All language subtitles for S42E11 - Chasing Pluto.en

Pluto, an icy dwarf planet
three billion miles from Earth.

Our most powerful telescopes
see only a blur, until now.

We have lift-off.

A space probe called
New Horizons is on its way.

This is an epic journey.

To the far reaches
of our solar system.

It's going farther

than any exploration
by human beings ever has.

To capture images
of a mysterious world

that may hold the secret to the
origins of our solar system.

Are there going to be surprises?

Absolutely.

But not all the surprises
are good.

About 1:55 p.m. local,

we've lost signal
with the spacecraft.

Could it be we hit something?

But a last-minute rescue
saves the day...

as Pluto comes into focus,
revealing a world stranger

than we ever imagined.

Wow!

There's a heart on it!

"Chasing Pluto,"
right now on NOVA.

Major funding for NOVA is
provided by the following:

We love science.

Supporting NOVA and promoting
public understanding of science.

And the Corporation
for Public Broadcasting,

and by PBS viewers like you.

Thank you.

And Millicent Bell,

through the Millicent
and Eugene Bell Foundation.

Additional funding
from Roger and Vicki Sant.

January 19, 2006.

An Atlas 5 rocket,
a 212-foot powerhouse,

is prepped for launch
at Cape Canaveral.

It was one of those days
where you say to yourself:

This is it.

Project succeeds or fails today.

Because when things go bad
on launch,

they usually go bad
in a spectacular way.

T minus five, four,
three, two, one...

We have ignition and liftoff

of NASA's New Horizons
spacecraft

on a voyage to visit
the planet Pluto and beyond.

It's the fastest launch
ever recorded...

36,000 miles per hour.

New Horizons needs
all the speed it can muster,

on a journey that will take it
clear across the solar system,

to attempt something unique
in the history of spaceflight:

get an up-close
and personal look at Pluto,

a mysterious, distant world

unlike anything
we've explored before.

Back on Earth,

at the Johns Hopkins Applied
Physics Laboratory,

the mission operations team
for New Horizons

is not quite ready to celebrate.

Once the rocket took off,

there was a great feeling of joy

and then you hold your breath
for a while

because you're not done
until you get the signal back

from the spacecraft
that everything's okay.

We don't have a mission

until we know that spacecraft
is communicating with us.

And so they wait.

Everything is a concern.

Things we've thought about
we know we've solved.

To try and anticipate
so many eventualities,

it's the challenge
of spaceflight.

Almost an hour passes.

And then, Mission Ops receives
the first signal

from New Horizons.

Scientists turn
to each other and go,

"I love you, man!"

It was an astonishingly
happy time.

And that's the greatest feeling,

because now we know we have
a mission to Pluto.

This is just the first
of many challenges to come

on a journey that will take
almost a decade.

Just nine hours
after leaving the launch pad,

it was already crossing
the orbit of the moon.

A trip that took
Apollo astronauts three days.

But even traveling tens
of thousands of miles an hour,

it will take over nine years
for New Horizons

to reach its destination,
to explore the far reaches

of our solar system, more than
three billion miles from Earth.

Beyond the planets
we've come to know...

Mars with its rocky red surface,

the gas giant Jupiter
with its raging storm,

and Saturn
with its stunning rings.

Uranus, where turbulent winds
blow over 500 miles an hour,

and Neptune, a planet
so far from the Sun,

it takes 165 years
to complete just one orbit.

Finally New Horizons
will arrive at Pluto,

a world we can only picture

with the help of artwork
like this, at least for now.

Who can tell us more
about the planets?

Back in the 1950s,
every grade schooler

was taught there were
nine planets,

Pluto being the last
and loneliest.

Everybody loved Pluto because
it was this funny oddball

sitting out there
at the very edge.

You don't find that kind
of name recognition

and emotional connection
and interest level for Uranus,

or Mercury,
or going down the list,

but somehow Pluto just naturally
attracts people's attention.

What makes Pluto so popular?

It may have something to do
with a playful bloodhound

named Pluto the pup.

It turns out the Disney
character made its debut

around the same time the planet
was discovered.

Over the years we've gotten
to know this beloved little pup.

The same can't be said for this
mysterious little world.

The truth is,
Pluto and its moons

have only been observed
from billions of miles away.

Our best images,
nothing more than a blur.

In fact, one of the biggest,
baddest space telescopes

in our arsenal, the Hubble,

which takes stunning images
of enormous distant galaxies,

can only capture these pixelated
images of Pluto,

because not only is it
far away, it's really small.

