Nova (1974–…): Season 33, Episode 15 - Voyage to the Mystery Moon - full transcript

Nova follows the Cassini probe on it's voyage to Saturn's moon Titan. Along the way it examines a variety of other wonders of the solar system before attempting to land and photograph the surface of Titan.

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Saturn

Mysterious

Hauntingly beautiful

A swirling ball of gas,
embraced by heavenly rings

that span over 150000 miles

Circled by more than 40
moons in dizzying orbits.

So distant, going there could
only be a dream, until now.

NASA and the European Space Agency are
teaming up for the most ambitious
unmanned space project ever launched.

Across more than 2 billion miles, it
will battle the bitter cold of space,

thread the rings of Saturn,

survive the heat of entry and
brutal impact of landing,



and beam pictures and data back
from Titan, its largest moon.

NOVA follows this fantastic voyage to
Saturn, on a quest to solve some of the
greatest mysteries of this alien world.

Up next, Voyage to
the Mystery Moon.

Saturn, Lord of the Rings

few sights in the solar system are more
strikingly beautiful than this celestial
sphere,

embraced by its
majestic rings.

This giant ball of gas,
750 times larger than Earth,

visible as a golden star,

has captivated our imaginations since
we first looked up at the night sky.

But it wasn't until 1980,

when we were able to get a close-up
look at the sixth planet from the Sun.

The Voyager deep space probes flew past
Saturn and sent back tantalizing
glimpses of this distant world,

and Saturn's mysterious rings
were seen closer than ever before.

Voyager got there and found this
bewildering array of, of structure in
the rings.



And people set about trying
to explain it right away.

What are the rings?

How were they formed?
When were they formed?

And how long will they last?

But the rings weren't the
only feature Voyager explored.

For the first time, detailed images
of Saturn's moons were sent back

more than 40 in all,

from dozens of minor moons, to
one nearly half the size of Earth.

It was named after Saturn's
mythological brothers, the giant Titans.

Titan was unlike any moon
that had ever been seen.

It had clouds and an atmosphere
10 times denser than Earth's.

Frustratingly, a thick layer of
orange haze shrouded its surface.

We saw this fuzzy ball, and the
immediate reaction is, "What's

below those clouds?" You know,
"What are these clouds made of?

What is hidden
behind that layer?"

Whatever was hidden, it
had to be a solid body,

or else its atmosphere would
have long ago escaped into space.

As Voyager confirmed, the atmosphere was
nitrogen-rich and included organic
molecules,

perhaps resembling the
atmosphere of the early Earth.

Could Titan play a unique role in helping
us understand the origin of life on Earth?

If you look at our solar system,
there are only four bodies

that have atmospheres and are
actually solid bodies themselves:

the Earth, Venus,
Mars and Titan.

Venus is just so hot that one can melt lead on the
surface; there's... there are no organic molecules.

Mars today is very cold, very dry, very
thin, not a good place for organic molecules.

And so we're left with Titan.

Voyager moved on ?out towards
Uranus, Neptune and beyond?

but Voyager's spectacular
images of Saturn and its rings,

and this enticing glimpse of
Titan, left scientists wanting more.

The combination of the
spectacular structure in the rings,

the hazy atmosphere of Titan,

just left every scientist
with a great curiosity.

Immediately, there was a feeling that we
had to return to Saturn and stay there
for a longer time.

So in 1990, NASA and ESA,
the European Space Agency,

team up for an unprecedented
collaboration,

a new mission to
Saturn, with a landing on Titan.

To get there, they need to build a
spacecraft to travel more than two
billion miles,

battle the bitter cold of space, thread
through the rings of Saturn,

withstand the intense heat of
entry and the brutal impact of landing,

and ultimately beam back
pictures and data.

Their odds of success seem about
as likely as throwing a basketball

from NASA's launch site at Cape Canaveral, Florida,
through a hoop in ESA's command center in Germany,

without touching the rim.

The spacecraft they design to
accomplish this mission, they name Cassini,

after the 17th century astronomer who
discovered gaps in Saturn's rings.

Built by NASA's Jet Propulsion
Laboratory,

the Cassini deep space probe carries
an amazingly complex array of instruments.

