Original subtitles

Strangers from afar.

Where might these come from?

These aliens.

This sculpture studio makes models of aliens

for the movies.

The creatures crafted here have appeared

in over 20 Hollywood films.

But extraterrestrial life isn't something

that just exists in the movies.

I think it is, without doubt in my mind,

that life has originated elsewhere.

Whole rest of me is screaming

that the universe is probably teeming with life.

Surely life exists in environments

completely different from Earth's.

As space exploration proceeds,

scientists are growing more confident

as to how they envision alien life.

But what makes these scientists so sure

that life does in fact exist in outer space?

The answer must be sought on the cosmic front.

Is our existence in this universe

an isolated phenomenon?

Or is space, in fact, teeming with life?

For answers, scientists are placing great hopes

on one of the moons of a planet far, far away.

More than a billion kilometers from Earth

lies the planet Saturn.

Hidden amidst its rings,

is a moon with good prospects of harboring life.

Here's a backlit view of Saturn.

Beyond its familiar set of rings

is an outer ring that is thinner and fainter.

The E Ring, discovered in 1967.

The blueish-white E Ring includes

one extremely significant body circling Saturn.

Enceladus, one of Saturn's many moons.

Diameter, 500 kilometers.

Its bright white color comes from ice.

Enceladus appears to be covered in it.

This image of Enceladus was taken

by the Voyager II spacecraft in the 1980s.

Seeing it, many scientists were astonished.

The moon's surface is remarkably smooth.

The elimination of craters in some areas

suggests massively transformative tectonic events.

Could it be that whatever is happening on Enceladus

has something to do with the E Ring?

As we shall see, the very human desire to solve this riddle

leads us to place great hopes on the existence

of extraterrestrial life.

And lift off of the Cassini spacecraft

on a 1,000,000,000 mile trek to Saturn.

The Cassini Saturn probe left Earth in 1997.

Its primary mission, to examine the relationship

between Enceladus and the E Ring.

Cassini's voyage to Saturn took seven years.

It reached the planet's vicinity in 2004.

A quarter century after the Voyager mission,

the mysteries of Enceladus are finally being addressed.

In the western American state of Colorado

is located the Cassini Imaging Labroratory.

Here is where the imaging data

collected by the Cassini probe are analyzed.

The leader of the imaging team is Carolyn Porco.

She says that starting with Cassini's very first image,

as it approached Enceladus,

she was filled with astonishment.

This was it.

Enceladus appears darkly in this backlit image.

Some might think the image anti-climactic,

but Porco deliberately chose this backlit mode.

Some suggestions were that there

might actually be geysers,

there might be little volcanic kind of geysers

coming off the surface of Enceladus,

spewing tiny ice particles into orbit around Saturn

and forming the E Ring.

We, in fact, had planned our sequences of images

to include observations where we're looking

in the direction of the sun,

so that if there was a plume of very tiny particles

we would be able to see it.

Here's an example of back-lighting

using a humidifier.

We create a fine mist, normally invisible.

But if we then shine a light on it from behind...

the mist becomes clearly visible.

This backlit effect was precisely what Porco had intended.

Let's return to that first Cassini image.

If we look closely at the south pole of Enceladus,

we see what Porco had been hoping to see,

a conspicuously bright portion.

A month later, a backlit Enceladus

was photographed once again.

In the same location,

one could clearly make out filaments of light,

a plume being sent from Enceladus into space.

Analysis of the images revealed

that this plume extended more than 100 kilometers.

What really, I think, made everybody

just stand back in awe,

was the magnitude of this phenomenon.

July 14th, Cassini began a major phase of research.

Reducing altitude to 168 kilometers,

it made detailed observations of the terrain

near the south pole of Enceladus.

The mysterious moon then displayed features

that even Porco had not anticipated.

A number of vertical blue streaks.

No craters at all, just this series of parallel fractures

stretching for 130 kilometers.

The anticipated volcanic topography was not present,

but it was equally clear that the area

had seen robust geological change.

