos looks like

an asteroid,
but it behaves like a moon.

So which one is it?

PROF COX:
We may soon have an answer.

The Japanese space agency Is
planning an audacious mission

to Phobos in 2026.

NEW SPEAKER: The MMX mission,

the Martian Moons eXploration
mission,

aims at going to Mars' moon

and bringing some samples
of Phobos back to the Earth.

SPEAKER 1: I'm really confident

that, as soon as we have
a sample of it on Earth,

we'll Know almost straight
away what Phobos is.

PROF COX: But landing
on Mars's tiny moon,

with its low gravity,

drilling into its surface
and getting the samples

all the way back to Earth
in a single round trip...

...1S no mean feat.

People have wanted to explore
the Martian moons

for a long time, have tried
to send missions there,

but they've failed
for a number of reasons.

(COMMS IN RUSSIAN)

Unfortunately,

Phobos 1 didn't work on its way
to the Mars system.

(COMMS IN RUSSIAN)

And then Phobos 2 got there
and sent back

a little bit of data
and then was lost contact with.

PROF COX: In 2011, the Russian
space agency, Roscosmos,

made a third attempt.

REPORT: The Phobos-Grunt probe
blasted off

from Baikonur Cosmodrome.

But the Russian spacecraft
failed to fire its own engines

to set it on its path to Mars.

DR CHAN: When a mission fails,
it's devastating,

it's disappointing,

but we've got to learn
from mistakes.

We need those failures to help
us develop our instruments,

to develop our mission
in order to make it a Success.

PROF COx: /f all goes to plan,
the Japanese mission

will transform
our understanding

of what Phobos is,

giving new insight into
how the moons and planets

of our solar system formed.

The MMX spacecraft
is amazingly capable.

It's got cameras
and spectrometers and a rover

and two sampling mechanisms.

But it's also doing something
that's never been done before,

which makes it hard.

And so, to be ready for that,

you have to put things through
a whole array of tests.

They'll vibrate everything the
way it will when it launches.

They'll put it through
hot and cold temperatures,

like you'll experience
from direct sun

or from being
in the cold of space.

PROF COX:
If the mission succeeds,

the return spacecraft is due
home with its samples in 2031.

PROF RUSSELL: When the sample
gets back to Earth,

we'll analyse it
in our laboratories to find out

what it's made of
and therefore what Phobos is.

Understanding the origin
of Mars' moon, Phobos,

will help us to take
a step forward

to understand the evolution

and the formation
of our solar system.