Nova (1974–…): Season 47, Episode 14 - Touching the Asteroid - full transcript

♪

NARRATOR:
A daring mission

to reveal secrets of our
solar system's distant past...

PATRICK MICHEL:
Asteroids are actually tracers
of our history.

NARRATOR:
and help safeguard
our future.

DERRICK PITTS:
Asteroids might strike
the planet.

The damage created by that would
be absolutely enormous.

(loud explosion)

NARRATOR:
Can this spacecraft
unlock this asteroid's secrets

by grabbing a piece

and bringing it back to Earth?



ANJANI POLIT:
This has really proven
to be difficult.

DANTE LAURETTA:
We literally expected this
asteroid to look like a beach.

That is not what it looked like
at all.

♪

It's just rocks everywhere.

VICKY HAMILTON:
Oh, my gosh, those big boulders

were just not what we
were expecting to find.

MICHEL:
When we go to see an asteroid,

all our assumptions are usually
totally...

(chuckles):
Messed up.

♪

LAURETTA:
There's a million things
that could go wrong

and the show could be over
at that point.

NARRATOR:
"Touching the Asteroid,"



right now, on "NOVA."

♪

♪

CORALIE ADAM:
We spent years preparing
for this,

analyzing every scenario.

♪

It's very nerve-racking.

♪

HAMILTON:
This is an object
we've never been to,

something that's never been done
before.

(mechanism whirring)

MIKE MOREAU:
We're really pushing
the envelope of what

the spacecraft
and the team can do.

(mechanism whirring)

POLIT:
I'm very excited
and also very nervous.

CARL HERGENROTHER:
You've gotta persist at it,

you gotta know what you're
doing,

and sometimes you just
have to be lucky.

♪

NARRATOR:
More than 200 million miles
from Earth,

a spacecraft named Osiris Rex
approaches an asteroid.

In Littleton, Colorado,

a team of space explorers
nervously waits,

hoping their spacecraft
can do something extraordinary...

grab a piece of an asteroid
named Bennu.

LAURETTA:
Osiris Rex is going to be

the largest sample collection
robotically in the history

of solar system exploration.

NARRATOR:
If all is working as planned,

the robotic explorer
is reaching for the surface,

grabbing as much rock, dirt,
and dust

as it possibly can.

Just five seconds later,
it will retreat.

Osiris Rex must complete this
critical task

totally on its own,

with no human at the controls.

LAURETTA:
We won't know what has happened

until we get away
from the asteroid surface.

This is a really
nail-biting moment.

NARRATOR:
Once the spacecraft
safely leaves the surface,

it will store its precious cargo
and bring it back to Earth.

Even a small handful of asteroid
dust could answer big questions.

MAITRAYEE BOSE:
It's really amazing that these

tiny specks of dust grains
can tell you so much

about how our universe formed,

how our solar system formed,

how asteroids like Bennu formed,
and how Earth formed.

(loud explosion)

NARRATOR:
They could even provide clues to
how life emerged on our planet.

BASHAR RIZK:
There is truth out there,

there is an objective reality,

and all you need to do
is go out and find it.

(mechanism whirring)

NARRATOR:
Other missions have gone
in search of that truth before,

attempting to grab bits and
pieces of distant space rocks.

Back in 2004,
the Stardust spacecraft

flew through the tail
of a comet.

It had a tennis racket
type of a collector,

is the best way to describe it.

It was a grid,

and it was able to put that grid
out as it flew

through the comet tail,

and collect those particles,

stow it into its sample return
capsule, and return it to Earth.

NARRATOR:
While it was an arduous task

to find the microscopic
particles

trapped inside the grid,

researchers made profound
discoveries

that have revolutionized
our understanding

of solar system formation

with about one milligram
of space dust.

♪

In 2005, the Japanese space
exploration agency's

Hayabusa mission attempted
to grab a piece of an asteroid

named Itokawa.

The mission was filled
with mishaps.

YUICHI TSUDA:
There were a lot of troubles.

We had a lot of discouragement
or disappointment.

♪

Hayabusa was like Apollo 13.

It was a, it was a
successful failure.

I mean, they had so many things
go wrong,

yet they still managed to get
the spacecraft back to Earth.

(indistinct radio chatter)

NARRATOR:
It was a first...

Bits and pieces
of asteroid dust and dirt

were brought back to Earth.

But their take was small...

only about 1,500 tiny grains
of Itokawa.

BOSE:
The Hayabusa samples
were specifically grains

that are between 20 and 100
microns in size.

So just to give you an estimate

of how small that is,

diameter of human hair

is between 100 to 200 microns
in size.

And so, we're looking at
particles that are

half the diameter or smaller.

♪

NARRATOR:
The amount of asteroid dust
Osiris Rex could scoop up

is enough to fill a few
grande size coffee cups.

PITTS:
If we were able to collect

that much material, it would be
orders of magnitude larger

than any other sampling
ever done

at any asteroid anywhere, ever.

NARRATOR:
In fact, it would be
thousands of times more,

and could reveal mountains
of solar system secrets.

MAN:
Ten seconds, nine, eight,
seven...

NARRATOR:
September 8, 2016.

