NOVA

Is there life beyond Earth?

To find out, we might look no farther

than the planet next door.

Mars may be our best hope for resolving the ultimate mystery

of creation.

It is the one planet

out there that is Earth-like enough

that we can imagine that life might have taken hold

on that world.

If we go to Mars, will we find that, yes,

the same events that led to life on Earth

happened independently on this other planet?

And if we find evidence on our very next planet, Mars,

then you have to say

that has to be so common across the Milky Way,

across the universe, you know that we are not alone.

Mars has more in common with our world

than any place we know of in the universe.

But it's still a world away.

Getting an astronaut there to search for life is beyond us.

So for now we must resort to the next best thing...

Robots.

Mars today is a busy place.

Three satellites orbit it.

Three landers ponder its surface.

They're finding a wealth of clues.

Holy smokes! I'm just blown away by this.

When that first data comes down,

the sense of astonishment is indescribable.

Oh, wow!

We would never have thought

of looking for organisms like this on Mars.

But they're also discovering that, in its past,

Mars had some dark secrets.

Life can survive in pretty harsh conditions,

but there are limits.

Around four billion years ago,

there was a cataclysmic event.

And this was big.

This thing went wham... Right into the planet.

Four and a half billion years ago, two young planets emerged,

both brimming with promise.

But something went very wrong with Earth's twin.

Is there life on Mars?

Up next on NOVA.

Captioning sponsored by EXXONMOBIL,

DAVID H. KOCH,

the HOWARD HUGHES MEDICAL INSTITUTE,

the CORPORATION FOR PUBLIC BROADCASTING

and VIEWERS LIKE YOU

for NOVA Mars eludes us.

Even as this planet surrenders its secrets,

it remains stubbornly guarded about one...

The question we have come in pursuit of, above all others.

The geology is fascinating,

the climate is interesting, atmospheric science.

There is any number of things that you can study

about the planet, but to me what makes Mars special

is its potential as an abode for life.

If there's life on Mars,

there could be life throughout the universe.

CHRIS McKAY: If it happened twice,

right here in our own solar system, then we would have,

for the first time, a good answer to the question,

Is the universe full of life?

The answer would be yes.

The Holy Grail of Mars exploration

is finding some form of Martian biology,

what's often called the Second Genesis.

Did life start on Earth and Mars?

Did it evolve in a totally different way

than Earth-life did?

Peter Smith has been involved with seven missions to Mars.

Each has only driven home how difficult it is to get there.

This is the Mars Polar Lander Mission Control

at the Jet Propulsion Center.

The Mars Polar Lander is about to touch down on the surface.

Smith and his team should get word any moment.

They wait...

There's nothing worse than no signal.

...and wait, for a signal that never comes.

I was trying

to hold out a little hope that maybe it landed

and the communication link hadn't quite set up yet,

but I had the worst sinking feeling.

The mood doesn't look too good over there.

During its descent, the Polar Lander disappeared.

You felt like

somebody very close to you in your life,

someone you love very dearly, had died

through some tragic accident.

At the time, Smith was already preparing his next mission,

another lander called Mars Surveyor.

But after the failure of Polar Lander,

NASA canceled the mission.

Oh, it was just miserable.

All fell apart.

All my house of cards just collapsed.

Smith didn't give up.

To take the technology from those failed missions

out of mothballs, and repurpose it for another lander.

Every precaution would be taken to make sure

this one would make it.

He christens the new mission Phoenix.

We are rising from the ashes,

and we're going back to Mars.

Zero and liftoff.

And so, Phoenix it is.

Sending a mission to Mars

is somewhat like hitting a golf ball across the solar system.

We'll see if we got our hole in one.

Nine months later.

Smith is back on track to search for signs of life on Mars.

Three, two, one, mark...

Mission Control at NASA's Jet Propulsion Laboratory.

If Phoenix lands,

it'll be thanks to the engineers here today who made it happen.

But no one knows better than Smith what could go wrong.

Standing by for touchdown.

Touchdown signal detected.

Finally, Peter Smith has arrived on Mars.

By gosh, we are going and doing it.

We have a great chance of making a new discovery on Mars.

It's the thrill of my life.

Now that Phoenix has landed,

NASA is sharing supervision of the mission with scientists

at the University of Arizona, where Smith is based.

Phoenix is in the far north of Mars,

so it has just three months before the polar sun will begin

to set for the long winter,

and with it will go the lander's power supply.

Time is already running out.

This is the 39th time we've tried to reach Mars

and only the seventh time we've actually landed there.

It is a quest years in the making.

The first to attempt it were the Soviets.

During the 1960s, they launched eight missions.

They failed eight times.

It wasn't until the late '70s

that we'd get our first close view of the Martian surface,

with the two Viking Landers.

Each bears a $60 million box,

packed with three biology experiments

that are, in their day, state of the art.

They're designed to test the soil

for the presence of organisms.

A member of the science team is Carl Sagan.

There may be warm, wet kinds of organisms in a dormant state.

It may be that by dropping them in liquid water,

Viking might have a very pleasant surprise

in detecting such organisms.

Now the screen for touchdown.

Touchdown! We have touchdown.

Hopes are running high.

Many people are ready to exclude

the possibility of large organisms on Mars,

but I see no reason to do that.

And I think it's possible that, for example,

the Viking Lander camera may pick up

organisms that happen to be walking by the Viking Lander.

A silicon-based giraffe will be detectable

if it walks by the Viking Lander camera.

But when the pictures come in,

there are no signs of giraffes.

As the experiments proceed, the news gets bleaker.

That this was devoid of life,

that Mars was just a barren desert,

that it may have been interesting

four billion years ago,

but today it's lacking in those ingredients

that would allow life to flourish.

Those ingredients for life are common on Earth.

Billions of years ago,

life as we know it needed three things to begin.

One is an energy source, like heat...

From the volcanic fury

of the Earth below and the sun's rays from above.

Two are organics... Carbon-based molecules;

not living things, but the building blocks of life.

But the third is scarce in our solar system:

the medium that helps the chemicals intermingle.

The most important requirement for life is liquid water,

and that's the defining requirement for life

in terms of our solar system.

There's plenty of energy, there's plenty of carbon,

there's plenty of other elements

on all the planets in our solar system.

What's rare is liquid water.

Not only did Viking find no life, but no water, either.

Mars was pronounced a wasteland.

DAN McCLEESE: It was really a bummer.

Mars was "dead," unquote.

That was kind of the outcome in the newspapers.

And so we had a hiatus of missions to Mars of 20 years.

Mars slipped away from the limelight.

Then, in 1996, NASA scientists unveil a Martian rock,

a meteorite that had landed in Antarctica,

which appears to hold the fossilized traces

of microscopic life.

Or so they think.