All language subtitles for the.planets.us.s01e02.480p.hdtv.x264.rmteam

Mars.

The red planet.

Many scientists believe
that the first person

to set foot on its surface
is alive today.

Perhaps it's you.

If it is you, then welcome
to your ultimate travel guide.

Using real images and data,

we will take you to some of
the most jaw-dropping landscapes

discovered in our solar system

right here on Mars.

We don't have anything like this
on earth.

Places that may change

the way you think
about our own world...

Is there life beyond the earth?

This is probably one
of the most profound questions

that's ever been asked
by the human mind.

...on a journey
that will test the endurance

of any traveler.

Traveling to Mars
is not for the faint of heart.

At the dawn of the
next golden age of exploration,

here's your quintessential guide
to the martian frontier.

Oh, it's beautiful.

Have you ever dreamed about
traveling out of this world?

My name is Mike Massimino,

and I turned that fantasy
into a reality

when I space-walked to repair
the Hubble space telescope.

Great job, Mike.

Now as we expand our knowledge
of our solar system

from Mercury
to the cosmic unknowns,

I want to take you
on a personal journey to...

-- Captions by vitac --
www.Vitac.Com

captions paid for by
discovery communications

welcome to "the planets."

I'm Mike Massimino.

Ever since my space missions,

I've thought about which planet
in the solar system

I'd like to visit.

Hands down, it's Mars.

So far, humans have only
touched down on our moon,

but that could change.

NASA is planning on sending
its first astronaut to Mars

as soon as 2030,

but there's a whole lot more

we need to find out about
our neighbor before we visit.

The red glow of Mars

is a constant feature
in our night sky.

But it's only
when viewed up close

that this rusty planet
begins to reveal its secrets.

It promises to wow any visitor

who just traveled
the seven months it would take

to get there from the earth
by spaceship.

Other than our home planet,

there is no world
we know in such detail.

That's thanks to the numerous
satellites and rovers

we've sent there
over the past 50 years.

And the landscapes
they have looked down upon

tell astonishing stories.

Vast plains riddled
with hundreds of thousands

of craters, deep canyons,
and strange rock formations,

and views not seen
anywhere on earth.

We've photographed
every corner of the planet,

and plans are now under way to
send the first humans to Mars.

But what does it take
to get there?

How can we survive
on the surface?

And where are the best places
to explore?

For those ready for adventure,

the best place to start is
a well-known martian landmark --

Gale crater,

a vast scar on the planet

and home to NASA's flagship
rover, curiosity, since 2012.

The crater itself dwarfs any
similar features here on earth.

Every day, curiosity
sends back detailed images

from within the crater.

This is one of them.

And here,
at the data science institute,

professor Sanjeev Gupta is part
of the team studying them.

This is the crater rim
over here.

This is 150 kilometers
in diameter.

It's a really big feature.

And there,
in this view over here,

what we can see is mount sharp.

That's 5 kilometers high.

That sits in the center of the
crater, so it's really amazing

'cause you really get
a sense of this mountain

that's sort of
towering high above us.

That's a mountain
over 93 miles across

and over 3 miles high.

But professor Gupta
isn't simply enjoying the view.

Today, we know Mars
as a dry, desolate world,

but some images suggest
that wasn't always the case.

Gale crater was chosen as
the landing site for curiosity

after a very lengthy
selection process.

Orbiters had discovered evidence

that the rocks
at the base of mount sharp --

so, the rocks
that we can see over here --

had evidence for hydration.

Long before
curiosity left earth,

satellite images like this

hinted there was more to
this crater than meets the eye.

And what's beautiful
in this image

is that you can see
these canyons or valleys

carved into the crater rim,

and this is really suggestive

that water flowed down
the crater rim

and eroded these canyons.

Secondly, we can see
all these beautiful layers here

that form the base
of mount sharp.

These layers are enriched
in hydrated minerals.

So, those are minerals
that contain water.

Curiosity's mission?

To follow the elusive trail
of water on Mars.

So, essentially,
the orbital images

provide us clues on where to go,

but we really need
to be on the ground,

looking carefully at these rocks
from a few meters away,

and that's why we send rovers
to Mars.

Once the rover touched down,

it quickly began picking up
more clues.

These are actually pebbles

that are a few centimeters
in diameter.

