All language subtitles for Discovering.The.Cosmos.S01E03_English

♪

NARRATOR: Planet Earth.

Our home.

We are part of an astounding
interdependent ecosystem

coating its surface,

containing a dizzying
variety of animals and plants.

Life is amazing.

But it seems incredible
that life exists at all.

Extreme forces
dominate the cosmos.

[explosion]

It could not appear more hostile

to the existence and
survival of fragile organisms.

Planet Earth has long
seemed a unique oasis

in a violent barren universe.

But groundbreaking science
is now challenging this view.

DR. DRAKE: How, when and where

life might have
arisen in the universe,

it's probably the
most important questions

that modern science
can hope to address.

NARRATOR:
Scientists are revealing

the incredible
alchemy of starlight.

DR. SANDFORD: The
UV photons can come in

and break a molecule in half.

NARRATOR: They are
uncovering explosive secrets

about the origins
of life on Earth.

DR. SUTHERLAND: We
were literally gobsmacked

at the results we got.

NARRATOR: And they are detecting
telltale traces of life

on other planets.

DR. MCKAY: That's
big, that's huge.

I don't see why life
wouldn't have started on Mars.

NARRATOR: And as new technology

brings the skies above
into ever-sharper focus,

the conclusions
are mind-blowing.

DR. BATALHA: When I go out
at night and look at the sky,

I don't see those
pinpoints of lights as stars.

I see them as planetary systems.

NARRATOR: Many scientists
now believe we are not alone.

DR. MCKAY: Earth, and
life on Earth, is not unique.

All the clues are
pointing in that direction.

[birdsong]

♪

NARRATOR: Life is astounding.

Inside every cell of
every plant and every creature

lies a
staggeringly complex world

sustained by
intricate organic molecules.

DR. MCKAY: The
simplest cell on Earth

is the most complicated
thing we can imagine.

All sorts of molecular machines
working together, processing

information, processing
matter, processing energy,

all to ensure the
survival and the reproduction

of this little, tiny organism.

NARRATOR: How such
complex structures ever came

into existence has long been one
of Earth's greatest mysteries.

But 21st century science

has started to look
beyond our planet for answers

and come to some
incredible conclusions.

DR. DRAKE: The rest of the
universe is actually central

to the whole question of
the origin and evolution

of life on Earth.

Without the rest of the
universe, we wouldn't be here.

NARRATOR: It starts with the
universe's building blocks --

atoms.

All giant organic molecules,
like DNA, contain countless

atoms in intricate formations,
mostly the big four --

hydrogen, oxygen,
carbon and nitrogen --

with a sprinkling
of heavier elements.

But where do the
atoms originate?

And how did they come
to form these structures?

It turns out that to
uncover the secrets of life

we must track the
evolution of the cosmos itself.

13.8 billion years ago,

the universe
begins with the Big Bang.

Within a second it cools
enough for particles to form.

And within a few
hundred thousand years

these particles combine, forming
the first simple atoms --

hydrogen and helium.

These ancient atoms are
the foundations of everything.

At this early stage of
the universe's evolution,

the ingredients do not yet exist

to make even the most
basic molecules of life.

And as space expands,
these atoms are in danger

of dissipating into the void.

But already they feel
the force of gravity.

Under its influence,

everything that
matters will come together.

DR. BATALHA: Gravity
is a fundamental driver

for the creation of
structure in the universe.

The universe was a
relatively uniform volume

of hydrogen and helium
that was rapidly cooling

because of the expansion.

But the devil's in the details.

There were regions that
were slightly over-dense.

And where you had
those over-dense regions,

gravity was able
to kick in and create

even more over-dense regions

that led to all the
structuring complexity

that we observe in the
visible universe today.

NARRATOR: Over a few
hundred thousand years,

gravity creates
spiraling regions so dense

their temperatures
begin to rapidly increase.

The swirling
gases form huge discs

far larger than
our solar system.

Temperatures in their centers
surpass 100 million degrees.

And suddenly the
first stars are born.

From this moment on, primordial
stars appear in the billions

and cast the first
light on the universe.

But they will also transform it.

