Original subtitles

For 13 years, the Cassini spacecraft explored astounding worlds,

Saturn and its moons.

We discovered things we never imagined.

All of these strange, bizarre landscapes, geysers erupting out of

We were so stunned by the images.

I mean, people were just going around in shock.

But Cassini started running out of fuel.

Scientists at NASA had to decide what to do next. And the answer was actually

pretty spectacular.

Cassini goes where no spacecraft has gone before.

A death flight revealing the deepest secrets of Saturn.

Beyond Jupiter lies Saturn, a planet circled by multiple moons and

rings. It's like a miniature solar system.

Imagine having a mission with the power, the instruments, the capability to

explore all aspects of the Saturn system.

That mission was Cassini.

It would become our eyes and ears in the Saturnian system for over 13 years.

But by September 2017,

Cassini's almost out of fuel.

Cassini has been orbiting Saturn and studying that Saturn system for over a

decade. End the mission. We're going to lose control soon. So rather than let it

just go derelict, we headed into Saturn.

Go out with a bang.

The Kaffini team goes for broke.

They program the probe to head straight for the planet.

How cool is it to sort of sacrifice everything you've got to sort of learn

last bit of information and then crash and burn?

We are in the atmosphere.

As Kaffini was careening toward his death, It still had instruments that

continued to work, and as each instrument died, there was still a set

back data and information.

Cassini wasn't designed to plunge through Saturn's atmosphere.

No one knew how long it would last before burning up.

I remember sitting in a room with my colleagues on Cassini and watching that

radio signal, that sharp green peak that told us Cassini was still linked to the

Earth.

We could monitor the atmosphere as we flew into it. And right up until the

it was sending back signs.

I was really impressed by how long Cassini lasted in the Saturn atmosphere.

mean, go NASA engineering.

As Cassini plummeted down at 77 ,000 miles per hour, it was bombarded by gas

molecules in Saturn's atmosphere.

Friction started tearing Cassini apart as it struggled to maintain contact.

As the antenna turned away, we actually saw a secondary little peak, and we

thought, okay, Cassini, hang in there, keep fighting.

And then just that green flat line.

Cassini's heartbeat was gone, and we knew the mission had ended.

vaporized in the Saturnian atmosphere, and so it has become a part of Saturn

itself.

Cassini's Death Plunge was just the last of a series of daring dives.

Prior to ending Cassini's mission by sending it into Saturn's atmosphere,

engineers and scientists came up with an idea.

Let's do dives into the region between the tops of Saturn's clouds and the

innermost area of Saturn's rings.

Beginning in April 2017,

Cassini ventured between Saturn and its rings 22 times.

Scientists call it the grand finale.

On these dives, Cassini got closer to Saturn's cloud tops than any spacecraft

ever had before.

Saturn is an enormous ball of hydrogen and helium, a gas giant.

Fundamentally, it's a really very different kind of planet than we're used

our everyday life.

Cassini snaps close -ups of the planet's gaffiest surface.

The pictures reveal.

A turbulent and stormy world.

We think of some storms on Earth as being particularly violent. If you've

been in a hurricane, that's not a fun place to be.

But the storms on Saturn, the wind patterns on Saturn, can make that look

mere breeze in comparison.

On Saturn, one storm stands out.

Its location is marked by a distinct shape.

One of the really weird things is that once the bands go around Saturn, they're

all circular until you get to the pole.

And then there's a hexagonal band up there. No one expected that.

During its lifetime, Cassini took multiple images of the hexagon.

Whenever we posted an image of the hexagon, the hits to the website went

the roof.

I think people thought it was so mysterious.

When I first saw this, I was blown away.

I mean, who could imagine having something this regular, almost

the atmosphere of a planet? It's really just phenomenal.

In 2018, Cassini data reveals this hexagonal storm could be a towering

hundreds of miles in height.

It's this gigantic structure. It's many thousands of miles across.

And right in the center, right at the pole, is this sort of permanent vortex,

permanent hurricane.

