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Cosmos (1980): Season 1, Episode 6 - Travellers' Tales - full transcript

Carl Sagan looks at the planets Jupiter and Saturn by examining the work of Galileo, Huygens, and the Voyager probes.


Imagine that we are
travelers from the stars...

...bound for the sun.

We would discover it surrounded
by four giant, cloudy, gas worlds:

Blue Neptune and its
frozen moon, Triton.

And then farther in,
Uranus and its dark rings...

...made perhaps of organic matter.

Saturn, the jewel of the solar system...

...set within concentric rings...

...composed of a billion icy moons.

And finally, flanked
by massive satellites...

...the largest planet, Jupiter.

Its multicolored clouds...

...studded with flashes of lightning.

Still farther in...

...closer to the sun...

...there are no more giant planets...

...only a host of lesser worlds...

...made of rock and metal...

...some with a thin envelope of air.

They huddle about the sun...

...with almost no internal
heat of their own...

...tiny places with solid surfaces...

...one of which is a
blue and pretty world...

...called Earth.

Half-covered with clouds...

...it is the home planet of travelers...

...who have just learned
to sail the sea of space...

...to investigate close-up...

...Jupiter, Saturn,
Uranus and Neptune...

...its brothers and sisters
in the family of the sun.

Human voyages of exploration
to the outer solar system...

...are controlled, so far, from a
single place on the planet Earth...

...the Jet Propulsion Laboratory...

...of the National Aeronautics
and Space Administration...

...in Pasadena, California.

Here on Sunday, July 8th, 1979...

...the Voyager 2 spacecraft...

...began its close passage
by Jupiter and its moons.

General science systems...

JPL MAN: ...are you
ready with status check?

Yes, I am.

SAGAN: The spacecraft
had been instructed...

...how to explore the Jupiter system...

...by a sequence of
commands radioed earlier...

...to its onboard computers.

Power, 450 watts.

Power is go at this time.

DSE systems.

LACP mode is far and counter.

We are at take 210.

Direction last recorded was
reversed, and the track is track one.

Here we check how faithful
an emissary Voyager is.

Does it understand the commands?

How is its health, its temperature...

...its brains...

...its heart?

Yes, detailed science is coming up...

"A" systems...

...completed the status check...

...and the spacecraft is go.

Roger. Thank you.

SAGAN: The modern ships that
sail to the planets are unmanned.

They are beautifully constructed...

...semi-intelligent robots.

Voyager's eyes are two
television cameras...

...designed to take tens of thousands
of pictures in the outer solar system.

Along with other instruments, they
are mounted on a scan platform...

...which points at passing planets.

Voyager's brains are three
integrated computers set amidships.

It communicates with Earth
through a large radio antenna...

...mounted like a sail.

Voyager bears a message for
any alien civilization...

...it may one day encounter
in interstellar space.

Its louvers open and shut to help
control the onboard temperature.

But Voyager cruises
so far from the sun...

...that it cannot depend on solar power.

Instead, it has a small
nuclear power plant...

...quarantined from
the rest of the ship.

Many things can go wrong
in such pioneering missions.

So people are a little uneasy...

...at Voyager mission control.

Jupiter is surrounded by a shell of
invisible but extremely dangerous...

...high-energy charged particles.

If Voyager flies too close...

...its delicate
electronics will be fried.

A collision with a small boulder
in the rings of Jupiter...

...could send the spacecraft
tumbling wildly out of control...

...its antenna unable to find
the Earth, its data lost forever.

Voyager 1 and Voyager 2...

...were launched a month
apart in late summer of 1977.

After many alarms and close calls...

...they successfully arrived months
apart at the Jupiter system...

...where they worked brilliantly...

...providing the first close-up
views of mighty Jupiter...

...and its four large
and mysterious moons:

Io, the innermost of the four...

...Europa...

...and moving away from Jupiter...

...Ganymede...

...and the outermost big moon...

...Callisto.

In a mission that
costs a penny a world...

...for every human on the planet Earth.

Voyager's passage by Jupiter...

...accelerated it in a close
encounter with the planet Saturn.

Saturn's gravity will
propel it on to Uranus...

...and in this game of cosmic
billiards, after Uranus...

...it will plunge on past Neptune,
leaving the solar system...

...and becoming an
interstellar spacecraft...

...destined to wander forever...

...the great ocean between the stars.

And if Voyager should, sometime
in its distant future...

