All language subtitles for Spaces.Deepest.Secrets.S06E07.Curse.of.the.Comets.WEBRip.x264-CAFFEiNE[eztv]

Narrator: Comets --

Mysterious visitors from
the edge of our solar system.

A comet is a giant chunk of ice
and rock the size of a mountain

That is hurtling through space
at 300 miles per second.

Narrator:
These giant, dirty snowballs

Slam into planets.

Plait: When a big comet
hits a planet,

There are megaton-sized
explosions in the atmosphere.

Narrator:
But they may also deliver life.

Comets can bring the seeds
and the fertilizer of life

To spread across a planet.

Narrator:
Where do comets come from,

And what can we learn
from landing spacecraft

On a distant comet?

To find out,
we will strip comets apart.

We'll pull off
their spectacular tails

And crack open their icy cores

To reveal the secrets
locked inside.

♪

-- Captions by vitac --
www.Vitac.Com

Captions paid for by
discovery communications

♪

Comets.

They appear without warning
and blaze across the sky.

They seem very distant
and very tiny,

But really, they're some of
the most dramatic things

You could possibly look at.

They would appear
out of nowhere.

They'd be huge.

They'd be bright, and they were
omens to ancient people.

We've seen them as omens as war
or good times, bad times.

Narrator: Now pioneering
missions and experiments

Are revealing there is far more
to comets than we thought.

♪

Comets travel in huge orbits
around the sun,

Up to hundreds of thousands
of miles per hour.

In their wake, they leave
a tail millions of miles long.

♪

Pulling away this dusty trail
reveals a glowing sphere

Of dust and gas.

Hidden deep inside

Tumbles the cold, rocky heart
of the comet, the nucleus.

♪

Beneath its crust
lies a glistening prize --

Rocks and ice frozen since
the dawn of the solar system.

Understanding comets could
unlock the secrets

Of our planet's evolution.

♪

For centuries, comets were
astronomical curiosities,

Cosmic wanderers
that orbit the sun

Until a truly cataclysmic event.

♪

Jupiter -- 1,000 times
bigger than earth,

Its gravitational field reaches
far into space.

♪

In 1993, astronomers watched
as this giant planet

Captured a comet called
shoemaker-levy 9.

Shoemaker-levy 9 was a comet
that came close to jupiter

And broke apart,

And it formed what we call
the string of pearls.

Narrator: As the comet fractured
into 21 fragments,

Scientists gained new insights
into these balls of ice.

When you say a comet
is a big chunk of ice,

You might think about
a big iceberg

Careening across the sky.

But, in fact, as shoemaker-levy

Fell into the gravity field
of jupiter,

It was pulled apart very easily,

And the strength of it was more
than, like, cotton candy.

Narrator: Comets aren't
wandering icebergs.

They're fragile clumps
of ice and rock.

And shoemaker-levy 9
had an even bigger surprise.

Sykes: People realized that
this string of comets

Is going to actually hit
jupiter,

And so the world
was prepared to watch this.

♪

Narrator: The fragments
of shoemaker-levy 9

Hurtled toward jupiter.

♪

Stripping the planet apart shows
how they pierce the atmosphere

At over 100,000 miles per hour.

♪

The biggest chunks exploded
with hundreds of times

More energy than earth's
entire nuclear arsenal.

♪

The impacts left dark scars
the size of earth.

It was spectacular.

So every time one of these
cometary fragments

Struck the jupiter atmosphere,
there was a huge explosion,

You know, like a multi-megaton
explosion in the atmosphere.

Narrator: Shoemaker-levy 9
was a wake-up call.

When we first knew
that comet shoemaker-levy

Was going
to collide with jupiter,

We scientists thought
we were looking at

A once-in-a-lifetime opportunity

To see an incredibly dramatic
event, but that changed.

Now we understand that
it happens far more often

Than we were aware of.

Narrator: Astronomers spotted
evidence of massive impacts

Right across the solar system,

Causing damage
on a planetary scale.

Shoemaker-levy
really changed our idea

Of what living in our
solar system is actually like.