But even at this resolution,

they suggest
something intriguing.

Using these precious pixels,

a computer-generated image
reveals Pluto has

a surprisingly varied surface.

The light areas
could be miles and miles of ice.

The ices are the most
obvious signature that you see,

but you can discern that there's
other components there as well.

We just don't know exactly
what they're made of.

But here's what we do know:

one of the few planets
in the solar system

with such a varied surface
is planet Earth.

We also know that Pluto has
a rather bizarre atmosphere.

During its 248-year orbit,
as Pluto gets closer to the Sun,

its frozen surface starts
to thaw

and its atmosphere
slowly emerges.

What we see in the atmosphere

is gases that are coming
off the surface,

creating a temporary
atmosphere, perhaps.

Pluto has a unique type
of atmosphere

in this outer part
of the solar system

that we've never studied before.

An area so distant and elusive

we knew almost nothing about it
until the 1990s,

when powerful new telescopes
discovered lonely little Pluto

wasn't so lonely after all.

It's part of a region
in the outer solar system

beyond the orbit of Neptune
called the Kuiper Belt.

And it is enormous.

Billions of miles from the Sun,

the Kuiper Belt is filled
with hundreds of thousands

of icy objects.

While they may look
like asteroids,

which are made of rock
and metal,

these objects, hidden in the
solar system's deep freeze,

are made of a mixture
of rock and ice.

These are basically
frozen remnants

of the early part
of the solar system

that are still in the freezer.

You can start to read
this fossil record

of how the solar system evolved
by looking at these objects.

You can't say
for the New Horizons mission,

"Been there, done that,"
because it hasn't.

We've already explored
the terrestrial planet region,

the giant planet region.

Now we're exploring

a completely new portion
of the solar system

that's never
been touched before.

We don't know what we're going
to find, we really don't.

And I think that that's what
really makes this so exciting.

How do you design a spacecraft
that can survive

a three-billion-mile journey
to parts unknown?

Any time you explore
something new,

there's always a little risk.

The New Horizons mission

faced a huge number
of challenges.

We're going to the outskirts
of the solar system, you know,

30 times farther
from the Sun than the Earth.

And so in order to get there
in a reasonable amount of time

we had to build the lightest
possible spacecraft

that we could,

put it on the largest rocket
we could.

There was no opportunity
to fly big solar arrays

because the sunlight
is just too faint,

so we carry
a nuclear-powered source.

We have a suite of instruments,
seven instruments

to do very different things.

And they weigh less than about
70 pounds, all of them together.

Seven scientific instruments

not much bigger
than a grand piano

with whimsical names
like Pepsi, Swap,

and an antenna named Rex.

Two are named
after the lead characters

in the 1950s television show
The Honeymooners,

Ralph and Alice.

All of these instruments
will analyze Pluto's surface

and geology, and reveal secrets
about its mysterious atmosphere.

Back in the 1980s,
one of the best ways

to observe Pluto's atmosphere
was with this,

a C-141 cargo plane

with a makeshift observatory
on its side.

The Kuiper Airborne Observatory

was not what you'd call
a first-class ride.

The Kuiper Airborne Observatory
is not built for comfort.

You're on headsets
the whole time.

It's very loud, it's very cold.

The telescope, it's
in the middle of an airplane.

It bounces around.

But by flying a telescope
above the weather,

they had a chance
to capture a rare event

called a stellar occultation.

During this event,
an object, like Pluto,

passes in front of a bright star
blocking its light.

If the object has an atmosphere,
the light gradually fades out,

then slowly fades back up again.

But if it doesn't,
the light abruptly disappears,

and then quickly reappears.

This is a recording
of what happened

onboard the Kuiper
Airborne Observatory

the night of June 9, 1988,
when a group of researchers

were determined to find out
if Pluto has an atmosphere.

The light behind Pluto
slowly faded,

and the crew made history.

I was fortunate enough
to be involved.

I would call that the beginning
of my being an astronomer,

and it's a pretty good
beginning.

One of the instruments
onboard New Horizons

that's designed to study Pluto's
elusive atmosphere is Alice.

This model is an actual size
model of Alice.

Alice is an ultraviolet
spectrometer.

It's a telescope that breaks up
light into a rainbow.

Every chemical element
reflects and absorbs light

in a unique way,

creating a pattern
as distinct as a fingerprint.

Hydrogen's fingerprint
looks like this,

while nitrogen's
looks like this.

Powerful Earth-based telescopes
have already detected molecules

of nitrogen, methane and carbon
monoxide on Pluto's surface

and in its atmosphere.

