All language subtitles for 47F2FB7BF9F40473E3567FD14576818C_eng

In 1610, Galileo pointed his telescope at
the planet Saturn, then the furthest known

planet, and noticed that it sort of had...
ears.

400 years later, a little
probe called Cassini

finally looked back at us
from behind those ears.

Rings, of course, catching sight of Earth.

A single bright pixel in a dark sky.

But like the responsible child
she is, Cassini still phones

home every week to check in
with proud but anxious parents.

You know, if there's ever any problems,
I worry about her.

And I want to find out that everything is
okay, and say, call me and let me know how

things are going, or
I'll just sort of look over

everyone's shoulder as
we work together to fix it.

Besides breathtaking images of the
sparkling rings, there was Saturn itself,

and a bizarre six-sided polar storm with a
massive hurricane at its center.

And... the moons.

62 of them, including the most bizarre
worlds in our solar system.

Titan, with its choking atmosphere,
hiding rivers and lakes of liquid methane.

And Enceladus, its cracked ice surface
spewing water.

Telling of oceans below.

Oceans that could mean extraterrestrial
life.

And now, Cassini is braced for a grand
finale.

A series of dangerous
dives between the

innermost ring and
Saturn, headed for oblivion.

These are the stories of a
lonely blue marble, sending its

intrepid little machines to
places no human can yet go.

To the far ends of the solar system and
beyond.

She's the coolest, hottest, most
complex, and most expensive

probe we've ever sent out
there into the wild blue yonder.

Technically, in ancient
ancient times, Cassini is

a flagship class NASA
ESA ASI robotic spacecraft.

Built and controlled by people from 17
nations.

Before we shot her out
to Saturn, all we'd had

were glimpses of the
jewel of our solar system.

Glimpses provided by the pioneers that
flew past in 1979.

And Voyagers 1 and 2 in 1981.

But Cassini would be the first to get to
Saturn.

Saturn and stay and stay and stay.

Slated for a four-year mission,
she just will not give up.

And she's still out there, eight years
after her expiration date.

And the pictures she's sending back keep
bringing scientists to tears.

She's rewritten the textbooks about
Saturn, the rings, the moons, Titan.

So many things have changed because of
Cassini.

Roll program is in.

And liftoff of the Cassini spacecraft on a
billion-mile trek to Saturn.

Her journey started on October 15,
1997, as a Titan 4B Centaur rocket tore

into the night sky, bearing
the precious bus-sized probe

and slinging her into a
crazy seven-year flight path.

She went pinwheeling through the inner
planets, starting with two loops around

Venus and once around Earth two years
later.

Then she hurtled through the asteroid belt
and hooked up with the Galileo space probe

at Jupiter in 2000 to tag-team the solar
system's largest planet for six months.

Finally, in 2004, Cassini started sending
back her first detailed pictures of Saturn

as she made her
approach, capturing two

massive storms joining
to become a single one.

And snapping pictures of two new moons.

Cassini then winged by the bizarre little
Phoebe, probably a primordial rock from

the birth of our solar system,
snagged by Saturn's immense gravity.

Then on the first day of July,
in 2004, came the most nerve-wracking,

nail-biting part of the mission.

Decades of planning, seven years of
flying, and it all came down to this.

Firing her main engines to slow down,
just enough to be captured by Saturn,

and put safely into orbit.

Since it takes more than an hour to
communicate with the craft at that

distance, there was nothing her Earthlings
could do if something went wrong.

The slightest miscalculation would have
sent Cassini spinning by, taking with her

several billion dollars
worth of hopes, and

breaking the hearts of
her many human parents.

Light up the rockets.

Here we had to do a 96-minute burn to get
Cassini safely into orbit.

And I remember waiting and
waiting, and of course, if an

instrument doesn't work
quite right, I worry about her.

And part of the burn was when she was
behind the planet.

So we had to wait and wait and wait.

The Doppler has landed.

It's going to end up.

Finally that signal came out, and it was
just exactly on the plot.