So it's kind of a creepy eye -like thing staring back at us.

Each side of the hexagon is as wide as the Earth.

It seems artificial. How do you get a hexagon -shaped storm or cloud structure

on Saturn?

Scientists think that Saturn's spin interacts with the air currents to

this symmetrical shape.

But they don't know why it's lasted for decades.

That's the puzzle.

How can you get a six -sided jet stream that's stable for so long?

But while the hexagon's shape is stable, the color has altered.

Over four years, it has changed from mostly blue to golden brown.

The transformation is linked to Saturn's seasons.

The seasons on Saturn are caused by the same thing on Earth. It's the tilt of

the planet.

And so as Saturn is going around the sun and its north pole is tipping toward

the sun, you start to get more light up there.

This sunlight interacts with the atmosphere, producing suspended

called aerosols.

It actually looks a lot like smog. It turns things more orange. So over time,

the hexagon went from blue to orange.

The color change happened during one of Saturn's northern hemisphere summers.

But mysteriously, the very center of the hexagon remained blue.

Now, this could have been for two reasons.

Maybe the haze never formed in the eye because the eye was shielded from the

sun, and the sun is responsible for creating the brownish haze that we see

Saturn.

Another reason is maybe the actual vortex is sucking the haze down.

Maybe there's something like the eye of a hurricane.

There's haze that forms over it, but it gets sucked down into the eye.

But the storms on Saturn aren't the only extraordinary thing about the weather.

When Cassini dives through the rings, it discovers rain.

Rain falling onto the planet from space.

April 2017,

Cassini embarked on its grand finale following a daring new path.

We decided to time in between the rings and the planet to go to a place no

spacecraft had ever flown before and make a unique set of measurements.

It was uncharted territory.

They didn't know exactly what they were going to find.

There could be stuff there that could have destroyed the Cassini spacecraft.

Instead, Cassini encountered something totally unexpected.

Rain.

On Earth, it rains quite a bit.

We're getting that rain from rain clouds, which are basically just a few

up. On Saturn, it also rains, but it turns out it's raining onto the top of

upper atmosphere, and that rain is coming from space.

In 2018, Cassini data revealed the colossal weight of the downpour.

Icy -grained rain hit Saturn at a rate of several tons per second.

It's completely unlike anything we've ever seen.

Suddenly we've discovered rain at Saturn, but there aren't any rain

Where is it coming from?

The answer is Saturn's ring.

The first thing you think of when you hear the word Saturn is the ring.

They're the most dramatic and unique aspect of that planet.

From afar.

Saturn's rings look like just one whole structure, but when you look up close,

it's actually a bunch of ice crystals and ice rocks that make Saturn's ring.

The ring material ranges in size, from duff grain to boulders the size of

houses.

Saturn's rings are well above the atmosphere of Saturn. They're way out in

space. And under normal circumstances, those particles of ice making up the

would just orbit Saturn forever.

But things are a little bit weird.

Something is making these orbiting ice particles fall inward as a kind of

hail.

Material is dripping inwards from the rings and falling into the clouds of

Saturn. It's like a rain with no rain cloud.

Like a cosmic rain trickling in and falling down.

Cassini discovers the rain is a mix of different kinds of ice particles, but

doesn't reveal why they actually rain down.

Then the researchers realized the ice grains were statically charged.

Ultraviolet light from the sun, for example, can blow off an electron.

And that gives these particles a charge, just like rubbing a balloon on your

hair makes it stick to a wall because of the static charge.

Well, if you have particles that are like that, they can be affected by

magnetism. And Saturn has a very strong magnetic field.

Earth's magnetic field springs from its spinning molten iron core.

Although Saturn probably has a rocky center, it's mostly a giant ball of

hydrogen and helium.

But deep in its interior, scientists think something much more exotic is

on.

We don't have enough data to know exactly what's going on in Saturn's

but we do know the broad strokes.

