Original subtitles

Curiosity touched down on Mars in August 2012.

It's an epic-making mission.

The goal is to delve into the unknown world

beneath the surface for signs of past habitability.

A diamond-tipped drill on a robotic arm does the delving.

Samples of rock and soil obtained in this way

are analyzed on the spot.

Scientists are looking for organic compounds

that might have permitted life on Mars.

Curiosity and the entry descent landing system

are revolutionary.

It's a real laboratory, and it's a laboratory on wheels.

What that means is that we can take it

around to different places and study the rocks,

and from that reconstruct different environments

that existed in the early history of Mars.

However, Curiosity has been afflicted

with a host of problems, from computer glitches

to solar interference with communications.

We may have lost the rover forever.

But Curiosity surmounted such crises

and resumed its quest.

It soon discovered beneath the famously red Martian terrain

an unexpected world of gray.

This finding greatly increased the chance

that life has indeed been possible on Mars.

Curiosity is continuing its rambles on Mars.

This program tracks its adventures

over the course of one year.

Curiosity first entered the Martian atmosphere

in August 2012.

Executing thousands of commands,

it approaches its landing area.

One mistake could send it crashing into the surface.

We are at power flight.

Rover is guided

to its target landing area by radar.

As it descends it must skim

over a 5000 meter high mountain range.

Sky Crane is starting.

Safe on Mars.

Curiosity has landed safely on Mars.

Two minutes later.

Got a thumbnail.

It's the wheel! It's the wheel!

We have wheels down on Mars.

The first imaged received

was the brilliant globe of the Sun

shining a benediction on Curiosity's mission.

Then far off in the distance

rose the 5000 meter peak of Mount Sharp.

There was no way to know in advance

that the rover would be oriented so that you could see that.

But is was really great to see the mountain

that we had observed from orbit,

and realized that we could make that target someday.

The rover had landed

in a giant crater near Mars' equator.

Some scientists speculated

that once there was a great body of water here.

That made it the perfect place

to search for conditions permitting life.

Curiosity's adventures were about to begin.

The day after the landing.

Curiosity raises its head and looks about slowly.

It has two pairs of navigation cameras.

These cameras can cover a 360° panorama,

taking 3D images of the surrounding terrain.

Two high resolution cameras

are also affixed to the mast

for distant and wide shots.

The procedure is to take multiple color images

then combine them so as to produce a detailed panorama.

From the pebbles in the foreground

to the formations several kilometers in the distance,

all is revealed in vivid detail.

Now that Curiosity's imaging systems have been checked out,

it's time to confirm mobility.

Mission control commands the rover to start moving.

First off, it goes 4.5 meters directly ahead.

Then it executes a 120° turn.

Next it will move backward 2.4 meters.

Even these baby steps put mission control

under agonizing pressure.

At this time

Mars is about 260 million kilometers from Earth.

For each command to reach Curiosity,

it takes over fifteen minutes.

Then for the result to make its way back to Earth,

it takes another fifteen minutes.

In the unlikely event

that some mistake is made in a command,

it could be fatal to the mission.

In the present case, they've waited three hours

since sending the commands.

An image arrives from Curiosity.

The rover's tracks on the Martian surface,

precisely as commanded.

This is a promising start.

Curiosity landed at the red dot

in the plains at the base of Mount Sharp.

The rover's first destination lies 500 meters to the East

at the seams of three rock plates

comprised of different materials from different eras.

We recognized that were gonna be able to study

a kind of a rock that we saw from orbit

that had this signature of very high thermal inertia.

And we thought maybe that water was involved,

and precipitating minerals had filled in the pore space.

That's why we decided to go,

because we thought maybe the property of thermal inertia

has something to do with water.

Curiosity fixes its navigation cameras on its destination.

Mars, the red planet, glows in the night sky.

It is Earth's neighbor.

Could it harbor life?

People have long pondered that question.

One of them in the late 19th century

was the American astronomer, Percival Lowell.