It looks totally different, unique.

Not only did the imaging team

get this incredible look at this region

that no one had ever really seen before,

which is the south pole of Enceladus,

and not only did we find that it was geologically unique,

it was characterized by this set of fractures,

and was crater free, very bright.

The team called the blue streaks Tiger Stripes.

The tectonic activity across this area

was indicated also by the surface temperatures.

The average on Enceladus is minus 200 degrees Celsius.

But the Tiger Stripe showed a dramatic increase,

to minus 80 degrees Celsius.

Some researchers estimate

that the highest portions of that area

rise to minus 20 degrees.

Furthermore, the nature of the plume was revealed.

Analysis of the data showed it to be comprised

mainly of ice and water vapor.

Conclusive images were also recorded.

Clearly, what had looked like perhaps a single flare,

actually incorporated more than a dozen

individual jets or geysers.

Moreover, the jets were issuing

along the Tiger Stripe fractures.

And the material they released into space

has been forming one of Saturn's rings.

The blueish-white E Ring is thus a band of ice chunks,

formed by high-volume eruptions of ice from Enceladus.

I keep calling it

the Enceladus Interplanetary Geyser Park, you know?

That would be a great place,

that would be one of the sight-seeing,

top-10 sight-seeing locales in the solar system.

If we could actually land

on the Tiger Stripes, we would be able to see their jets

ejecting ice and vapor from the ice fissures

at fearsome speed, some 100 meters per second.

Rising as high as 100 kilometers,

they would present a thrilling spectacle.

And many scientists have begun to believe

that Enceladus must harbor life.

Why do they think so?

The Austrian Alps have an elevation exceeding 3,000 meters.

Near their summits lie glaciers.

One scientist thinks that this area

bears a striking resemblance

to the Tiger Stripes of Enceladus.

Richard Hoover is an astrobiologist with NASA.

This is a world of extreme cold,

minus 15 degrees Celsius, even in daytime.

An ice cave provides entry to the inside of a glacier.

Sunlight cannot reach into the ice cave.

This is a world of darkness, like Enceladus,

which exists so far from its sun.

10 minutes into the ice.

A huge space opens up.

Ah, it's incredible.

Fantastic.

Ah, this is absolutely magnificent.

This has been dubbed the Ice Palace.

Huge columns of ice.

Hoover posits that the Tiger Stripe area on Enceladus

must look like this.

The spectacular ice stalactites hanging down

from the surface and from the walls.

These kinds of formations may actually be occurring

in the Tiger Stripes of Enceladus also,

where the ice crystals are forming,

and then, under the gravitational field,

falling inward toward the center within the crevasses

of these magnificent Tiger Stripes.

One sees no plants here, no animals,

merely a world of extreme cold, a world of ice.

It might appear that no life

could exist in such an environment.

But Hoover thinks differently.

He extracts an ice core and carefully bags it.

The ice he brought back from the Ice Palace

is melted in its hermetically sealed bag, and then analyzed.

First step, microscopic examination.

Nice motility.

Wonderful.

Blinking right here, this is a bacteria swimming.

You see? Yeah.

Microorganisms living in a world of ice.

Here, too, nothing but ice it had seemed.

Yet there was life.

In his lab, Hoover preserves samples of ice

collected from around the world,

including the South Pole and Iceland.

He has found microorganisms in all of these samples.

This image conveys the fantastic capabilities

of these microbes.

The white images are microorganisms,

the black background is the water.

The membranes covering these creatures' cells

is made of material that protects them from freezing.

Rather than freezing themselves,

they melt the surrounding ice.

It has been confirmed

that there are certain forms of life capable of existing

in a minus 40 degree Celsius environment.

I believe it is very possible that there could be life

in the Tiger Stripes of Enceladus.

They're much hotter than what anyone believed possible,

and we now know that microorganisms

live in glacial ice all over the planet Earth,

therefore there could be microorganisms

alive and thriving in the Tiger Stripes of Enceladus.