MAN:
three, two, one,
and lift-off of Osiris Rex,

its seven-year mission
to boldly go

to the asteroid Bennu and back.

HAMILTON:
There is nothing quite like
launch.

The power of a rocket
is immense,

and even if you're several miles
away from it,

you really feel that, you know,
in your body.

LAURETTA:
The only way I can describe
the experience

is transcendental,

because your whole career
has led up to that moment,

and there's a million things

that go through your mind
that could go wrong,

and the show could be over
at that point.

♪

So, you kind of just have to

reach that peaceful moment

inside yourself and enjoy it,
experience it,

and whatever is going to happen
is going to happen.

MAN:
Osiris Rex has gone supersonic.

(cheers and applause)

♪

NARRATOR:
As an Atlas V rocket hurls the
spacecraft out of Earth's orbit,

the people behind the mission

trust that math and gravity

will guide it across
millions of miles

to its tiny target.

MOREAU:
The first several months
of the mission

went very smoothly,

the spacecraft was slowly
approaching Bennu.

♪

The next step now
is all eyes on the prize,

focused on collecting the sample
and bringing it back to Earth.

NARRATOR:
Why are we going to Bennu?

What makes this asteroid
so intriguing?

HERGENROTHER:
One of the first jobs
I had on this mission

was actually to find an asteroid

that we can go to.

And you would think
that would be easy.

I mean, like, nowadays,

there is almost a million
asteroids that we know about.

NARRATOR:
Like Vesta,
pockmarked with craters.

Potato-shaped Ida
has its own moon.

Chariklo is the smallest known
celestial object with rings.

But scientists have had their
eye on Bennu for over 20 years.

HAMILTON:
From Earth,

Bennu is a barely
discernible dot of light,

even from Earth telescopes
on mountaintops,

you really can't get
a good picture of Bennu.

NARRATOR:
Why, then, is this mysterious
dot in the night sky

one in a million?

♪

1999.

The Arecibo radio telescope and
the Goldstone Deep Space network

took this series of radar images
of Bennu.

Although grainy and pixelated,

they start to paint a picture
of this tiny asteroid.

LAURETTA:
We were able to

map its shape and its rotation,
and really get

a pretty good idea
what size it was going to be

and what the overall structure
of the asteroid

was going to look like.

♪

NARRATOR:
Bennu is shaped
like a spinning top.

It completes a full rotation

about every four-and-a-half
hours.

When it comes to its size,

this space rock
isn't much taller

than the Empire State Building.

But it's Bennu's location
that really piques

the team's interest.

PITTS:
Typically, when we think about

where asteroids exist
in our solar system,

we think about
the asteroid belt,

which is a region in space

between the orbits
of Mars and Jupiter.

But there are a whole class
of asteroids like Bennu

that we identify as near-Earth
asteroids,

because their trajectory
brings them close to Earth

at some point.

NARRATOR:
There are more than 20,000
near-Earth asteroids.

The closer an asteroid
is to Earth, the easier it is

to reach with a spacecraft.

HERGENROTHER:
You're limited by the rocket
you can use,

you're limited by how long
the mission can be,

because, you know,
time is money.

So if you want to go to easy-
to-get-to, accessible objects,

they have to be really close
to the Earth.

NARRATOR:
Of course, if an asteroid
is in our neighborhood

and easy to get to,
that can also mean it's easy

for the asteroid to get to us.

PITTS:
65 million years ago,

an enormous asteroid

crashed into the Earth...

(loud explosion)

...creating an enormous cloud
of dust and dirt

that blocked out sunlight
all across the planet.

Vegetation could no longer grow
in adequate quantities

to keep the herbivores

of the planet alive.

So there was an enormous
extinction event

that took place.

We mark that period of time as
the end of the era of dinosaurs.

♪

DAVID JEWITT:
This asteroid did

a lot of damage from which,
you know, modern-day society

would not survive.

PAUL SAÁNCHEZ:
There is a real threat.

We know that.

I mean, we, we can see

the scars on the planet.

The planet has been hit before;
it will be hit again.

NARRATOR:
Researchers predict
that as early as 2175,

Bennu's orbit could be on a
collision course with Earth.

PITTS:
Should that happen,

the damage created by that
would be absolutely enormous.

(loud explosion)

The energy that it would release
would be equal to

1,200 megatons of force.

That's larger than
all of the nuclear explosions

since World War II.

SAÁNCHEZ:
It is not going to end

life on the planet.

That, that is not going
to happen.

But it does have enough energy
to wipe out a city.

If it hits on a populated area,
that city will be gone.

(loud explosion)

LAURETTA:
We need to take this seriously.

The chance of an impact is low,

but the consequences
are very high.

NARRATOR:
A deeper understanding
of near-Earth asteroids

could help future scientists

design a mission to deflect or
disrupt these potential killers,

but they can also help reveal

secrets of the Earth's
distant past.

PITTS:
Asteroids actually are remnants

left over from the earliest
periods in the history

of our solar system.

They essentially have locked up
inside them many of the secrets

of what the solar system
was like when it first began.

♪

NARRATOR:
4.5 billion years ago,

as the planets
in our solar system formed,

gas and dust stuck together,
forming pebbles.