What you can see when you look
at the pebble outlines

is that they have
rounded shapes.

So they've been,
basically, rounded

during a transport process.

And they're too large

to be moved
and rounded by wind processes,

and so the only way we can
actually get this rounding

is by water flow.

I think it's irrefutable

that there was once water
flowing at the surface on Mars,

based on
the geological evidence.

But even
with its smooth surface,

Gale crater wouldn't be
the best landing site on Mars.

So the question remains, where
should you first touch down?

This canyon is Valles Marineris,

named after the mariner 9, the
NASA mission that discovered it.

The scale of the canyon
is breathtaking.

It is like the Grand Canyon
on earth, but supersized.

In places, its walls
plunge 6 miles down,

a unique geological formation

not matched
anywhere else on the planet.

And it's thanks to this geology
that this vast canyon system

makes the ideal landing site
for martian explorers.

Astrogeologist Dr. Jim rice
is confident in this conclusion.

He's been involved
in selecting Mars landing sites

for every NASA mission
since Mars pathfinder in 1994.

You want something fairly flat,
not too rocky, not too dusty.

And because we use parachutes
to help slow us down

in the entry
to the martian atmosphere,

we're gonna be lower
in elevation.

And the views while
landing would be jaw-dropping.

Valles Marineris is a great spot

because it's basically kind of
like the Grand Canyon here.

It's like someone has taken --

a giant surgeon with
a scalpel making an incision

and opened up the crust
of the planet,

allowing you to see deeper down,

and deeper down in geology
is further back in history.

It's this view inside the planet

that is the big draw
for Dr. rice,

but for most of us,
the epic scale alone

would be enticing enough.

Now, that canyon
is 10 times longer

than the Grand Canyon here,

it's four times deeper,
and about 12 times wider.

Another way
to think about it is,

the vast expanse
of this canyon system,

the length of it would be from
New York City to Los Angeles.

So that truly is the grand
canyon of the solar system.

Valles Marineris
would provide the ultimate draw

for any martian visitor.

But it's not just the views
that are attractive.

Touching down inside
Valles Marineris

could help answer
long-held questions

about the chasm's formation.

Images like this,
taken from orbit,

give us some clues
to its history.

Once theory
is that ancient volcanoes

ripped apart the surface,

creating a rift that running
water continued to carve.

But only by landing there can
we gather the conclusive proof.

What you want to do
as a geologist

is get to outcrop
like we see right here,

a slab of rock
you can get up and interrogate

and kind of taste, so to speak,
with your instruments.

If you're a martian coming to
earth, you'd probably come here,

because you'd get a good idea

of the geologic history
of the earth

from the rim
all the way down to the floor.

You know, most of these rocks

record oceans
that came and went,

mountain chains
that came and went,

deserts that came and went.

You know, on Mars,
I think it'd be safe to say

you'd go back 3, 3 1/2,
maybe even 4 billion years

at the floor of the canyon
down there.

I'd go in a heartbeat.

Would you take
the chance to travel to Mars?

Visiting the red planet
is not just about sightseeing.

Once you get there,
you'll have to survive

some of the harshest conditions
in the entire solar system.

Years of hard work and planning

went into my missions
to the Hubble space telescope,

but preparing to go to Mars
is a whole other story.

There'll be
ice-cold temperatures

and solar radiation
coming at you from every angle.

So to meet these challenges,

scientists are coming up
with some useful new tools

to help us survive.

Mars is a barren world,

with its water and atmosphere
long lost to the hands of time.

For human space travelers,

it would be an absolutely
inhospitable environment.

That is why researchers

have descended upon
the volcanoes of Hawaii,

an environment on earth
that closely matches Mars

in terms of landscape, at least.

They're trying to figure out
how we can survive

on the desolate
and hostile planet.

Michael lye and his team
have designed a space suit

to simulate Mars missions
here on Hawaii.

Once you land on Mars, you're
basically living in a vacuum.

It's got an atmosphere,
but not much.

And while you're there,

you won't be able to go outside
and breathe naturally.

Temperature-wise, it's gonna be
extremely cold many times.

And it's generally
a pretty hostile environment --

solar flares, U.V. radiation,
Alpha particles,

other kinds of radiation
from the sun,

as well as cosmic radiation

that's coming from all over
the solar system and beyond.