And we all applauded in such tremendous
relief.

Okay, we have burn complete here.

Four years for this moment.

Now began a decade of
orbits, a tango of discovery,

unlike anything any
spacecraft had done before.

Skimming Saturn's moons
and rings, and getting

her dance partner
ready for its close-up.

Saturn itself was ablaze with storms of
unimaginable force.

The place crackled with giant lightning
strikes.

A gorgeous aurora at the South Pole,
created by its enormous magnetosphere,

and invisible explosions of charged gases
through that magnetosphere.

That Cassini made visible.

This magnetic envelope of the planet,
and how it breathes continuously,

and how it rotates with the planet.

So we have thousands of movies now, of an
environment that to our eyes is invisible.

The rings were even more dazzling than any
had imagined.

Stretching across hundreds of thousands of
miles.

Yet sometimes, only ten feet thick.

They're made of particles of pure water
ice.

Some microscopic.

Some the size of mountains.

We used to think of rings as these
individual particles kind of bumping into

each other, and sort of floating around in
space.

And we now know
that the bulk of Saturn's

main rings, particles
actually stick together.

And they form these long, long rings.

Strands that we call wakes.

And that these wakes line up like the rows
of a marching band.

They have grooves, if you like,
like an old-fashioned record.

Created as wakes of moons which are
orbiting.

Some of the moons are in the rings.

Some of those moons are outside the rings.

And these waves give an interesting
texture.

They break apart and they reform.

So there's this beautiful cosmic dance
going on inside the rings.

For the next eight months,
Cassini whirled back and

forth across an unimaginably
beautiful space scape.

Then Cassini started arcing
toward Titan, Saturn's largest

moon, and the one that had
long held scientists spellbound.

All these years, Cassini had carried a
hitchhiker with her.

A little lander called Huygens,
that was set to become

the first probe to land on
a moon other than our own.

Because Titan had an atmosphere.

And atmospheres have implications.

This orbiter would carry a
probe that would actually

parachute down into
the atmosphere of Titan.

And we would have cameras, we'd have
instruments to measure the temperature,

pressure, composition, and then land for
the first time on an icy moon.

Titan has a really dense atmosphere.

A denser atmosphere than here on Earth.

Nitrogen-like here on Earth.

But methane, natural gas,
which is being converted into

complex organic molecules
by sunlight and radiation.

And the chemistry that's occurring in
Titan's atmosphere today may resemble what

Earth was like before life evolved and
created the oxygen we all breathe.

We want to understand when you have
organic materials sitting on the surface

of a moon for millions or perhaps billions
of years, what's in there?

On Christmas Eve, 2004, Cassini cut the
apron strings on the little Huygens craft,

the brainchild of the European Space
Agency.

Three weeks later, scientists around the
world held their collective breaths as the

little craft dropped toward Titan's
surface.

You could almost imagine
if you're riding along with

the probe, you go slam
into the atmosphere of Titan.

A giant parachute pops up
and now the heat shift and the

windshield falls away and your
instruments are dangling there.

You're basically sort of sensing and
smelling and measuring the atmosphere

around you and your cameras are looking
around to the sides and looking down.

We just saw more and more haze and fog and
haze and haze until finally the probe

broke through that haze and we got to see
the surface of Titan for the first time.

The surface of Titan was strangely familiar
and utterly bizarre at the same time.

The little craft seemed to have
landed on the equivalent of a

mud flat or shoreline with little
ice pebbles scattered around.

But on the negative
350 degree surface of

Titan, these pebbles
were made of methane ice.

The nearby lake, a lake of methane.

And then Cassini went into orbit around
Titan and revealed with his radar system

that there indeed are
lakes of liquid natural

gas and other molecules
on the surface of Titan.

They evaporate just like here on Earth,
create clouds of methane which rain back

on the surface, creating rivers of liquid
natural gas and lakes.

Like water on Earth, that rain had cut
channels and gullies in the Moon's surface.