These are like the earliest
formed solids that you can find.

NARRATOR:
Pebbles grew into boulders.

Of course, in all this mess,

there's lots of collisions
going on.

♪

NARRATOR:
Boulders into mountain-sized
asteroids.

BOSE:
You have all these asteroids
hitting each other.

You have proto-planets that are

being hit by these asteroids.

It's chaotic.

(loud impact)

NARRATOR:
When the dust settled,
the planets had taken shape.

But there was plenty
of material left over...

millions of small chunks
of rock, metal, and ice.

MICHEL:
These asteroids are actually
tracers of our history.

So if you take a planet,
a planet is like an omelet.

NARRATOR:
A complex mix of ingredients
assembled bit by bit.

You start with
the two yellow eggs...

PITTS:
Perhaps a pepper, an onion...

SAÁNCHEZ:
Salt...

...and possibly cheese.
(laughs)

♪

You put them in a pan,

it warms up,

and then it's transformed
into an omelet.

So if I show you an omelet,
and you never saw eggs before,

you would never be able

to deduce that you started
with eggs.

♪

NARRATOR:
Just like an omelet,
planet Earth's ingredients

have been scrambled and cooked
over time.

Earth has been changing.

You have volcanoes.

You have earthquakes.

And it's difficult to know
exactly what Earth was like

at the very beginning
of the formation.

♪

HAMILTON:
Asteroids like Bennu,
on the other hand, are remnants

of that very, very earliest
part of solar system history,

so they're little time capsules
that record

what kinds of chemistry
was present.

NARRATOR:
And they may contain
some of the same key ingredients

in Earth's original recipe,

including one very special
ingredient

that none of us could live
without.

LAURETTA:
We knew Bennu was very dark,

and that was one of the prime
reasons that we picked it.

We think that means that it has
a lot of carbon on its surface,

and particularly in organic
molecules.

♪

NARRATOR:
Carbon forms the backbone
of all life on Earth.

It's in land, air,
and the ocean.

And in every plant and animal.

But how did it all get here?

PITTS:
It would be much easier if we
could just say that carbon

was right here to begin with,
but if we actually look

at the very earliest history
of the development of Earth,

the first 600 million years,
this planet is entirely molten.

♪

It's a cauldron of lava
and magma.

NARRATOR:
With surface temperatures
estimated at at least

3,600 degrees Fahrenheit,

any carbon near Earth's
molten surface would have

evaporated into space.

PITTS:
So we still have this mystery
on our hands: how did carbon

get to this planet?

NARRATOR:
Did this key ingredient for life

actually hitch a ride to Earth
on comets and asteroids?

MICHEL:
One of the idea

is that this impact brought
all the element that favor

the emergence of life on Earth.

♪

NARRATOR:
In 2014, one extraordinary
mission

of the European Space Agency,

named Rosetta,
found some important clues.

PITTS:
The intention of Rosetta

was to land onto the surface of

Comet 67P, so that we could
better study

what the surface composition
was like.

NARRATOR:
The mission made history when it
dispatched a lander named Philae

onto the surface of Comet 67P,

the first landing of its kind.

ANDREA ACCOMAZZO:
We have done something
nobody had ever done.

This is an achievement not only
for ESA, but for mankind.

NARRATOR:
But the mission also made
a landmark discovery:

carbon molecules
that are crucial

for building life on Earth.

The Osiris Rex team hopes
Bennu's surface will offer

new carbon clues,
and help solve the mystery

of how Earth got its carbon.

That is, if they manage to grab
a piece of it.

RIZK:
The asteroid is an unknown.

You don't know when you get
there, or when you're planning

the mission, that this is going
to be a sampleable place.

♪

NARRATOR:
Observations made by the
Spitzer Space Telescope

provided clues to answer
this question.

Spitzer's cameras see infrared,

a form of light
that signals heat.

In space, infrared instruments
can pick out objects too dim

or difficult to see,

like a distant galaxy

or a tiny asteroid.

Spitzer was able to see
how Bennu warms up

when bathed in sunlight,
as seen here in red.

It also revealed that when
the asteroid's surface rotates

out of the sun, it quickly
cools, appearing green and blue.

HAMILTON:
If you imagine being
at the beach, during the day,

the sand grains,
they're very, very small.

They absorb heat
very, very quickly.

At night, those little sand
grains cool off very quickly.

The sand is nice and cool.

NARRATOR:
Some materials cool more slowly.

Rocks that sit in the sun
all day hold on to their heat

for a longer time.

Based on the speed
of its cooling,

Bennu appeared to behave
more like sand.

Bennu was heating up
and cooling off very quickly.

We literally expected this
asteroid to look like a beach.

♪

NARRATOR:
The kind of soft, smooth surface

even a toddler could scoop up
with ease.

HERGENROTHER:
Our interpretation

of the data at the time
suggested that it had

a fairly benign surface.

NARRATOR:
With evidence of Bennu's
smooth surface, rich in carbon,

along with its nearby location,

it seemed like an ideal choice.

HERGENROTHER:
So that's why we ended up
going there.

It really came from a million
to Bennu.

NARRATOR:
August 2018,
two years after launch

and a million miles still to go,

Osiris Rex takes its first
onboard image.