Through a quirk of nature,

stars will generate all
the raw materials of life.

DR. BATALHA:
Stars are interesting.

They behave in interesting ways,

but they're actually
quite simple structurally.

It's a ball of plasma that's
balanced by gravity pushing in

and gas pressure pushing out.

♪

NARRATOR: Stars
stave off collapse

through the power
of nuclear fusion.

Simply put, extreme
gravitational pressure in

the core forces hydrogen atoms
to fuse into heavier helium,

releasing tremendous energy.

DR. DRAKE: The starlight
that we see essentially comes

from Einstein's
famous equation -- E=mc2.

Well, the mass of the
products of that nuclear fusion

is a little bit
less than the mass

of the products
that went into it.

And so we have a
little bit of mass left over.

And this leftover mass
can be converted into energy.

NARRATOR: The energy
keeps the star from collapsing,

allowing fusion to continue.

This process now creates all the
missing ingredients of life.

DR. DRAKE: Stars are essentially
the cauldrons of the universe

where the elements are made.

♪

NARRATOR: Inside the
helium cores of massive stars,

totally new
elements are now forged.

For the first
time, huge quantities

of oxygen, carbon and nitrogen
are fused into existence.

DR. BATALHA: Lo and behold,
that's exactly the stuff

that our own human
bodies are made out of.

We are literally
made of star stuff.

NARRATOR: The most massive
stars continue to create

heavier and heavier elements.

But fusion engines
don't last forever,

and all stars come to an end.

The biggest with a bang.

DR. BATALHA: Because you
don't have any more energy,

there's nothing
to support the star.

It's gonna
collapse and then detonate.

[explosion]

NARRATOR: 13 billion years ago,

the death of the first
generation of massive stars

spreads new atomic
elements into the void.

The universe reaches
a crucial threshold.

For the first time it
contains everything necessary

for life to form.

Ancient hydrogen
has now been joined

by huge quantities of
oxygen, carbon and nitrogen,

alongside trace amounts
of the heavier elements.

And astronomers have discovered
that almost immediately

they start along
the path to life.

DR. OÖBERG: After you had
this first generation of stars,

you enter into a universe
that's full of chemistry.

You have suddenly
a chemical universe

which you did not have before.

NARRATOR: By analyzing the light

reflected by
interstellar dust clouds,

astrochemists can
determine their composition.

Over the decades,
as their observations

became more precise, they
made an astonishing discovery.

The universe is
filled with water.

DR. OÖBERG: Water, this
really important molecule

here on Earth, is one of the
most abundant molecules

that we find in space.

NARRATOR: In the
immensity of the void,

individual atoms
rarely interact.

But the dust grains
of heavier elements,

formed from the
debris of exploded stars,

turn out to be a form
of galactic flypaper.

DR. OÖBERG: We had realized
that where these molecules form

is on the surfaces of
these tiny, little dust grains.

These are little
interstellar catalysts.

NARRATOR: Given the opportunity,
oxygen bonds with hydrogen.

These two most
abundant reactive elements

form huge amounts of water.

Carbon and nitrogen
join them, and simple gases,

including ammonia and
methane, are added to the mix.

The dust cloud
chemistry appears unremarkable.

But new discoveries
suggest it is the basis

of everything biological.

Because in the heart of
these clouds, gravity ensures

that a second generation
of stars is taking shape.

The first
generation made the elements.

The second will kick-start
the chemistry of Life.

♪

NARRATOR: Ten billion years ago,

a second generation
of stars began forming

in the hearts of
element-rich dust clouds.

Today, experiments
reveal their presence

may have coated
the surrounding dust

with the
building blocks of life.

[radio chatter]

In cutting-edge facilities,
astrochemists are recreating

the extreme
conditions of outer space.

Dr. Scott Sandford leads a team

at NASA Ames
Research Laboratory.

DR. SANDFORD: We're trying
to make a little piece of space

right here in the laboratory
so we can study what happens

in those kinds of environments.

At the South Pole in
the middle of the winter

I think you get
down to temperatures

that are something like minus
60 or 70 degrees centigrade

or something.