...encounter beings from some
other civilization in space...

...it bears a message.

A phonograph record. Golden, delicate...

...with instruction for use.

And on this record are a sampling
of pictures, sounds, greetings...

...and an hour and a
half of exquisite music...

...the Earth's greatest hits.

A gift across the cosmic ocean...

...from one island of
civilization to another.

The record bears in English...

...an additional handwritten
greeting that says:

"To the makers of music,
all worlds, all times."

These voyages of
exploration and discovery...

...are the latest in a long
series which have characterized...

...and distinguished the human species.

In the 15th and 16th centuries...

...you could travel from Spain
to the Azores in a few days.

The same time it takes now to
cross that little channel...

...from the Earth to the moon.

It took, then, a few months to
traverse the Atlantic Ocean...

...and reach what was
called the "New World"...

...the Americas.

Today it takes a few months to cross
the ocean of the inner solar system...

...and reach Mars and Venus,
wich are truly and literally...

...new worlds awaiting us.

In the 17th and 18th centuries...

...you could travel from Holland
to China, say, in a year or two...

...the same time it
takes now for Voyager...

...to travel from the Earth to Jupiter.

And in comparison to the
resources of the society...

...it cost more then to send
sailing ships to the Far East...

...than it does now to send
spaceships to the planets.

The passion to explore...

...is at the heart of being human.

This impulse to go, to see, to know...

...has found expression
in every culture.

Africa was circumnavigated
by Phoenician sailors...

...in the employ of
an Egyptian pharaoh...

...in the 7th century B.C.

The islands of the
Pacific were settled...

...by skilled and heroic
navigators from Indonesia.

Great fleets of ocean-going junks...

...left the ports of
Ming Dynasty China...

...to explore India and Africa.

A century later, three
ships left Spain...

...under the command of
an Italian navigator...

...to discover the Americas.

And then a Portuguese
expedition succeeded...

...in sailing all the way
around this blue globe.

These voyagers of many cultures...

...were the first planetary explorers.

They have bound the
Earth up into one world.

In our exploration of other worlds...

...we follow in their footsteps.

Our present spaceships
are the harbingers...

...the vanguard of future human
expeditions to the planets.

We have traveled this way before...

...and there is much to be learned...

...by studying those great
voyages of a few centuries ago.

In the 17th century...

...the citizens of the
new Dutch Republic...

...pursued a course of
vigorous planetary exploration.

Holland was then a
revolutionary society.

It had just declared its
independence from the powerful...

...but stagnant Spanish empire...

...and with a newfound
self-confidence...

...Holland embraced, more fully
than any other nation of its time...

...the spirit of the
European Enlightment.

It was a rational, orderly
and creative society.

But because Spanish ports and
vessels were closed to the Dutch...

...the economic survival
of the tiny republic...

...depended on its ability to
construct, man and operate...

...a great fleet of
commercial sailing vessels.

The Dutch East India Company...

...was a combined governmental
and commercial enterprise...

...which sent shipping to the
far corners of the world...

...to acquire rare commodities and
resell them at a profit in Europe.

Such voyages were the
life's blood of the republic.

Navigational charts and maps
were classified as state secrets.

Ships sometimes left with
sealed sailing orders...

...the crews embarking for
an unknown destination...

...more than a year away on
the far side of the planet.

These expeditions were not
only commercial exploitations...

...although there was
certainly plenty of that.

Beside the usual appeals
of ambition, greed...

...national pride and the
thirst for adventure...

...the Dutch were also motivated by
a powerful scientific curiosity...

...and a fascination
with all things new.

New lands, new peoples...

...new plants and animals.

This building, then the
Amsterdam town hall...

...still attests to the
hardy self-assurance...

...of its 17th-century architects.

Its lavish crystal
adornments still reflect...

...the glittering pride they
felt in their accomplishments...

...and their prosperity.

It took shiploads of
marble to build this place.

Constantin Huygens, a poet
and diplomat of the time...

...said that this town hall
dispelled what he called...

..."the Gothic squint and squalor."

The Middle Ages had ended,
the Enlightment had begun.

Up there, do you see...

...is Atlas supporting the
heavens on his shoulders.

And beneath...

...is Justice with a golden sword...

...and golden scales flanked...

...by Death and Punishment.

And who is it that Justice
is trampling underfoot?

Why, it's Avarice and Envy...

...the gods of the merchants.

The Dutch knew that the
unrestrained pursuit of profit...