Within Saturn's interior, extreme pressures and temperatures force

stop acting like a gas, turning it into spinning liquid metallic hydrogen.

You've got this band of electrons that can just wander freely through that

fluid. So in that way, liquid hydrogen under extreme pressure can act like a

metal.

The magnetic field, generated by the spinning metallic hydrogen outer core,

pulls the ice particles from the rings.

These charged ice particles are then drawn in by Saturn's field.

They follow the magnetic field lines and rain down onto the atmosphere of

Saturn.

Cassini had revealed several tons of material is raining down on Saturn every

second. But how much stuff is actually in the rings?

Again, Cassini provides the answer.

In the final days of Cassini, we actually flew in between the planet

the rings.

And the gravity data was able to separate out how much mass is coming

planet and how much is coming from the rings.

And the surprise was that the rings are actually not very massive at all.

Even though they cover an area as big as the moon's orbit around Earth, Saturn's

rings are 100 ,000 times less massive than our own small planet.

They're lighter than we thought. There's not as much material there.

The mass of the rings is a valuable clue about their age.

A more massive ring can hold itself together for much longer than a less

ring. So if there's not a lot of stuff there, it must be younger.

So how long have Saturn's rings been in place?

And what's keeping them there?

It's something that I don't even think I could have imagined if I tried.

As Cassini orbited Saturn, It revealed incredible insights into the planet's

ring.

The photos that came from Cassini of the rings are unlike anything that I could

ever imagine.

If I was an alien visiting our solar system, I don't know what would stand

to me more, the blue marble or Saturn and its amazing rings.

One of the biggest questions about the rings is how old are they?

Could something like that really have existed from the beginning of the solar

system, or is it relatively recent?

Cassini provided an answer.

The rings could be as young as only 100 million years old.

A couple of clues, the low mass and the fact that they're so bright and icy that

it hasn't had time to get polluted from all the micrometeoroids and darkened.

over a long time like the age of the solar system.

So the amazing thing is that, you know, if you were on Earth about the time of

the dinosaurs, there might have been a Saturn in the sky with no rings.

So if the rings didn't form at the same time as Saturn, how did they form?

And what's keeping them in place?

To form the rings 100 million years ago, you need to find an object, maybe a

comet, or a moon gets too close to Saturn.

Saturn's gravity tears it apart and forms the ring.

As the object is torn apart, the pieces spread out around Saturn to form the

rings. They keep colliding, breaking into smaller and smaller pieces.

Like pebbles on a beach.

subsequent jostling and self -collisions between each other will take the sharp

edges off of them, creating rounded particles.

From a distance, Saturn's rings appear incredibly thin and almost perfectly

flat. But appearances can be deceptive.

One of our last results from Cassini as it took its final plunge into Saturn was

as he flew past those rings.

We noticed that the rings were actually not a uniform density.

That's something that nobody had seen.

I mean, you had to get really close to see that, and it wasn't expected.

I'm a ring scientist, and I just love seeing that detail and trying to figure

out why do Saturn's rings look the way they do.

There are very intricate structures, knife -edged little ringlets, and almost

like the grooves in a record.

Begs the question, of course, where do those structures come from?

The clue is hidden within the rings.

There's not five rings. There's not 500 rings.

There's thousands of rings. There's potentially millions of tiny little

with small gaps between them and sometimes large gaps.

And Cassini saw that there are moons.

embedded inside the rings.

These moons and moonlets seem to be shaping the rings.

When I think about the rings of Saturn, I almost hear symphonies playing in my

head. It's all about this wonderful structure and these harmonies, the

between gravity.

So we use the word resonance.

Saturn's moons stirred the ring particles with their gravitational pull,

creating waves.

There's a special place where the resonance exists.

Imagine where the ring particles would go around twice for each single time the

moon goes around.

It's like pushing someone on a swing. If you push them at just the right rate,

they go higher and higher.

And these places are where the waves generated.

So there's this ballet, this dance between the ring and the moon.

