All language subtitles for The Universe - 2x08 - Space Travel.en

ln the beginning,
there was darkness...

and then, bang...

giving birth to an endless
expanding existence...

of time, space, and matter.

Now, see further
than we've ever imagined...

beyond the limits of our existence...

in a place we call "The Universe."

lt promises
to deliver technologies...

that will carry us
everfarther and everfaster.

But it's fraught with constant
and lethal peril.

Flying in outer space is like
going through a shooting gallery.

lt will test the limits of human capacity
and human ingenuity.

lf something goes wrong,
what do you do?

Nothing. Youjust die.

Welcome to the age
of space travel.

ln ways scarcely even imagined,
the steady hand of progress...

is poised to deliver humanity
to the heavens.

For ages, the mysterious
splendor of the universe...

has enticed us
from its remote heights.

At last, its mysterious
temptations are within reach...

and man's destiny
can be fulfilled.

l don't know
if it's writ in our genes...

but anytime you see
something at a distance...

and it piques your curiosity...

the first thing you want to do
is get a closer look.

So, while telescopes get you
pretty far in this regard...

those things that are
sort of close enough...

to be within the reach
of our space program...

why not take the trip?

T-minus ten, nine...

main engine start.

Five, four, and lift-off
of Space Shuttle "Atlantis."

Prying free
from our home planet's grip...

ranks among the greatest
of human achievements.

But no one since 1972 has ventured
beyond the Earth's orbit.

Our space program
has been stuck for thirty years.

We simplyjust go
around the planet Earth.

lt'sjust like Columbus exploring
the NewWorld for the first time...

and then spending
the rest of his life...

simply puttering
around the Spanish coastline.

What's the problem?

There's a dirty
little four-letterword...

and that is "cost."

lt costs about $10,000 to put
a pound of anything into orbit.

lmagine John Glenn
made out of solid gold.

That's what it costs to put
John Glenn oryou into orbit.

lt would cost about $20 million...

foryou to take a weekend trip
up to the Space Station.

lt would cost about
a half a billion dollars...

foryou to go to the Moon.

And foryou to go to Mars...

would probably cost
tens of billions of dollars.

One way to reduce the cost
of reaching space...

would be to find a more efficient way
to overcome Earth's gravity.

Remember the story
of Jack and the Beanstalk?

Jack was a little boy who climbed
the beanstalk into heaven.

Well, imagine a space elevator
such that you hit the "up" button...

and the elevator
takes you into the heavens...

just like
Jack and the Beanstalk.

lnstead of building
from the ground up...

the space elevatorwould be
built from the top down.

A satellite
in geosynchronous orbit...

would drop
a 60,000-mile cable back to Earth...

where it would be anchored
to the surface.

Nowwe are within striking distance
of being able to create fibers...

that can withstand the tension...

oftraveling at enormous
velocities in outer space...

as the space elevator
rotates with the planet Earth.

So it never falls
because it rotates...

at the same rate
as the planet Earth.

The elevator"s compartment
would simply roll up the cable...

shuttling travelers
and supplies into orbit...

where it would wait
for a spacecraft.

This system would entirely replace
a conventional rocket launch.

And that might reduce
the cost of space travel...

by a factor of a thousand.

Think about that.

Then you begin to realize
that perhaps a trip to outer space...

may be no worse
than an airplane ticket.

But beyond the limits
of Earth's comforting embrace...

exotic menaces
await every space traveler.

Flying in outer space...

is not like taking a nice ride
in the country in a car.

lt's like going through
a shooting gallery.

To an unsuspecting voyager...

it might seem the universe
is taking aim with a firearm.

There are particles in space...

even dust-sized particles,
pebble-sized particles...

that are traveling tens
of thousands of miles an hour...

and sometimes even faster.

More than half a million
of these projectiles...

measuring
over an inch in diameter...

are zipping around
our planet right now.

They include pieces of glass
broken off of solar cells...

paint chips from spacecraft...

and debris
from rocket booster engines.

And in deeper space,
there's more danger...

from pebble-sized meteors
called micrometeoroids.

A small piece of dust can crack glass,
it can penetrate metal...

it can pulverize plastic.