You have to wear a space suit

the entire time
you're on the surface of Mars.

Temperatures on Mars
can plummet

to below negative-195 degrees
near the poles.

Containing virtually no oxygen,

the wispy atmosphere
has a pressure of just 0.6%

of what can be found
at sea level here on earth.

This is why space suits will be
one of the critical components

for any future human missions.

So, you need something

to protect you
from essentially exploding

or at least having your skin
all stretched out

and the blood boiling
and getting the bends,

things like that.

The way space suits
are designed now,

they're mostly
pressurized spacecraft.

Essentially, they're almost like
a mini spaceship.

Oh, it's beautiful, Mike.
It really is.

Martian visitors will require
a full face helmet,

permanent oxygen supply,
life support,

and electrical systems

just like astronauts on board
the international space station.

But you'll have to look
beyond your space suit

for safety and shelter.

The next location
in our Mars travel guide

is one that could provide
some much-needed refuge

for the weary traveler --
the Tharsis region,

home to some of the largest
volcanoes in the solar system,

including Pavonis Mons.

This may not look like
a typical home,

but buried just beneath
the surface of this volcano

is a unique feature that offers
protection from the elements,

and, remarkably,
similar features

can be found right here on earth

if you know
where to look for them.

We're out here
on an A'a flow in Hawaii.

This lava flow originated
towards the summit of Mauna Loa

and has flowed
about 20 kilometers

towards the ocean here.

But what you don't see
is that this lava flow

is covering a vast network of
lava tubes that is now below us,

and that's
what we want to get to.

Volcanoes are cool

'cause we find them
all over the solar system.

Volcanism
is a fundamental process

for shaping planetary bodies,
for shaping moons,

so the more we can learn about
it, the more we can understand

our solar system
and our universe.

The surface of Pavonis Mons

is riddled with lava tubes
like this,

natural caverns that formed

when the planet
was still volcanically active.

NASA volcanologist
Dr. Brent Garry

has dedicated his career
to understanding these features.

As a lava flow is coming down,

these tube systems can form
underneath a solid crust.

So you'll have a hard crust
on the outside,

and the interior
will be the lava,

the liquid rock
flowing through it.

Think of the London underground.

It's like a subway system
of lava going through there.

And as the lava drains out,

that's when we're left
with these giant cavern systems

that we see here,
that we're inside right now.

Today, Dr. Garry
is using light detection

and ranging technology,
or LiDAR,

to create a 3-d model
of this lava tube in Hawaii.

What we're building
with all the LiDAR scans

is a map of a lava tube.

LiDAR is an optimal system
to use

because it doesn't need
its own light source.

It can see in the dark.

Until we land on the red planet,

mapping lava tubes on earth
is Dr. Garry's best chance

of understanding
their martian equivalents.

This is a map created on one
of his previous expeditions.

Here, we're flying through

one of the collapse pits,

and what we're capturing

is the shape, the dimensions,

the morphology of the whole
entire lava-tube system.

But we're also capturing
the details

of all the different textures

that are on the inside
of the lava tube.

Traveling to Mars
is not for the fainthearted.

You need to be prepared for
a harsh, dynamic environment.

Micrometeorites rain down,

dust storms rage
for weeks at a time,

and radiation levels are up to
250 times higher than on earth.

Lava tubes would provide
much-needed sanctuary

for any travelers weary of
the ferocious martian climate.

And for those
willing to venture outside,

the lava tubes
provide the perfect base

to explore the rest
of the Tharsis region

and its staggering volcanoes.

Home to 12 volcanoes
near the martian equator

and stretching
across 2,500 miles,

the volcanoes here
are record-breaking --

up to 100 times larger
than anything on earth,

including the largest volcano in
our solar system, Olympus Mons.

This would surely be one
of the top tourist attractions

for any traveler visiting Mars.

No trip is complete without
sharing these spectacular sights

with your family and friends,

but a postcard
wouldn't make it home to earth.

Instead, scientists are coming
up with cutting-edge technology

to make sure our loved ones

never miss a moment
of our martian adventure.

Communication to mission control
during space travel is vital.

And for me,
it was also essential

to stay connected to my family.

It was on my second mission

that I sent
the first tweet from space.