We suspect it has

a number of others that we
simply can't detect.

As the spacecraft flies
just a few thousand miles

above Pluto, Alice will search
for those fingerprints.

Then, at the end of the flyby,
the spacecraft will turn around

to give Alice a one-of-a-kind
view of Pluto's atmosphere,

as seen through the light
of the Sun.

We can use the Sun
as our light source

to probe the atmosphere

and look for those fingerprints
of certain types

of atoms and molecules.

While Alice probes
Pluto's atmosphere,

her partner, Ralph,
an infrared spectrometer,

will be hard at work searching
for those chemical fingerprints

of molecules on Pluto's surface.

We want to know what's causing

the very bright surfaces
on Pluto, which we think

is exotic snowflakes of
molecular nitrogen and methane.

But there are other regions
that seem to be devoid

of those snowflakes
and are probably much redder,

darker hydrocarbon deposits.

Ralph will finally reveal
what these strange,

dark regions are made of.

But to get up-close
and personal images of Pluto

requires an instrument with
a one-of-a-kind telephoto lens.

The largest imager on board
New Horizons, named LORRI,

will capture extraordinary
images of Pluto's surface.

LORRI will take pictures
so detailed

that if it was flying
over New York City,

you could see the Hudson River,
the East River,

even Central Park.

To put this in perspective,
this image of the Big Apple

was taken by a satellite

traveling about 400 miles
above Earth.

LORRI is so powerful,

it could capture
the same amount of detail

from more than 7,000 miles
above Earth.

But sending a telescope
with a lens like this

into the grueling subzero
temperatures of the Kuiper Belt

is risky business.

When you have a telescope,

it's opened to space,

and so it's cooling
through that opening.

The result is that you're
putting part of camera cold,

part of it warm,

and that changes
the shape of the telescope

and that tends to put it
out of focus.

And you can end up with pictures
that look like this.

To solve this problem...

...they turn to a material
found in bulletproof vests.

What makes vests
like this so strong

is a compound
called silicon carbide.

LORRI is made out of
a special version of it

which is able to tolerate
temperature gradients

without distorting its shape.

But it's also very strong
and very light.

There's a lot of things
that might go wrong,

and we've tried to anticipate
all those things

and work out contingency plans,

and contingency plans
for those contingency plans.

We've been working for years
to get the spacecraft ready,

prepare for everything
you could think of.

In the end, it just...

You know, you just have
to sit there and wait,

and it just either works
or it doesn't.

For the New Horizons team,
waiting to find out

if all their hard work
will pay off

just may be the toughest
challenge of all.

During the Pluto encounter,

the spacecraft's
basically pre-programmed

to do everything on its own.

If it gets into trouble,
we can't help.

We can't give it a call and say,

"Whoops, you're looking
at the wrong thing.

Adjust your sights
a little bit to the left."

That's because when
the spacecraft flies by Pluto,

it will take
four-and-a-half hours

for a radio signal
to reach Earth

and another
four-and-a-half hours

for instructions
to get back to the spacecraft.

If something went wrong,
it would be more than nine hours

before we could tell it
to do something.

The most important science

is happening really only
over about a 12-hour period.

The timing has to be precise
because the onboard commands

all have a predetermined time
that this is supposed to happen.

If that time changes too much,

we'll get a lot of pictures
of black space

and we'll miss the science.

February 28, 2007.

New Horizons has been en route
for a little over a year.

Back at mission operations

at the Johns Hopkins
Applied Physics Laboratory,

the team prepares
for the spacecraft's

first real test since launch.

As New Horizons nears Jupiter,

it must hit a mark
just 500 miles wide,

where it will get pulled
into the gas giant's gravity

and get flung out.

At that point, it will be
traveling a lot faster.

Think of it like a clever
maneuver used in roller derby

called "the whip."

One skater pulls another,

propelling her forward
with greater velocity.

That's what Jupiter's gravity
will hopefully do

for New Horizons.

At mission operations,
the tension is palpable,

especially for the mission
operations manager,

Alice Bowman,
also known as "MOM."

Status check.

She has spent years
preparing for this moment,

and she knows all too well

what it means
if this maneuver should fail.

It would take years longer

to get to Pluto
if you did not have that flyby.

If you think nine years
is a long time,

adding another couple years
onto that,

that would have been
intolerable.

The clock is ticking.

MOM, along with
the Mission Ops team,

waits to receive telemetry
from the spacecraft.

This data will reveal
whether New Horizons

successfully pulled off
the gravity assist or not.