The eyes of Cassini are two
sophisticated cameras.

One is a very long focal length, very high resolution,
but you get little postage stamp-like coverage.

And so you want to also carry a camera with
a larger field of view, shorter focal length,

that covers a greater amount of territory, so you can put your
little postage stamp coverage in context, in geological context.

Cassini is also loaded with a powerful radar,
designed to punch through Titan's hazy atmosphere.

And that's not all.

Riding aboard Cassini on this seven-year mission
is a small probe, built by the European Space Agency.

Named Huygens, after the
astronomer who discovered Titan in 1655,

this probe is designed to
actually land on the moon's surface.

It will see, sniff, touch and
listen to the mysterious moon,

radioing back images and
data to orbiting Cassini,

under conditions that no
one can precisely predict.

The atmosphere could have been thicker than
we thought or thinner than we thought,

warmer or cooler. We had no idea what
the surface was, so there was no guarantee

that the probe would keep working
after it hit the ground.

The engineers need to make sure
that Huygens is tough enough for the job.

Every aspect of the super sensitive probe's design
and construction must be put to the test.

When the probe slams into
Titan's atmosphere,

it will produce temperatures
of over 20,000 degrees Fahrenheit,

more than twice the
surface temperature of the Sun.

And it's this heat shield
that is designed to withstand it.

If the probe
survives the heat of entry,

successful landing will depend on the precise
opening of three small parachutes.

Packed for seven years,
these parachutes have to deploy,

unfold and inflate in
sequence or the mission will be lost.

During the two-and-a-half-hour descent, specially designed
onboard cameras will act as the eyes of the probe.

It is these cameras that will send
home the first glimpse of Titan's surface.

For Huygens' imaging specialist,
Martin Tomasko,

it is imperative that his
cameras don't miss a thing.

What we're trying to get is kind
of the skydiver's eye view,

as if you were outside the probe
and falling down through the atmosphere.

We don't want to land near some interesting
object like the Grand Canyon and not know it's there.

To see through the haze has been
notoriously difficult. We hope that our big advantage

is that we'll
fall through the haze,

and eventually we'll be under most of the haze
and be able to see the surface that much more clearly.

After descending
through the orange shroud,

the climax of the mission is
touchdown on Titan's surface.

We set up a facility in the lab that would enable us to simulate
what would happen when Huygens hit the surface of Titan.

This device called a penetrometer,
will measure the force of first contact.

You get a very different signal if you strike,
for example, a sheet of solid ice,

if you hit semi-compacted snow, if you, if you struck
a liquid, if you landed in a lake, for example.

You know, we used to joke and say we would
either thud, squelch or splash down,

and that really is quite a good description, because it
could have been any of those scenarios or a mix of them.

By 1997, the Cassini-Huygens spacecraft
is built and assembled,

but there is one major challenge:
together, their weight is massive.

The Cassini spacecraft is the largest interplanetary
satellite that NASA has ever built and launched.

The big problem is how to get this
six-ton leviathan into space.

The most powerful rocket on Earth, the
mighty Titan IV, is selected for launch,

delivering over 3.4 million
pounds of thrust.

But even this will
not be enough.

For not only does Cassini have
to break free from Earth's gravity,

it has to travel almost a billion
miles to Saturn, on a small amount of fuel.

The only way for
Cassini to make the journey

is to pick up additional energy from a flight path that
takes advantage of an unusual convergence of the planets.

The energy that we needed to get out in the solar system,
out to the planet Saturn had to be supplemented

by... partially provided by gravitational
encounters with the planets.

The important thing is to gather energy
from the gravity of the planet you're flying by.

First, Cassini will be routed via the
Earth's nearest neighbor, Venus.

This planet's gravitational
pull will accelerate Cassini,

increasing its speed by over
8,000 miles per hour,

but this still will
not be enough.

Cassini will need to return for
a second boost from Venus.

Then it's the Earth's turn, accelerating Cassini
with a fling out towards its next rendezvous,

Jupiter.

Eventually, the spacecraft will clock up a speed of 50,000
miles per hour before reaching its final destination

Saturn.

That's the theory

but will it work?

