Finding Life Beyond Earth Page #8

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changes its orientation,

it sees Enceladus silhouetted

by the sun...

and vast jets of ice

erupting into space.

These actual images reveal

the jets are blasting

hundreds of miles out

from the Tiger Stripes.

Carolyn and her team

are stunned.

PORCO:

Never did we expect that we were

going to see something

like a whole forest of jets

shooting hundreds of kilometers

into the sky above Enceladus.

It was like nothing

we'd ever seen before.

NARRATOR:

Could Enceladus also have

an internal energy source

like Io and Europa?

Scientists believe

that when Enceladus orbits

the massive Saturn,

friction from gravitational

forces

causes it to heat up, melting

ice in the moon's interior

in the same way as on Europa.

They believe the jets consist

of liquid water,

vaporizing and freezing as it

meets the cold vacuum of space.

They shoot upwards

at 1 ,200 miles per hour.

PORCO:

Enceladus is being flexed

as it's orbiting Saturn.

That's like flexing a paperclip;

it creates heat inside,

and we think the heat maintains

the liquid under the surface.

NARRATOR:

Excited by this discovery,

the team programs Cassini

to fly through the jets

and collect particles.

After several fly-throughs,

Cassini's spectrometers

detect in the jets

some of the basic chemical

building blocks of life.

That was tremendously

exciting to find

because not only do we think

there's liquid water there,

not only is there an enormous

amount of excess heat,

but we also have

organic materials.

That's the trifecta

that we are looking for,

the three main ingredients

for a habitable zone.

NARRATOR:

But could this strange and alien

world actually support life?

Carolyn imagines

what it would be like

to hunt for the answer

on the surface of Enceladus.

PORCO:

Walking on the surface

of Enceladus,

as you approach

the Tiger Stripe fractures,

you would first encounter

a region

that is continually blanketed

in snow.

The sky is inky black.

Walking is like floating,

it has very little gravity.

If we had the sun at our back,

we wouldn't see anything.

But if we put ourselves

in the right geometry,

looking in the direction

of the sun,

then suddenly we see something

that I think would be

the greatest spectacle

this solar system

has to offer:

giant ghostly fountains

shooting skyward.

Fine, sparkly, icy crystals,

most of which eventually

fall back down

and coat the surface

in a blanket of snow.

If we are correct,

that the jets of Enceladus

derive from pockets

of liquid water

in which life

might have gotten started,

a scoop full of Enceladan snow

might-- just might--

contain the remains of

microscopic living organisms.

NARRATOR:

Since Cassini's instruments

cannot detect the signatures

of life itself,

there is no evidence yet

of microscopic organisms

in these jets.

But the discovery makes

Enceladus a prime candidate

for future missions.

To me it's like there's a sign

on Enceladus that says,

"Free samples, take one."

We just gotta fly through the

plume and collect the stuff.

We don't have to drill,

we don't have to dig,

we don't have to scurry around

looking for it.

It's being injected into space.

NARRATOR:

The discovery of a new

energy source

and the possible oceans

of liquid water

inside planetary moons

point to potential

new footholds for life

in our solar system.

Meanwhile, discoveries

here on Earth

are revealing that life

can withstand

an even wider variety

of conditions

than previously thought.

Missions to extreme environments

are showing that microbes

can live in dry deserts

and thrive in lakes

full of poisonous arsenic.

Bacteria survive in slimy

colonies on cave walls

dripping with sulfuric acid,

living off noxious hydrogen

sulfide gas.

And microbes flourish

in toxic rivers

of corrosive industrial waste.

GREEN:

We now know it's possible

for microorganisms

to exist in these large acidic

and even poisonous regions.

SHANK:

The more we look at the extreme

habitats on Earth,

the more we find life there.

We're pushing back the limits of

where life can live all the time

through our own discoveries.

NARRATOR:

From freezing glaciers to

super-heated hot springs...

from high deserts blasted

by ultraviolet radiation...

to deep mines miles

underground...

and ocean trenches where

sunlight never penetrates,

scientists are discovering

that life finds a way

to adapt and thrive.

McKAY:

Life on Earth can exist

in many extreme environments,

and it can do

many remarkable things.

And we're learning

more every day

about how flexible

and remarkable

life on Earth really is.

NARRATOR:

So, could environments

on other worlds

previously thought too harsh

for life be worth a second look?

GREEN:

We've really gotta

put ourselves

out there in terms of thinking

what the possibilities are.

McKAY:

When we first started looking

for life on other worlds,

we were looking

for Earth-like conditions.

"Okay, well, we got

to have water,

got to have an energy source,

got to have carbon."

But to me, the number one

question-- the big question--

is:
Is there another type of

life on another world

somewhere in our solar system?

NARRATOR:

So Chris wants to know, if life

could develop in new ways,

perhaps even using

different kinds of chemistry,

then could even the most

inhospitable places

offer surprising new footholds

for life?

One such place is one

of Saturn's moons

visited by the space probe

Cassini--

Saturn's largest moon, Titan.

Cassini detects

organic building blocks

in the atmosphere,

and the spacecraft's radar

reveals something mysterious

beneath clouds

at the south pole.

It looks like a lake of water.

Further flybys reveal it's just

one of hundreds

scattered across both the north

and south poles.

It was exciting and mysterious

to see all these different lakes

and to try to understand

what's going on.

NARRATOR:

Titan is the first world

other than the Earth

known to have a liquid

on its surface.

But at minus-290 degrees,

this liquid can't be water.

Analysis of infrared light

reflected off the lakes

reveals that they are filled

with super-chilled liquid

methane and ethane.

On Earth, these hydrocarbons

are gases we use as fuel.

Data now reveals that methane

on Titan carves river valleys,

forms clouds,

and even falls as rain.

Liquid methane acts

a lot like water on Earth.

But could it act

the way water does

as an essential foundation

for life,

allowing organic molecules

to dissolve, mix and interact?

It's a question astrobiologist

Chris McKay is investigating.

McKAY:

Our general theory of life,

based on our one example

on Earth,

is that we need a liquid.

Some people would argue that

that liquid has to be water.

Well, on Titan,

we can ask the question,

"Well, what about another

liquid?

Could some other liquid

besides water do the trick?"

NARRATOR:

For life to exist on Titan,

Chris believes one fundamental

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