Red is bad, green is good,

gray means you don't have
any data.

Finally, they hear
from the spacecraft.

PI, this is MOM on Pluto One.

Spacecraft telemetry
for all subsystems is nominal.

Spacecraft is outward bound
from Jupiter

and we're on our way to Pluto.

So far, so great.

This is good.

By stealing some momentum

from Jupiter
along the way to Pluto,

we can actually increase
the speed of the spacecraft

by about 20% and cut three years
off the travel time.

And at the same time,

because in order to do
the Jupiter flyby

you end up coming
fairly close to it,

it gives you an opportunity
to do some great science.

It was the only time we were
going to have large objects

for the cameras
to actually point to and say,

"Okay, are we doing this right?"

We used all the instruments
on New Horizons,

but LORRI was prominent.

Okay, thar she blows.

Oh, wow!

Look at that!

And we got both of them,
we got both of them.

It's beautiful!

From more than
a million miles away,

LORRI captures a sequence
of images

of the eruption of a volcano
on Jupiter's moon Io.

It was the first time

that a time-lapse
had ever been made

of any volcano anywhere
in the universe off the Earth.

So it was really unique.

It's another plume!

Perfect image.

Yeah!

We were extremely lucky
we got these fantastic movies.

It made all those sleepless
nights and all that hard work

very much worth it.

After the gravity assist,

New Horizons
goes into hibernation.

Only essential systems
are up and running.

This limits the amount of wear
and tear on the equipment.

For most of its nine-year
journey, it will be asleep,

but once a week, the spacecraft
phones home to MOM.

This is MOM on Pluto One,
status check.

And MOM lets the whole team know

if all systems
are in working order.

As New Horizons makes its way
across the solar system

to the last and loneliest planet
to be explored,

back on Earth, a revolution
in astronomy is taking place.

After 75 years as the solar
system's ninth planet,

Pluto is getting
its walking papers.

Pluto was, since 1930, a planet.

He had stature, he had friends.

Could it be the final indignity

for the farthest and smallest
planet in our solar system?

Size doesn't matter!

The public takes to the streets
to fight for Pluto.

Go, Pluto!

Pluto forever!

It's been America's
favorite planet

since it was discovered
back in the 1930s

by the unlikeliest
of planet hunters.

Clyde Tombaugh was
a self-educated farm boy

who attended
a one-room schoolhouse.

His first job in astronomy
included cleaning telescopes

and sweeping up
at the Lowell Observatory.

He spent the rest of his time
searching for something

that could be causing
disturbances in Neptune's orbit:

the mysterious "Planet X."

Every few nights,

he placed a photosensitive
glass plate on the telescope,

securing it
so it would not shift.

Then he exposed the plate
for one hour

to the universe.

During that time, the motorized
telescope slowly moved

to compensate
for Earth's rotation.

Several days later,
he'd retrace his steps,

taking pictures
of the same sections of the sky

he had photographed earlier.

Then, using an ingenious device
called a blink comparator,

Clyde aligned the two images

to carefully examine
their differences.

The blink comparator enabled him
to shift back and forth,

searching for the subtlest
of changes.

Although the human eye is good
at spotting differences,

finding a dim celestial object
billions of miles away

was a daunting task.

Month after month,

he forged ahead
through a harsh, cold winter.

He almost froze to death

one night because his fingers
got so numb,

he couldn't get
the trap door open

to get out of the dome.

They were having
a lot of problems

with the photographic plates
breaking in the cold weather,

and he invented
a new plate holder

that would keep the plates
from breaking,

and that's what led
to the discovery.

After patiently searching
for almost a year,

a determined Clyde
finally found a tiny dot

slowly moving
across the night sky.

Can you see it?

Here it is.

Two months later,
the Lowell Observatory

proudly announced that
a young assistant

had discovered the ninth planet
in our solar system.

Because of the discovery,

my dad got his college
education.

Otherwise, he probably
would not have been able

to afford to go to college.

The discovery was, I would say,

the driver of our life
in many ways.

After discovering Pluto,
Clyde taught astronomy,

and for decades to come,
he searched for another planet

in the far reaches
of the solar system.

But as hard as he
and other astronomers looked...

And they looked hard...
Nobody found anything.

Until astronomers David Jewitt
and Jane Luu

took on the challenge.

They started a search
that would take a lot longer

than they could ever imagine.

Why did it take so long?

It was a matter of technology
catching up with the problem.

While it's easy
to see distant stars

because they radiate light,

other celestial bodies
are much harder to see.