We're like 200
degrees below that.

And ten degrees
above absolute zero.

NARRATOR:
Sandford's ice cold experiment

is designed to shed
light on a mystery --

how simple molecules in
space became more complex.

Because
astrochemists have discovered

the universe's
second generation of stars

kick-started chemistry.

Stars generate visible light
but also ultraviolet light,

at the high end of the
electromagnetic spectrum.

DR. DRAKE: The ultraviolet light

is essentially
like visible light

except it's more energetic.

It can do things that
visible light can't do.

NARRATOR: Sandford and his
team create their own UV light,

which they focus onto a
super-cooled film of molecules,

simulating the surface of dusty
grains found in outer space.

They have
discovered that the UV light

creates a chaotic
burst of chemical activity.

DR. SANDFORD: The UV
photons can have enough energy

that can come in and
break a molecule in half.

♪

NARRATOR:
Bombarded by the UV rays,

the simple molecules
split into reactive fragments

that recombine into
more complex structures.

Because by chance,
the abundant carbon atoms

want to form multiple bonds.

DR. MCKAY:
Carbon naturally forms

more and more complex molecules.

It naturally brings in
nitrogen and oxygen atoms.

So carbon is the master chemist.

NARRATOR: Carbon-based molecules
form the basis of all biology.

And in recent decades
astronomers have detected traces

of crucial biological
molecules known as amino acids

in the dust and
debris of outer space.

But they could be just
the tip of the iceberg.

Sandford's
simulations have produced

an incredible array
of organic molecules

including those
found in DNA itself.

With these
simple building blocks

all of life can be constructed.

DR. MCKAY: Think
of like a Lego kit,

little tiny blocks
that kids play with,

and you stack them together.

That's what biology does
-- makes wonderful structures

out of the simplest blocks.

NARRATOR: Evidence
that life's building blocks

may be
commonplace in the universe

has led a new
generation of scientists

to question the
uniqueness of life on Earth.

DR. SANDFORD: The universe
seems to be sort of hardwired

to produce abundant amounts

of very complex
organic molecules.

DR. OÖBERG: It really
does seem like the universe

is set up to
produce a rich chemistry,

to produce the kind
of organic molecules

that we think are
so important for life.

NARRATOR: But the hostile
environment of outer space

is no place to stick the
building blocks together.

♪

DR. OÖBERG: Starlight
is absolutely fundamental

to create chemical complexity.

But it's really a
double-edged sword.

So it can promote both
creation of molecules,

but it can also destroy them.

NARRATOR: The high-energy
radiation emitted by stars

continually devastates the
very molecules it helped form.

The irradiated
environment of space

is too unstable for the
chemistry of life to continue.

But beginning 10
billion years ago,

as clouds settled
around newborn stars,

out of the swirling dust new
sanctuaries would start to form.

♪

NARRATOR: Powerful
telescopes are transforming

our knowledge of
young star systems.

DR. OÖBERG: We have a
new set of eyes in the sky.

We have the ALMA
telescope down in Chile,

which is this amazing
array of 66 telescopes

that's working in unison.

NARRATOR: The ALMA
array has a magnification

ten times that of
previous telescopes.

Its extraordinary definition

allows us to witness
how young star systems

evolve over time.

One such young
star is TW Hydrae,

lying 175 light
years away from Earth.

ALMA's power means
we can actually see

the star's disc of dust

and how it is marked
by circular grooves.

Astronomers believe they
know what generates them.

From the moment a disc forms,

dust grains are aggregating
into larger particles,

which gravity draws together.

In a few million years
some massive accretions

of dust and ice absorb
everything in their orbits,

clearing paths through the dust.

We call them planets.

In the cold outer zone of the
disc, gas and ice giants form.

Like Jupiter and
Saturn in our solar system,

their cores are
molded from icy dust,

and they are smothered
in the hydrogen and helium

they draw in from
the surrounding disc.

They are hostile places.

But closer to the hot star,

where its rays
have cooked the dust

and blown away
the surrounding gas,

another type of planet can
form from the remaining debris.

We call them rocky planets.

Freed from the
smothering gases of the disc,

rocky planets can form
their own atmospheres.