His observations of the planet over 15 years

led him to conclude that there were

traces of numerous canal-like structures

on the Martian surface.

Lowell concluded that, unquestionably,

Mars too boasted an advanced civilization.

But in the 20th century

Mars missions sent back images

showing no trace of actual canals.

What the images did show, however,

looked like traces of the flow of water.

Even if there was no intelligent life,

might there not at least be some primitive organisms?

Speculation mounted.

What are the requirements for life to exist?

On Earth, there are a minimum of three.

First, liquid water.

Among its many and varied functions,

it conveys nourishment to every part of our bodies.

Second, an energy source.

This is vital for such basic aspects of life

as growth and reproduction.

Third, organic compounds.

These are the raw materials

out of which life takes shape.

In 1997, however, the Pathfinder probe

made a stunning discovery that seemed to dash hopes

of life of Mars.

With expertise in both geology and biology,

Jack Farmer has been a valued contributor

to every major Mars mission from Pathfinder onwards.

I suggested that we go to the outflow channel

called Ares Vallis which was draining

from this terrain of potentially lots of different

kinds of habitable environments,

carrying water from the subsurface up,

draining out and depositing right where we landed.

However, when the surfaces

of the rocks and ground were inspected directly,

scientists were disappointed.

The rust colored Martian terrain

looked extremely inhospitable.

Jack Farmer calls such a highly oxidized surface

"a real killer for life."

Oxidation reactions are always going on

on the surface of Mars,

and this kind of surface skin of basaltic materials

like this gets turned into something like this.

So Mars is red for a good reason, I guess.

This is how it happens.

Cosmic rays pass right through the thin Martian atmosphere

directly striking the planet's surface.

That produces a large number of active oxygen atoms.

They bind with iron in the rock,

producing the characteristic rust color of oxidation.

Active oxygen has a powerful impact on organic compounds,

the very building blocks of life.

It splits them off, disintegrating the compounds.

If they're there, they are there very shortly,

oxidized then turned into CO².

The bleak, reddish surface of Mars.

It proclaims the fierce oxidation of a sterile world.

Hopes faded for even a historically habitable Mars.

But now, Jack Farmer and other scientists

are following a promising new lead.

They are looking inside rock formations

where cosmic rays cannot reach.

If you go in the subsurface, different story.

If you can get down deep enough

where there could be water present,

then you've got a whole different ball game,

and I think you could open the door for life down there.

Could there be,

hidden beneath the arid terrain of Mars,

an entirely different environment,

one hospitable to life?

Answering that grand question is Curiosity's mission.

Pre-op checklist completed, Curiosity is good to go.

As if to pray for an indefinite continuation of its mission,

Curiosity etches the infinity symbol in the Martian soil.

August 27th, about three weeks since the landing,

Curiosity is ready to venture forth.

One of its early finds is a strangely shaped rock.

This pyramid-shaped rock, about 30 centimeters on an edge.

It makes a good test subject for some new equipment.

The ChemCam, a laser spectrometer and imager.

As the laser beam bores in,

the ChemCam analyzes light from the vaporized rock

to determine composition.

The pyramid rock is found to be a volcanic rock, basalt,

rich in metals like iron and magnesium.

Its remarkable angular shape

is thought to be the result of wind erosion.

Curiosity continues its trek

through fantastically bleak scenery.

As it travels, its cameras record some incredible sights.

Like this partial solar eclipse.

Mars has two moons.

One of them, Phobos, has passed overhead,

partially obscuring the Sun.

This is the first time a Martian solar eclipse

has been captured so distinctly.

Curiosity soldiers on, sending back image after image

at a pace of more than 200 a day.

One image in particular catches the attention

of mission scientists back on Earth.

It was taken just 100 meters from the landing site.

It shows a large number of pebbles strewn about

at the base of some uplifted bedrock.

Very similar terrain can be seen on Earth.

Dry river beds.

These pebbles were rounded by friction

as the current ran its course.