And as we prepare
for future missions to Mars,

what about space texting?

Researchers are suggesting
that we try that,

along with some
other groundbreaking methods.

With so many stunning images,

it's easy to forget just
how isolated Mars is from earth.

Intrepid travelers will need a
way to keep in touch with home.

NASA engineer Dr. Kara Beaton
is part of the team

investigating
how future Mars explorers

will be able to communicate.

The shortest journey

that you would have
for a Mars mission

is close to three years.

It's about six months
of transit time there,

and then you need to wait for
about a year or year and a half

on the surface
before you can begin

your return journey
back to earth.

Three years in isolation

with a very small crew
of just a couple people

and limited communication
with family and friends on earth

is a big challenge that NASA
is currently looking into.

Today,
Dr. Beaton and her colleagues

are testing prototype
communications backpacks.

So, because
of the very large distances

between earth and Mars --

anywhere from 35 million
to 225 million miles --

there is a communication delay
between someone talking on earth

to someone on Mars
and vice versa.

So if I were to have
a conversation with you

and I'm on Mars
and you're on earth

and I speak
over a voice comm loop,

it would take anywhere from 4
to 22 minutes to get to you,

and then, for you to respond,

it would take another
4 to 22 minutes

for me to hear that response.

By seeing
how these sorts of delays

impact real fieldwork,

Dr. Beaton and her team
are able to develop solutions.

So, we've come up
with different techniques

for how to best communicate.

So, obviously, voice is one way,

and certainly,
that's a viable option,

but we've also found
that text-messaging is good

because that allows
the crew members

to do something else on the side

while they're waiting
to hear a response.

But in a real Mars mission,

how would you actually send
and receive these messages?

To begin,
you'll need one of these --

a nearly 230-foot
radio telescope.

Richard Stephenson
is a radio engineer

here at the Canberra deep space
communication complex

in Australia.

The deep space network
is capable

of sending and receiving
high-frequency radio signals

billions of miles away,

even to the very edges
of our solar system.

The deep space network has three
complexes around the globe,

and they're spaced around
about 120 degrees apart.

So, as the earth rotates,
we can provide 24/7 coverage

to any of the missions
that we're supporting.

These radio dishes are
our eyes and ears on the planet,

and any information
we get back from Mars

is received right here.

Well, this antenna --

deep space station 43
is our 70-meter antenna.

It's a very heavy-duty antenna.

We're looking at 4,000 tons
of steerable metal.

So regardless of wind, weather,
we can support the spacecraft

that need
to communicate to earth.

As we prepare to send
the first human explorers

to the red planet,

building up a martian
communication infrastructure

is going to be key.

The deep space
network's motto is

"don't leave earth without us."

We're the traffic control
of the solar system.

Thanks
to radio telescopes like these,

strategically positioned
around the globe,

travelers to Mars won't be
isolated from everyone

back on earth.

If you're one of them,

you'll be able to communicate
with your loved ones every day,

waxing lyrical about
the epic wonders you have seen.

These telescopes
will be the sorting offices

for the most spectacular
postcards in the universe.

Despite its stunning landscapes,
Mars has a dark secret,

a history shrouded
in mystery and destruction.

If we are ever going to plan
future expeditions to Mars,

we've got to understand
its violent past.

For the past 50 years,
unmanned spacecraft and rovers

have gathered
incredible images and data

about our elusive neighbor.

But even though
Mars is the planet

that we know the most about,

there's still a lot
to understand

before we consider living there.

This is Orcus Patera crater.

Nearly 250 miles long,
it dwarfs any features nearby.

No one knows quite how
this unusual teardrop crater

was formed.

The latest
in a long line of mysteries,

it will provide an intriguing
stop on any martian adventure.

Mars has a lot of craters.

Most of them are circular.

You can see these craters
40 or 50 kilometers across --

they tend to be circular.

But there are some that are not.

Now, if I were going to Mars,

the one I would like to go to
the most is the whopper.

It looks like a whale.

In fact,
it's called Orcus Patera.

"Orcus" means "whale."

So, there's something odd.

Look at all the other craters.
They're round.

What formed this?

Coming down.

Until we go there ourselves,

our best shot
at answering that question

is to re-create the impact
here on earth,

and professor Peter Schultz
has just the experiment.