...posed serious threats
to the soul of the nation.

A less allegorical symbol...

...is down here, on the floor.

It is a great inlaid map...

...stretching from West
Africa to the Pacific Ocean.

The whole world was
then Holland's arena.

In a typical year,
many sailing vessels...

...set out halfway around
the world for the Far East...

...on voyages of exploration
and discovery, of trade...

...journeys taking years to accomplish.

Down the west coast of Africa, through
what they called the Ethiopian sea...

...skirting the southern
coast of Africa...

...through the Straits of Madagascar...

...and on past the
southern tip of India...

...to the Spice Islands
and present-day Indonesia.

Another set of voyagers went
south then east, to New Holland...

...later renamed Australia.

And still other journeys ventured
through the Straits of Malacca...

...to the Empire of China.

But Holland was a small country
forced to live by its wits.

There was a strong pacifist
element in its foreign policy.

Never before or since has
Holland boasted such a galaxy...

...of scientists, mathematicians,
philosophers and artists.

This was the time of the
great painters, Rembrandt...

...and Vermeer.

Because Holland was tolerant
of unorthodox opinions...

...it was a refuge for intellectuals...

...fleeing the thought control and
censorship of other parts of Europe...

...much as the United States
benefited enormously in the 1930s...

...from the exodus of intellectuals...

...from Nazi-dominated Europe.

And so it was that
17th-century Holland...

...was the home of the great
Jewish philosopher Spinoza...

...who Einstein admired so much...

...of Ren Descartes,
a pivotal figure...

...in the history of
philosophy and of mathematics...

...and the home of a political
scientist named John Locke...

...who was to have a powerful...

...and profound influence...

...on a group of philosophically
inclined revolutionaries...

...named Paine, Hamilton, Adams...

...Franklin and Jefferson.

The Dutch University of Leyden...

...offered a professorship to an
Italian scientist named Galileo...

...who had been forced
by the Catholic Church...

...under threat of torture...

...to recant the heretical position...

...that the Earth went around
the sun and not vice versa.

Galileo had close ties with Holland.

His first astronomical
telescope was based...

...on a spyglass of Dutch manufacture.

And with it, he discovered
the craters of the moon...

...the phases of Venus and the
four large moons of Jupiter.

Becoming an exploratory power...

...made Holland a vital intellectual
and cultural center as well.

The improvement of sailing technology
spurred technology in general.

A key problem in navigation was
the determination of longitude.

Latitude could be determined easily...

...the farther south, the more
southern constellations you could see.

But longitude required
precise timekeeping.

An accurate shipboard clock...

...would continue to keep
time in your home port.

The rising and setting of stars
would give you the local time...

...and the difference between the two...

...would tell you how far
east or west you had gone.

Technological advance
required the freest...

...possible pursuit of knowledge.

So Holland became the leading
publisher and bookseller in Europe...

...translating works
written in other languages...

...and printing books that
had been censored elsewhere.

Adventures into exotic lands...

...and encounters with
strange societies...

...shook complacency.

They challenged the prevailing wisdom...

...and showed that ideas which has
been accepted for thousands of years...

...might be fundamentally in error.

In a time when kings and emperors
ruled much of the planet...

...the Dutch Republic was governed,
more than any other world power...

...by the people.

They enjoyed a certain
material well-being.

But the interiors of their houses...

...celebrated by a generation
of Dutch painters...

...suggest restraint and discretion.

The officers of these ships
of exploration and trade...

...would return from
their long voyages...

...share in the goods
they had acquired...

...and discuss the wonders
they had encountered.

Holland prospered in
its freedom of thought.

In Italy, Galileo had
announced other worlds.

Giordano Bruno had speculated
on intelligent life elsewhere.

For this they were
made to suffer brutally.

But in Holland, the astronomer
Christiaan Huygens...

...who strongly supported both
ideas, was showered with honors.

Christiaan was the son
of Constantin Huygens.

The elder Huygens
distinguished himself...

...as a master diplomat of
the age, a man of letters...

...a close friend and translator
of the English poet, John Donne.

Constantin Huygens was also an
accomplished composer and musician.

It was Constantin who had
discovered a young painter...

...named Rembrandt van Rijn...

...in several of whose works
he subsequently appears.

He opened the doors of his house...

...to artists, musicians, writers...

...statesmen and scientists.

A feast of goods and ideas...

...from all over the world awaited them.