Now the eroded dried up channel is littered with them.

Compare them side by side.

Similar indeed.

This is incontrovertible proof

that water used to flow in this region.

The first of those three requirements for life

has already been satisfied.

Experts can use the size and disposition of the rocks

to guess how that river flowed in ages past on Mars.

The river would have been about knee-deep

and it flowed at about the speed of a human walking.

So when we saw the ancient stream bed gravel,

you think of flowing water.

And one of the things you want to do

is go with the flow.

Follow that river, see if you can see where it takes you.

Because on Earth when you follow a river,

it either leads to an ocean or it leads to a lake.

So Curiosity goes with the flow eastward.

What sort of scenery awaits it?

Before we follow Curiosity any further,

let's acquaint ourselves with the hard work

done by the mission control staff.

This is mission control at JPL.

Work continues here regardless of day or night.

The main reason for that is the time difference

between Earth and Mars.

Mars takes longer to rotate on its axis than Earth does,

so its day is 40 minutes longer

which means the time difference between Earth and Mars

after three days is two hours.

After six days, it's four hours.

The gap widens.

Curiosity can be activated only during the Martian daytime,

but there are times when that might be

in the middle of the night on Earth.

One of Curiosity's planners and drivers, John Wright,

is starting work at 9 PM.

It's the beginning of a hard day's night.

His first step is to review the log

of the previous day's itinerary.

Next he analyzes closely

the 3D images produced by Curiosity

and decides which route to take next.

So with 3D I can see there's a small mound here,

there's a large mound right here,

so if I'm gonna be driving forward,

I'm gonna go over that mound

and then down a fairly steep hill on the other side.

So I might say maybe that's a little steeper

than I would like to drive.

Let's try to analyze some other areas.

So we might look at other areas.

I had to work sometimes all night,

sometimes all night, sometimes halfway

from the middle of day to the middle of night.

All different kinds of odd shifts.

Tadaima!

Okaerinasai!

Well sometimes I would go,

since my wife would be asleep when I would go home,

I'd go someplace to a late night restaurant and have dinner

or breakfast or whatever it was

because it was just easier to do that.

But then after all that work

to find something really interesting and really amazing,

it does make it worthwile.

I mean, that's why we are here.

It's just to do exactly that.

About two months after the landing.

Just short of its next science destination,

Curiosity encounters a new formation.

The Rocknest drift of windblown sand and dust.

Curiosity takes this opportunity

to test for organic compounds,

which are vital to life

and are a key target of the mission.

The SAM laboratory suite is highly efficient

at detecting organic compounds.

Paul Mahaffy is NASA's principal investigator

for these analyses on the Curiosity mission.

So this is a full size model of SAM on Mars.

This is the electronics box.

This is the mass spectrometer.

This is the gas chromatograph,

and our third instrument,

the tunable laser spectrometer, is down here.

All these analytical instruments

are packed into a laboratory suite

about the size of a microwave oven.

And in fact, samples introduced into it

are heated at high temperatures.

The gasses given off by this process

are then analyzed minutely by the mass spectrometer

to determine their constituents.

When the sand and dust of the Rocknest site were analyzed,

the results where stunning.

Trace amounts of chloromethane,

an organic compound, were detected.

At last, a key ingredient for life on Mars

had been discovered.

The scientific community was all abuzz.

However, at a hastily called news conference,

the project's leaders were cautious in their claims.

SAM has no definitive detection

to report of organic compounds

with this first set of experiments.

The SAM laboratory suite

had been assembled in a terrestrial cleanroom.

Despite all the team's precautions,

could impurities have entered it?

Possibly, it was those impurities that had been detected.

As far as the first analysis

of the Rocknest sample is concerned,

we certainly couldn't definitively rule out

that most or even all of that carbon might be from Earth.

But this uncertainty only intensified

the hopes placed on Curiosity.

Soon, the rover would arrive

at its primary science destination,

where it would be expected to find definitive proof.

December 7th, 2012.