ADAM:
Bennu was still

just a point source...
It was unresolved.

It looked like a star,
essentially,

in our optical navigation
photographs.

NARRATOR:
Even as they get closer, Bennu's
true nature remains hidden.

The fact that we were going
so close to Bennu

and still knew so little
about its properties,

made it really exciting
and amazing.

RIZK:
It's a little bit tricky.

Not all the information that
you need is available.

So you can't evaluate,
in some sense, the risk.

NARRATOR:
December 3, 2018.

Osiris Rex finally reaches
its destination.

We have arrived.

(applause)

NARRATOR:
It's a great accomplishment,

and now, with the spacecraft
just 12 miles

from Bennu's surface,
the team gets ready

to gaze upon the first close-up
images of the asteroid,

excited to see a smooth
and sandy surface.

LAURETTA:
I told the team

we should be expecting
a large beach,

and so, it's going to be easy
to find a place

to collect the sample.

That is not what Bennu looked
like at all.

♪

It really blew our minds
when the data started coming in.

It's just rocks everywhere.

HAMILTON:
Oh, my gosh,

those big boulders

were just not what we were
expecting to find.

DANI DELLAGIUSTINA:
When we got the first images
of asteroid Bennu...

(chuckling):
I was a little concerned,

a little worried, because
the surface is very rough,

very rugged.

♪

NARRATOR:
Osiris Rex team member

Dani DellaGiustina knows a thing
or two about rugged terrain.

She spends her weekends
about an hour outside

of Tucson, Arizona,

rock climbing,

and the rest of her days...
And nights...

as the lead scientist

on the Osiris Rex
image-processing team.

Her job: to create a detailed
map of Bennu's rocky surface.

DELLAGIUSTINA:
I think a big part of our role

on the mission is, is
to not just be

the people that are
processing the images,

but that also help guide
their interpretation.

NARRATOR:
Bennu is remarkably deceptive.

Shadows cast by the sun
alter its appearance.

These two images were taken
of the same location

on the asteroid.

The only difference?

The time of day they were taken.

And when it comes to finding
a nice, flat spot

to grab a sample...

DELLAGIUSTINA:
The orientation of the surface
is kind of all over the place.

Some of it is angled this way,

and then an adjacent patch
of surface

might be angled that way.

And as you can imagine,
that creates a lot of difficulty

when we're trying to find
a smooth patch of ground

on the surface of the asteroid.

♪

Sometimes it's really easy
to see something

in one of the images
that we've taken of the surface

of the asteroid

that I might relate back
to an experience I've had

rock climbing.

And then I have to check myself,
and remember that rock climbing

might give me
some false intuition

about what I'm seeing on Bennu.

We're looking at a surface
of a planetary object

that is completely distinct
from Earth.

NARRATOR:
One of those differences:

the strength of Bennu's gravity
in comparison to Earth's.

Earth is trillions of times
more massive than Bennu.

Its strong gravity

creates enough pressure and heat
inside the Earth to melt rock,

and ultimately,

cook up the solid stone Dani
can safely scale.

But Bennu lacks that
gravitational power.

Bennu is such a small object
that gravity

is extremely small...
It's microgravity.

Which is just what it sounds
like...

very, very, very small amount
of gravity.

So you're not necessarily going
to compact or compress

these kinds of materials.

The boulders that make up Bennu

might be really fluffy
and porous.

NARRATOR:
So porous that if Bennu
was placed on Earth,

under the pressure
of our planet's gravity,

the boulders might simply
fall apart.

Maybe these boulders,
once we push on them...

(blows raspberry):
They crumble.

But we don't know that.

So we cannot take the risk.

NARRATOR:
There's no way for the team
to know what kind of surface

they are now dealing with.

MOREAU:
We left Earth with a spacecraft

that had a lot of capabilities
and was designed to handle,

you know,
a wide range of unknowns,

and Bennu's challenged us

to the extreme.

DELLAGIUSTINA:
Sometimes things don't go
as planned.

It's not always easy...
(chuckles)

Or straightforward.

But there's also this
incredible feeling

when you know that
you're seeing something

that nobody has ever seen
before.

It's really powerful,

and that sense of awe,

it hasn't gone away.

♪

NARRATOR:
For most of December,
Osiris Rex spies on

the asteroid from every angle.

MOREAU:
We began executing these series
of maneuvers to fly by closely

and estimate for the first time
what the mass of Bennu

was going to be.

And that was very important,
because until that point,

we had a really large
uncertainty in what

Bennu's actual mass was.

And we only had a few weeks
from the time that we started

doing these fly-bys,
and we determined

what we were
really dealing with,

in order for us to learn enough
about Bennu

to get into orbit safely.

♪

NARRATOR:
New Year's Eve 2018.

MOREAU:
Someone had the idea that it
would be fun to dress up

like we were going
to a New Year's Eve party,

'cause we're all going to be at
work on December 31.

("Auld Lang Syne" playing)

NARRATOR:
As the rest of the world
rings in the new year,

the team faces one of the
biggest challenges

of the mission:

to guide Osiris Rex

into orbit around Bennu.