The philosopher Descartes,
who visited him here...

...said of Constantin Huygens...

..."I could not believe
that a single mind...

...could occupy itself
with so many things...

...and acquit itself
so well in all of them."

He even excelled at
the art of parenthood.

He was a tender and loving father.

His son, Christiaan, flourished
in this rich environment...

...demonstrating extraordinary
talents for languages, drawing...

...law, science, engineering,
mathematics and music.

"The world is my country," he said...

..."science my religion."

Light was the motif of the age...

...the symbolic enlightenment of
freedom of thought and religion...

...the light that suffused
the paintings of the time...

...and light as an object
of scientific study.

The microscope was invented
in Holland at this time...

...and became a drawing-room curiosity.

Its inventor was a friend
of Christiaan Huygens...

...a man named Anton Leeuwenhoek.

The first microscopes
were developed from...

...magnifying glasses used by drapers...

...to examine the quality of cloth.

Leeuwenhoek and Huygens...

...are the grandfathers
of much of modern medicine.

Because, to his amazement...

...Leeuwenhoek discovered a universe...

...in a drop of water:

The microbes, which he
described as "animalcules"...

...and thought "cute."

Leeuwenhoek and Huygens...

...were among the first people
to see human sperm cells...

...a hitherto hidden microcosm
of the human life cycle.

Leeuwenhoek had discovered
the microbial world.

Huygens had argued from his
telescopic observations...

...that Mars was another world...

...and probably, an inhabited one.

What a waste of a planet, he thought...

...if Mars were barren.

So the Viking search
for microbes on Mars...

...can be traced directly back
to Huygens and Leeuwenhoek...

...in 17th-century Holland.

The telescope and the
microscope developed here...

...represent an extension
of human vision...

...to the realms of the very small...

...and the very large.

Our observations of
atoms and galaxies...

...were launched in this time and place.

From the bending of
light through a lens...

...Huygens advanced the idea...

...that light was a kind of wave.

He ground and polished lenses...

...for the successively larger
telescopes he constructed...

...although it did take
him a time to figure out...

...how to use them properly.

Huygens was the first person
to see a surface feature...

...on the planet Mars.

He was the first person to speculate...

...that Venus is completely
covered with clouds.

He was the first person to understand
the nature of the rings of Saturn.

"Saturn is surrounded," he wrote...

..."by a thin, flat ring...

...which nowhere touches
the body of the planet."

His discoveries with the telescope...

...who by themselves
have ensured his place...

...in the history of
human accomplishment.

Huygens was the discoverer of Titan...

...the largest moon of Saturn.

The immense size and changing
clouds of Jupiter entranced him.

Astronomers, as well as navigators...

...need accurate clocks to time
the movement of the heavens.

Huygens was the inventor of
many precision timepieces...

...including the pendulum clock.

To illustrate the sun-centered
universe of Copernicus...

...he built computers that reproduced
the clockwork of the heavens...

...from Mercury to Saturn.

The machines he designed, he signed...

..."Christiaan Huygens, inventor."

He was delighted that
the Copernican system...

...was widely accepted in
everyday life in Holland...

...and acknowledged by astronomers,
except those, he wrote...

...who "were a bit slow-witted
or under the superstitions...

...imposed by merely human authority.

Across the sea of space...

...the stars...

...are other suns."

A point which Huygens
appreciated perfectly well.

He reasoned that if
our planetary system...

...involved the sun and
planets going around it...

...that those other suns should
likewise have a retinue...

...of planets going around them...

...and also that many of the
other planets were inhabited.

He set forth these conclusions...

...in a remarkable book...

...bearing the triumphant title...

...The Celestial Worlds Discovered.

The subtitle is...

..."Conjectures Concerning...

...the Inhabitants,
Plants and Productions...

...of the Worlds in the Planets."

He wrote this book sometime
shortly before his death...

...in the year 1690, in this study.

By and large...

...he imagined that the
environments of the other planets...

...and also the inhabitants
of the other planets...

...were pretty much like
those of 17th-century Europe.

I wonder if he imagined...

...traveling to those other
worlds which he had been...

...the first to examine close-up...

...through the telescope.

Perhaps he dreamt that voyages
of discovery to the planets...

...would one day be like the
voyages of geographical discovery...

...in his time and place.

He did imagine of
extraterrestrial beings...

..."that their whole bodies,
and every part of them...

...may be quite distinct
and different from ours.

'Its a very ridiculous
opinion," he says...