Considering the sheer tenacity of life,

it could well exist on Enceladus, too.

Of that, Hoover is convinced.

Carolyn Porco, leader

of the Cassini Imaging Central Laboratory.

Porco believes that truly potent conditions for life

are present under the ice of the Tiger Stripes.

She thinks there's a large body of water there

in its liquid state.

Water, it's the reason there's life on Earth.

Across our globe, all sorts of lifeforms

use water in all sorts of ways.

Porco is convinced a huge amount of water

lies under the Tiger Stripes.

This was about 153.

Her conviction originated

during analysis of the Cassini images,

when she noticed something distinctive about the jets.

And that's why it's clear.

It's clear here, you can see the extent of it,

how big it is.

What we're seeing in these images of the jets,

those are tiny ice particles,

and we see so much of the solids,

compared to the vapor

that is detected by the other instruments,

that the most plausible way to get that

is from saying that the material

starts out as a liquid

and the liquid droplets eventually freeze

and become the particles that we see.

Measurements show the diameter

of the particles to be less than 1/100th of a millimeter.

If these geysers were shooting out

only broken-up bits of surface ice,

it is difficult to explain how so many particles

could become so small.

But if it was water that was gushing up,

freezing after the spray had become droplets,

then that would explain the large quantity of ice particles.

But Saturn, around which Enceladus revolves,

is one point four billion kilometers from the sun.

That's 10 times farther away than Earth.

That's why the surface temperature of Enceladus

averages minus 200 degrees Celsius.

Any water on it would freeze, becoming ice.

On this moon of ice,

how could a large body of water exist in a liquid state?

NASA's Jet Propulsion Laboratory, JPL,

is located in the suburbs of Los Angeles.

Inside is the control room for the Cassini space probe.

Today they are again instructing the probe,

1,000,000,000 kilometers away, near Saturn.

Recently, Cassini has uncovered facts

supporting the theory that liquid water

is present on Enceladus.

In October of 2008, Cassini drew very close to Enceladus

on a low-altitude flyby.

It was able to pass through the jets,

and to analyze their constituent matter minutely.

One thing detected in the jets was ammonia.

If ammonia is dissolved in water,

it permits the water to maintain its liquid state

even in temperatures as low as minus 97 degrees Celsius.

In other words, it functions like antifreeze.

But there is another factor

melting the ice on this frigid moon.

The movements of another of Saturn's moons, Dione.

Enceladus revolves around Saturn on an orbit

in-between Saturn and Dione.

Enceladus completes one orbit every 33 hours.

It takes Dione exactly twice as long,

66 hours, to complete its own circuit.

As a result, once every 66 hours,

Saturn, Enceladus, and Dione are all lined up.

Subjected to the gravitational pulls of both these bodies,

the spherical shape of Enceladus

is distorted into an ellipsoid.

Then, as the alignment breaks up,

Enceladus reverts to a sphere.

When this happens enough times,

the interior of Enceladus experiences

a build-up of frictional heat.

That melts some of the ice in the crust.

It turns into liquid water.

The hypothesis is that then,

as the surrounding ice fractures,

the water gushes out in jets.

May be a body of liquid under the surface of Enceladus,

so the jets are an indication to us actually

that we have on Enceladus

a place where life might have gotten started.

An ocean under the ice of Enceladus,

nurturing diverse forms of life.

That's the vision of another scientist as well.

Yasuhito Sekine is a scientist at the University of Tokyo.

He believes that the warm environment

of this ocean under the ice serves as a cradle of life.

Such gravitational distortions

have huge consequences.

Sekine believes that not just the icy crust,

but the underlying rock is affected as well,

producing frictional heat.

Actually, the kind of sea floor

envisaged by Sekine for Enceladus

has a close counterpart right here on Earth.

Here, the seabed is 1,500 meters below the surface.

Volcanic activity expels water

heated to 300 degrees Celsius.

These are called hydrothermal vents.

Here in a world of darkness

beyond the reach of the sun's rays,

hydrothermal energy nourishes a variety of lifeforms.