Narrator: Scientists launched
a fleet of spacecraft

To find out more
about these cosmic wanderers.

Woman: We have ignition
and liftoff of a delta ii rocket

Carrying deep impact.

Narrator: Nasa fired their
deep impact probe into a comet,

Hoping to unlock its secrets...

...And the european
space agency's rosetta mission

Steered a lander
onto a comet's surface.

♪

On November 12, 2014,

The philae lander touched down
on the surface of comet 67p.

This was the first-ever landing
on a comet.

[ cheers and applause ]

♪

Missions to comets
like rosetta have given us

Glimpses of the nucleus.

It's one of the darkest objects
in the solar system.

A jet-black coating
on its surface

Absorbs 98% of all light.

So far, no mission has ever
brought back a sample

Of what lies beneath.

♪

The dark crust conceals

A cosmic time capsule
of rocks and gas,

Untouched since the birth
of our solar system.

♪

♪

Today's comet chasers
are planning a mission

To pierce this time capsule.

Joseph nuth is developing
a comet-penetrating harpoon.

He uses a giant crossbow
to fire a missile into samples

That mimic a comet's nucleus.

We're testing the system to see
exactly what can go wrong,

And we're pushing it to try
to make things go wrong.

Man:
Three, two, one, fire.

♪

Narrator:
Joseph designs his missile

To bring a sample back to earth.

The tethers retract the system
back up into the spacecraft.

The spacecraft flies away,

Eventually brings
the sample home to us.

Narrator:
But for the mission to succeed,

Joseph must pierce the crust
surrounding the nucleus,

And he has no way of knowing
how hard it is.

♪

A comet starts life
with no tail and no crust.

As it approaches the sun,

The increasing heat vaporizes
the ice on the surface,

Exposing a dark,
powdery layer of dust.

♪

It forms a thin sheet covering
the icy core of the comet.

♪

But with each orbit,
the heat of the sun

Bakes the dust into
a harder and harder crust.

When joseph's machine
intercepts a comet,

He will have just one shot
at piercing the crust.

So he tests his harpoon
on a range of surfaces.

Nuth: This is
like going into cement.

Okay.
-List is at 900.

That sounds of tension.

Ready?

Three...

Two...

One.

Fire!

♪

We hit.

It barely penetrated.

It actually rolled over.

This is the kind of thing
we want to avoid, and we will.

We'll just have to work on it
a little more.

Narrator: While joseph
fine-tunes his harpoon,

Nasa searches
for a suitable target.

A successful rendezvous
will depend

On predicting a comet's path.

♪

♪

Narrator:
Comets are frozen enigmas.

Until recently,
we've known little about

Their immense journeys
through space...

...Because we could
only see them

When they ventured close
to our planet.

There's always a lot of fanfare

When a really large comet
comes in towards earth,

And you can actually see it
in the sky.

But, in fact, we live
in an environment of comets.

There are many small comets
that we never see from earth.

Narrator: When we do see comets
from our planet,

It is because
of their iconic tails,

And comets only produce
these spectacles

When they are close to the sun.

♪

The source of a comet's tail
is inside the nucleus.

As the comet approaches the sun,
pockets of frozen gas heat up

And erupt in icy jets.

♪

They rip up to 3 tons
of dust and gas

From the core every second.

♪

This forms a glittering tail,

Reflecting sunlight
and making it glow white.

They have a long tail
streaming off, which sometimes

Can be bright enough
to see with the unaided eye.

And they circle around the sun,
moving across the sky

Over the course
of a few weeks or months.

And then they disappear
into the dark,

And sometimes never
to be seen again.

♪

Narrator: But scientists
can track comets

Even when they are far
from earth.

Astronomer peter jenniskens
searches for signs

In the night sky.

Jenniskens:
The sky is alive.

You really see the earth
move through space.

You really feel that we are
part of the universe.

Narrator: Peter uses cameras to
pinpoint the glowing debris

Comets leave behind.

When a comet's orbit
takes it close to the sun...

...Its dust tail leaves behind
a stream of debris.

♪

Every time the comet returns,
the tail leaves more dust.