That's because light
has to travel

all the way from our Sun
to the object,

reflect off its surface,

and then make the long journey
back to Earth.

By then, it's barely visible.

David and Jane hoped that
advances in digital detectors,

now standard
in today's smartphones,

would help them see
a whole lot more.

After searching for five years,
they finally found something.

Here is the set
of discovery images

for the first object.

So you can see this object

drifting from this picture
to this one to this one.

It's drifting slowly
to the left.

When they found several more
of these slow-moving objects,

David and Jane could finally
declare Pluto is not alone.

In fact, it's got
plenty of neighbors.

They named this new region
of the solar system

the Kuiper Belt,
after Gerard Kuiper,

the astronomer who proposed
its existence back in the 1950s.

The discovery of the Kuiper Belt

expanded our understanding
of the solar system

in a profound way,

but it also put Pluto's
planetary status in jeopardy.

Is it a planet

or a Kuiper Belt object,
one of many?

My Dad knew there were rumblings
in the wind, and it upset him.

It certainly was not easy
for my father.

But the final blow
was yet to come.

A few years later,
a young astronomer

decided to look for more objects
in the outer solar system.

Mike Brown was determined
to do something really big:

find a Kuiper Belt object
larger than Pluto.

We even thought
we might be finding things

the size of Mars,
the size of the Earth.

We really had no idea.

So when we started off
doing this back in 1997,

it was pretty exciting to think
what might be out there.

At the Palomar Observatory
in California,

Mike had access to the largest
digital camera on earth.

The images were uploaded
to his computer,

where he analyzed them
every morning.

With technology on his side,

the discoveries
just kept on coming.

We found Quaoar,

which is an object
out in the Kuiper Belt

that's about half the size
of Pluto.

The next year,
we found something

about three-quarters
the size of Pluto,

and in the following year,
we found this thing,

and it was so bright
and also moving so slowly,

moving so slowly
because it was so far away.

After all this time,
Mike couldn't believe

he might finally have found
what he had been looking for.

I looked at it and I thought,
"This can't be right."

If it's that bright
and moving that slowly,

it's the furthest thing
we've ever found

and it's the biggest
thing we've ever found,

and it must be bigger than
Pluto, and that's crazy.

It was the first object
to be discovered

that could have been larger
than Pluto.

That caused a ruckus because,
well, if Pluto's a planet,

then this has got to be
a planet, right?

And so what are we going
to call these things?

Most people really
didn't care that much

about this thing that
we just discovered.

They wanted to know, "Well,
what does it mean for Pluto?"

It's like, "Oh, yeah, you found
something bigger than Pluto.

But what does it mean
for Pluto?"

For the past century, the IAU...

The International
Astronomical Union...

Has been in charge
of naming celestial objects,

but it couldn't give
Mike's discovery a name

without knowing if it was
a Kuiper Belt object

or the tenth planet.

I think it started
an interesting conversation

because we didn't really have
a definition for planets, okay?

You know, it came
from the Greek "wandering star,"

and we did need a better way
of classifying things

as being planets or small bodies
in the solar system.

At the IAU meeting in Prague,
a vote was taken

on a new definition
of the word "planet."

Pluto's fate came down to
the phrasing of just one line:

"a planet has cleared the
neighborhood around its orbit."

Pluto resides
in a crowded neighborhood

filled with thousands
of Kuiper Belt objects.

Unlike larger planets,
tiny Pluto

doesn't have enough gravity
to clear them out of its way.

It also has
an extreme elliptical orbit

not on the same plane
as the rest of the planets.

Eight major things
which dominate the solar system

are planets.

They're all big.

They go in circular orbits
in one disk around the Sun.

And everything else
is much smaller.

Those are not planets.

So according to the IAU,
Pluto is not a planet;

it's a "dwarf planet."

There has been
a consensus developed

that Pluto is a dwarf planet,

and you know,
I have no problem with that.

The controversy comes in
when you try to say

a dwarf planet is not a planet.

Well, it seems a little
ridiculous

to have "planet" in the word,
the designation for an object,

and say somehow
it's not a planet.

In a sense, this question

of how do you label
certain objects

is less important
than understanding

that objects like Pluto,
the Earth, Jupiter, exoplanets

come in a remarkable variety

and in remarkably
different configurations

across the universe.

While Pluto may no longer be
the solar system's ninth planet,

it turns out
it's got plenty of company.

Planetary scientists continue
to discover more dwarf planets,

giving them temporary nicknames
like "Santa" and "Easterbunny."

We've discovered that
the outer solar system

is littered with small planets.

These are typically rocky
and icy objects.