After about four Earth months,

the rover has finally reached

its primary destination for exploration.

A new type of terrain has come into view.

To the southeast, a bulge of bedrock.

To the northeast, a low-lying area.

Curiosity heads into the low-lying area.

What will it find?

A basin stretching as far as the eye can see.

The bedrock is cracked but flat,

like an interminable expanse of stepping stones

in some giant garden.

The character of the rock is much different.

We have mud cracks and things of that nature

that suggest perhaps this was a lake,

actually a shallow lake that would dry out occasionally

and produce cracking.

This dried out lake bed

has been named Yellowknife Bay.

That ancient river Curiosity discovered

right after setting out had once flowed down here,

and created a magnificent lake.

Next, Curiosity will put a drill to work

to obtain a historic first sample

from underneath the red ground of Mars.

The rover descends carefully into the bay itself.

It will spend the next 40 days

exploring the bay's every nook and cranny.

And then we drove up

to another particular part of the outcrop

where you could go up it

centimeter by centimeter by centimeter

and do a detailed study.

And then we did that.

And then ultimately that helped us

pick the place that we wanted to drill.

The basin was vast.

Where to drill was indeed a matter

requiring thought and planning.

Curiosity finally finds a target

that looks perfect for drilling.

A flat and stable rock bed.

It is given the name John Klein.

February 8th, 2013.

Whether it's been day or night on Earth,

John Wright has continued his skillful maneuvering

of the Curiosity rover, and he's been formulating

complicated commands to operate the drill.

He runs simulation after simulation.

Accurately excavating the target spot

requires extremely delicate manipulation

of Curiosity's robotic arm.

So when you put the arm out,

it just sags down because of the weight,

and it can sag up to 7 or 8 centimeters

below where you command it to.

When you say, go to 10 centimeters,

it says, well in this configuration

I might have 5 centimeters of droop,

so I'll command it to 15

and expect it to droop down to 10.

That, making sure all that worked right,

was the stressful part.

After spending more than five hours

assembling the command sequences,

Wright sends them to Curiosity.

The next day brings images of the results.

That's an image here of our first hole on Mars.

Big success.

This was the first time in history

that human beings had drilled a hole into another planet.

Note the color.

Beneath the red surface, gray rock tinged with green.

I think when we first saw the color of the rock

that was being exposed as the result of drilling

was one of the most exciting moments

of the entire mission to me.

It was right up there with landing itself,

because when you see this gray color,

and you know the chemistry in advance.

When the iron is more in the reduced state,

you can get a grayer color,

which is the the color of, say for example,

iron metal is gray because all the iron

is reduced in that state.

The sample extracted from the rock

is placed into SAM, the specialized on board laboratory.

There it's analyzed for the presence of organic compounds.

But just when mission control

thought the data was coming in fine.

It'll be hard to see above the noise floor

in the FFTs given how weak the low gain signal is.

An unforeseen circumstance.

The main computer controlling all of Curiosity's equipment

has developed a serious glitch.

The data stream has suddenly been suspended.

The mission specialists concentrate as a group

on troubleshooting the problem.

They pinpoint the culprit.

The main computer's flash memory,

dedicated to preserving Curiosity's analytical data.

What's worse, further analysis reveals

that after several hours if nothing is done,

Curiosity will cease receiving instructions from Earth.

This computer would stop talking to Earth.

We wouldn't be able to send commands to it.

It would do no more help for us,

and the computer would be forever locked

in this perpetual loop never communicating to us again.

We may have lost the rover forever.

If communication with Curiosity becomes impossible,

the rover will be stranded on Mars

as a pile of very expensive junk.

Is there no way to prevent that worst case scenario?

Their discussions produce in the end

an all-or-nothing solution.

We've got to do something.

We've got to kill this computer.

It's not going to kill itself.

This computer is going crazy.

We have to take it offline.

So the troublesome primary,

or A-side computer, will be taken offline

and they'll switch to the B-side backup.