It is one of the most elegant things I've ever seen.

But the rings aren't just being shaped into waves by the moon.

They're being held in place by them.

Through gravitational interactions, these moons might be shaping the rings,

shepherding them, keeping their flock in a nice, tight orbit around the planet.

In 2017,

Cassini reveals there are more than one or two moons shepherding the rings.

A whole team of moons holds Saturn's outermost visible ring, the A -ring, in

place.

One of the really cool things that Cassini discovered during its death dive

that there are seven moons of Saturn that are all working together to keep

ring system in configuration.

So it's like the Magnificent Seven holding this thing together.

Of the seven magnificent moons, the biggest is Mimas.

It's one -eighth the size of our moon.

The smallest, Pan.

is only 20 miles across.

Acting in combination, these moons hold all of Saturn's rings in check.

So it's these seven moons working together, forming the ring system that

today.

Cassini has truly opened our eyes to the wonder of Saturn's rings.

and many moons.

Saturn has a lot of moons.

I mean, a lot of moons.

And they're all really interesting and different.

Coming up with an exact number is a little difficult because it almost

every year as we discover a new one.

The latest count is over 60 moons, each with a different character.

But one has a split personality and a very dark size.

May 2017.

Cassini was on its grand finale.

The probe snapped its last photo of a strange moon two million miles from

Saturn.

Iapetus.

Iapetus was discovered hundreds of years ago, and right from the start, it was

recognized that one side of it was very bright and the other side was as dark

as... dark can be.

This dark and light moon confused Italian astronomer Giovanni Cassini when

first spotted it in 1671.

It's been puzzling scientists ever since.

So we get there with Cassini, and of course Hiapetus was a very major target

us because we were interested to know what was with this.

crazy two -toned moon.

Cassini reveals that the answer lies even farther out from Saturn in the form

another moon.

There's one pretty big but really dark moon, Phoebe, that's outside of Iapetus

and is orbiting the opposite direction around Saturn.

Phoebe orbits Saturn four times farther out than Iapetus.

As it travels around the planet, micrometeorite impacts on the moon's

generate a cloud of dark dust.

The dust from Phoebe actually creates a large ring.

A ring of dark, dusty material that's drifting inwards towards Saturn, going

opposite direction of Iopetus, which is the perfect material for Iopetus to

sweep up in its orbit to create one dark side.

Iapetus has one dark side because it's tidily locked to Saturn.

One side always faces the planet, while another side

drives forward through the dust.

It's plowing through a bunch of dust that's sticking to the front side, kind

like bugs on a windshield.

Cassini discovered this dark dust makes the leading side warmer than the

trailing bright side by 50 degrees Fahrenheit.

When you have something that's dark, like the dust on the leading edge of

Iapetus, that gets warmer. It absorbs sunlight better. And if it's warmer,

things that can evaporate more easily, like water, for example, tend to blow

the surface.

The front side gets darker and warmer.

Any visible ice turns to vapor and makes its way to the colder trailing side,

where it refreezes.

So the white side gets whiter, and the dark side gets darker.

So you have the self -sustaining dark side and bright side, and you wind up

this two -faced moon.

Iapetus's two sides are strange.

But Cassini discovers that they're not the weirdest thing about this moon.

The weirdest thing is that it is a walnut.

Iapetus has a mountain range that exactly circles its equator all the way

the moon, a mountain range higher than the Himalayas.

These mountains are over 12 miles high, more than twice the altitude of Earth's

highest peak, Mount Everest.

It's crazy. It's this huge, crazy ridge on this really strange moon.

How do you form a smooth equatorial mountain ridge around an entire world?

A really interesting idea is that for some period of time, Just like Saturn

itself has this gigantic ring system, Iapetus had a ring system as well.

Over time, Iapetus' ring collapsed, falling into a circle around the moon.

As it fell to the surface, it built up a mountain range right below where the

ring was orbiting.

So that all that material just built up and built a mountain range, ringing the

equator all the way around.