October 15, 1997: With the planets
in perfect alignment,

from NASA's launch site at Cape Canaveral, in
Florida, Cassini blasts into the night sky.

It sort of lit this cloud up,
like a Chinese lantern, from within.

It was quite spectacular and, and you just think,
"Wow, you know. It's out of our hands now. "

The seven-year journey, covering
2.2 billion miles in all, begins.

With Cassini-Huygens now
en route to Saturn,

scientists will soon have the opportunity to
explore the mystery of Saturn's majestic rings

and its enigmatic moon, Titan.

Two years into its journey, the spacecraft
loops around Venus a second time

and swings
back past the Earth.

Here, the JPL scientists check
out Cassini's high-power radar.

It scans a huge swath of South America,
and everything is in working order.

The radar seems to
be operating flawlessly.

Next, they perform a simulation to test
the radio link between Huygens and Cassini.

The Huygens probe itself doesn't have enough
power, and it doesn't have a large enough dish

to transmit its data, the
scientific data that it collects on Titan,

directly back to the Earth.

So what will happen is that it uses the
Cassini spacecraft as a data relay.

The test is to make sure that Cassini
is receiving all the data from Huygens,

but when the results
come back, they are alarming.

We were expecting to
receive all the simulated data.

Unfortunately, we did not receive
very many of those data.

We lost, well, it's... we lost maybe 90
percent of the data, sometimes even all of the data.

If Cassini fails to
receive the data from Huygens,

then when the probe descends to Titan,
there will be no results, no pictures, nothing.

A crucial part of
the mission will be lost.

Huygens' European team calls a meeting
to discuss the situation.

As one of NASA's
imaging specialists for Huygens,

Martin Tomasko cannot believe
what he is hearing.

They said, "We've performed the test, and we didn't get
any signal, but the test accomplished all of its objectives. "

And some of us were
sitting around the table saying,

"What? What exactly are
you trying to sell us?" You know,

you've accomplished the objectives
of conducting the test,

but you've actually succeeded in proving
the thing is not going to work.

Six months of painstaking
detective work finally pinpoints the problem.

When Huygens is descending
to Titan,

Cassini will be speeding away from
it at 12,000 miles per hour;

they will no longer be able to communicate
on the same frequency.

It was enough to, essentially, put
the link between the two out of alignment.

It was as if Huygens was
transmitting on, on Radio One, on one frequency,

and Cassini was receiving on Radio
Two, a slightly different frequency,

so this was potentially
disastrous.

Retuning the
receiver is impossible.

Cassini is out in space, over
300 million miles away.

There was no way we could repair, so
we had to find a new mission scenario

which would, which would allow us to live with this
problem but still to recover the, the whole mission.

After months of research, they
devise an ingenious plan.

Although they can't retune
Cassini's receiver,

they can shift the signal it is picking up by
using a basic principal known as the Doppler Effect.

If they can slow Cassini down,

it will receive the radio waves that Huygens
is sending at a lower frequency,

solving the problem.

All in all, it took us
six months to find a solution,

but it took us two years to design all the
detail of the solution and to test it.

We are not going to lose any
science, so it's a very successful recovery.

Both teams are now hopeful that Huygens has a
good chance of sending back its precious data,

when it finally reaches Titan.

By the year 2,000, Cassini is now a
billion and a half miles out in space

and arrives at Jupiter,
the giant of the solar system.

With a planet twice as
massive as all the others combined,

Cassini's cameras face
their biggest test yet.

Jupiter's majesty is revealed
as never before.

Its swirling gaseous atmosphere is
seen with breathtaking clarity.

But Cassini has to move on

across another 500 million
miles of space

before it reaches its
final destination.

For imaging team leader Carolyn Porco,
the Jupiter pictures are a triumph.

But her true goal is the planet she has
devoted her career and heart to studying,

Saturn.

To know that we can know so much about
our solar system and about our cosmos,

for me, makes life meaningful.

It's very much like
being in love.

It's very much that kind of a relationship,
where you want to know more and, and you want to be one

with the person you're in love with or the topic that
you're studying. It's, it's, it's kind of this... it's a connection.

It's really a connection. And for me, it's,
it's like being allowed a glimpse of the miraculous.