But there were dry formations
here too, including dunes that

stretched for miles and miles,
reaching 100 meters high.

And 3,000 meter mountains,
suggesting tectonic

forces at work here,
similar to those on Earth.

That methane, that gas that's
in your stove, plays the same

role on Titan that liquid
water plays here on the Earth.

You could have methane as a gas and form
clouds.

You could have methane rain that falls on
the surface, and that's what created huge

seas about the size of the Great Lakes on
the Earth.

Could there perhaps be some very
interesting life in the lakes on Titan?

After the long-anticipated
excitement of Titan, Cassini

headed for a close look at a
tiny moon called Enceladus.

No one thought this shimmering little ball
of ice, barely 300 miles across,

could rival Titan scientifically.

But they were wrong.

Its sparkling surface
is ridged and cracked,

and seemingly scraped
along its southern pole.

Here, these strange blue cracks,
dubbed tiger stripes, 75 miles long and

hundreds of feet deep, resemble fault
lines on Earth.

The cracks were about to get stranger and
far more thrilling.

Cassini's thermal sensors
picked up heat coming out of the

ice ball, 200 degrees warmer
than the rest of the planet.

Enceladus is a small ice ball, but it's
a crazy world in orbit around Saturn.

It's the widest object in the solar system
when we flew by it, and yet it has a lot

of geologic activity evident on its
surface, so something was happening there.

Pirouetting to take a look back at the
cracks silhouetted against the sun,

Cassini captured giant jets
of water, spewing hundreds

of miles out into space
from the tiger stripes.

They shoot out at 1,200 miles per hour.

Vaporizing and then freezing.

It was a stunning moment.

It has this tidal forcing that's squeezed
on it, kept the ocean a liquid,

and what happens that's so neat at
Enceladus is that there are actually four

fractures at the South Pole
and jets of this water and

ice come squirting out into
space, and we had no idea.

Back on Earth, Cassini's stunned
controllers quickly reprogram the probe to

fly right through the jets, collecting
particles.

And what they found was even more
stunning.

Organic molecules, the basic building
blocks of life.

Because the geyser's erupting,
and they could guide the spacecraft very

close, they could actually fly through it
and look to see if there's water there,

and there is water, and looking for the
chemistry that's there.

Enceladus is really special.

It's giving us free samples.

And so Cassini has multiple times flown
through.

You can imagine it sniffing the gas and
getting coated with these icy particles,

and some of them come in in our sample,
and we know their composition.

To our surprise, we found out that in looking
at the particles, the ocean was salty.

And it was salty and had a very similar pH
to our own ocean here on the Earth.

Here on Earth, wherever there's liquid
water, whether it's deep in the ocean and

very hot, or in rocky places or in ice,
there's microbial life.

So it certainly suggests microbial life
could have evolved on Enceladus because it

has all the properties that the Earth had
when life began here.

And so if we go back with more
sophisticated instruments, perhaps with

the free samples, we could answer that
question.

Enceladus held another shocker for the
scientists.

Most of the water spewed out of its south
pole falls back onto the planet's surface.

You could imagine standing on
Enceladus, putting out your hand,

and there'd be this gentle snow
coming down all around you.

But the fastest moving particles break
away from the moon.

But the very tiniest particles,
things that are smaller than the diameter

of a human hair, they escape
from Enceladus's gravity

and they go on to form
a ring called the E-ring.

The indefatigable probe wrapped her
original four-year mission in 2008.

During the next two
years, Cassini zipped

past Titan 26 times and
Enceladus seven times.

Dione, Rhea, and Helene each got a single
royal wave from the probe.

It would be years later, in 2013,
that Cassini flew behind the ring and

looked back at Earth, our home planet,
a single pixel in the vast solar system.

And there was no slowing her down as she
made whirling visits to moon after moon,

ring after ring, before she began a series
of adjustments to take on one final

spectacular mission,
one that NASA, with the

help of the public,
dubbed the Grand Finale.

This is prop.