Walnut -shaped Iapetus is not the only strange moon around Saturn.

Cassini discovered a moon hiding many secrets beneath its icy surface.

Enceladus, a moon that could even harbor life.

2017, Cassini captured six images of Enceladus, one of the most

intriguing moons in the solar system.

Enceladus is a relatively small moon of Saturn that's pretty easy to ignore, but

once you pay attention to it, hosts a lot of surprises.

We've known something was unusual about this icy world ever since the Voyager

mission took photographs in 1980.

We thought that Enceladus would be frozen solid, and yet we knew from

data the surface of Enceladus was bright white.

And we could see on the surface that vast tracks of it were smooth, at least

the resolution that we had with Voyager.

And that immediately says that there's been internal activity, because that's

really on an airless moon. That's the only process that could erase craters.

Scientists suspected something was actively resurfacing Enceladus,

filling in its craters to make it smooth and bright.

Then Cassini sent back pictures of Enceladus, backlit, and all was

We saw these icy jets shooting out from Enceladus, and everyone was so amazed

that a moon so tiny and as soon to be a frozen solid ice cube could be so

active.

Jet of almost luminous material spraying out of geysers.

When I first saw a picture of a geyser on Enceladus, I mean, I was floored.

That's amazing. I had no idea that that was even possible.

The Cassini discovery of geysers on Enceladus was a game changer.

All of a sudden, here's water jetting out.

It was, like, too good to be true.

Cassini revealed the geysers are blasting out liquid water.

Enceladus is not a solid ball of ice.

As we got more data from Cassini, we found that Enceladus had a wobble that

too large for a body that was frozen solid all the way through, and that told

that a liquid water ocean circled a rocky core.

Enceladus has liquid water under its surface, and it may very well be an

basically covering the inside of that moon.

But where's the heat coming from?

When planets and moons form.

Their cores are incredibly hot.

But they cool down over time.

The smaller the planet, the faster it cools.

A tiny world like Enceladus, over a billion miles from the sun, should have

frozen solid by now.

That's what we expected.

If things were smaller, then they would be roughly dead and they'd be covered by

craters. But Enceladus shows us that that's not the case at all.

How could a tiny moon so far from the sun have enough warmth for liquid water?

One idea is tidal heating.

If you've ever played racquetball, you know if you play the game the ball heats

up. And this is because as the ball hits the racquet or the wall, it's getting

squished and then it relaxes.

Saturn's gravity squishes and relaxes Enceladus as it orbits the planet,

it. like a racquetball.

But this alone wouldn't generate enough heat to stop Enceladus' water from

freezing. Something else must be going on in the core.

What if the core of Enceladus is actually...

kind of gravelly, instead of it just being solid, it's actually made of rocks

and pebbles and gravel all put together.

Then what happens is, as the tides are stretching and squeezing it, those rocks

are rubbing together, and that actually generates even more energy.

2017.

A computer model based on Cassini data revealed this tidal friction generates

more energy than America's biggest power station.

Water, heated to 194 degrees Fahrenheit, rises to the surface.

It sprays through cracks in the moon's south pole, creating misty plumes.

As we flew seven times through and tasted and sampled the gas in the

we found salty particles, that the ocean was salty, very much like the Earth's

ocean. We found hydrocarbons, methane, carbon dioxide, ammonia.

We found the key ingredients for life coming out of the jets of Enceladus.

So remarkable.

In 2018, scientists reanalyzed the Enceladus data and found something

even more remarkable.

Complex organic molecules.

What they found were larger organic compounds than initially thought there.

first it was just dust and water and some basic organics. Now they're seeing

more complex stuff coming up from Enceladus' interior. And that asks the

question, what else is down there?

On Earth, we find life huddled around hot vents on the seabed.

Could the same be true in the oceans of Enceladus?

Could these complex organic molecules be signs of life?

My favorite name for them is goo.

They're gooey things.