Many have atmospheres.

Many, possibly most, have moons.

All the things we're used to

in the planets
we're familiar with,

but in miniature.

I think a decent analogy is

when you see a Chihuahua,
it's still a dog

because it has
the characteristics

of the canine species,
just in miniature.

Not everyone agrees with
Alan Stern's canine analogy,

and as more Kuiper Belt objects
are discovered,

how did our outer solar system

end up with these
pint-sized dwarfs?

To answer that,
we may need to look back

at the birth
of the solar system.

We think

that the solar system
began to form

about 4.5 to 4.6
billion years ago

when a cloud of nebula,
a cloud of gas and dust,

fell in on itself
because of its own gravity.

As it fell together,

it began to turn
into a great disc

of orbiting, swirling material.

It's that disc of gas and dust

that we think turns
into planets.

You make a planet
from material sticking together

and building
larger and larger pieces.

Scientists theorize
that planets form

when this material starts
to stick together.

Pebbles turn into boulders,

boulders into mountain-sized
comets.

Comets turn into protoplanets.

Protoplanets turn into planets.

After objects reach a certain
threshold in their mass,

they can grow more rapidly
than they could before

because they have
substantial gravity.

Gas giants like Jupiter
and Saturn

siphoned up massive amounts
of hydrogen and helium,

sweeping up everything in sight.

It seems plausible that Pluto

originally formed
somewhat closer in to the Sun,

but then as those major planets
got larger and larger,

it got pushed
to a more distant orbit.

We think that objects like Pluto
and the other Kuiper Belt bodies

are really the remains of that
process of planet formation.

They are sometimes called
planetesimals,

celestial objects that somehow
stopped growing.

Dwarf planets were arrested

in the mid-stage
of planetary growth.

They are actually
planetary embryos.

And to study those objects

rather than objects that grew
to much larger scales

will give us a great window

into the process
of planetary formation.

Perhaps we can find clues

in the surface of Pluto
and its composition

that point towards
that deep history

and in turn tell us
about the architecture

of the solar system
as it is now.

Where did that come from?

How did that happen?

Pluto may even hold clues

to unravel
another great mystery.

As far as we know,
the requirements for life

are water, energy,
and organic matter.

A large number of dwarf planets

may have all of these
ingredients.

There are very reputable models
of Pluto

that suggest that there's
a vast interior ocean

and that these may be common
inside the dwarf planets.

Wherever you have water,
then you have the potential...

And I want to stress that word,
"potential"... for biology.

So it may be that
the dwarf planets

are not only
the most common kind of planet

in the solar system,

they may be
the most common abode for life

in the solar system.

Clearly, organic chemistry,
carbon chemistry

can take place on the surface
of objects like comets

and probably
Kuiper Belt objects too.

Whether or not that relates

to the existence
of life on Earth

I think is a totally open
question.

But just understanding
the chemical richness

of our solar system
and the universe

is a big piece of the puzzle,

and it's a piece of the puzzle
that we need to solve.

June 8, 2008.

New Horizons has been
soaring through space

for more than two years.

Today, it passes
the orbit of Saturn.

In three more years,
it passes Uranus.

It's spent half a decade
traveling through space,

and it's still running
like clockwork.

But then the unexpected happens,

putting the entire mission
at risk.

Images taken
by the Hubble Space Telescope

reveal Pluto has not one,
not two, not three, not four,

but five moons.

All of these moons
probably all formed

in the same big
cosmic collision taking place

about 4.6 billion years ago,

where two Pluto-sized objects
rammed into each other,

and now we're seeing
the aftermath of that.

In the end,
Pluto remained intact,

but the other object
broke into pieces,

forming the five moons
that we know of,

some very oddly shaped.

All of these small moons
are debris generators,

creating the potential
of millimeter-sized dust

forming a ring around Pluto.

The spacecraft is flying so fast
through the Pluto system,

roughly 30,000 miles per hour,

that if it hit even
a millimeter-sized particle,

it could blow a hole
in the spacecraft

and it could destroy
the mission.

Back in 1967,

this almost happened
to the Mars probe Mariner 4.

It ran into a cloud
of space dust.

And over the course
of about 45 minutes,

they were seeing thousands

of impacts on the spacecraft,
completely unexpected.

Clearly, there are particles
out there that we can't detect

that could potentially cause
a loss of mission.

How much of a beating
can New Horizons take?

We're about to find out

at one of the most powerful
shooting galleries in the world.

NASA's hypervelocity gun

can shoot the tiniest of pellets
up to 17,000 miles per hour.

