NOVA

February 18, 2021.

Perseverance, NASA's newest rover,

one of the most sophisticated planetary probes ever built,

is approaching Mars

on an epic quest to hunt for life beyond Earth.

We are under a minute

from cruise stage separation.

130 million miles away,

a team of researchers anxiously waits...

Heading alignment.

As Perseverance attempts to land

where no rover has dared land before...

Inside a crater

that might be filled with ancient Martian life,

but is definitely filled with cliffs

and sand traps

where a rover can crash

or get stuck for good.

We're heading toward the ground

at race car speeds.

So there's no way we're going to joystick this down.

For the first time in the history of Mars exploration,

a rover is equipped with

the intelligence to try to steer itself out of danger.

There's a very specific timeline of events

that have to happen at the correct time for

the entire process to succeed.

Perseverance signals its progress...

Sky crane maneuver has started.

As the team monitors every step.

If the rover manages to land in one piece,

for about two years, it will drill into Martian rock

that could hold evidence of ancient life,

then collect samples and store them.

For the first time, we are going to collect

rock samples and bring them back to Earth.

In the future, another rover will retrieve the samples

Perseverance collects.

And through a series of daring missions...

that sound more science fiction than science fact...

the samples will be brought to Earth,

where researchers can examine them

in far greater detail.

We have this amazing technology

that can really can get those samples,

bring them back to Earth,

and do all the really cool analysis

that we want to do here on Earth.

This is a very, very large undertaking

involving thousands and thousands of people

from all over the world.

Thousands of researchers

with one shared goal.

"Looking for Life on Mars," right now, on "NOVA."

Did life ever exist on Mars?

And if it did, what would that mean for us?

How special is life on Earth?

Why do we not see it on Mars today?

Did it ever evolve on Mars?

What does it take to get life

to evolve on a planet?

That question about life

is the one that really perplexes and, I think, really drives us.

Something about our desire to not be alone

keeps pushing us forward in the search for life.

I like to call it "CSI: Mars," right?

You know, it's, it's literally this investigation

where you're finding all these little clues

to put together your story.

The tale of our celestial neighbor, Mars.

The red planet.

It captures the imagination.

Thousands of images paint a picture

of a barren, alien world.

At the same time, there's something about Mars

that's strangely familiar.

I was born on the Navajo Nation.

It's a high desert area

that actually has rolling desert hills,

canyons, and rock formations, and mountains,

and all of that looks like the Martian landscape.

When I look at the pictures of Mars,

I see the Mojave Desert, right?

Without the cactus.

But I can't tell the difference if this image

is from the Mojave Desert or if this is from Mars.

To me, it makes me want to know more.

It makes me want to know, you know, what happened to Mars,

or was there life there?

Can the Perseverance rover finally answer

this question?

We've been searching for the remnants of life

on the red planet for decades,

from the Mariner orbiters

to the successful landings of Viking 1 and 2...

...through the twin rovers Spirit and Opportunity

that crisscrossed the planet.

We've been building our knowledge

of the Martian environment

through so many decades and so many achievements

from so many engineers before us.

But it was the discoveries

of the most cunning robotic detective

to ever explore Mars, a rover named Curiosity,

that set the stage for the Perseverance mission.

September 14, 2012,

40 days after Curiosity landed on Mars,

it stumbled upon the unexpected.

I remember the moment those images came down.

We were all at the Jet Propulsion Laboratory

at the time, and we were all huddled

around a giant computer screen,

and, and I was just gazing at this in astonishment,

because it's not what we had expected.

We came across a whole bunch

of cobbles,

and when we saw that, everybody's jaw just dropped.

"Oh, my gosh, look at this, this is perfect."

It is the classic example

of a river deposit.

Each one of those rocks, they had to get bounced around

in some type of environment that was going to turn them

from something that was chunky and sharp and angular

to something that was rounded.

Rivers do that.

Rivers on Earth do that very well.

And so when we saw this, it was our first evidence of a river.

Evidence that water once flowed

on the surface of the red planet.

On Earth, all life needs water to thrive...

...from the giant blue whale

to tiny microbes.

The scientists on the team have discovered

all these telltale signatures in the rocks

that there were rivers and ancient lakes that existed

for hundreds of thousands, if not millions of years.

You can think of Mars

as... back in time, of course...

as being Earth's slightly smaller, slightly colder sister.

Between 3.9 and 3.5 billion years ago,

we think that Mars was a warmer and wetter place.

And what's interesting about

that is that's the same sort of time interval

that life got going on Earth.

We have two planets with similar environments

at similar times.

One of them, on Earth, is inhabited.

Why wouldn't we expect that the one on Mars would be inhabited?

Curiosity found evidence of a once-wet world.

But here on Earth, for life to thrive,

it needs more than water.

It needs nutrients.

We tend to simplify

that search for what type of nutrients

as what we call CHNOPS.

When people say CHNOPS, what they're saying is carbon...

Hydrogen... Nitrogen...

Oxygen... Phosphorus...

Sulfur.

And we spell all those,

the first letter of all those out,

it's called CHNOPS.

These six elements make up

roughly 99% of the mass of the human body.

In fact, they make up about 99% of the mass

of all living things.

If life, as we know it, ever existed on Mars,

finding CHNOPS was key.

Could Curiosity, a laboratory on wheels, find CHNOPS?

The rover scooped up samples of Martian soil

to decode its chemical composition.

What we found was a diverse chemistry

that included carbon, hydrogen,

some nitrogen, oxygen, and sulfur,

and eventually we found some phosphorus.

There's plenty of chemical energy available for life,

if it had ever lived there.

That's really been the big discovery

of the Curiosity rover mission.

Curiosity found the ingredients necessary for life

to emerge, but not life itself.

Curiosity has not, in fact, detected evidence

for life, because it does not have the instruments

designed for that purpose.

Perseverance is designed to take the next step

in Mars exploration,

as it ventures into unexplored territory

to search for samples of Martian rock

in Jezero Crater.

If you want to set yourself up for success

for finding ancient life, that is the place to go.

This orbital image reveals

what makes Jezero Crater so intriguing.

The key thing that led us to Jezero

was this beautiful delta, beautifully visible from orbit.

We think that delta must be somewhere around

three billion years old or older.

This delta sits at the end of a beautifully expressed

sinuous river channel that came in from the northwest,

flowing into the crater rim, and filling up