When the earth passes
through this gritty trail,

These dust particles burn up
on the atmosphere,

Creating a meteor shower.

♪

Every morning, peter checks
what his cameras have detected.

Jenniskens:
At the beginning of the night,

You see these thick streaks,
which are airplanes,

And here, the clouds are
gradually fading,

And the stars
are coming in view,

And all these short streaks
are little bits of comet dust.

Narrator: His software
determines the direction

This dust falls to earth
and the path of the comet.

Jenniskens: That allows us
to calculate the comet orbit.

If we know what the orbit
of the comet is,

Then in principal, you could
look along that comet orbit

And see a comet
coming close to the earth

That could potentially hit us.

Narrator: Peter's team
has mapped the orbits

Of nearly 4,000 comets
just from their dust.

♪

But comets don't just
trail dust.

They also produce
a mysterious blue tail.

The power behind it is the sun.

Our star emits massive amounts
of ultraviolet radiation...

...And it also ejects
the solar wind,

A vast stream of electrons
and protons

That shoot deep into space.

This combines with
ultraviolet radiation

To form the comet's blue tail.

♪

When ultraviolet radiation
hits the gassy sphere

Around the nucleus,
it creates a bright blue plasma.

♪

Then the solar wind
pushes this blue plasma

Out in a straight line,

Producing what scientists call
the plasma tail.

♪

This makes comets
even more spectacular

When they fly past earth.

But this blue tail
is vulnerable.

The sun can make it
and break it.

♪

Comet encke orbits the sun
very tightly.

But in 2007, it hit trouble.

A massive solar storm
blasted the comet...

♪

...And ripped off
its plasma tail.

A nasa probe captured
this extraordinary event,

The first proof that comets can
lose their plasma tail.

♪

Encke never wanders
far from the sun,

But other comets have orbits

That stretch to the very edge
of the solar system.

These long-distance travelers
hold clues

About one of the biggest
mysteries in science.

When we see comets
flying around,

They are the leftover remnants

Of the formation
of our solar system.

Narrator:
Could these frozen time capsules

Reveal how life on earth began?

♪

♪

Narrator:
4.6 billion years ago,

Our solar system was born.

The shock wave from a supernova
forced cosmic dust

Into a gigantic rotating ring.

Most of this debris
clumped together

To make the sun and the planets.

But how did the comets form?

♪

Today, comets orbit two
main areas of our solar system.

The nearest comets come
from a region

Just beyond neptune called
the kuiper belt,

A huge ring of icy debris.

But 1,000 times farther out,

Almost a light-year away...

...Comets swarm together
to form the oort cloud.

♪

It's a gigantic sphere,
a cosmic snow globe

Teeming with an estimated
2 trillion icy dirt balls.

♪

Comets are at the very edge
of our solar system

And go as far as, like,

A quarter of the way to
our nearest star.

So they're way out there.

There are comets that are so far
out, we will never see them.

Narrator: We now find comets
across the solar system.

But where were they born?

Mike zolensky sends planes to
the edge of space to find out.

♪

He attaches dust traps
to a modified spy plane.

Zolensky: Inside this metal can
are the dust collection plates.

They're coated with a sticky oil
to make particles stick to them.

Narrator: The sticky collector
deploys at 60,000 feet.

♪

But capturing comet dust
so high in the atmosphere

Puts the flight crew at risk.

♪

At that altitude,
the pressure is so low,

The blood boils
at body temperature.

So the crew must wear
a life-preserving pressure suit.

♪

♪

Each flight lasts up to 8 hours,

But even
the most successful mission

Collects less than 100
tiny grains of comet dust.

Zolensky: We started collecting
these particles in 1981.

The goal is to have the plane
fly many times

So we have a large selection
of comet grains to sample.

Narrator:
Mike takes these samples

To an ultra-clean
storage facility,

The cosmic dust laboratory,

The largest collection of comet
debris on the planet.

♪

Here, mike and his team analyze
the dust for clues

About where the comet was born.

Their collection includes dust
that came from much farther away

Than earth's atmosphere.

Man: Zero, and liftoff
of the stardust spacecraft

Returning a time capsule
with the elements

Of the formation
of our solar system.