It's the first time a spacecraft

will attempt to orbit
an object this small.

LAURETTA:
We're used to flying spacecraft
in orbit around the Earth,

around Mars,
around the other large planets,

and you can predict
with a high degree of accuracy

where your spacecraft
is going to be in the future

because you understand
the gravity field so well.

NARRATOR:
It's the strong and persistent
gravity of these larger planets

that helps hold a spacecraft
in orbit.

But when you're in a
microgravity environment,

all these other forces become
significant.

ADAM:
One dominant force acting on the
spacecraft other than gravity

is the solar radiation pressure,
or the sunlight,

interacting with the surface
of the spacecraft.

PITTS:
When we talk about
radiation pressure

from the sun,
we're actually talking about

the photons of energy
that are coming from the sun

pushing on the spacecraft.

Bennu is such a small object,

this caused
the spacecraft operators

to have to do a kind of dance
between that microgravity

of the asteroid itself and the
pressure of the radiation

coming from the sun
on the spacecraft.

MOREAU:
The navigation team has
had to model

all of these forces
to a fidelity

that's kind of unheard of for
planetary exploration.

ADAM:
This was the culmination of
years of work

and analysis and planning
for this moment.

Bennu became the smallest object

to ever be orbited by a
spacecraft,

and Osiris Rex became

the record holder for
the lowest orbit ever achieved

around a planetary body.

NARRATOR:
The spacecraft is now less than
a mile above the surface.

The new year seems to be off
to a great start,

but just one week later, Bennu
has another surprise

in store.

HERGENROTHER:
So, this is what I was doing
the morning of January 7.

NARRATOR:
While browsing through
images of the asteroid,

team member Carl Hergenrother
notices something strange.

So, I'm blinking
through the images,

blinking through the images,
blinking through the images,

and all of a sudden,
I come up to

one image in particular,

where I notice what looks like
a star cluster

right off the edge
of the asteroid,

where there shouldn't be this
many bright stars.

And these are bright.

And I'm looking at it,
and I was, like, "Well,

"that's a pretty big
star cluster.

It doesn't look like
any of the ones I know."

NARRATOR:
Hoping to get a more detailed
view of these strange stars,

Carl increases the brightness
and contrast of the images

and spots something
even more bizarre.

HERGENROTHER:
Wow.

These extra stars start turning
into streaks.

NARRATOR:
Tiny streaks,

like the streaks that appear
in images

taken at night
on a busy highway.

I had in the back of my mind
this little nagging feeling.

Maybe the asteroid is doing
something

that we didn't quite recognize.

NARRATOR:
He decides to investigate.

HERGENROTHER:
I started drawing lines through
these streaks

back to the asteroid.

It was over probably a half-hour
of time when I realized...

It didn't, like,
come immediately, at once...

that, oh, what I'm seeing
is what I'm seeing.

All these streaks kind of coming
from the same place,

which means what you're seeing
is a, kind of a,

an instantaneous event... boom.

(explosive sound)

NARRATOR:
The glowing dots no longer look
like a cluster of stars,

but bits and pieces of rock
and dust flying off Bennu.

I mean, it looks like
the asteroid just exploded.

I walked over, I grabbed Dante,

and he just turns white.
(laughs)

I think, literally, my jaw
hit the floor at that point.

It looks like this thing
has just turned into a comet

and is blasting particles
into outer space.

So, my first response was,
"Are we...

Is this okay for the
spacecraft?"

Immediately, we got the
spacecraft team in a room

within minutes to start looking
at this information

and saying, "Okay, do we need to
fire the engines

"and get away from this
asteroid,

or are we okay to stay
in orbit?"

NARRATOR:
They can't immediately tell
how big the particles are...

and worry that one could be
moving fast enough

to pack a damaging punch
if it hits the spacecraft.

ADAM:
We quickly built up tools
to analyze

how the particles were moving

by observing what the velocities
were and the sizes.

NARRATOR:
But careful analysis reveals
the particles are fairly small,

ranging in size from less than
an inch up to four inches.

And more importantly,

they are traveling at
a relatively slow speed.

ADAM:
The velocities were low enough
for the particles that

even if, they would essentially
bounce off the spacecraft

if they even came close.

LAURETTA:
And then the whole mood
of the team changed.

It's, like, "Okay, we don't
have to worry.

"Now this is a really exciting
scientific discovery.

"What is going on?

"Bennu is an active asteroid.

How can that possibly be?"

♪

HERGENROTHER:
This may happen on every single
asteroid that's out there.

And it's just, we were the
first mission

that had the right
instrumentation,

and we're at the right distance,

and we're taking the right data,
to actually detect this,

but they all might
be doing this.

So this may be
a common phenomenon

everywhere in the solar system.

NARRATOR:
What's causing this phenomenon?

Carl has a theory.

It could be as simple as just
meteorites

hitting the surface,
constantly, you know...

The meteors you see when you
look up in the sky.

PITTS:
We might think that
the solar system's done.

Everything is settled in place.

But that's not the case.

The solar system is still under
construction,

so to speak.

There are still asteroids
that collide with other objects.

(explosion)

HERGENROTHER:
It isn't just, you know,
asteroids crashing

into the Earth
and killing the dinosaurs.