The problem is once they've shut down the main computer

will the backup boot up properly or not?

There are absolutely no guarantees.

But there are also no alternatives.

So the main computer is shut down

and the backup is switched on.

The result?

We waited and waited.

When the minute came, 5-4-3-2-1...

Nothing. We saw no signal.

We all looked at each other.

Uh... Did we do the math wrong? Go check the math.

No, we didn't do the math wrong.

Now we're very nervous

that maybe we messed this whole process up

and that we missed the command or did something wrong.

Project staff all resign themselves to the worst.

Three minutes later,.

There is a signal.

Later on we realized

that the new computer watch hadn't been updated.

So that makes sense,

but we didn't realize it was off by three minutes.

But we were very relieved.

Once we saw that signal, we knew we were in good shape.

Curiosity had surmounted the crisis,

and obtained some hard-won samples of gray Martian rock.

The precious analytical data

were successfully streamed to Earth.

Washington DC.

NASA held a press conference at its national headquarters.

Project leaders reported on Curiosity's latest achievements

and on the possibility of past life on Mars.

Yellowknife Bay.

This was an ancient environment with the right elements,

minerals indicating a near neutral environment,

and slightly salty liquid water.

All the prerequisites to support life.

A habitable environment.

The first step was to introduce

the gray powder obtained by the drill

into the CheMin instrument, a component analyzer.

Analysis confirmed that the deeper the sample,

the weaker the oxidation of the rock.

This finding meant that the second requirement

for life on Mars, an energy source,

had now been satisfied.

It's a battery, and basically these minerals

that Dave and Paul were telling you about,

they're effectively like batteries.

Some of them are negatively charged,

and they have various oxidation states.

The difference in oxidation states

meant that electrons could flow

from areas of weaker oxidation

to areas of stronger oxidation.

Even the minute flow of these electrons constitutes energy,

and could promote an environment

conducive to the nurture of microorganisms.

Jack Farmer points out

that similar environments occur on Earth.

This is a sample from inside a cave,

in a place that sunlight does not reach.

But check it out under a microscope,

and masses of a stringy microorganism

are still living in the sample.

It always participates in the oxidation of reduced iron

and systems like that.

So it's mining this reduced iron spring for its energy.

It's not using sunlight, because there's no sunlight there.

It's using only chemistry, redox chemistry.

Curiosity had proved that even under the surface of Mars,

an energy source existed sufficient to satisfy

one of the three requirements for life.

We're no longer just looking at a red rusty Mars.

We have evidence that there is something going on

in the shallow subsurface.

You don't have to go very far, right? A few centimeters,

and you're into a totally different world.

Next there was the question

of whether the rock samples contained

the final requirement for life on Mars, organic compounds.

Concerned about potential contamination from Earth,

the Mars team had given Curiosity's

on board analytical equipment a blank run

to establish base lines.

Only then did they introduce the sample for analysis.

The result.

Another finding of chloromethane.

It was nearly five times the amount detected

during the blank run.

Clearly, most of what was detected in the sample

had not been brought along inadvertently from Earth.

But Paul Mahaffy, in charge of the analysis,

knew they could not jump to any conclusions.

Chloromethane alone is insufficient

to guarantee the presence of life.

Chloromethane compounds are the simplest class

of organic compounds that you can find.

It's very much on the simple end

of the types of complexity that we're looking for.

Curiosity will have to locate

more complex organics.

Undaunted, the rover heads off

to its next science objective.

However, it will first undergo an ordeal

even more harrowing than the last.

Up to this point in the mission,

Curiosity has faithfully executed every command sent to it.

But ever since that glitch developed

with the main computer,

Curiosity has been run by its B-side, or backup computer.

If this backup computer develops any serious trouble,

that really will be the end for this groundbreaking mission.

We also need to figure out what happened

to the A-side, and figure out whether or not

we can restore it so that we can use it again

if we need to in the future.

A new problem is looming.

At this crucial moment,

solar interference with the mission's communication signals.