Spring of 2004:

Cassini is
closing in on Saturn,

but just before contact,

mission planners calculate a precise course
to send the spacecraft past Phoebe,

Saturn's outermost moon.

Until now, all that scientists had
seen of Phoebe is this picture,

taken by
Voyager, 23 years ago.

But this time Phoebe is in the
cross hairs of Cassini's powerful cameras.

Picture after picture
returns with astounding detail.

We buzzed Phoebe, okay? We came within
2,000 kilometers of its surface.

You could reach out and
touch it, is what it looked like.

So it's very exciting. We saw
features that were, were 30 meters across.

The images of Phoebe reveal
an ancient surface,

pitted with craters
created over billions of years.

But Phoebe is just
an appetizer,

a taste of what is to come.

June 2004:

At the Jet Propulsion Laboratory
in California,

NASA's team has piloted the Cassini spacecraft
across 2.2 billion miles of space

and is still right on target,

fast approaching one of our solar
system's greatest enigmas,

the rings of Saturn.

Very little is known
about them.

The questions that we scientists have about
Saturn's rings are the questions that

an ordinary person might be moved to
ask when first seeing them, you know?

"What caused them? How did they get there? How
long have they been around? How long are they going to last?"

Answering these questions is
one of Cassini's prime objectives.

A good opportunity for close-range observation will come
as mission control maneuvers Cassini into orbit around Saturn,

because that means
passing right through the rings.

Voyager revealed that the
rings are made up of rock-hard ice,

ranging in size from a
grain of sugar to a large house.

The rings, just 300 feet
thick and a vast 38,000 miles wide,

are chaotic and dangerous.

All the ring particles, billions and billions
of them, are in orbit around the planet Saturn,

and they're moving at quite a clip, something like 10
kilometers per second-faster than a high-speed bullet.

If you were in Saturn's rings, you would be in a mass of particles
that were bumping into each other and rolling over each other.

If you were a ring particle, you would get bombarded
from one side and then from the other,

as one particle bounced
off of another, all around you.

Entering directly into the
rings would be suicide.

But NASA's JPL
team has a plan.

They calculate a course for the spacecraft
through a 15,000 mile gap in Saturn's rings.

Even so, with one small miscalculation,
Cassini could be torn apart.

Even a very small particle
could be the end of Cassini.

If it hits a particle as small as a
grain of rice, that would be enough,

because of the high speed at
which it's moving, to end the mission.

But particles from the rings are not
the only danger that Cassini faces.

It also has to slow down. That
means firing up its main engine.

Any malfunction, and
Cassini will simply fly past Saturn,

lost forever in the
void of space.

That engine had not been used very
frequently over a period of seven years;

that makes you nervous.

You know, it's like you have a car, a brand new car that you
put in the garage, and every once in a while, you turn it on.

And then you have an emergency, and you get in
the car, and you turn it on-it better work.

June 30, 2004:

The press gathers at JPL for news of the most
critical part of the seven-year trek across the solar system.

The ring insertion
maneuver begins at 7:36 p. m.

First, Cassini rotates to
use its giant antenna as a shield

to protect it when it passes
through the gap in the rings.

You can image how anxious
some of us were,

knowing that it all hinged on one 90-minute period,
where we would have to perfectly just slip into orbit.

All eyes are on a radio signal being sent
by Cassini's auxiliary transmitter.

If the signal continues, then
flattens out at the bottom of the graph,

they'll know
that Cassini survived.

A $3.2 billion mission and 14 years
of work all hinge on this one moment.

The Doppler has flattened out.

Cassini has arrived.

When the images return,
Saturn is revealed as never before.

I just
- don't know what to say. I'm kind of speechless.

Oh, absolutely exciting! This is
the culmination of 22 years of effort,

and just seeing the Lord
of the Rings in its big glory.

We are amazed about the detail we are
seeing and the sharpness in the rings.

You wait years to
have this kind of a moment.

These remarkable images begin to provide
new clues to some of Saturn's oldest mysteries:

What are the rings made of?
And when were they formed?

Since Voyager, scientists have known the
rings are composed of rock-hard ice.

Cassini is revealing far more about
the composition of the ice.

The rings are made of ice, just like
the stuff you've got in your ice cube trays,

and almost 100 percent pure
water ice with some small contaminants.