The dust particles
New Horizons might run into

range from the size
of the head of a pin

down to the size
of a grain of sand.

These little objects
may not look very dangerous,

but imagine a sandstorm
with winds so strong

that just one grain of sand
could kill you.

The gun is loaded.

The room is cleared.

This gun is so powerful,

metal is pulverized
from the impact.

A pellet is propelled
down this 120-foot-long barrel

to a target
made of the materials

used in the construction
of the spacecraft.

The first layer
is the gold thermal blanket

that covers New Horizons.

The second layer
is the spacecraft's wall.

The third layer,
a thin metal plate,

represents the heart
of the spacecraft:

the electronics
and scientific instruments.

Test after test is conducted,

tiny pellets slammed
into the target

at lightning speeds.

The results are mixed.

Most of the pellets penetrate
the gold thermal blanket

but are stopped by the wall
of the spacecraft.

But not all.

In fact, some, like this one,
punch a hole right through it.

A few more holes like this

could put a quick
and violent end to the mission.

The potential for a debris
impact that came out

through the detection
of the newer moons

does add another layer
of complexity to the flyby.

The New Horizons team
had to come up

with alternate flight plans,
or trajectories,

for the spacecraft to travel.

This is the ideal trajectory
they are hoping for.

There are actually
four different trajectories

that we could potentially go on,

and we may not know
until a couple of weeks out

which one we're going to be on.

The worst possible scenario is
it comes into the system,

it starts taking images,

it gets destroyed
by some impact,

and we'll never see the images,

which is pretty nerve-wracking.

I want to see the results.

I'm glad I'm not the person
waiting for that data to come.

On the approach,
we have planned observations

to look for any other debris,

or we're calling them hazard
now... not moons, hazards.

It's funny how things change.

There'll always be
a little nagging question,

you know,
"Did we make it through?"

So that first beacon
that says we made it through,

everybody is just going to...

They'll breathe a sigh of relief

and then they'll look
at each other and go,

"Oh, I knew it all along."

August 25, 2014.

New Horizons reaches
Neptune's orbit

on the 25th anniversary
of Voyager 2's encounter.

The original mission
was designed

to study only Jupiter,
Saturn, and their moons,

but Voyager 2 went on
to take stunning images

of Uranus, Neptune,
and its moon Triton.

In the '60s and the '70s

and the '80s we were exploring
new planets all the time.

First to Mars, first to Venus,
first to Mercury,

first to Jupiter,
first to Saturn.

That came to an end in 1989
with Voyager.

It's been 25 years,

and now we're doing
the next first mission.

That's epic.

December 6, 2014.

After years in hibernation,
the spacecraft is waking up.

The final leg of its journey
is about to begin.

Tonight, we're ending
hibernation.

We have been hibernating
the spacecraft

for most of the
three-billion-mile journey

across the solar system.

That's over now.

It's really quite
a historic day.

Once the spacecraft
has checked

that all systems are up
and running,

it will send a report
back to MOM.

So when we receive

a signal from the spacecraft,

it's data that
the spacecraft sent

four-and-a-half hours earlier.

And it requires a special
network of radio antennas

to receive it.

Theses enormous antennas
are spaced across the globe

so as the Earth rotates,

the team can stay in touch
with the spacecraft 24/7.

The spacecraft has
a ten-watt transmitter.

That we can pick that signal up
on Earth is incredible.

In comparison,
your average radio station

uses 50,000 watts
to transmit a signal.

It is an amazing accomplishment,
and a lot of that's due

to the technology
that's at the stations,

at the Deep Space Network,
these amazing antennas.

Getting ready for showtime here.

A few members of the team
have gathered

in the room next door,
hoping to celebrate.

But that moment will only arrive
when a very tense MOM

gets word from NASA's
Deep Space Network

that they are starting
to receive a signal

from New Horizons.

Data begins to show up
on her screen.

Did we get it?

We got it.

But before she can breathe easy,

all members
of the Mission Ops team

must verify that all systems
are in working order.

RF, MOM on Pluto One.

Status Check?

RF is green.

Power status?

Power system is green.

Propulsion status?

Propulsion is green.

Oh, there we go!

We have a nominal wake-up

of the New Horizons spacecraft
on our way to Pluto.

The team is ready
for the next leg of our journey.

We've got an encounter coming.

Yeah!

Yeah, how about that?

Some days,
it just goes like clockwork.

Here we go, cheers.

We're just gonna all take
a big breath now.

To Pluto and beyond!

Hear, hear.

To history.