I read you five minutes.

Be ready.

System straight science.

We have X-band carrier signal detection.

The start of Cassini's final orbits began
on April 23, 2017.

In many ways, even after
20 years in space, this

seemed like a brand
new mission for the probe.

The first of these daring orbits took her
high above Saturn's North Pole,

flying just outside its narrow F-ring.

And through the water-rich plume of
Saturn's moon Enceladus.

Then, in an attempt to squeeze even more
great science, scientists figured out how

to alter the craft's trajectory,
bringing it dangerously

closer to the planet
than it's ever been before.

They found that if we fly by Titan in just
the right way, we can actually jump from

just outside the rings all the way across
the planet.

We can cross the rings and
dive through a gap in between

the innermost ring and
the top of the atmosphere.

Now this gap is only a thousand miles
wide.

A task so bold and
risky that it could only be

undertaken at the end of
its long and storied journey.

Today is a potentially very historic day
for Cassini.

It may be the last main
engine rocket firing of the

entire mission after about
180 burns over our 20 years.

Being in charge of the propulsion system,
it's with a tinge of sadness, I think,

that we may never use that rocket engine
again.

Of course, the Cassini mission is all
about the science and tonight we commence

the F ring orbits, actually
orbiting for the first

time between the rings
themselves and the planet.

Very exciting.

Cassini plunged past Saturn
every six days as our cameras

provided the first ever ultra-close
images of Saturn's clouds.

A gorgeous aurora at the South Pole,
created by its enormous magnetosphere...

and rings.

Cassini took this series of photographs
over a one-hour time frame just before

turning the saucer-shaped antenna towards
the direction of its trajectory,

protecting the craft crossing Saturn's
rings.

And you feel like you're there and you can
reach out and touch the rings.

And then that space between the rings and
the planet, measuring the particles and

fields and plasma, what's going on in that
region?

These final dives were
used to reveal the mass of the

rings, which gave scientists
an idea of their age.

Early findings suggest that they may
perhaps be just 100 million years old,

much younger than the 4.6 billion year old
planet they surround.

Cassini is revealing Saturn from the
inside out, with our gravity and magnetic

field measurements, we get to see inside
the planet.

How deep do the winds go?

How is the magnetic field generated?

What's the length of Saturn's day?

As Cassini began to run out of fuel,
making it unnavigable and unresponsive to

trajectory commands, its team
back home had to take into account

the possibility of life existing
on one of Saturn's moons.

They could have parked it in an orbit
around the planet nearly indefinitely.

But that would have involved an
unacceptable risk.

The probe could eventually get snagged in
the gravity well of Titan or Enceladus,

where extraterrestrial life may be getting
a foothold.

It's possible that despite all this time
and space, and the extreme conditions she

has faced, little Cassini could have hardy
Earth microbes clinging to her.

So, to protect these worlds,
for planetary protection, we

decided to end the mission by
going into Saturn's atmosphere.

September 15, 2017, marked the end of
Cassini's bittersweet grand finale.

NASA controllers plunged the craft into
the maelstrom of the gas giant.

She continued to send back data until the
very last second.

We want to know as we get deeper and
deeper into Saturn's atmosphere,

what's it made of and what's there.

So we'll be gathered,
I'm sure, with our Cassini

family watching that
tiny signal on the screen.

And then as the atmosphere
gets too dense, it will

just turn her away, and then
the end will come quickly.

She'll be torn apart, a giant fireball
going through in Saturn's atmosphere.

And if

you think about it, as
she disintegrates and

melts, her molecules
will become part of Saturn.

A very wonderful ending for this
spacecraft.

She studied Saturn, and her end is going
to be with Saturn.

She isn't just, you know, bits of metal
and wires and things.

She's really the hopes and
dreams of all of the scientists

and engineers and all of the
people who put her together.

And so when I go and look at the night sky
and I see Saturn, I'll see Cassini,

because she'll be there.

NASA Jet Propulsion Laboratory,
California Institute of Technology