Going back.

This is the NASA
Ames vertical gun range,

a unique facility

that simulates high-speed
celestial body impacts

on a small scale.

Today, professor Schultz

is trying to re-create
the Orcus Patera crater.

This is a case of trying
to simulate what happens

when you have
a giant projectile --

an asteroid or even a moon --
collide with Mars.

So, we're gonna try that here.

The target sits

inside a large pressure-
controlled impact chamber.

So, at the chamber,

we can control
the atmospheric conditions.

And we have a projectile

that will be launched
to go through this hole,

this launch tube,

maybe about eight times the
velocity of a speeding bullet.

So now all we have to do
is really lock and load.

Professor Schultz
has rigged the gun

so that it fires at just
15 degrees from the horizontal,

simulating
an oblique meteor strike.

With everything in place,

the final step
is to fire the projectile.

Rolling.

Oh, good!

We got it, we got it,
we got it, we got it.

Let me see, let me see,
let me see.

5.60 kilometers per second.

Well done, sir.

Whoa!

It looks like it worked.

So, instead of getting
a round crater,

we have an oblong crater,

and we have an oblong crater

that has multiple impacts
downrange.

There's a really low rim here,
high rim there, and a shelf.

And it requires
a very low-angle impact,

and I think
that's what's happened on Mars.

The crater is almost
a mirror image of Orcus Patera,

scoured lengthways
across the landscape.

And professor Schultz has
a theory for how it was formed.

A moon going around Mars
is in an orbit,

and eventually,
that orbit decays,

gets closer and closer to Mars.

In fact, the moon Phobos
going around Mars right now

will collide with Mars

in something like 28 million,
maybe 30 million years.

So, when that happens,

it'll come in
at an extremely low angle,

grazing, just like a spacecraft
trying to come in for a landing,

except it's not gonna land
so well.

It's gonna collide

and form a crater
very similar to Orcus Patera.

Mars has
two potato-shaped moons --

Phobos and Deimos.

But Peter's audacious thought

is that there was once another
lost moon orbiting the planet.

The theory makes sense,
but the jury remains out.

Situated close to some
of Mars' largest volcanoes,

other scientists argue
that volcanic forces

could have created the crater

by stretching and compressing
the ground.

If we are to discover
the crater's true origins,

we must go there ourselves,

because it's only
by studying landscapes up close

that we can
fully understand them.

Imagine
standing atop the crater rim

rising a mile
above the surrounding plains,

looking into the depths
of the crater below.

What an incredible
and enigmatic stop

on your adventure across Mars.

Just like preparing
for a trip to a foreign land,

smart packing
will be a must for Mars.

So what should
you fill your suitcase with?

For starters, you may want
to bring a winter coat.

Mars is nicknamed the red planet
because of its crimson color.

But take a closer look,

and you'll see
beautiful white swirls.

Learning more about
these mysterious white ribbons

may unlock the secrets
of how Mars formed

and where it's headed.

Your ultimate
travel guide to Mars

includes marvelous canyons,

the most spectacular volcanoes
in the solar system,

and even underground caves.

But there's no better place

to explore the mysterious
martian landscapes

than at the southernmost reaches
of the planet.

It may be
well off the beaten track,

but the extra effort required
to get there will be worthwhile.

This is
Mars' Southern polar cap,

one of the coldest places
on the planet.

Temperatures here can drop below
minus-248 degrees Fahrenheit.

It's an icy destination

that planetary scientist
Dr. Meg Schwamb

has long held a fascination.

So, we're standing
on a dormant volcano

on the big island of Hawaii.

And so, this is where we have

some of
the world-class telescopes

that are observing
the night sky.

So, I'm really interested
in the south pole of Mars,

and so how that can tell us
more about Mars' past

and its current history.

On a clear night,
the poles of Mars

can even be seen through small
telescopes from here on earth.

Amateur images like these

show the bright ice caps against
the red disk of the planet,

but their true wonder
is only truly revealed

with images taken from orbit.

At over 248 miles wide
and almost 2 miles thick,

the Southern polar cap
is a freezing vision

of swirling white on an
otherwise rusty-colored planet.

Though it may look much like
the south pole on earth,

it has one crucial difference.