They're all crashing
into each other,

and they're all breaking up
and throwing off pieces.

So everything is really dynamic,
and you're just kind of watching

the solar system evolve
in real time.

HAMILTON:
Bennu has been a great puzzle.

There's been things we've seen
that we never expected to see,

such as particles being ejected
off the surface.

Some things that we thought
we would see that we haven't.

RIZK:
Everyone is enormously
superstitious right now.

We try not to say anything good
about the project,

because it'll jinx it, right?

I mean, this is...

...a mindset that's
as old as humankind, right?

NARRATOR:
The team has no reason
to be overconfident.

As Osiris Rex circles Bennu
at close range,

taking thousands of pictures,

there's still no sign
of a safe spot to approach.

POLIT:
We started to become
a little bit worried,

wondering if we would actually
find a safe location to sample.

NARRATOR:
Selecting the right site
is crucial,

because it needs to accommodate
a unique device,

the first of its kind

and key to the success
of the mission.

At Lockheed Martin,
a team spent years

developing the Touch-and-Go
sample acquisition mechanism...

TAGSAM for short.

LAURETTA:
Our approach is new,
the intention to collect

a large amount of material
is new.

NARRATOR:
TAGSAM has an 11-foot-long arm

designed to reach down

and touch Bennu.

This is the only part of the
spacecraft

that's going to make contact
with the asteroid surface.

So, it's about 30 centimeters
in diameter.

It looks like a really amazing
piece of technology,

but quite honestly, it's,
it's an air filter.

(machine whirring)

We put this TAGSAM device onto
the surface of the asteroid,

and then we blow down
high-pressure nitrogen gas

to kind of agitate the soil

and then basically scoop it up
in a giant air filter.

We have tested TAGSAM
hundreds of times,

and we've found that the contact
time is very dependent upon

whether or not the surface
is stiff,

like a very strong gravel bed...

in which case the contact time
will be short...

or if the material is a little
bit softer,

it allows the TAGSAM head
to sink into the surface,

potentially up to as long
as ten seconds.

After that, the spacecraft will
fire back-away thrusters

and will leave the surface.

LAURETTA:
Then our job is to figure out
what happened.

We'll actually be able
to turn it around,

and if everything goes exactly
right... it's not guaranteed...

but we may actually be able
to see right inside the TAGSAM

and see if there's anything
inside there that we collected.

But we're not relying on that
imaging data

to verify successful
sample acquisition.

We can actually extend
this way out

and we can rotate it around

360 degrees.

NARRATOR:
Think of the spacecraft
like a merry-go-round.

SAÁNCHEZ:
So if you have a merry-go-round
that is completely empty,

if you are on your own and
you're just trying to push it

so it can go faster,

you can do that quite easily.

But then just imagine
that there's another kid

that comes around, and he wants
to get on the merry-go-round.

Now you try to push it again
to make it spin,

but it is much more difficult.

NARRATOR:
The more mass
on the merry-go-round,

the more difficult
it is to push.

The same will be true
on Osiris Rex.

If there's more mass
in the collector,

then the spacecraft
will spin slower.

By measuring precisely

the change in speed
Osiris Rex spins,

the team can calculate how much
sample was collected.

We can know exactly
how much we have... absolutely.

(whirring)

If we discover we don't have
enough sample,

then we have two more attempts,

as we have two more gas bottles
onboard the spacecraft,

so we can go back down

for a second or a third
TAG attempt if needed.

(indistinct chatter)

NARRATOR:
November 2019.

Space explorers
from around the world

come together for an
international asteroid workshop.

Members of the Osiris Rex team
are there.

And so are members of Japan's
second mission to an asteroid,

Hayabusa2.

LAURETTA:
Initially, there was
a little bit of a rivalry

between the two missions.

It was, like, those guys
have the same idea

that we have.

But we very quickly realized

that we're all part
of one community.

And I think most importantly,

what we're trying to do
is really hard.

(indistinct chatter)

NARRATOR:
After the first
Hayabusa spacecraft

returned with its payload,

the Japanese space exploration
agency decided

to launch another,
more ambitious mission.

TSUDA:
We were sure

we could make a better
spacecraft.

♪

NARRATOR:
In 2018, Hayabusa2 arrived

at a new target, an asteroid

that turned out to look a heck
of a lot like Bennu.

So when we saw this shape first,
we are very surprised.

SEIJI SUGITA:
The first impression was,

"My gosh, we, we
arrive at Bennu."

(laughs):
What are we gonna do?

NARRATOR:
Its name is Ryugu.

When you show these two bodies
to a layman,

he would say these are twins.

NARRATOR:
Although Ryugu is about
twice the size of Bennu,

they have the same shape

and they're both carbon-rich
asteroids covered in boulders.

Why are these asteroids
so similar?

Planetary scientist
Patrick Michel, who is a member

of both the Osiris Rex
and the Hayabusa2 teams,

has a bold theory.

MICHEL:
I proposed the theory that

they may come from
the same parent body.

NARRATOR:
The idea is that
millions of years ago,

that parent body was struck
by another space rock.

In the aftermath,
the dust literally settled,

as the leftovers were drawn
to each other by gravity.