Sekine hypothesizes that Enceladus, too,

has an environment like this.

One that gives rise to a distinct ecosystem.

In 2009, Cassini observation data were announced,

data that apparently supported Sekine's hypothesis.

An article in the science journal, Nature,

detailed the elements composing the jets of Enceladus.

This graph compare the constituents of comets,

which are thought to contain the ingredients of planets,

with the constituents of the jets of Enceladus.

The amounts of methane, ammonia,

and other constituents are similar.

The article also pointed to the possibility

of a constituent unique to Enceladus,

molecular nitrogen.

Sekine believed that the presence of this molecular nitrogen

proved the presence of hydrothermal vents.

With help from the Japan Agency

for Marine Earth Science and Technolgy, Sekine experiments

to see how Enceladus might produce molecular nitrogen.

He's already replicated the composition of the jets.

Basically water, carbon dioxide, and ammonia.

Those ingredients are then mixed

with a common mineral, Olivene,

to see what the reaction will be.

The ocean in Enceladus is thought

to be several kilometers deep,

creating tremendous water pressure.

That high pressure environment is approximated here

by using a special device to apply

300 atmospheres of pressure to the mixture.

The temperature is 300 degrees Celsius,

about the same as Earth's hydrothermal vents.

Will molecular nitrogen be produced?

It's been a week since the experiment started.

What has happened to the material

subjected to this high temperature,

high pressure environment?

Finally, the component analysis.

Molecular nitrogen,

the same component found by Cassini.

Molecular nitrogen is generated

by the decomposition of ammonia molecules.

Ordinarily, ammonia is a substance

that does not decompose at low temperatures.

The presence of molecular nitrogen

indicates a high temperature environment.

The hidden high temperature, high pressure

deep-sea world on Enceladus.

Lifeforms that can survive in similarly harsh environments

have been found here on Earth.

They were discovered at hydrothermal vents

in the Indian Ocean.

They can survive in temperatures

reaching as high as 122 degrees Celsius.

Thermophilic methanogens are bacteria

that thrive in high temperature,

high pressure water.

In fact, this experiment

confirmed the production of molecular hydrogen,

the energy source for methanogens.

If organisms like methanogens exist on Enceladus,

then hopes rise that this could lead

to a world of diverse lifeforms.

Enceladus is one point four billion kilometers

from the sun.

Under its icy surface is an ocean of water.

On that ocean's floor, hydrothermal vents

similar to those on Earth.

Fostering a rich ecosystem,

based on lifeforms similar to methanogens.

That's how Sekine pictures Enceladus.

The clue was provided by the jets of Enceladus.

And that faint outer ring of light

in which Enceladus is situated

reflects our shining hope

that we are not alone in the universe.

That was October, 2010.

This stunning news of an Earth-like planet

that might be able to sustain life

reverberated around the world.

A planet like our own planet Earth,

one on which life could exist.

The discovery was made from the volcanic island of Hawaii

in the Pacific Ocean.

Mauna Kea, an inactive volcano,

has an elevation of 4,200 meters.

On its summit are perched astronomical observatories

operated by the United States, Japan,

France, and other countries.

The Keck Observatory.

Scientists used one of the Keck's telescopes,

whose 10 meter aperture classes it

among the largest in the world,

to make the discovery.

Steven Vogt is a professor

at the University of California's Santa Cruz campus.

He's part of the team that found

a planet that may support life.

So this is the Keck One telescope.

This is where I do my planet hunting.

Glises 581g is a very special planet.

It reminds us the most of our own Earth.

This very special planet that Vogt discovered,

what sort of planetary body is it?

The night sky is punctuated with points of light.

Most are fixed stars outside our solar system,

each shining with its own light, like our own sun.

One of them is this reddish star, 20 light-years away.

That means it takes 20 years at the speed of light

for its image to reach Earth.

It's only about 1/3 the size of our own sun.

The planet that Vogt discovered orbits this star.