..."that it is impossible
a rational soul...

...should dwell in any
other shape than ours."

You could be smart,
Huygens was saying...

...even if you looked funny.

But he then went on to argue...

...that they didn't
look all that funny...

...that extraterrestrial
beings must have...

...hands and feet and stand upright...

...and have writing and geometry.

Even that the four moons of Jupiter...

...the Galilean satellites,
were there in order to provide...

...a navigational aid, a convenience...

...for the sailors in the Jovian oceans.

Well, maybe.

(WOOD CREAKS)

That bit of speculation
is probably wrong, but...

...think of a citizen
of the 17th century...

...with the courage and insight...

...to imagine other landscapes
and other intelligences.

Might there really be mariners...

...on a million other worlds?

In his book, Huygens wrote:

"What a wonderful and
amazing scheme have we here...

...of the magnificent
vastness of the universe.

So many suns. So many earths.

And every one of them
stocked with so many animals.

Adorned with so many seas.

How must our wonder and
admiration be increased...

...when we consider the prodigious
distance and multitude...

...of the stars?"

The Dutch called their
ships "flying boats"...

...and the Voyager spacecraft
are their descendants...

...true flying boats...

...bound for the
stars, and on the way...

...exploring some of those
worlds which Christiaan Huygens...

...a man from Earth...

...knew and loved so well.

Travelers' tales:

A main commodity...

...returned by those sailing
ship voyages of centuries ago...

...were stories.

Stories of alien lands
and exotic creatures.

They evoked a sense of wonder and
stimulated further exploration.

Those tales of strange worlds...

...enabled some Europeans
to see themselves anew.

There had been accounts of
headless people, foot people...

...cyclops people.

Now the Dutch brought
back fantastic stories...

...of giant hunters...

...dodoes...

...rhinos...

...leopards...

...and other creatures.

Modern voyagers also
return travelers' tales:

Tales of a world shattered
like a crystal sphere.

A place where the ground is covered...

...with what looks like
a network of giant cobwebs.

A world with an underground ocean.

Tiny moons shaped like potatoes.

A yellow and red pockmarked land...

...with lakes of molten sulfur...

...and volcanic eruptions
300 kilometers high.

And a place called Jupiter...

...so large that a thousand
Earths would fit inside.

There are no mountains, valleys,
volcanoes or rivers there.

Just a vast ocean of gas and clouds.

Everything we see on Jupiter
is floating in the sky.

But there's much that is
fascinating about Jupiter.

As the solar system condensed out
of interstellar gas and dust...

...Jupiter acquired most of the matter
not ejected into interstellar space...

...and which didn't fall
inwards to form the sun.

Jupiter is made mostly of hydrogen
and helium, just like the sun...

...and had Jupiter been a few
dozen times more massive...

...the matter in it...

...might have undergone thermonuclear
reactions in the interior...

...and Jupiter would have
begun to shine by its own light.

Jupiter is a star that failed.

Had it become a star...

...we would be living in
a double-star system...

...with two suns in our sky...

...and the nights
would come more rarely.

Deep below the clouds of Jupiter, the weights
of the underlying layers of atmosphere...

...produce pressures
which are much greater...

...than any that are found
anywhere on the Earth.

The clouds are this layer here.

The deep interior is
this high-pressure place.

The pressure is so large...

...that electrons are squeezed
off hydrogen atoms, producing...

...liquid metallic hydrogen.

But at the very core of
Jupiter, there may be a lump...

...of rock and iron...

...a giant Earth-like world
under astonishing pressures...

...hidden forever at the
center of the largest planet.

Just before Voyager...

...encountered Jupiter, you could
see that giant planet at night...

...shining in the sky as our ancestors
have for the last million years.

And on my way to study
the Voyager data...

...arriving at the Jet
Propulsion Laboratory...

...I thought that Jupiter
would never be the same again.

Never again just a point
of light in the night sky...

...but forever after, a place
to be explored and known.

To see the first close-up images
of a world never before known...

...this moment is one of a greatest joys
in the life of a planetary scientist.

In the early morning hours of
July 9th, 1979, on the real-time...

...television monitors at the
Jet Propulsion Laboratory...

...we began to learn about
a world called Europa.

These are the modern explorers.

Men and women trained...

...in astronomy, physics,
geology or engineering.

Many devoting five to eight
years to this single mission.

JPL MAN: Cassen's model for Europa
says if you start with a liquid...