Narrator: In 2000, nasa's
stardust mission captured dust

From the tail of a comet,
and 6 years later,

It brought these samples
back to earth.

This tray was the capture tray
for the spacecraft.

It's always scary to have
the entire tray out

And in the lab at one time
because you could destroy,

You know, a large amount of
samples all at once.

This was a $220 million mission,
which means each of these cells

Technically cost about
$1 million.

Narrator: Scientists used to
think that comets formed

In the icy outer reaches
of the solar system,

Where we find them today.

But chemical analysis of
this comet dust

Shattered this theory.

Really, you'd be surprised
to find not only was that wrong,

It was really wrong.

We see minerals that consist
entirely of titanium

And calcium, aluminum oxides.

Those must have formed
at very high temperature,

Thousands of degrees c,

Obviously right up next to
the sun.

Narrator: Comets began life in
the inner solar system,

Not in the cold outer regions
where we now find them.

Zolensky:
That's why it's so exciting

To do this kind of mission,
because you head off

In new directions
you never thought of before.

Narrator: How did material
that formed near the sun

End up trillions of miles away
in the oort cloud?

♪

4.6 billion years ago,

Our solar system was a swirling
cloud of dust and gas.

This fused together to forge
giant planets like jupiter.

♪

Its gravity captured some
of the remaining dust and rocks

And slung the rest out trillions
of miles into outer space.

These rocks mixed
with frozen gas and ice

To form the comets that we now
find in the oort cloud.

♪

The reason the oort cloud
is there

Is when the planets
were forming,

The gravity kicked out lots
of material very, very far away.

Some of it escaped
the solar system entirely.

So when you see a comet
coming back from the oort cloud,

In some cases, it's come from
nearly a light-year

Or 2 light-years away.

It's had a very long journey
to get to us.

Narrator: Comets are
our long-distance travelers.

From the depths
of the solar system,

They can tear towards the sun

At hundreds of thousands
of miles an hour.

And sometimes, comets throw us
a curveball.

♪

Just beyond the orbit of saturn,

Astronomers tracked
a slow-moving rocky object

Over 100 miles across.

At first, they thought it was
a new planet

Until the dead rock
suddenly got brighter...

...And grew a tail.

It's both a planet and a comet.

Named chiron,

This was the first of
a new breed of cosmic bodies --

Centaurs,

The biggest comets
roaming our solar system.

The discovery of centaurs
reminds us

That our understanding
of comets is still evolving.

Scientists now think comets
also hold clues

About our planet's
remarkable appearance.

Could they be the reason
water covers

So much of the earth's surface?

♪

♪

Narrator: Comets are far more
than balls of ice.

They smash into planets,
causing massive damage.

♪

Their dust ignites into
dramatic meteor showers,

And they preserve fragments from
the birth of the solar system,

But they also hold clues
about our own planet's past.

♪

Today, water covers
70% of the earth's surface,

Making our home unique
in the solar system.

Plait: If we were
too much closer to the sun,

A lot of that water
could have evaporated off.

We would have gotten
a runaway greenhouse effect,

And the earth would be very hot,
like venus.

And if we would
have been farther out,

It would have been much cooler,

And we could have turned
into mars.

But as it is, we're in just
the right spot from the sun.

We're at the sweet spot

Where we can have liquid water
on the surface

And keep it there
for billions of years.

Narrator: But where did
earth's oceans come from?

♪

Comets carry a hidden payload.

Under the dark,
baked-on crust...

...They are crammed with
dust and rocks.

But much of their core
is frozen water.

Comets can carry
hundreds of billions of gallons

Of this vital liquid.

♪

But did they bring water
to earth's oceans?

To help solve this
4 1/2-billion-year-old mystery,

Scientists first need to find
water created

During the violent birth
of our planet.

♪

Geologist lydia hallis
has special permission to hunt

For this ancient liquid on
the volcanic island of staffa.

♪

We've got the columns of basalt
that rise out of the ocean.

And inside this basalt,
there's trapped water,

Hidden water in the rock.

Narrator: The rocks captured
this water as our planet formed.