From gases leached
from their own rocks.

They can let heat
down to the surface

but protect it from the
worst of stellar radiation.

And if they are just the
right distance from their star,

something special can happen.

[thunder]

Water can become liquid.

By chance, the universe has
created the perfect environment

for a more gentle
chemistry to take place.

DR. MCKAY: From the
biological perspective,

why planets are
so useful is because

they allow water
to become liquid.

It really is that simple.

Planets allow for liquid water.

Liquid water allows for life.

NARRATOR: But mysteries remain.

How could oceans of
water reach the surface?

And how could
chemistry become biology?

[thunder]

NARRATOR: Four
billion years ago,

our solar system
was in its infancy.

But something was happening on a
rocky planet close to the sun.

The Earth was
becoming a water world.

This crucial change
would make the planet

a rare sanctuary for life.

DR. OÖBERG: Liquid water is
absolutely crucial for life.

It is amazing the number
of elements and molecules

that can become
dissolved and therefore react

to form more complex molecules.

NARRATOR: The
Earth's orbit lies in

what scientists refer to
as "The Goldilocks Zone,"

a distance from our sun where
the temperature is just right

for liquid water to
pool on the surface.

But there is a mystery.

Some believe Goldilocks planets

should lack the resources
to fill their own oceans.

DR. OÖBERG: The problem with
forming in the Goldilocks Zone

is that you're
forming too close to the star

to form from icy grains.

And that means
that you form dry.

We see an Earth that has large
amounts of water on the surface.

So the question is where
did all that water come from?

NARRATOR: The answer
may lie in the heavens.

Then, as now, the
solar system was filled

with asteroids and comets,
formed alongside the planets

from the same
icy grains of dust.

But it's believed that
four billion years ago

the solar system was unstable.

Some gas giants
migrated in their orbits,

the
gravitational pull disturbing

millions of these projectiles,

hurling some towards the Earth.

These icy rocks
could have delivered

more than enough
water to fill the oceans.

DR. OÖBERG: Having
an early instability

in your planetary system

and planets moving
around stirring things up

might be very important

to deliver water to
otherwise dry, rocky planets.

And I think from a
chemistry point of view,

what's really
interesting about that

is that the water
did not come alone.

NARRATOR: Buried in their
ice were organic molecules,

the building blocks of life.

When organic molecules
encountered liquid water,

miracles could happen.

♪

NARRATOR: High in the mountains
of Chile lies El Tatio,

a volcanic geyser field.

Dr. Maria Eugenia Farias is an
expert in this unique ecosystem.

DR. FARIAS: Tatio
is a beautiful place,

but also it is
like a time machine.

This is a very important place

to study the
early Earth conditions.

Because here we are over 4,000
meters over the sea level.

Here there is a
lot of UV radiation

and we have these geysers

produced because
of volcanic activity.

Those are similar
conditions to the early Earth.

♪

NARRATOR: Four billion years ago

the surface of the young Earth

was alive with
volcanic activity.

Organic molecules of carbon,
hydrogen, nitrogen and oxygen

mix with traces of phosphorus,
sulphur and other minerals

bled from the hot rocks.

This inhospitable
cocktail of chemistry

is ready to
transform the universe.

DR. FARIAS: In places like
this, chemistry became biology.

NARRATOR: But just how it
happened remains a mystery.

DR. MCKAY: We understand
life from biology looking down.

And we understand life
from chemistry looking up.

But we haven't yet got
those two ends to meet.

There's still a
gap in the middle

called "the origin of life."

NARRATOR: Cambridge, England.

♪

In the laboratories of
the Medical Research Council,

Dr. John Sutherland leads a team

dedicated to closing that gap.

DR. SUTHERLAND: Life
must come from chemistry.

It must be possible to
produce life from chemistry.

And we should be able
to recreate that process

in a laboratory.

NARRATOR:
Scientists like Dr. Sutherland

believe that the secret to the
origin of life and its evolution

lies with a
certain fragile, flexible,

self-replicating molecule called
ribonucleic acid, or RNA.