And think of life as a collection of gooey -like molecules. Now, that doesn't

mean that all gooey molecules are biological, but certainly biology makes

these complex organic molecules.

Deep in Enceladus's oceans, heat from hydrothermal vents drives chemical

reactions.

Combining simple molecules like methane and hydrogen into longer, complex

organic molecules.

Complex molecules that could serve as the precursors to life.

What's amazing is the chemistry of that ocean.

Everything needed for life is there.

The internal question is, is there life in the universe? And Enceladus is a

great place to try and answer that question.

And Cassini revealed secrets of another moon of Saturn with amazing chemistry.

A giant moon with Earth -like features.

Rivers, lakes, and dunes.

Titan.

September 2017.

Four days before the mission ended, Cassini flew past one of Saturn's most

spectacular moons,

Titan.

Here's why I like Titan. Not just because it has a name that means big and

strong, which makes you think of me, but because it has an extensive atmosphere

that's made primarily of nitrogen just like Earth.

Titan's always been a mystery.

What is hiding underneath that thick atmosphere?

Viewed through a telescope, this moon seemed little more than a hazy orange

ball. Then Cassini launched the Huygens probe.

It traveled beneath the clouds and sent back images of Titan's surface.

I almost...

Can't describe how thrilling it was, the landing of the Huygens probe on the

surface of Titan.

It was like a Jules Verne adventure come true.

The images that you see as you're coming through the atmosphere and the world

emerges, and it's this incredible world that looks so familiar.

Mountains and these streams flowing into this ocean.

Wow. You might be standing on the shores of a lake, but this lake doesn't look

like water.

Instead, it's methane.

It's much darker.

It's a frigid, bizarre world with geologic features that look familiar,

very, very alien setting.

Titan is like a home away from home, just colder by 350 degrees Fahrenheit.

The Cassini mission revealed that Titan is really exactly like Earth in terms of

its landscape.

In fact, almost a quarter of the body is covered in sand dunes, exactly like

what you see behind me.

But Cassini reveals Titan's dunes aren't what they seem.

The dunes on Titan are made of something completely different than sand dunes on

the Earth. We know most sand on the Earth is made of quartz.

But on Titan, sand dunes, it turns out, are made entirely of organics.

Titan sand is made from tiny particles of organic gunk called hydrocarbons.

These organic dunes contain the building blocks of life.

For scientists, this is a tantalizing hint.

Could Titan harbor life?

Here on Earth, there's life that exists in so many extreme environments, so it's

not impossible to think that life could have evolved to use the methane and all

of the other chemical constituents on Titan.

If life has developed on Titan, it's going to look really weird. It's going

be really different from life on Earth.

To me, there's going to be this wonderful moment in history when we

have another example of how life can be.

And if I had to place my bets on it, I think we're going to find it in the

Saturn system.

But Cassini's discovery of potential life sentenced the probe to death.

We didn't want to leave it just indefinitely in orbit because there was

fear that...

You know, should there be any earthly contamination on the spacecraft, you

want it crashing into Titan or Enceladus.

Cassini interacted with Titan one last time.

With a gentle nudge from Titan's gravity, we call it Titan's goodbye

We ended the mission with a plunge into Saturn's atmosphere, vaporizing

Cassini. and saying goodbye to our friend.

I hope you're all deeply proud of this amazing accomplishment.

I'm going to call this the end of mission.

Project Manager OpNet.

Although Cassini is gone, its legacy lives on.

Now we're sifting through all of the data collected, still finding

putting together the pieces of the puzzle to understand Saturn, the rings,

the moons.

Cassini is going to go down in history as one of the most scientifically

productive interplanetary missions that humanity has ever flown.

I'm immensely proud and... I feel enormously privileged to have been a

it.

Besides the amazing science Cassini returned, just the beauty of this

I think, sparked something inside of us.

Whenever I look up at Saturn now, I know that Cassini is there too.

And so Saturn is even a more special place.

Repair and Synchronization by Easy Subtitles Synchronizer 1.0.0.0