Since 1998, Vogt has worked with Paul Butler

of the Carnegie Institution for Science

to observe this red star.

The discovery of a life-supporting planet orbiting this star

resulted from more than a decade of scientific observations.

And then, there it was.

A planet they designated Gliese 581g.

Triple the mass of the Earth.

In orbit around its central star

at a distance of 22,000,000 kilometers.

That distance is significant.

To understand why, consider our own sun.

And consider liquid water, the source of life.

If a planet is too close to its parent star,

any water on it will evaporate,

but if it's too far away, the water will freeze.

For water to remain on the surface of a planet,

it needs to orbit its parent star

at just the right distance, like planet Earth.

The vicinity in which water can remain on a planet's surface

is called the habitable zone.

When Vogt tried to calculate

whether or not the planet he discovered

was inside a habitable zone,

he determined that it was right in the middle of it.

It was indeed a planet very much like Earth.

So the feeling of finding the first

known planet that could support liquid water

is a great feeling and was very exciting.

We'd been trying to do this for 15 years,

so this is, for us, this is the end

of a long journey in that respect.

So it's a wonderful feeling.

At long last, the discovery of a planet

that might have liquid water on its surface.

However, even with present observation technologies,

the best we can do is to estimate

the planet's mass and location.

The presence of liquid water on the surface

cannot be confirmed by direct observation.

Is there really water on Gliese 581g?

One researcher is trying to settle this question

using theory.

Professor Shigeru Ida of the Tokyo Institute of Technology

is using computer simulations to study planet formation.

To look into the question of whether or not

water is present on Gliese 581g,

Ida has studied what types of planets can be formed

by a central red dwarf star.

Planets originate from clouds of cosmic dust and gas

that group around a central star

at the time of its own birth.

As these dusts and gases coalesce,

they eventually form larger bodies, planets.

Ida has run 3,000 permutations

to see what sorts of planets might originate

from varying amounts of the same dusts and gases.

These are the results.

Each dot represents a planet.

The colors indicate what the different planets are made of.

Green means that the main constituent is rock,

as with planet Earth.

Red means a planet such as Saturn,

composed primarily of gases.

And blue indicates that the planet is made up

mostly of ice, like Neptune.

Vogt's observations put the mass of Gliese 581g

at triple that of Earth's,

and its distance from its star at 22,000,000 kilometers.

In other words, Gliese 581g

is not, like planet Earth, composed primarily of rock.

Rather, it's an ice planet, like Neptune.

And yet one can still have high hopes

that life does exist there.

Ida believes that Gliese 581g

was born as an ice planet in a cold region

far from its parent star.

In the course of tens of thousands of revolutions,

it gradually drew closer,

winding up in the middle of the habitable zone.

The result was that the surface ice melted,

becoming liquid water, creating an ocean planet.

The amount of water on such an ocean planet

would be quite different from what it is on our own planet.

Look at a cross-section of Earth.

It's made almost entirely of rock.

The oceans make up just 2/100 of a percent

of the total mass, a very thin layer.

Gliese 581g is different.

It's primarily water.

In fact, water makes up over 50% of the planet's mass.

The first planet ever to be discovered in a habitable zone,

Gliese 581g.

With a high probability of maintaining

vast amounts of liquid water.

Oceans bathed in the sunset-like glow of its red star.

What sorts of lifeforms might we find there?

What does a biologist have to say

about life on Gliese 581g,

an exoplanet outside our solar system?

Takeshi Naganuma.

He studies lifeforms in extreme environments

like volcanoes and deserts.

Given the persistence of life

in such extremely adverse circumstances on Earth,

he thinks extraterrestrial life must also exist.

One month after the announcement

about Gliese 581g, Naganuma is paying a visit to Ida.

Naganuma is hoping to learn more about

the environment on Gliese 581g,

so that he can consider the question

of life on that planet more deeply.

Ida's first step, to explain certain aspects

of Gliese 581g's parent star.

This brought up the question of the star's lifespan.