These contaminants, minute
traces of dust that come from meteors,

are the key to finding out
the age of the rings.

The basic principle is simple: the more contamination, the
longer the rings have been bombarded and the older they are.

The pollution is sort of a like a clock, because we're pouring
material in on top of the rings, and it's dark, non-icy material,

so the level of darkness in the
rings tells us something about their age.

To discover the level of pollution in the rings,
Cassini is equipped with a spectrometer

that translates chemical composition
into vivid color images.

What they show is surprising.

The spectacular range of structure in
the rings with reds and blue and aquas,

that was something that
was completely unpredictable.

The images show cleaner ice in shades
of blue, the heavier contamination in red.

So it appears that
the inner rings are older

and that the outer rings have
been made more recently.

It's definitely the case that there's a gradient
in composition across the rings, so that the rings

are less icy on the inside
and more icy on the outside.

As we go to the outside, the particles
become younger and fresher.

These new spectrometer images seem
to suggest an intriguing possibility

that perhaps Saturn's
rings are still being formed.

But beyond the riddle of the rings, another chapter
in Cassini's voyage is about to begin,

its encounter with
Titan, Saturn's mystery moon.

Christmas Day, 2004: Mission control
navigates Cassini into a safe orbit around Saturn.

Now they give the command to
release the landing probe.

They fire three explosive bolts,
and Huygens pushes away from Cassini.

In 1980, Voyager confirmed that Titan is
one of only four bodies in the solar system

that are solid and have
a substantial atmosphere,

the conditions that
gave rise to life on Earth.

Since then, what's beneath
Titan's orange veil

has captivated scientists'
imaginations.

Whenever we humans think that we might be approaching something
that is vaguely similar to Earth, we get very excited about it.

The prospect of something
familiar, but yet so distant, and so strange

is, is a very exciting
combination.

Billions of years ago on Earth, it's thought
that simple molecules may have spontaneously combined

to form more complex chemicals
that became the building blocks of life.

But Earth today is teeming with life;
it has taken over the entire planet.

This makes Earth problematic for studying
the leap from chemistry to life.

It's very difficult to use the Earth as a laboratory
for understanding how life began.

Life eats all of the organic molecules
that are present on the Earth today.

If we go to the laboratory and
try to simulate how life began,

we have limits on time and space. A laboratory
experiment might be this big;

a laboratory investigator might work for two or
four or 10 years perhaps, no more than that.

We really need a place where organic evolution
is happening on a planetary scale,

over billions of years, but is not being
ruined by the presence of life.

For years, scientists have been looking for a place
that has a similar primordial chemistry to early Earth.

Could Titan be that place?

Based on data from the Voyager mission, scientists know
the atmosphere of Titan contains nitrogen and methane,

made of carbon and hydrogen.

It's dominated by nitrogen,
but it has methane

and a whole range of hydrocarbon gases,
gases made of carbon and hydrogen.

Scientists also know of one other ingredient that's
crucial for making the leap from chemistry to life.

If we were to apply what is the essential
ingredient of all life, liquid water,

then we may well make some amino acids,
which are the building blocks of life.

But how could liquid water exist on Titan,
with a surface that's nearly 300 degrees below zero?

Control of Huygens is based at the European Space
Agency command center in Darmstadt, Germany.

Finally, the team is about to find out what
lies hidden beneath the orange veil.

On January 14, 2005, 150 miles above Titan,
Huygens slams into Titan's atmosphere.

The time has come to witness
Huygens' historic descent to Titan's surface.

The emotion in that control room,
I mean, it was absolutely tangible.

But the scientists will
have to be patient.

It's still a long wait before any data
is received back at Mission Control.

The fact that all the data
was transmitted to Cassini-

Cassini would then store the data and
only some hours later send it back to Earth

-meant that there was a delay
time of several hours.

So it was sort of unreal, knowing that things were happening.
We didn't know if they were good things or bad things;

they were happening, but
we knew nothing about it.

Now, operating on automatic, one minor malfunction
can terminate the whole operation.

We have to have a heat shield that works and protects
the probe from burning up during the entry.

