Destiny In Space Page #2

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orbiter and the satellite ...

the crew learned that they

could tighten it once again ...

showing that we can

control tethers in space.

Tether's under control.

Unexpected snags

are bound to arise.

But we learn from them

and keep moving forward.

To build more reliable spacecraft,

we need light but tough materials.

To test them, in 1984

we launched a satellite ...

with dozens of materials

attached to its surface ...

exposing them to the

wear and tear of space.

Columbia, Houston.

We have a tally-ho on LDEF.

We left it in orbit for six years,

long enough for an interplanetary trip.

Ready to go get it?

Then the shuttle retrieved it

and took it back to Earth.

We found a wealth of information

embedded in these panels.

Splatters.

As the microscopes reveal ...

the vacuum of space

is anything but empty.

This pattern, I don't

know what this is.

A continuous bombardment

of micrometeorites ...

pitted the surfaces with craters.

But the most serious hazard

in space is radiation.

As the shuttle hangs suspended

above the Earth's horizon ...

we see only the lights of

its cargo bay in the darkness.

But we can't see the harmful cosmic

radiation that is everywhere here.

High-energy charged particles ...

are streaming out from

the Sun and other stars.

On Earth, we are protected

by the atmosphere ...

and the surrounding

magnetic field.

In space, the radiation can

penetrate the walls of our craft.

A Japanese x-ray satellite reveals

vast clouds of radiation ...

erupting from the Sun.

On interplanetary trips ...

we'll have to retreat to

heavily shielded onboard shelters ...

whenever solar storms are sighted.

Most of the planets are too

hostile for people to visit.

But that doesn't stop us

from exploring them.

Okay, understand. We have a go

for deploy, so we're starting out.

Five, four, three ...

two, one, mark.

- Do we have motion?

- I see motion.

It's stable? It's clear of the ASE.

Where humans cannot safely go ...

we send remotely controlled

robot explorers.

Commanding them from Earth ...

we use their electronic eyes and sensors

to explore the alien landscape.

In 1989, the Galileo spacecraft ...

began a five-year journey to Jupiter ...

the largest planet

in our solar system.

Galileo just kind of dissolves

out into nothingness ...

as it goes into the

darkness of space.

And that's the last we saw of it.

Early images of Jupiter were

sent back to Earth in 1979 ...

by two robot probes named Voyager.

This was our first opportunity

to marvel at its Great Red Spot ...

three times the size of Earth.

The molecular building

blocks for life ...

may be swirling within Jupiter's

turbulent atmosphere.

If Galileo's probe confirms this ...

we should gain new insights

into the origins of life.

Though it is our nearest planetary

neighbor, Venus was always a mystery.

Thick cloud layers blocked

our view of its surface.

Then we sent a spacecraft

named Magellan to orbit the planet.

Its radar eyes could see

through the clouds.

Magellan collected so much data ...

that we can now explore the surface

as if we were actually there.

We begin 60,000 feet up.

To help scientists

recognize its features ...

a computer has exaggerated the

height of the terrain 10 times.

Perhaps these pancake domes ...

were caused by lava pushing through

weak spots in the surface.

These craters, some the

size of Connecticut ...

were made by collisions

with comets and asteroids.

On Earth, ancient craters like these

have been eroded by wind and water.

But there is little

wind and no water here.

Venus swelters beneath a thick

atmosphere of carbon dioxide ...

which acts like a greenhouse:

It allows sunlight to filter in,

but then traps the heat inside.

The surface temperature

is hot enough to melt lead.

In the distance, the great

Gula Mons volcano.

We are now soaring more than

The long, smooth strips

that now and then cross our path ...

are small portions of the surface

that Magellan's radar did not scan.

The Magellan craft has shown us the

fantastic surface of an alien planet ...

where no human could

ever hope to land.

But there is another world in our

solar system that people can visit.

Future generations of explorers

will walk upon Mars.

Do you know what that is?

To prepare the way for them,

we could send a robot like this ...

to scout a landing site.

We might dispatch a whole flock of

these helpers to explore the terrain.

Unlike us, they are almost

immune to radiation ...

and need no air or water.

And they never get homesick.

Robots like this

Russian Mars rover ...

being tested in

Death Valley, California ...

have already been programmed

for difficult tasks ...

like negotiating rugged terrain.

More elaborate versions could

help us construct a Mars base.

But operating them

will be a challenge.

At the speed of light,

a single command ...

takes up to 20 minutes to

travel from Earth to Mars.

If there is or ever has been life

somewhere else in the solar system ...

Mars is a good place

to look for traces.

A great rift valley splits

open the Martian plain.

It is as long as the

entire United States.

We are now descending

from 40,000 feet ...

into a part of the valley

known as Candor Chasma.

It is five times deeper than

the Earth's Grand Canyon.

The height of the terrain

has not been exaggerated.

This is how it really looks.

Life as we know it must

have liquid water to develop.

Water may have flowed

through these canyons long ago.

Perhaps it nourished life.

Fossil life forms may lie exposed

on the floor of these canyons.

If we find any, it would

be our first proof ...

that life has existed beyond Earth.

It would mean that life

probably is abundant in our galaxy ...

and awaiting discovery

in the universe beyond.

Today, Mars is a frozen world.

The average temperature here is

lower than at the Earth's South Pole.

But long ago, when water

may have flowed here ...

it must have been warmer.

We don't know

why Mars turned so cold ...

but perhaps it could be made

to change once again.

Could future generations

somehow transform Mars ...

into an Earth-like world

where people could live?

To do it, we might imagine some-

how raising the temperature ...

to build up the atmosphere

and melt the ice caps.

This would create

lakes and rivers.

Then we could introduce plants

to fill the air with oxygen.

Animals and people

could now breathe the air.

A new world might be ready

for us to colonize.

What would life be like on Mars?

Perhaps we could

build farms and cities.

Or perhaps we will leave

Mars as we found it.

Those decisions will be

made by our descendants.

If terraforming is even possible,

it would take thousands of years.

By then, we may have

left our solar system ...

to explore the stars beyond.

Though it would take about 100,000 years

to reach them with present technology ...

future generations

may travel faster.

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