So, as you can see behind me,

there's some white
dotting the surface,

and that's actually some snow
left after

from one
of our recent snowfalls.

But on Mars, in the south pole,

there isn't water ice
that's exposed, or snow.

It actually snows
carbon dioxide.

Often referred to as dry ice,

in the martian winter,
this frozen carbon dioxide

blankets the Southern reaches
of the planet.

Come spring, when it melts, it
transforms straight into a gas,

dramatically changing
the landscape

and creating
a remarkable phenomenon.

So, what happens
on the south pole of Mars

is that you have this layer
of semitranslucent ice

on top of the dirt,

and when the sun comes up
in the spring and summer,

the sunlight penetrates through
down to that dirt layer

and heats up.

Because it's warm, the carbon
dioxide ice in contact with it

starts to turn into gas.

And so now you have
a layer of gas

trapped
underneath a layer of ice.

The consequences of
this thaw are quite spectacular.

So, when this gas is trapped
underneath this ice sheet,

it breaks through in any way
it can through the ice.

And when it gets to the surface,
it creates these jets or geysers

on the surface
of the south pole of Mars.

Gas is rushing out
maybe a few meters --

not much further, we think.

But it brings up this dust and
dirt from below that ice sheet.

If I was standing
on the surface of Mars,

you'd see these sort of
dark jets coming up,

and it's the local surface winds

that blow these material
into these dark streaks.

And then, when there's
no more carbon dioxide ice,

it disappears.

Seen from space,

this windblown dust
creates breathtaking landscapes.

But these images
aren't simply pretty.

They tell us
about the martian climate, too.

If we can study how
these geysers form, these jets,

and how the wind
sort of blows these material,

we can learn more
about the martian atmosphere.

This process
is completely alien.

We don't have anything like this
on earth.

These features
disappear each year,

but they leave behind
another wonder in their wake --

the real spiders from Mars.

If we look a little deeper
into these images,

what we find, that when there's
no carbon dioxide ice anymore,

the fans go away.

And what's left
in many of these areas

are these kind of dendritic,
like, spider-like features,

which actually has been
informally dubbed spiders,

or aranea forms.

These erosion channels
meet in a central pit

resembling the body
and long legs of a spider,

legs that can stretch
for hundreds of miles

and can take more than
1,000 martian years to grow.

Explorers lucky enough
to stand at the south pole

during a martian summer

would gaze upon these
alien spider-like features

stretching across the landscape.

They would be offered
a taste of martian weather

and witness the dramatic proof

that Mars is far from
the dead and unchanging planet

that many people assumed.

Mars' icy poles
provide some respite

from the desert landscapes
that cover most of the planet.

And the more adventurous
traveler

may also choose to follow the
elusive trail of liquid water

on the martian surface.

In doing so, they will uncover
the hidden story

of ancient Mars.

Thanks to the curiosity rover,

we now know that Gale crater

was once the site
of an ancient lake.

But where did all the water go?

And how did it shape
the landscape we see today?

To see that, Dr. Gupta

needs to look at Gale crater
3.8 billion years ago,

just after it was formed
by a meteor impact.

So, this is really cool here.

We've got
an augmented reality sandbox,

and so what I'm doing now is,
I'm creating the crater rim.

So, there would have been
a mountain

in the center of the crater

formed
during that impact process.

That forms
the core of mount sharp.

When Gale crater first formed,

it's thought Mars had a much
more substantial atmosphere,

making the planet warmer and,
therefore, wetter than today.

And the water fell across
the planet's surface

as rain and snow.

We've got rain forming
on the crater rim

and then gushing out
into the center of Gale crater

and building up.

As it poured down
into the crater,

its water shaped many
of the features we see today.

Imagine,
if you have heavy rainfall,

rainfall over hundreds of years,

the landscape
gets progressively eroded

and carves
deep canyons and valleys.

The sediment
eroded from those gullies

would have washed
into Gale crater,

forming those river deposits
that we can see so beautifully

in the images
that curiosity takes.

And then the climate changed.

It lost its atmosphere
and became arid and hyper-cold,

and all that water evaporated.

And we were left with a crater
infilled with sediment.

The rusty,
ancient surface of Mars

has enigmatic landscapes
at every turn,

from towering sculpted peaks
to hidden underground caverns.

And if you are one
of the first explorers,

you will need to study
every detail.