We have a series of explosive bolts that has to fire
to release the heat shield and deploy the parachutes.

They all had to work perfectly. If you make a mistake
there, you lose the rest of the mission.

Everything has to be relayed from
Huygens to Cassini then back to Earth,

so they are not expecting to
receive any news of Huygens' fate for hours.

But then, they get a surprise. They pick up
a signal, not from the orbiting mother ship,

but direct
from Huygens itself.

A few minutes ago we have received confirmation
of the carrier signal from Huygens.

It tells us that the probe is alive, the entry has been successful,
we are under parachute, and the probe is transmitting.

In Green Bank, West Virginia, the giant
360-foot dish of the Robert C. Byrd radio telescope

is pointing directly at Titan.

It is listening for
even the faintest of signals.

We were kind of eavesdropping on the
conversation between Huygens and Cassini.

So the strength of the signal
which we deal with is

practically the same as the
strength of the signal from a mobile phone,

but located, not in your pocket
or my pocket or somewhere nearby,

but at a distance of one billion
kilometers, on Titan.

Receiving a radio signal from Huygens is the first
indication that all is going according to plan.

This is absolutely fantastic news. It's like
hearing the ringing tone on the phone.

It tells us the phone is working. There's no
information on it yet but it's, it's absolutely fantastic.

The radio signal from Huygens is
too weak to relay any scientific data.

For that, Mission Control will
need to wait for Cassini.

We were told to expect the data at 15:24,
Central European Time, in the afternoon.

And, I remember, 15:24
came and went,

and we were
looking at the screens.

We knew where the numbers should have
appeared and absolutely nothing.

And we're thinking, "How is it possible
that everything could have worked well on Huygens

and we wouldn't get data?" And we say, "Oh yes,
it could have worked perfectly on the probe,

but if the orbiter didn't receive it, this
all could, we could still lose the whole thing. "

You know, the minutes ticked by,
it got quieter and quieter;

we were looking at each other.

And two minutes goes by, and four minutes goes by,
and six minutes goes by, and there's still nothing.

And we're all just shaking our heads, and there's
just gloom, absolute gloom over the whole audience.

15:30 so this was six minutes after we
were led to believe the data would come through

I can remember looking at one particular screen,
and where there was a large gap before, suddenly

a whole column of green
figures appeared.

And this was the first science
data from Huygens.

Finally, the Cassini mother ship is sending all
of Huygens' scientific data back to Earth.

Although the probe actually
landed on Titan's surface some hours ago,

only now can the scientists begin their
own descent onto Saturn's mysterious moon.

But for Martin Tomasko, the
first images he receives are murky.

We saw a lot of inside of the milk bottle pictures in
the beginning, you know? It's just all washed out.

Somewhere between 50 and
70 kilometers, we thought

we'd come out through the bottom of the haze, have clear
views of the surface. Well, that was not the case.

If the haze continues all
the way to the ground,

Huygens will fail to
obtain crucial photographic data.

We finally got close enough to the ground to see the ground
through the haze, at 30 kilometers altitude only,

and, and that was, that was beautiful.
That was, that was the first stuff we saw.

After decades of wondering what
the surface of Titan looks like,

scientists now get their first
glimpse beneath the haze

and discover a
surprisingly Earthlike geography.

I sort of looked, looked up and
there was this projection screen,

and the first thing you see is these
river valleys everywhere, and you think, "Wow!"

All of a sudden, you could see these drainage channels,
and it seemed to come together over, over the highlands,

over the bright material. And when you got to the dark material,
there was this low region that looked like a flat lakebed.

You know, after all this

you go down through the haze, and there it is, this dry riverbank
that looks like a backyard in Arizona somewhere.

Having survived the descent unscathed, the most
anticipated moment in the entire mission

is the touchdown on Titan.

Upon contact, Huygens' penetrometer reveals
the nature of the surface at the landing site.

We're sitting on icy grains,
which have the consistency of sand.

It's sort of gravel, fine gravel you might see
on a river shore or on a dried up lakebed.

When the probe, hot from the
friction of entry, contacts the icy surface,

the surface melts and Huygens' chemical
sniffer detects a curious spike.