Some of it is still
sealed inside.

This is just a piece of basalt

That's fallen
from these cliffs up there.

Let's see if we can
break it open.

Inside, there are tiny crystals
that look sparkly,

And that's what we're interested
in analyzing in the laboratory.

Narrator:
Lydia examines the rock samples

Under a powerful
electron microscope

To pinpoint the ancient water.

Here's the electron image
of the basalt sample.

What I'm looking for
in this sample

Are these darker regions
in the image.

Narrator: Lydia extracts water
from these areas

And checks
its chemical signature,

A molecular label that
reveals the water's origin.

If this water is the source
of earth's oceans,

Their chemical signatures
should match.

Hallis:
What we're finding is that

The chemical signature
of this water

Is different
from that of the ocean's.

♪

Narrator:
But telescopes have analyzed

The chemical signature of water
in passing comets.

This may solve lydia's puzzle.

Hallis: If we mix
the chemical signature

Of this water that was trapped
when the earth was born

With a chemical signature
of the water inside comets,

It matches that
of the earth's oceans.

So comets must have made
some contribution

To the earth's oceans.

♪

Narrator:
Nearly 4 billion years ago

In a period called
the late heavy bombardment...

...A barrage of comets
hit our planet.

They exploded on the surface
and released their watery cargo

In huge plumes of vapor.

♪

This created a layer
of thunderclouds

That made it rain
for millions of years.

♪

The water from the comets
mixed with the water

Already on the earth,

And together,

They made the earth
the blue planet it is today.

Recent findings
bring this model into question,

But if comets did deliver water
to the earth,

Could they have done
the same thing elsewhere?

There's evidence on mercury.

Airless and sun-blasted,
it's the last spot

In the solar system
you'd expect to find water,

But some places
at mercury's poles

Are forever locked in shadow.

Craters that could be comet
impacts riddle these areas...

...And deep inside them,
a layer of dark dust...

...Conceals hundreds of billions
of tons of frozen water.

♪

Comets may be part

Of the universe's
water delivery service.

But could they carry
an even more precious cargo?

Did comets seed life on earth?

♪

♪

Narrator: Comets --

Dirty snowballs
made from rock and ice.

When they collided
with the ancient earth,

Comets may have helped
form our oceans.

But could they have delivered
something else to our planet?

Are comets also
the bringers of life?

As far as we can tell,
the early earth was mostly

A hot, dead rock,
and yet here we are,

This wonderful,
rich environment of life.

Well, where did that come from?

What actually brought
the building blocks of life

To the earth?

Narrator:
The answer lies hidden deep

Under a comet's
glistening shroud.

♪

The comet's core contains
a cosmic chemistry set...

...Frozen ammonia, methane,
and carbon dioxide...

...Molecules that can combine
to form amino acids,

The building blocks of life.

♪

But could amino acids
really form on a comet

Hurtling through
the cold vacuum of space?

♪

♪

Nasa scientists are trying
to answer this question.

Scott sanford is building
an artificial comet.

Sanford: On a comet, we would
be taking very simple things,

Like water, methanol,
carbon dioxide.

But we can mix them
in the proportions

We think are actually in comets.

So one of the things we're
obviously interested in knowing

Is amino acids, which we know
are critical for life on earth,

Are these made
under these conditions?

Narrator:
Scott mixes the gases

And recreates
the environment of deep space.

Sanford: Well, if we're gonna
simulate a comet,

We want very low temperature
and we want to be in a vacuum.

So that's what this device
does for us,

And this device here
is a cryocooler,

Which is cooling our samples
down to a temperature

Right now of about 16 kelvin.

So that's minus 430 fahrenheit.

No one is allowed to put
their tongue on this.

Narrator:
Scott sprays the mixed gases

Onto a revolving piece
of metal foil,

And then adds
one final ingredient --

Ultraviolet radiation
that mimics sunlight.

But this radiation
provides energy

That triggers
chemical reactions,

And these reactions
could produce amino acids.

So here we have data taken
from our experiments.

Each one of these peaks

Represents
one or more compounds,

New chemicals we made
in our experiment.