Each landmark holds its own
clues to Mars' mysteries,

and there is no greater mystery

than whether life exists
beyond the earth.

As a stranger from earth,

will you be greeted
by martian life when you arrive?

When people meet me
for the first time,

the question
I get asked the most is,

"is there life
somewhere else in the universe?"

And while I don't know for sure,

I love the possibility that life
could exist on other planets.

So how do we find this life,

whether it be past,
present, or future?

There's one scientist that says
the proof is in the salt.

To stand a chance
of finding life on Mars,

it's thought travelers will need

to journey
to a region of the planet

unexplored by landers or rovers.

Perched in the remote
Southern highlands,

Terra Sirenum
is a land of cratered terrain

capped in crystalline
mineral deposits.

It's thought that if we're going
to find signs of local wildlife,

past or present,
then this will be the best spot.

Of all the questions
astrobiology asks,

probably its biggest one is,
is there life beyond the earth?

When we're assessing
whether a planet is habitable,

we're looking
for some basic things.

We need some liquid water

for all those chemical reactions
to happen in,

we need a source of energy, like
sunlight or chemical energy,

and we also need
some basic elements

like carbon and phosphorus.

All those things have
to come together in one place

for life as we know it,
at least, to be able to grow.

Before our first
spacecraft arrived in the 1960s,

the idea of visitors to Mars

setting foot
on a lush, living planet

seemed like
a perfectly reasonable idea.

In the early history of Mars,

the planet would have looked
quite a lot like early earth.

There would have been
liquid water on the surface.

Maybe it would have been warmer.

Perhaps during
that period of time,

it could have sustained biology.

But about 3 1/2 billion years
ago, that water froze up,

and the planet
become what we know today --

pretty much a desert world.

Because of that,
it was never able

to sustain the sort
of evolutionary development

that you can see
around you here.

So we need to look
in places on Mars and on earth

that could give primitive life
a fighting chance.

There are two types of places.

We might look
in briny, salty solutions.

Those brines
could still be liquid

on the surface of Mars today.

And we're looking
at ancient salt deposits.

In those salts,

maybe we might try and look
for signs of past life.

With that in mind,

astrobiologists
like professor Cockell

started searching for the
perfect spot to hunt for life.

And in time,
images taken from orbit

revealed more than 200 places
in the Terra Sirenum region

where thick salt layers exist.

The Terra Sirenum region of Mars

has salt deposits
from ancient ponds and lakes

that essentially evaporated --

the last remnants
of liquid water on Mars.

And these salts in Terra Sirenum

could preserve or record
the existence of life on Mars.

And to support this theory,
professor Cockell

has been investigating some

of the most remote and
inhospitable places on earth.

So, here we've got some samples
from the Negev desert.

Microbes that live in those
environments are very tolerant

of both high temperatures
and extreme dryness.

And then, these microbes
are from a lake in Canada

that has very high
concentrations of sulfate,

similar to the sorts of salts
that we find on Mars.

Finding living
bacteria in places like this

tells Cockell and his team

that Mars-like environments
here on earth can support life.

But that's
only half the picture.

So, this is a sample
from a very extreme environment.

It comes from a kilometer
underground in a salt mine.

This is the sort of sample

you might be able
to find in Terra Sirenum

if you dug
down beneath the surface.

The question is,
could these microbes

also survive under the
conditions on present-day Mars?

We've subjected these microbes

to similar sorts of environments
that you might find on Mars,

so no oxygen,
very low amounts of energy,

very low concentrations
of nutrients.

And in those sorts
of environments,

these microbes can not only
survive -- they can also grow.

What these results show us

is that some of
these salty environments on Mars

may well have been habitable.

It may not look like much,

but this is the closest thing
to life on Mars anyone has seen.

I often joke that
if you send me to Terra Sirenum

with a microscope and a shovel,

I can tell you
within a few hours

whether there's life on Mars.

Astrobiologists
like professor Cockell

are building a case
that the salt plains on Mars

are potentially habitable.

The inquisitive traveler
prepared to dig deep

might just find
some of the local wildlife

sheltered
beneath the subsurface.

It would be the discovery
of the century

and proof that life probably exist
elsewhere

in the universe too,

and it would be the perfect end
to an epic journey.