This is material
that has sort of come together,

clumped itself together,

and then through
its own gravity,

has held itself together.

NARRATOR:
Bennu and Ryugu are
collections of massive boulders,

rocks, and pebbles that formed
at about the same time.

You might even call them distant
cousins.

Why these cousins have the same
spinning top shape

is a mystery the teams
hope to unravel.

HERGENROTHER:
So it's kind of cool that

we're both going
to very similar objects

that might even be related.

NARRATOR:
But there's one
baffling difference.

Osiris Rex has detected minerals
inside of Bennu's rocky surface

that contain
the remnants of water.

Water, like carbon,

is a key ingredient for the
development of life on Earth.

LAURETTA:
We had a very strong signal

that there's a lot of water on
the surface of the asteroid.

Maybe as much as ten percent

of the minerals contain water
inside them.

NARRATOR:
In comparison,
cousin Ryugu is parched.

We don't have that much water,
it's very dry.

So fundamentally different.

♪

NARRATOR:
Also different

is Hayabusa2's strategy
of finding a landing site.

They deploy several robots
to the surface,

equipped with a suite
of instruments.

MICHEL:
So you have a camera,

you have something to measure
the temperature of the surface,

and something
to measure the composition.

NARRATOR:
Some bots traverse the surface
by hopping.

The whole robot can rotate, kick
the surface, and then jump.

NARRATOR:
The bots collect data
and images.

The team picks a sample site

and releases a target marker
to mark the spot.

In February 2019,

they make their first attempt

to collect a sample.

YOSHIKAWA:
Touchdown is very risky,

so we are very nervous.

NARRATOR:
Finally...

(cheers and applause)

The signal comes in.

(applause)

The whole control room
was so excited.

(cheers)

I remember the scream of my
Japanese colleagues

when we knew this was a success.

NARRATOR;
Later, they receive a series
of images from the spacecraft

as it touches Ryugu's surface
and pulls away.

What they see surprises
everyone.

Even though the surface of Ryugu
looks like

it's covered in boulders,

as soon as a force was applied
to the surface of that asteroid,

you saw small particles flying
everywhere.

The surface is very fragile,

maybe softer than expected.

That actually gives me a lot of
confidence

in our sample collection
technique.

I think even if we made contact

with one of those boulder-y
surfaces,

the material is probably
very loosely bound,

easily broken apart.

So, in the worst-case scenario,

where we hit the top of a
boulder,

I still think we're gonna get
a lot of sample.

NARRATOR:
While this appears
to be good news

for the Osiris Rex team,

there's no guarantee that
Bennu's surface will be similar.

In spite of all of the
information

that we've collected so far,

there are still some things

that we just can't know
about Bennu

until we actually make
first contact with the surface.

When we go to see an asteroid,

all our assumptions
are usually totally...

(chuckles):
Messed up.

They turn our understanding
on, on its head.

NARRATOR:
A few months later,

the Hayabusa2 team goes for a
second sample.

This time, they blast
a copper projectile

into the surface of Ryugu
to form a crater,

in search of the most pristine,
untouched sample they can find.

The crater does excavating
for us.

It takes that uppermost layer of
the surface

that's been exposed

to solar wind
or micrometeorite bombardment

for hundreds of thousands
or even billions of years,

and removes it
and allows us to get

a little bit further
into the subsurface.

♪

NARRATOR:
They collect
this buried treasure

from inside the crater
and stow it.

Although Hayabusa2
has made two attempts

to grab a piece of Ryugu,

the team has no way
of measuring their bounty.

Unlike Osiris Rex,

that must wait until the
spacecraft returns back home.

December 2019.

The Osiris Rex team has been
taking

thousands of pictures of every
inch of Bennu,

searching for the best site
to sample.

RIZK:
Our current image count is
53,000 images.

NARRATOR:
Osiris Rex will use these
tens of thousands of images

to navigate its way to the
sample site.

LAURETTA:
So after we completed

our global mapping campaign
of the asteroid,

we identified a sample site,

about 55 degrees north latitude,

so pretty far up.

NARRATOR:
The team christens the site
Nightingale.

Near the north pole of Bennu,
this crater looks ideal.

It looks great from a
sampleability perspective.

It's got the finest-grain
material over a large area.

So, if we could get in there
and contact the surface,

we're highly confident that

we're gonna be able to get
a sample from it.

NARRATOR:
But nearby
is one major obstacle.

It has a giant rock just off

to the southwest of the crater.

I give it the nickname
Mount Doom

from "The Lord of the Rings."

NARRATOR:
Bennu's Mount Doom is
as tall as a two-story building.

And we got to fly right
over that

and then down into the crater
in order to get the material.

NARRATOR:
The size of the crater where
they will grab a sample

is not what they hoped for.

This circle is the area the team
thought they needed

in order to safely touch the
asteroid,

about 164 feet wide.

There is nowhere on the surface
anywhere close to that

that is free of hazards.

NARRATOR:
The size of the new "safe" area
in Nightingale

is about 26 feet.

FREUND:
Our landing area

is much smaller than what
we had anticipated.

The TAG site right now
is about several parking spaces.

So it's a lot smaller area
that we need to target.