This has been a very long road.

For the MOM!

Thank you.

Well, it's just amazing.

We are on the other side
of the solar system,

and where we were meant to be.

When we talk
about the spacecraft,

we talk about it as if it's,
you know, our child, our baby.

When it does something
that we don't expect,

we relate it perhaps

to "terrible twos"
or something like that,

so it really...
it becomes part of us.

Over the years,
hundreds of people

have dedicated themselves
to this historic mission.

For many team members,
revealing Pluto's secrets

is the challenge of a lifetime.

The New Horizons mission

has been a large part
of my life,

and it's been the majority
of my children's lives.

I think they can't even imagine
what it'd be like

to have this data from Pluto,

because they've been
looking forward to it

for their whole life.

As New Horizons gets closer
and closer to Pluto,

the team determines
there are no more moons

and little risk of the
spacecraft being destroyed

by debris.

They looked and they
looked and they looked,

but they couldn't
find any new moons.

I think they were kind
of disappointed

from a scientific standpoint,
but from a hazard standpoint

it was really good news.

But the good news
is short-lived.

About 1:55 p.m. local, we've
lost signal with the spacecraft.

You just feel that pit
in the bottom of your stomach.

You're thinking, "Oh, my God,

I can't believe
this is happening."

Your pulse goes up a little bit.

Could it be these millions of
miles away, we hit something?

Searching for a solution,
mission ops tries to connect

with New Horizon's
backup computer,

which transmits on
a different radio frequency.

Right away, Deep Space Network
locked up onto that signal

and it was such a great feeling
because we found our spacecraft.

Turned out that the main
processor had reset

and it had switched over
to the backup processor.

That's sort of like
your worst nightmare

a week before an encounter.

We knew that we could fix it.

The question was:

were we going to be able to do
that in enough time?

Alice, I swear,
didn't get any sleep.

But she said she slept
on the floor

for a few minutes one night.

For a couple nights slept there.

You know, just like a child
that's sick,

you want to be there to help it
recover along the way.

The team fixes the problem

just seven days before
New Horizons is set

to fly by Pluto.

We did it with four hours to
spare, or something like that.

Yes, things are definitely
back onto track.

And the pictures
are flooding in.

Every day, it's been getting
better and better.

We've been getting beautiful
stuff for the last week.

We are drooling
with anticipation.

The next picture from LORRI
that we will see

is a full-frame image of Pluto.

And it's the one that we think
is really going to tell us

what's happening.

I almost can't wait for it
to come down.

Taken almost half a million
miles away,

this is New Horizons last
portrait of Pluto

before its closest approach.

Scientists speculate
the light areas are ice;

the dark could be a dusting
of organic molecules

that fall from the atmosphere.

Wow.

This is the heart, right?

This is the heart-shaped region,

being traced out here.

Clearly there's
a lot of craters.

Boy!

It really is breathtaking
and awe-inspiring.

I've never seen anything
like this before.

But there's one more hurdle,
and it's a big one.

The world watches

as the team tensely awaits
a signal from New Horizons

that it has made its closest
approach to Pluto

less than 8,000 miles
above the surface

and survived
with all systems intact.

Stand by for telemetry.

PI, MOM on Pluto 1.

We have a healthy spacecraft.

We've recorded data
of the Pluto system,

and we're outbound for Pluto.

We did it.

Very relieved and happy, yes.

No, I mean, every polling
that was done,

every subsystem that reported in
was like music to my ears.

It's never sounded that good.

The next day,
the tiny spacecraft,

three billion miles from home,
starts beaming back...

The first close-up pictures
of Pluto,

with icy mountains
11,000 feet high,

and Pluto's biggest moon,
Charon,

with hardly any impact craters.

It will take about 16 months
for New Horizons to send back

all the photos and data
it has gathered...

and years for scientists
to analyze it,

slowly revealing Pluto's secrets
as New Horizons itself

heads out through the icy
Kuiper belt and beyond.

At pbs.org/NOVA.

Get the latest updates

from New Horizon
mission control,

and take a closer look
at the surface

with the most recent images

from the probe's
close encounter with Pluto.

You can also watch
original video shorts,

explore in-depth reporting,
and dive into interactives.

Find us at pbs.org/NOVA.

Follow us on Facebook
and Twitter.

This NOVA program
is available on DVD.
How could a Malaysian airliner
disappear without a trace?

To order, visit shopPBS.org
or call 1-800-PLAY-PBS.

NOVA is also available
for download on iTunes.

Captioned by
Media Access Group at WGBH
access.wgbh.org