Amongst all the other things
we made

In our cometary simulation,
we made amino acids.

Narrator: This experiment shows
that the building blocks of life

Can form in the extreme
conditions of deep space...

...And comets are good
at delivering payloads to earth.

♪

These impacts may have been
a key stage

In the formation of life

By fusing amino acids
together to form proteins.

These complex molecules
can survive that collision.

And not only that,

Simple organic molecules
can be cooked

Into even more
complex molecules.

So comets can bring the seeds
and the fertilizer of life

To spread across a planet.

Narrator: There are trillions
of comets in our solar system.

If each of these had the ability
to seed a planet,

Then maybe we're not alone.

If life here is
somehow related to comets

Bringing these wonderful,
rich organics here,

It very well may have happened

Elsewhere in the solar system
as well.

Narrator: Comets might
be seeding life

All over the cosmos.

♪

60 light-years away
from the sun...

...Far beyond the kuiper belt
and the oort cloud...

...Astronomers have spotted
a huge band of comet dust

Wrapped around a younger star
called eta corvi.

♪

The dust could be evidence
that comets are raining down

On the planets
orbiting this star.

♪

They might be seeding life
on this alien world

At this very moment.

♪

But what if comets could spread

More than the building blocks
of life across the cosmos?

What if they could also deliver
living organisms?

♪

♪

Narrator:
Life, as far as we know it,

Only exists in one place --

Earth.

But what if life came here
from elsewhere?

What if comets brought organisms
from outer space.

Oluseyi: One huge unanswered
question that we have is,

How did life on earth originate?

And one idea
is what we call panspermia,

And that is the idea
that life came to earth

Via some space rock or a comet.

Narrator:
According to panspermia,

Primitive organisms survive deep
inside the comet's nucleus...

...With a dark crust
and thick ice protecting them

From the harsh conditions
of outer space,

But could these fragile life
forms really survive

A massive collision
with a planet?

♪

In England, scientists are
about to find out.

It's an exciting question,

And if you don't study
the exciting questions,

What are you doing?

Narrator: Mark burchell
uses a giant gun

To simulate comet impacts.

He works with plankton,

A form of life that has existed
for billions of years on earth.

So we're taking a solution of it

And loading it
into our projectile

As if it were a comet
which has been seeded with life.

We then place it in our gun,

Ready to fire at our ocean.

Narrator: Mark's ocean
is a bag of sterile water,

A liquid that contains
no trace of life.

Right?

Narrator:
And this is no ordinary gun.

Compressed gas accelerates
the projectile

To over 14,000 miles per hour.

♪

♪

That was the gun firing,

And now we hopefully have
a successful shot.

Narrator: Could anything survive
this immense collision?

The water is what
we're interested in.

Mark cultures the water,
and 3 days later,

The change is dramatic.

Life has more than survived.

It has flourished.

Most of what we fire will die,

But about 1 in 100,000
will survive.

And that doesn't sound a lot,

But that's all you need
here on earth

To seed an ocean
with life from space.

Narrator: Mark's research
suggests that life could survive

The massive forces of
a comet impact.

And it raises a vital question.

If life didn't begin on earth,
where did it come from?

There's this wonderful push
to try to find life

Outside the earth,
to try to find alien life.

Well, the amazing thing is,
maybe all you need to do

Is look in the mirror.

The building blocks of life
did not start here.

They came from somewhere else.

So the aliens are us.

Narrator:
Our understanding of comets

Has changed dramatically
over the past 20 years.

♪

Comets wreak havoc when
they collide with planets.

♪

But these impacts
also bring ingredients

Vital to the formation of life.

Comets can bring life
to a planet.

They can bring water to
a planet.

But also, they can destroy life
on a planet.

They were omens
to ancient people.

They were omens of good
and they were omens of bad.

And now, in modern science,

We're finding that this is
absolutely correct.

Narrator: Comets are fleeting
visitors from deep space...

♪

...Traveling time capsules from
the dawn of the solar system.

Without comets, our world
might be very different --

Earth may not be the blue planet
we see today...

...And humans
might not even exist.

♪