DR. SUTHERLAND: DNA bears
all the hallmarks of being

the product of evolution,
its ancestor being RNA.

And RNA looks to us like
the product of chemistry.

NARRATOR: The large RNA molecule
naturally self-assembles

from much
simpler molecular rungs.

But for years, Sutherland's
team has tried to determine

how an ancient
prebiotic chemical soup could

naturally generate RNA rungs
from even simpler molecules.

Finding the correct balance
of chemical ingredients,

temperatures and
radiation levels

remains a challenge.

But Sutherland believes that at
the heart of the key reactions

lies one
molecule, hydrogen cyanide.

DR. SUTHERLAND:
Hydrogen cyanide has certain

chemical properties
which are highly conducive

to produce more
complex structures.

NARRATOR: The problem is that
to form enough hydrogen cyanide

requires a huge burst of energy,

equivalent to an
endless lightening storm.

This has long been
thought unrealistic.

But the team has
recently discovered the answer

may lie beyond the clouds,

in another gift
from outer space.

♪

NARRATOR: In their search for
the origins of life on Earth,

some scientists now believe

vital chemical
reactions on the surface

may have been
triggered by meteor strikes

that were common events
four billion years ago.

[explosion]

New experiments
have demonstrated

that when the largest
meteors vaporize on impact,

the incredible
temperatures generate

a high-energy chemistry,

creating huge quantities
of a key reactive molecule,

hydrogen cyanide.

At the same time,
the impact crater

forms the perfect hydrothermal
volcanic environment

for organic chemistry.

♪

When John
Sutherland's team in England

recently simulated
this chemical scenario,

the ingredients
spontaneously produced

many key molecules they
had been struggling to form.

DR. SUTHERLAND: We
were literally gobsmacked

at the results we got.

It could be that life starts

as a result of
really aggressive events

taking place in the
early solar system history.

These incessant impacts
were actually giving rise

to a very, very
interesting chemistry

that would ultimately give rise

to the molecules required
for life and life itself.

NARRATOR: It looked like they
might have hit upon the process

that had generated
the first RNA molecules.

The evidence is compelling,
but the proof remains elusive.

What we do know is
that at some stage

between 4 billion and
3.5 five billion years ago,

single-celled organisms,
the simplest form of life,

evolved from the chemical
soup and gained a foothold.

Successive generations became

increasingly
robust and adaptive.

The volcanic
streams at El Tatio are

some of the most inhospitable
environments on the planet.

But even here these simple
forms of life can thrive.

DR. FARIAS: I love
bacteria; they are amazing.

They are so simple, and
this is their main advantage.

Because if you are
simple you can adapt quickly

and you can live in
these extreme environments.

You can see yellow, green, pink.

All are surviving at high
temperature, high UV radiation.

And in fact they
are making stones.

Just in the same way they
did 3.5 billions of years ago.

NARRATOR: Over time,
the mineral excretions

from mats of bacteria

can form distinctive stony
structures -- stromatolites.

3.7-billion-year-old
fossilized stromatolites

are the earliest
records of life on Earth.

But microbe-made structures

may also have left a
record of life on Mars.

♪

For over a decade
NASA's Mars rovers

have been
exploring the Red Planet.

New observations have
noted remarkable similarities

between El Tatio's
geyser field stromatolites

and rock formations photographed
by the Mars Spirit Rover.

These appear to support the idea
that four billion years ago

there were two living
planets in our solar system.

DR. MCKAY: I don't see why life
wouldn't have started on Mars.

Early Earth, early
Mars are very similar.

And they're
similar during the time

when we know life
first appears on Earth.

The most
important feature of Earth

is that it has liquid water.

The most clear
evidence we have of early Mars

is that it had liquid water.

So whatever you
fancy is necessary

for the origin of life on Earth,

Mars would have had
the same environments.

NARRATOR: But today,
Mars is cold and dry.

Water predominantly
exists in the poles as ice.

So what happened to her oceans?

A clue lies in her atmosphere.

It's 100 times
thinner than that of Earth.

DR. MCKAY: The thickness of the
atmosphere is like a switch.