...you can put in enough
energy to keep it liquid.

But Cassen said in order for there
to be enough heating going on...

...you had to start the heating
before Europa basically cooled off.

But what about relief from the cracks?

...and Europa there's
a twin, a pair there...

You can't look at a world
so different from ours...

...without wondering how both were made.

Just rotate it out a little bit.

Voyager presented us with six new
worlds in the Jupiter system alone.

The more you learn about other worlds,
the better you understand our own.

We speculate, criticize, argue,
calculate, reflect and wonder.

We return again to the
astonishing data, and slowly...

...we begin to understand.

The Dutch sailing ships brought
back rare and valuable commodities...

...from the new worlds they visited.

Our Voyager spaceships...

...return rare and
valuable information...

...to computerized wharves on
this shore of the sea of space.

Here the data are allowed to be stored,
enhanced, processed and treasured.

Maps of alien lands will be
generated from this information.

In this electronic warehouse are
tens of thousands of images...

...of previously unknown worlds.

How does a picture from the
outer solar system get to us?

Sunlight shines on Europa, and
is reflected back to space...

...where some strikes the phosphors...

...of the Voyager television
cameras, generating an image.

The image is radioed back
across the immense distance...

...of half a billion kilometers...

...to a radio telescope on
Earth. One in Australia, say.

The telescope then
passes the information...

...via communications
satellite in Earth orbit...

...to Southern California.

There, it's transmitted by a
set of microwave relay towers...

...to a computer at the
Jet Propulsion Laboratory...

...and there it is processed.

The picture is like a
newspaper wire photo...

...made of perhaps a million individual
dots of differing shades of gray...

...so fine and close
together that at a distance...

...the constituent dots are invisible.

We see only their cumulative effect.

The information for the spacecraft
specifies how bright or dark...

...each dot is to be.

After processing, the dots are
stored on a magnetic disk...

...something like a phonograph record.

By this day, there were already 11,000
pictures from Voyager 2 in our...

...electronic library.

Finally, the end product
of this remarkable set...

...of links and relays...

...is a hard copy which comes
out of this machine showing...

...in this case, the
wonders of Europa...

...which were recorded for the
first time in human history, today.

It is absolutely astonishing.

Voyager 1 got very good pictures
of the other three big moons...

...Galilean satellites of
Jupiter, but not of Europa.

It was left to Voyager 2 today...

...to get the first close-up
pictures of Europa...

...where we see things that are
only a few kilometers across.

At first glance, it looks
like nothing so much as...

...the canal network of Mars that Percival
Lowell imagined existed on that planet.

We see an amazing, intricate
network of crisscrossing...

...straight and curved lines.

Are these straight lines ridges?

Are they troughs?

Is it connected with plate
tectonics on the Earth?

How does it illuminate the other
satellites of the Jovian system?

At this moment, the
vaunted technology...

...has produced something astonishing.

But it remains for...

...the limitations and
cleverness of another device...

...the human brain, to figure it out.

Fortunately, we have plenty
of pictures to help us.

What about Gene's idea of
geysers down the troughs?

Geysers down the troughs?

LARR Y SODERBLOM: You need
a mechanism to drive it.

SAGAN: Larry Soderblom,
Voyager imaging team.

LARRY: An idea was proposed a while
ago that we might have a sort of...

...champagne-bottle
model. And that's...

You seal the crust and have
liquid underneath that solid crust.

Do you have then a condition which
is an explosive effervescence?

SAGAN: Lonnie Lane,
deputy project scientist.

You have enough resolution in
some of these pictures that...

...you don't see
anything spread laterally.

Do we have the high-resolution piece?

-It was right here.
-There it is.

We'll pick out the relief,
and if we're going to see...

...the things we recognize...

SAGAN: Weeks after the pictures
from Europa were received...

...we were still
debating what was in them.

It's as if we almost got to the...

Look at the mesas here.

We almost got the resolution
needed to see the craters.

The craters which would last
indefinitely on a crust this thin.

Apart from the rseaus...

...there's a set of very
fine small dots, markings...

...mostly in the mottled terrain.

Like those guys. Do
you think those are...

...sites of outgassing,
calderas, fumaroles, solfataras?

I don't know, but I'll tell
you one thing I just found...

Look right here.

It disappeared.

See the central peak?

See the little hole?

I think it's an impact crater.
Look at the central peak.

SAGAN: There are almost
no impact craters.