With an orbital period almost double Earth's,

Mars finds itself, once every two years,

on the opposite side of the Sun from Earth.

In other words,

The Sun is interposed between Earth and Mars,

blocking a direct line of communication.

The Sun emits an exceptional amount of charged particles.

They stream off the Sun as the solar wind.

When signals are sent from Mars to Earth,

the solar wind can interfere,

letting only some of the data arrive.

What's even scarier is that commands sent to Curiosity

could be corrupted en route,

delivering the wrong instructions.

So for about a month, communications with Curiosity

will be deliberately shut down.

Project engineers are desperate

to get the main computer back online

before Curiosity goes into standby mode.

The computer repair work continues day and night.

We did it all in about three and a half weeks,

and just in time for conjunction.

It was a very exciting month of March.

Succeeding in their repairs

before the conjunction of the Earth, Sun, and Mars,

the team is able to safely ride out

this period of suspended communications.

After one month Curiosity is back online,

communicating with Earth.

Engineers immediately send commands

for a second drilling experiment.

And again, grey Mars appears.

But analysis once again only finds chloromethane

No complex organics.

Does this mean there are in fact

no complex organics at all on Mars?

At this point, one scientist offered a new proposition

concerning the possibility of past life on Mars.

Chris McKay is a co-investigator on the Curiosity mission.

McKay has an explanation for why complex organic compounds

have not been found on Mars.

A clue, he says, is provided

by the large amount of perchlorate found on Mars.

What does he mean?

McKay demonstrates with an informal experiment.

OK, a little perchlorate,

and a little sugar.

Sugar represents the organics on Mars

that we would like to detect.

Sugar, the well-known complex organic compound

resulting from photosynthesis by the sugar cane plant.

As I heat it...

SAM detects organics in the same way

by heating the sample.

McKay is mimicking the basic process.

The sugar begins to melt.

That activates the perchlorate.

A moment later.

That's the perchlorate burning.

So the activated perchlorate

destroys complex organic compounds like sugar.

The reaction also produces chloromethane.

Once you heat up a sample with organics,

it's all gonna get turned into chlorinated organic compounds

like chloromethane.

Even if there was a biosignature in the sample,

say, some cells, they would be destroyed by the perchlorate.

But that means in a location

with less perchlorate there would be a better chance

of finding complex organics.

And McKay has a theory about just where to look.

Deeper underground.

That material certainly had organics

when it was deposited.

So something is bleaching the organics out,

and that something must be perchlorate chemistry

activated by radiation.

So we have to go deeper.

Curiosity's drill can go 10 centimeters deep at most.

But the side of a cliff might might provide a way

to get at exposed rock from deeper layers.

A place like Mount Sharp,

seen in that snapshot taken just after landing.

You go up Mount Sharp,

and then we find a place where a landslide

or an impact has removed material,

and we can get down below the ground

more than five meters with the rover.

That would be wonderful.

Day 299 since the landing.

Its investigation of Yellowknife Bay complete.

Curiosity has a new destination.

It's heading off to Mount Sharp.

There complex organic compounds,

those building blocks of life,

may yet await discovery.

Maybe we can find an environment

where there's not so much perchlorate.

Or maybe we can find an environment

that just has lesser amounts of oxidants.

That's what we are trying to do.

We are trying to figure out how to unlock the code

for the preservation of organics now.

As a geobiologist,

Jack Farmer greatly looks forward

to this next chapter of Curiosity's saga.

When you combine geology with the quest for life,

it's a whole other ball game,

and that's really what's kept me interested.

Being able to see through that story in the rocks,

to ask the question,

"Could life have survived here in the past?"

"Could it still be there today in the subsurface?"

It's only been one year so far,

and Curiosity has already shown us a brand-new gray Mars.

It's next destination on Mars is a land

who's colors and contours we still do not know.

Curiosity is exploring new territory

in the effort to determine whether or not

Mars has ever been able to sustain life.

That epic quest continues.