If it falls
below a certain level,

water will not stay as
liquid. It will just boil.

NARRATOR: Something destroyed
the atmosphere of Mars.

Many believe the
culprit was the sun.

Alongside light
and heat, our star

radiates invisible waves of
sub-atomic charged particles

capable of immense destruction.

We call this the solar wind.

DR. DRAKE: The
solar wind is essentially

the very outer
atmosphere of the sun

that's just flung out into space

with energy generated
from magnetic fields.

It is going from
500 kilometers a second

to 1,000 kilometers a second.

When it impacts a planet,

that's gonna have
some erosion power

on the planetary atmosphere.

NARRATOR: Four
billion years ago,

even as Mars's
oceans were taking hold,

the particles of the solar wind

were smashing into the
gasses of her atmosphere.

Over half a billion
years they scoured it away.

And the planet's
oceans evaporated into space.

This poses a big question.

How did life on Earth survive?

NARRATOR: Like all
stars in the universe

our sun continually sprays out

a stellar wind of
charged particles.

Billions of years ago
its constant scouring

destroyed the
atmosphere of Mars,

ending any chance of life
developing on its surface.

Which poses the question,

how did life on Earth
survive its onslaught?

♪

The island of Svalbard,
high in the Arctic Circle.

Dr. Lisa Baddeley is
heading to the office.

DR. BADDELEY: We are
about 1,000 kilometers south

of the North Pole.

It can get quite
difficult sometimes

when it's minus 40 degrees.

And then sometimes you
can get a complete white-out.

So I have to rely
completely on the GPS unit.

NARRATOR: Lisa
braves the conditions

because this is
the best location

to study a unique spectacle

visible from just a
few points on Earth.

DR. BADDELEY: And here we are.

NARRATOR: She's
here to witness a battle

between our planet and our star.

DR. BADDELEY: Well,
you may notice that

we've got the domes and the
cameras all pointing upwards.

So we're here to study
a very unique phenomenon

that we see in the sky overhead.

NARRATOR: In the high atmosphere
above, the conflict plays out

24 hours a day, 365 days a year.

The core of the
Earth is molten iron.

As the core rotates,

it generates a
powerful magnetic field.

This creates a
protective bubble,

diverting the charged
particles of the solar wind

away from the atmosphere.

The battle is continuous.

But the protective effect
is weakest near the poles,

and some particles shoot through

to impact atoms
in the atmosphere,

creating one of the
greatest shows on Earth.

The aurora borealis.

DR. BADDELEY: When
the whole sky is lit up

green and red and dancing,

you can stay out there
for hours without realizing.

It's an amazing thing to see.

You can see how dynamic it is.

And you can also
see little paths.

And that is actually the
Earth's magnetic field lines.

And these particles

are traveling down
these magnetic field lines

and into the atmosphere.

NARRATOR: What they hit
and what energy they have

determines the color
of the light produced.

It's beautiful,
but scientists believe

that an aurora
all over the planet

would eventually bring
an end to life on Earth.

Mars's dramatic decline

shows just how
vital this shield can be.

DR. MCKAY: Early in its history
Mars did have a magnetic field.

We know that from observations
on the ground and from orbit.

It was protected, then
it lost its protection.

NARRATOR: Many
believe that Mars' failure

to retain her watery environment
was the result of her size.

DR. MCKAY: Mars is ten times
less massive than the Earth;

it's a small guy.

As a result of
that, it cannot maintain

the active convective
molten core that Earth has.

All of Mars's
troubles really trace back

to the fact that it's too small.

DR. DRAKE: The example of
Mars is very instructive.

So life-sustaining
environments on planets

are not necessarily forever;

they're not necessarily
for billions of years.

They may only last a
few hundred million years.

Life on certain planets could
be a very transient phenomenon.

♪

NARRATOR: But if a
planet does stay stable,

the life it nurtures can
transform its environment,

which is useful.

Because initially life
was forced to stay small.

DR. MCKAY: When we
talk about life on Earth,

we usually mean trees
and animals and birds

and the things that we can see.

But, in fact,
that's just minor detail.

Life on Earth is microorganisms.

