Space's Deepest Secrets

Saturn's rings...

These cosmic wonders have both dazzled

and baffled astronomers for centuries.

Now new discoveries are set to reveal the true story

of these enigmatic structures.

When you hear the word "Saturn," the first thing you think of

are these beautiful rings, and they've been mysterious

since the very first time humanity observed them.

Where did they come from?

How old are they?

Astonishing new evidence suggests

Saturn's rings are breathtakingly young,

born during the age of dinosaurs.

The solar system's pretty old.

It's 4.5 billion years old.

If the rings have only been around

for tens of millions of years

or a hundred million years, that's weird.

How and why did the rings appear so suddenly?

And could they disappear just as quickly as they formed?

People say nothing lasts forever,

especially if it's a good thing.

Well, Saturn's rings... They may not last forever.

Now scientists battle to understand

how Saturn's rings got to be there...

Start the laser.

...What their destiny is,

and whether there's more to them than meets the eye.

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Saturn's rings... the crown jewels of the solar system,

spanning almost 175,000 miles.

But a closer look reveals that they're extremely delicate...

In most places, only 32 feet thick.

Inside them, ice... Billions of particles,

from superfine frozen dust

to huge chunks the size of icebergs.

Between the rings are strange gaps where moons feast on ice.

This incredible structure seems perfect

and eternal.

But appearances can be deceiving.

Scientists used to think the rings

were as old as Saturn itself.

But when a space probe called Cassini visits Saturn,

it reveals an uncomfortable truth...

Saturn's rings are far too clean.

The rings of Saturn are so bright and beautiful

because they're made of trillions of particles

of pristine ice.

The ice itself is actually not very dirty.

It's very, very reflective.

You almost have this beautiful mirror around Saturn.

And if the rings are old, why are they still so clean?

Nicolas Altobelli is trying to unravel this mystery.

If the rings are clean, could that be

because there isn't much dirt around Saturn?

Nicolas is trying to find out how much dirt falls

onto Saturn's rings.

Dirt in space is known as cosmic dust.

And Nicolas measures cosmic dust with an instrument

that's kept under lock and key

in a hyper-clean lab in the university of Stuttgart.

This is our cosmic dust analyzer instruments.

It's a perfect replica of the cosmic dust analyzer

on the Cassini space probe.

This instrument is made to detect dust particles...

Small grains of matter

which are as tiny as a human hair

up to maybe a few times the size of a grain of sand.

Cassini's cosmic dust analyzer

measures the dust streaming

into the saturnian system over 13 years.

Nicolas analyzes the results,

and what he finds is staggering.

Not only is cosmic dust

definitely falling onto the rings,

it's doing it 10 times faster than anybody thought.

After measuring the true abundance of the dust

far away from Saturn,

we are able to derive a 10-times-higher flux

at the rings than previously expected.

But if so much dust has been pulled into them

over the years,

how are they so bright and clean?

If the rings formed with Saturn 4.5 billion years ago,

they should be much darker.

The inescapable conclusion is that the rings are young,

seriously young.

From our data, the ring are a hundred

or a few hundred millions of years.

It's well possible that the dinosaurs could have

witnessed the formation of the rings.

100 million years is phenomenally young.

Saturn is 4.5 billion years old.

If Nicolas is right, Saturn has only had rings

for a fraction of its life.

We think of the planets as having been around

for 100% of the time of the solar system.

Well, Saturn's rings?

They've only been around for the last 2%

of the solar system's age, so they're very new.

But if the rings are so young,

how did they form?

They're made of billions of tiny particles,

like shrapnel from some violent event.

But what violent event?

And why and when did it happen?

At the university of Arizona,

physicist Erik Asphaug uses computer simulations

to investigate what this event was.

He believes clues can be found in the moons

that surround Saturn today.

The Saturn system is unique

of all the planetary systems.

Go beyond the rings and you get these middle-sized icy moons.

And then suddenly you have the giant moon, Titan.

Saturn has a vast number of moons... 62.

They're all fairly small, except one...

Titan... that's huge.

If you were to put all 61 of Saturn's other moons together,

they'd still be smaller than Titan.

And for theorists like Erik, that seems odd.

How did Saturn get one massive moon

and a whole series of smaller ones?

One of the ideas that I've put forward is that it got

to be that way through a series of collisions.

And what we're looking at now are the byproducts

of a series of collisions that formed Titan,

and it grew collision by collision,

spinning off all these fragments.

And that set up a messy, complex system

that leads to ring formation almost as a cascade of events.

The early solar system was an unstable place,

and very different than it is today.

The planets were in different, changing orbits,

and Saturn had only a handful of moons.

Could those moons have collided and formed huge Titan

and Saturn's other, smaller moons?

So what you're looking at here is one of our simulations,

which has an icy moon and another icy moon.

And so here we go.

And these two satellites will merge,

and it's a real mess because they don't merge right away.

They bounce, and then they bounce

with a little bit less energy, and they keep spinning up.

So when all is said and done, you've formed Titan.

It's an icy, rocky body.

And you end up with a whole forest of new moons of Saturn.

Erik's simulation shows that

the violence of Titan's birth

spawned many other, much smaller moons.

And the behavior of these small moons holds the key

to how Saturn's rings form.

The moons pull on each other.

They cross each other's paths until, billions of years later,

two of them get too close.

They spiral together and collide,

ejecting vast streams of icy material.

Saturn's gravity grabs the shattered moon fragments

and pulls them towards the planet.

Trapped in orbit,

the icy shrapnel spreads into a thick halo.

Over time, colliding particles

flatten the halo into a delicate disc,

eventually forming the rings that we see today.

When we look at Saturn's rings from Earth,

they look fairly static.

They're just the way they are.

Now that we've seen them up close,

we see it's an incredibly dynamic system

evolving all the time.

A series of cataclysmic events

created the rings that we see today.

But what if the formation of the rings isn't the final link

in this chain of violent events?

One of the amazing things is we think

this might be something of a cycle.

Maybe over time the rings will actually congeal

and form moons again.

Maybe Saturn's been doing this for quite a while.

Are Saturn's bright, shining rings destined to die?

Scientists scramble to find answers.

Does an ice-guzzling moon

in the outer edges of the rings hint at their ultimate fate?

Or have the world's most powerful telescopes

already witnessed the beginning of a very different end?

New evidence suggests

that Saturn's rings are astonishingly young.

They could have formed just 100 million years ago,

during the age of the dinosaurs.

This discovery creates a new unsolved mystery...

If the rings are recent additions to our solar system,

might they cease to exist just as abruptly as they began?

One possible answer lurks in the famous dark gaps

that are peppered throughout the rings.

Do these gaps suggest that something is eating the rings

from the inside?

The Cassini probe takes a closer look and captures sight

of one of the weirdest objects astronomers have ever seen...

A tiny, misshapen moon called Pan.

Even among Saturn's bizarre zoo of moons, Pan stands out