Wait, we just found one.

Almost none.

Therefore, finding one which is
alleged to be the exception...

...maybe it's not the
exception, but something else.

Perhaps, but you asked about those
little holes that we can't make out.

The big craters go away by
some rheological deformation...

...and the little ones stay
but are out of our resolution.

That's because they're one-tenth
the depth of the rigid crust.

Well, maybe.

SAGAN: Computer processing of
the pictures has revealed...

...at least a few features on Europa
which seem to be impact craters.

But something...

...has wiped out the big craters.

Computer processing also
played a major role...

...in one of the most amazing Voyager
discoveries made on the moon next to Europa...

...a world called lo.

Even from Earth we could tell
that lo had a strange color.

We knew that somehow sulfur had
been removed from its surface...

...and ejected into a great
doughnut of gas orbiting Jupiter.

Then Voyager 1 sailed close to lo.

There were a few places on lo which
looked like the mouths of volcanoes...

...but it was hard to be sure.

Then, Linda Morabito, a member
of the Voyager navigation team...

...used a computer to enhance
in a picture the edge of lo...

...in order to bring
out the stars behind.

Four days after the Voyager
1 encounter with Jupiter...

...I was looking at an
optical navigation frame.

In enhancing this particular quadrant,
what became very evident to me...

...was an anomalous crescent...

...in the upper left-hand
corner, just off the limb of lo.

SAGAN: What was it?

The plume was in exactly the position...

...of one of the suspected volcanoes.

We realized then that
what we were observing...

...was a volcanic plume and,
in fact, a volcanic eruption.

SAGAN: Voyager had discovered the
first active volcano beyond the Earth.

We then found that
lo has many volcanoes.

There are at least nine
intermittently active plumes...

...and hundreds, maybe
thousands, of extinct ones.

The plumes can eject sulfur and
other atoms off lo altogether...

...and account for the sulfur
clouds surrounding Jupiter.

Rivers of molten sulfur flow down
the sides of the volcanic mountains...

...and are the probable source
of Io's distinctive colors.

The volcanoes may be tapping some vast
underground ocean of liquid sulfur...

...beneath a surface that is
only a few thousand years old.

So far, in our voyages to
the outer solar system...

...we humans have stayed home...

...and sent robots and computers
to explore in our stead.

Someday, perhaps, we'll go ourselves.

But suppose...

...like those Dutch sea
captains of the 17th century...

...the computers aboard
Voyager could keep a ship's log.

That log, a combination of the
events of Voyagers 1 and 2...

...might read something like this:

Day 1: After much concern about
provisions and instruments...

...we successfully lift off from
Cape Canaveral on our long journey...

...to the planets and the stars.

Day 13: We have taken the first
photograph of the Earth and moon...

...as worlds together
in space. A pretty pair.

Day 170: A problem in the
deployment of the boom...

...that supports the
science scan platform.

If the problem is not solved...

...we will be unable to
take most of our pictures.

Day 207: Boom problem solved, but
failure of main radio transmitter.

If the backup transmitter also fails...

...no one on Earth will
ever hear from us again.

Day 215:

We cross the orbit of Mars...

...and enter the main asteroid belt.

Day 570: We can now make out
finer detail on Jupiter...

...than the largest telescopes
on Earth have ever obtained.

Day 640:

The cloud patterns are
distinctive and gorgeous.

No painter trapped on Earth...

...ever imagined a world
so strange and lovely.

The white clouds are ammonia
crystals, high and cold.

We do not know the nature
of the red-brown clouds.

Maybe phosphorous or sulfur as a stain.

Perhaps complex organic molecules of the
sort that led, four billion years ago...

...back on Earth, to the origin of life.

And what is the great red spot?

(COMPUTER HUMS)

It is an immense
swirling column of gas...

...reaching high above adjacent clouds.

So large that it could
hold half a dozen Earths.

Its motion hypnotizes us.

Some think that the red spot
is a great spinning storm...

...a million years old.

Day 650: Encounter. A day of wonders.

The ship maneuvers so
we can take pictures...

...of the multi-ringed
basin on Callisto.

Images of the astonishing
lined surface of Ganymede.

A close passage by Europa.

And, a view of volcanic lo.

We successfully negotiate the
treacherous radiation belts...

...and accomplish the
ring plane crossing.

Looking back, we marvel at the rings...

...and see the sun emerge
from behind the giant planet.

