Space's Deepest Secrets

Mars, Earth's cosmic neighbor,

more than 40 spacecraft have been launched to the red planet

seeking to unlock its secrets.

Now, NASA's new Perseverance rover

is on a quest to crack the planet's biggest mystery...

Was there ever life on Mars?

Ever since the very first mission to land on Mars,

we've been looking for signs of life.

We've seen tantalizing clues.

This could be the mission that finally answers the question.

How will Perseverance succeed where others have failed?

Could this mission discover that living things exist today

on the red planet?

If the Perseverance rover finds life on Mars,

that will change science and philosophy forever.

And how will Perseverance lay the groundwork

for humanity's next giant leap in space exploration?

Someday there will be humans who no longer

identify themselves as Earthlings,

but they will call themselves martians.

To find out, we will venture to the red planet,

voyage beneath its mysterious, dusty surface,

and explore its alien underworld to reveal the secrets

of this pioneering mission to Mars.

Captions paid for by Discovery Communications

Mars...

From orbit, the planet looks barren,

temperatures here plummet to minus 220 degrees Fahrenheit.

Its thin atmosphere is 95% carbon dioxide.

Cosmic radiation over 30,000 times stronger than

on Earth blast the surface.

Probes and rovers sent to Mars confirm that it appears

- to be a lifeless desert world. - When you look at the images

the rovers and landers have sent back from Mars,

it looks dry, dead, but that's Mars now.

What was it like a long time ago?

Well, the evidence for that shows a very different world.

Many space scientists believe that life could have

once thrived on the red planet.

Mars just squeaks in on the edge of what we like

to call the habitable zone.

Now, that means the region in a solar system

where liquid water could form

and could exist for long periods of time.

We know that water is the source of life on Earth,

and it might have been the case on Mars.

NASA has sent four rover missions

to explore Mars since 1996.

NASA's fifth rover mission called "Mars 2020,"

is the first task to seek out evidence of life on Mars.

This is Perseverance.

It's a six-wheeled

robotic vehicle about the size of an SUV.

Perseverance is the most ambitious rover

we've ever flown into space and that has ever gone to Mars.

Perseverance carries a suite of super sensitive instruments,

ground penetrating radar, onboard chemical analysis,

and X-ray detectors

to sniff out the signs of ancient life.

Every single inch of the rover has been carefully

thought through and designed.

All of this effort is in support of a chance

to really ask the question,

"has life ever existed beyond Earth?"

July 30, 2020. An Atlas five rocket blasts off

from NASA's Kennedy space center.

One hour after launch,

the capsule carrying Perseverance rover

separates and heads out into space.

Destination... Mars.

Launching a rover into space

and traveling more than 130 million miles to Mars

is the easy part of this mission.

The bigger challenge is how

to land a one-ton rover on the martian surface.

NASA engineers borrow the multi-stage system

used to land the curiosity rover in 2012.

It's a proven platform for getting robotic vehicles

from space onto the surface of Mars.

The heat shield comes into the top of the atmosphere

that starts to slow us down a bit,

but not nearly enough.

We have to release the parachute,

but the Mars atmosphere is thin,

so the parachute is not good enough on its own.

It doesn't slow us down enough to get to the surface safely.

Now falling at 180 miles per hour,

Perseverance is ready to make a controlled touchdown.

We come down on retrorockets,

hover, lower the rover down on the skycrane,

and then once it touches the surface and releases

that tension on the bridle,

pyros fire, cutting those cables.

The descent stage flies away to a safe distance and crashes,

and the rover is just there ready to go.

It's tremendously exciting and nerve wracking.

With Perseverance now landed safely on the martian surface,

the rover's mission begins.

Mars is just over half the size of Earth,

where within this huge area

should Perseverance look for life?

If you're looking for life on Mars,

finding evidence of this life or past life

isn't going to be equal in all places.

For example, if you land in the Sahara

on Earth versus the Amazon,

you're going to have a very different outcome.

The planet is big.

The rover is small.

So it's key that you put the rover in the right spot.

The key to finding traces of ancient life on Mars

is finding signs of water.

Liquid water is a super solvent.

It allows lifeless chemicals to mix

and transform into biological systems.

If there's one thing that Earth teaches is about life,

it's follow the water. Where you find water,

we found life on Earth.

There are no obvious signs of liquid water on Mars today.

How can scientists locate where liquid water on Mars

once used to be?

In 2004, the twin Mars rovers,

Opportunity and Spirit, beam images back to Earth

that could unlock the answer.

The cameras on board both rovers photographed

these strange martian objects.

Each one is roughly 1/5 of an inch across.

NASA scientists call these objects blueberries

because of their shape and color in these photographs.

Analysis reveals that these blueberries

are made from iron oxide.

And one theory claims there's only one way

that these rusty balls can form.

Blueberries start life as tiny specks of crystals

that exist inside waterlogged rocks.

Iron oxides from the rocks

wrap around the crystal spheres like rust,

turning them into small iron balls... blueberries.

Thousands of these can form near each other,

but to grow, they need huge amounts of water

to flush more minerals onto them.

Over millennia, strong winds erode the soft stone

around the hard blueberries, releasing them onto the surface.

The blueberries are evidence

that Mars once had rivers and lakes.

It's even possible that the red planet

had oceans of liquid water 4 billion years ago.

With all this evidence and all this data over all these years,

the story is clear.

Mars had rivers and river channels.

This means that the probability

that Mars harbored life is very high.

NASA research finds evidence that water covered

1/5 of Mars for over a billion years.

That's an area almost 40 times the size of Texas,

too large for one small rover to explore in detail.

Where on Mars should Perseverance focus its search

for ancient life, and what will it look like?

NASA's Perseverance rover is on a mission

to find evidence of ancient life on Mars.

The Perseverance rover and all of its subsystems,

everything about it is really this concentrated effort

in support of exploration and discovery, scientific discovery.

A chance to really ask the question,

"has life ever existed beyond Earth?"

Scientists believe these traces could exist

where water covered the red planet four billion years ago.

This area could make up as much as 20% of the surface of Mars.

So where in this vast area should the rover target?

When you're trying to find the perfect spot on Mars

to look for the evidence of life,

one of the things you need is standing water

for a long period of time,

something that wasn't just wet for a few days

and then dried up.

A clue to where to search for ancient life

lies in photographs taken from 180 miles above Mars.

Mars reconnaissance orbiter, or M.R.O.,

is a satellite that orbits the red planet.

Its camera captures images of the martian surface

in stunning detail.

The Mars reconnaissance orbiter

is essentially a spy satellite in orbit,

but instead of spying on the planet,

it's mapping it so that we can better understand it.

NASA scientists searched the M.R.O.'S photographs

for the traces that ancient rivers and lakes leave behind.

They find an intriguing feature in Jezero crater...

A deep depression close to the martian equator.

It's likely that Mars had lakes and rivers

4 billion years ago.

An asteroid or comet strike

explodes a mega crater 28 miles across.

Over time, two rivers break through its rim.

They create a deep body of water the size of lake Tahoe.

On its shore, the rivers form fan-shaped deltas

that are still visible today...

...long after the water the lake held for millennia dried up.

So in Jezero crater, we find not one,

but two beautiful river deltas. Now deltas are formed