Indeed, 10,000,000,000 years

would be more than double the age of our own sun,

which is only 4,600,000,000 years old.

That would mean that Gliese 581g

has had plenty of time to evolve

complex forms of life.

Ida says that Gliese 581g has plenty of water, but no land.

The only rock on this planet lies deep within.

With the ocean reaching depths

of several thousand kilometers,

there is no way that that rock could form dry land.

Learning that there is no land there

has convinced Naganuma that an Earth-like civilization

could not develop on this planet.

But the ocean would still be teeming with life, he says.

What form would that life take?

Let's take a look at the world of Gliese 581g

as envisaged by Takeshi Naganuma.

A vast ocean, no boundaries in sight.

Within it, life.

What are these?

Creatures of Gliese 581g.

They float near the surface, living off the red light

by means of photosynthesis.

Their flat shape enables them

to process as much light as possible.

Life exists not only near the surface,

but in the depths as well.

These tube-like creatures are an example.

They move by propulsion,

taking water in with their mouths

and expelling it from their rear ends.

At the same time, they filter plankton,

from which they derive nourishment.

Their flexible bodies can adjust

to variations in water pressure,

enabling them to range from the deep sea

to shallower waters.

And there would be an unexpected place

where life could develop as well.

Surrounding a planet that is triple the mass of the Earth,

the atmosphere of Gliese 581g

is estimated to be 100 times denser than Earth's.

Naganuma points out that such a thick atmosphere

would, in sense, approximate a liquid,

constituting a medium through which creatures

could easily float.

So airborne creatures might emerge as well.

Naganuma calls this particular extraterrestrial lifeform

Ballchutes.

Three eyes and a large brain.

What kind of life would they lead,

these sky-borne aliens?

This is the Gliese 581g sky

and the lifeforms that dwell in it,

as conceptualized by Naganuma.

These ballchutes, short for balloon parachutes,

produce methane and other light gases internally.

By regulating the amount,

they glide through the sky

like hot air balloons above planet Earth.

Or, by expanding their bodies into the shape of an umbrella

and then a parasol, they end their buoyancy

and descend slowly, like parachutes.

They negotiate the skies at will,

using their large brains and skillful bodies.

But eyesight development helps evolve

a totally different creature as well.

One that puts its superior eyesight to savage use.

That's right, these new glider creatures are carnivores.

When they spot prey, they go into a power dive

and spear their victim with their sharp jaws.

Then they use their long tongues

to suck out the brains of the ballchutes.

A plausible view of life and death on Gliese 581g,

whose long-lived sun has given it time

to evolve diverse lifeforms.

Naganuma has concluded that life there

would be dominated by big-brained creatures

that one might as well call aliens.

The universe is teeming with life.

That's a premise that scientists

are busy turning into a conviction.

Steven Vogt, a co-discoverer of Gliese 581g,

is himself setting forth on a new cosmic front.

So this is the part of the Automated Planet Finder.

Vogt has developed a device

to search for planets like Gliese 581g automatically.

You enter in the location of the fixed star

near which you want to search for planets,

and then it conducts the survey for you automatically.

It's being installed

at the University of California's Lick Observatory.

The fixed star around which Gliese 581g revolves

is a red dwarf star.

Such stars make up nearly 80% of the Milky Way.

So Vogt is confident there must be many more planets

like Gliese 581g that are capable of sustaining life.

So my expectations for the APF

are that we will find many Earth-like or Earth-size planets

capable of supporting life as we know it.

There's probably tens of billions

of such planets in our galaxy.

And so we hope to find the nearest ones with this facility.

I know we'll find them.

I'm certain of it.

The universe is teeming with life.

Someday that will be proved by scientific observation.

Vogt's passion will not permit him to abandon that quest.

The scientists on the cosmic front lines

of space exploration have detected places

both within our solar system and far beyond it

where life can exist.

In space, worlds unfold beyond our wildest imaginings.

They are merely waiting for us to discover them.

Humankind has only just begun

to challenge the cosmic front.