ADAM:
We have to eke out every bit
of error that we can in order to

get this bull's eye TAG
and get in there

and collect the sample.

NARRATOR:
To safely guide the spacecraft
away from danger,

the navigation team needs
extreme-close-up images

of Nightingale.

We can image an object the size
of a penny

on the surface of the asteroid.

NARRATOR:
These two bright spots
circled in green

are in the center of
Nightingale.

Each one is slightly smaller
than a penny.

With this level of detail,

the spacecraft should know
precisely where it is

as it makes its way
to the surface.

FREUND:
It's a very intelligent
spacecraft.

It can make some decisions
on its own,

and if it sees things go awry,

it goes ahead
and, and takes care of itself.

MOREAU:
The spacecraft autonomously
will be checking

its estimated position.

And if it's predicting us
to come down on a hazard,

we'll have to abort

and try again.

LAURETTA:
When you're flying by Pluto
or going into orbit around Mars

or landing on the surface
of a planet,

it's got to happen exactly
according to plan

and there is no second chance.

Osiris Rex,
we're more like a hummingbird.

We can go in, we can go back.

We can go in, we can go back
until the spacecraft decides,

"Yep, I'm coming in, place looks
good, let's go ahead

"and commit to the descent
to the surface

and collect that sample."

NARRATOR:
April 2020.

A tough job gets even tougher

as the team conducts a rehearsal
of TAG during a pandemic.

MOREAU:
The whole work-at-home shutdown
orders that started coming in

in March, they really hit our
team at the worst possible time,

because we were right in
the middle of the final testing

and preparations for this
rehearsal for TAG.

There was a handful of people
that had to go in

to Lockheed Martin, but the vast
majority of the team

watched from home.

♪

ADAM:
We were handing the reins over
to the spacecraft

to autonomously navigate itself
to the surface.

♪

MOREAU:
We brought the spacecraft to
within about 60 meters

of the surface of Bennu.

ADAM:
Seeing for the first time the
TAGSAM head descending

towards Nightingale,

it just kind of made it all
much more real.

MOREAU:
We were right on target

and the onboard navigation
system worked perfectly,

really exceeded all
of our expectations.

It's really a testament
to the team

and how they were able
to pull it off.

If there's one thing that was a
disappointment for the team,

it's just that after working so
hard to get to this milestone,

such a huge milestone
for the mission,

there was a sense of
disappointment, I think,

that we couldn't be together as
a team to celebrate it,

to celebrate the success.

(indiscernible radio chatter)

NARRATOR:
October 20, 2020.

After two rehearsals,

the team finally gathers
together

as Osiris Rex attempts
to touch the asteroid

and grab a piece of it.

ADAM:
I was sweating and just nervous

waiting for the signals
to come back.

MAN (on radio):
It's 0.7 meters.

The last ten minutes, as the
spacecraft was descending

towards the surface of Bennu,
was unreal.

♪

BIERHAUS:
There were so many feelings

running around in my head, it's
sort of hard to articulate them

in a small number of words.

It was this slow-motion
thrill ride.

MAN (on radio):
O. Rex has descended below
the five-meter mark.

NARRATOR:
At the crucial moment,
Osiris Rex makes the decision.

MAN (on radio):
The hazard map is go for TAG.

(woman cheers)
MAN (on radio):
Contact expected in 50 seconds.

MAN:
We're going in, we're going in.

(yelling):
And we have touchdown!

(cheers and applause)

We did it!

(joyful laughter)

(applause continues)

NARRATOR:
Finally, Osiris Rex touches
the surface of Bennu,

the culmination of years
of work.

ADAM:
I'm in awe, really.

Everything went
phenomenally well.

We came down only two TAGSAM
heads away from our target.

I mean, I couldn't have done it
better if I was sitting

on the spacecraft
guiding myself down.

I mean, I can't believe
we actually pulled this off.

It was a good day.
(chuckles)

♪

NARRATOR:
In a few months, the spacecraft
will leave Bennu

on a two-year journey back home.

In 2023, a capsule containing
precious rock and dust

will parachute down
to the desert of Utah,

and the next step of the
exploration of Bennu will begin.

We need to keep exploring.

It really goes a long way into
understanding who we are,

how we got here,

and what our long-term prospects
are on this planet.

RIZK:
Humans look for the unknown

and consider it a challenge.

They want to explore
what's out there.

Why?

Maybe it's built into our DNA.

♪

NARRATOR:
Rising temperatures.

SHEILA JASANOFF:
We need to reduce
the heating effect.

NARRATOR:
Can we stop them...

STEVE PACALA:
Every year, the damages
are worse.

NARRATOR:
from going too far?

Now, help may be on the horizon.

ALDO STEINFELD:
It's going to be revolutionary.

NARRATOR:
New technologies

that could turn down
the thermostat.

It's like science fiction.

NARRATOR:
But are they enough?

"Can We Cool the Planet?",
on "NOVA."

Next time.

♪

♪

ANNOUNCER:
To order this program on DVD,
visit ShopPBS

or call 1-800-PLAY-PBS.

Episodes of "NOVA" are available
with Passport.

"NOVA" is also available
on Amazon Prime Video.

♪