We are outward bound on our mission
to explore the outer solar system.

Ten thousand years from now...

...Voyager will plunge
onward to the stars.

We have made the ships
that sail the sea of space.

We travel past Jupiter...

...three quarters of a billion
kilometers from the sun...

...Saturn, one and a half
billion, Uranus, three billion...

...and Neptune, four and a
half billion kilometers away.

In our ship of the mind...

...we retrace the itinerary of
the two Voyager spacecraft...

...on their journeys
to Saturn and beyond.

Saturn was first glimpsed
through the telescope by Galileo.

Its rings first understood by Huygens.

But only now do we begin to
penetrate its deeper mysteries.

Saturn is the second largest
planet in the solar system.

Like Jupiter, it is cloud-covered,
and rotates once every 10 hours.

It has a weaker magnetic field,
a weaker radiation belt...

...and a grand, magnificent...

...exquisite system of rings.

The rings are composed of
billions of tiny moons...

...each circling
Saturn in its own orbit.

The biggest gap in the rings is
called the Cassini Division...

...after the colleague of
Huygens who first discovered it.

There are many other gaps...

...each produced by the
periodic gravitational tugs...

...of one of the larger outer moons.

From just beneath the ring plane...

...we see a sky full of moons.

Within the rings, the
individual moons become visible.

They are orbiting
chunks of snow and ice...

...each perhaps a meter across.

In young parts of the ring system,
there hasn't been enough time...

...for collisions to round
the edges of these fragments...

...the snowballs of Saturn.

Far from the rings,
bathed in its red light...

...we encounter Saturn's
immense cloud-covered moon...

...Titan.

It has an atmosphere
denser than that of Mars...

...and a thick layer of red clouds...

...which are probably composed
of complex organic molecules...

...produced by solar ultraviolet
light and other energy sources...

...from the methane-rich air.

No ship from Earth has ever
penetrated those clouds...

...and viewed, close-up, the
surface of this tantalizing world.

It seems likely that the
ground is covered, encrusted...

...with organic molecules
raining from the sky.

There may be volcanoes
and valleys of ice...

...and, just perhaps...

...hiding in the warm places,
some very different kind of life.

Near an ice cliff of Titan...

...through a rare break in the
clouds of organic molecules...

...we can see, looming and
lovely, the ringed planet, Saturn.

It is a view that will still be
appreciated centuries from now...

...by our descendants,
who will know it well.

As well as we have come to know...

...Hudson's Bay and the Barents Sea...

...Indonesia, and
Australia and New York.

They will look back to when Titan was
first seen by Voyager spaceships...

...on their epic journeys
past the giant planets...

...out of the solar system...

...to the great dark between the stars.

Since Cosmos was first shown...

...Voyager spacecraft have explored
the systems of the planets...

...Saturn, Uranus, and Neptune...

...and have now passed the outermost
planets on their way to the stars.

We inserted the flavor of those
encounters in our captain's log.

But with image processing...

...we've been able to
reconstruct astonishing movies...

...of some of these worlds.

Here, for example, is Jupiter,
with its great red spot.

And volcanic lo, spinning before us.

Icy Enceladus, a tiny moon of
Saturn, on much of which, somehow...

...the craters have melted.

And Miranda, of Uranus.

Austere, blue Neptune.

Or consider Titan, the
giant moon of Saturn.

We've taken the nitrogen and
methane in its atmosphere...

...irradiated it in the lab with
electrons of the sort that are...

...beamed at Titan from
Saturn's magnetic field...

...and we made this stuff...

...which matches, almost perfectly, the
observed properties of the Titan haze.

What is it?

It's a mixture of
complex organic molecules.

You drop some into water and,
among other things, you make...

...amino acids, the
building blocks of proteins.

So the starting materials of life...

...are raining from the skies
of Titan, like manna from heaven.

I can't wait until
the Cassini mission...

...sends an entry probe through
the organic haze of Titan...

...to its enigmatic surface.

The Voyager spacecraft rush on
past the planets and to the stars...

...still returning data.

As it left the planetary
part of the solar system...

...Voyager 1 turned back...

...to take one last portrait of
the planets of the solar system.

...and one of those
pictures was of the Earth.

A tiny blue dot, set in a sunbeam.

Here it is.

That's where we live. That's home.

We humans are one species,
and this is our world.

It is our responsibility to cherish it.

Of all the worlds in our solar system,
the only one, so far as we know...

...graced by life.