The amount of methane that the chemical sniffer
was detecting jumped very quickly,

and it jumped up in such a way that there
must have been, underneath this warm probe,

a pool of liquid methane.

From over a billion miles away, Huygens' landing
confirms what scientists had suspected,

that not only its atmosphere, but also the
surface of Titan contains the organic compound, methane.

It has been nearly 25 years since
Voyager took this first hazy image.

Now, with Huygens, comes this first close-up
image from the surface of Titan.

Can you show the first picture, cropped 448 on the screen please?
And we'll see Titan unveiled, as we haven't seen it before.

Huygens' camera reveals its landing
site as a dry riverbed,

with rounded pebbles made
of ice, beneath an orange sky.

If that image alone was the only piece of
data produced by the Huygens' mission,

I would say that
it was worthwhile.

But that image is not alone.

Others reveal networks of rivers, hills, and
valleys, and a surface made of damp sand,

a mixture of icy
pebbles and liquid methane.

Huygens, mankind's furthest
outpost in the solar system,

transmits data and images
for 180 minutes, then dies.

But Cassini, its mother
ship, lives on.

From its orbit around Saturn, it peers down as it passes
over the mystery moon and continues to reveal

a whole new picture of Titan.

Cassini was definitely not
just about getting Huygens to Titan;

Cassini was
about exploring Titan.

The orbiter has been unveiling
Titan in, in its own very special way.

Using remote sensing, infrared and radar imaging,
Cassini pierces through Titan's thick haze

and reveals that Titan's surface has
many familiar Earthlike features.

We're seeing river
channels, we're seeing erosion.

But, whereas on Earth we're
talking about rocks and liquid water,

on Titan it's ice
and liquid methane.

This is a world suffused with
methane, raining down from the atmosphere,

carving out hills and valleys, eroding ice rocks
and finally sinking into the sandy surface.

In addition to
erosion from methane rivers,

Cassini reveals that Titan's surface
appears to have also been modeled by lava flows.

But this is lava
as never before seen.

We saw some structures on the surface of Titan
that looked very curious; they looked like volcanoes.

But these are very different than the kinds of
volcanoes that you would expect to see on Earth.

These are what we
call cryovolcanoes.

Volcanoes on
Earth erupt molten rock,

but the cryovolcanoes on Titan's frozen world
erupt something altogether different.

The working fluid for a volcano on Titan is
water, but it's water mixed with ammonia.

And the result of that is it lowers the freezing
temperature of water from zero degrees centigrade,

down to as low as
minus-100 degrees centigrade.

If you could climb up to the summit of a volcano
like this and look down in its caldera,

you would see a very sticky viscous fluid
that's literally oozing out of the ground

and flowing down the flanks of this volcano,
much like a very, very fast glacier.

Methane in its rivers, nitrogen in its atmosphere
and now the presence of this bizarre form of water-

Huygens and Cassini have made
a remarkable discovery:

Titan may, indeed, have all the key ingredients
to form the basic building blocks of life.

These things all
operate on Titan,

under exotic conditions, in much the way that they
operate on the Earth, but there's no life on Titan.

And so it's telling us that the basic conditions
for a world where life can begin

could occur in many places,
but if temperatures are too cold,

the whole process is going to be slowed down.
And so, we're looking at an Earthlike world

where the chemistry has
just not gotten to the point yet.

In these oozing volcanoes, it
could be that organic molecules

are too frozen to combine and form
the more complex molecules of life.

But beneath the
surface, where it's warmer,

there could be living
microbes feeding on organic molecules

and producing some of the methane
in Titan's atmosphere.

Cassini will orbit Saturn
for years to come,

searching for more clues to the
oldest mysteries of the Lord of the Rings,

the age of the enigmatic rings
and how they were formed.

And the spacecraft will
continue to fly by Saturn's many moons.

Recently, Cassini revealed
that Saturn's fourth largest moon,

Enceladus, is erupting
plumes of icy crystals.

This suggests that pockets of water may
be just beneath the moon's surface,

adding Enceladus to the short list
of places in our solar system

that are
potentially suitable for life.

And Cassini will continue
to visit Saturn's largest moon,

a world both
alien and Earthlike,

a place that still
holds many secrets:

Titan, the
mystery moon of Saturn.