NARRATOR: For
nearly three billion years

single-celled microorganisms
were the only life on Earth.

They stayed simple because
they lacked a source of energy

that would allow them to
grow more structurally complex.

But by chance, a
species of bacteria evolved

that would change the game.

Its descendants still populate

the lakes of the
Atacama Desert in Chile.

DR. FARIAS: This mat,
it's made of bacterias.

Each layer has a color

and it means a
different bacterial community.

If we keep on taking away
we will find this green layer.

NARRATOR: These
are cyanobacteria.

As a byproduct of their
life cycle they produce oxygen.

DR. FARIAS: You can see
here these bubbles are oxygen.

NARRATOR: 2.5 billion years ago,

the cyanobacteria
became so abundant

they began to fill
the air with oxygen.

The Great Oxygenation Event
had profound consequences.

Free oxygen would
be the energy supply

that allowed life to grow

into complex
multicellular organisms.

♪

With access to oxygen

life went from building rocks

to building skyscrapers.

DR. MCKAY: We wouldn't be here

if those little
green microorganisms

hadn't produced
all this pollution

and contaminated the planet
irreversibly with oxygen.

We now rely on it.

We call it fresh air.

NARRATOR: Mankind
has come a long way.

But ever since
we first looked up

we have searched for signs in
the stars that we are not alone.

Now, 21st century technology
allows us to take that search

to the next level.

The quest for life in our
solar system has already begun.

Today, probes scour Mars.

And soon, NASA may
send others further.

DR. OÖBERG: There
are a couple of moons

in the outer solar system

that have liquid water
and they have organics.

And I see no reason why they
shouldn't have life on them

if that is all that is
needed for life to originate.

DR. MCKAY:
Enceladus in particular,

moon of Saturn with a geyser of
organic-rich water coming out,

we can just fly through it and
search for evidence of life.

I wanna do that.

We're gonna look for
the molecular skyscrapers.

These molecules of
design that are built by life

and that will be preserved even
after the organisms are dead.

We'll find them in
the soils on Mars,

we'll find them in
the ice in Europa,

we'll find them in
the plume of Enceladus.

And they will tell us
that there was life here.

[rocket engines roar]

NARRATOR: But if it
turns out that life

requires a planet like
our own with surface water,

we need to look further afield.

The Kepler Space
Telescope was launched in 2009.

It aimed to determine if any
planets orbited nearby stars.

Incredibly, it detected them
almost everywhere it looked.

We now believe
that in our galaxy,

one in five stars hosts a
potentially habitable planet.

DR. BATALHA: The
field of exoplanet research

has transformed completely.

When I go out at
night and look at the sky,

I don't see those
pinpoints of lights as stars,

I see them as planetary systems.

Kepler has fundamentally changed

the way I perceive the universe.

NARRATOR: The
challenge in the coming decades

is to discover signs of
life on these alien worlds.

A new generation of ground-
and space-based telescopes

is set to transform the search.

DR. OÖBERG: The next big
exciting telescope to come along

is the James Webb
Space Telescope, or JWST.

This telescope will be able
to look very close to the star

and really see what
the chemistry looks like

right where rocky
planets are forming.

NARRATOR: On Earth, one of
the most ambitious projects

is the Giant Magellan Telescope.

DR. DRAKE: The
Giant Magellan Telescope

should be able to look at the
atmospheres of nearby planets.

And this is
crucial for searching

both for signs of life,
for signs of oxygenation

that we think is
the signpost for life,

but also to determine whether
planets are actually habitable.

NARRATOR: Breakthroughs
in many fields of science

mean there is new
confidence in the quest

for extraterrestrial life.

DR. DRAKE: The fact
that we're now finding

planets around most stars

and the fact that we're now
seeing that chemical processes

that build up
organic molecules in space

seem to be quite common,

all this seems to be
pointing toward the direction

that life is maybe much
more common in the universe

than we may have
previously thought.

DR. MCKAY: Earth and
life on Earth is not unique.

All the clues are
pointing in that direction.

DR. OÖBERG: If
all that's needed is

a rocky planet and
water and organics,

life should be
abundant in the universe.