And that does happen in space
all the time.

But perhaps
an even more deadly danger...

not at all solid, lies in wait:
Radiation.

The devastating effects
of this invisible energy...

have been witnessed on Earth...

in the aftermath of the atomic
bombs ofWorld War ll...

and the nuclearfallout
of Chernobyl.

Distressingly,
our own life-giving Sun...

spews out streams
of poisonous radiation.

So realize that we've been
protected in this cradle.

We've been protected
by the atmosphere of the Earth.

The magnetic field
of the Earth gobbles up...

most of the flares from the Sun
to create the Aurora Borealis.

ln outer space, you get the Aurora
Borealis coming right at you.

There's no ozone layer...

there's no magnetic field
to protect you.

lt'sjust you and the harshness
of outer space.

At our home planet's
distance from the Sun...

roughly ninety million miles away...

several hundred million
solar particles...

pass through
each square inch of space...

every second around our Earth.

There's high-energy particles
streaming from the Sun all the time.

But every now and then...

there's an extra dose
ofthese particles.

The Sun burps up
high-energy radiation.

That's bad, too.

That level of radiation
it is never good for one's DNA.

Sunspots flare up
these extra doses of energy...

like a battery of cannons
bombarding the cosmos.

There's no way to know
that they're going to be here...

before they arrive.

Unfortunately,
there's still a risk of radiation...

even as we get
fartherfrom the Sun.

That's because
another invading energy lurks.

Known as galactic cosmic rays...

they hail from
the distant alien worlds...

of exploding stars
and black holes.

Galactic cosmic rays are particles
that are traveling at speeds...

very close to the speed of light.

Even a single particle of iron
slamming into your body...

can have the effect
of a Major League baseball...

at a hundred miles an hour.

They can be devastating.

Although heavy iron particles
are rare...

outside of the protection
of a spacecraft...

such as when an astronaut
performs a spacewalk...

thousands
of galactic cosmic rays...

do penetrate
the body every second.

Every 24 hours, the galactic
cosmic rays and solar particles...

attack a space traveler
with as much radiation...

as a surface dweller on Earth
receives in six months.

The human body won't immediately
feel the impacting radiation...

but in sufficient quantities,
it can be noticed.

Even with eyes closed,
the particles spark flashes...

when they strike
a space traveler's retina.

The flashes are not blinding,
and you have to ask yourself,

"Hmm, did l see something?"

And then you say,
"Oh, yes, l did."

And then its appearances are
a little different from time to time.

However, the human body
does feel the shock...

of this bizarre
weightless existence.

l think that the most dangerous thing
going into space...

is the loss of gravity.

Weightlessness causes
almost every system in your body...

to start changing,
and it doesn't stop changing...

until you get back onto a world...

where you're pulled down again
by its gravity.

One of the first casualties
of zero gravity...

is a space traveler's
sense of direction.

What's up and what's down?

Very good question.

And first of all,
it's whateveryou want it to be.

lfyou want this to be up,
that's fine...

but ifyou want this to be up,
that'sjust as good.

Most travelers will suffer
from motion sickness...

for the first few hours
or, most likely, days.

lt'sjust one of those things...

that you ought
to resign yourself to facing...

that everyone is very likely
to feel a little bit disturbed...

in terms of orientation.

Here on Earth,
scuba divers floating underwater...

experience the nearest sensation
of prolonged periods without gravity.

lt is for this very reason
that aspiring NASA astronauts...

train to live and work
in a gravity-free environment...

by subjecting themselves
for up to six hours at a time...

in a large water tank.

Now, scuba equipment, you still
experience the forces of gravity...

but it doesn't feel like it
because yourwhole body...

is uniformly buoyed by the water
that holds you up.

And except for the visual cue of
air bubbles floating to the surface...

swimming underwater can mimic
the sensation of disorientation.

But, as time passes
in the weightlessness of space...

the human body senses it no longer
needs to resist the force of gravity...

and begins shedding muscle
and bone mass.

When you're in space...

your body thinks you might
as well be lying in bed.

And so ifyou're not careful,
your bodywill atrophy.

To counter this,
each day in space...

an astronaut needs to exercise.

The legs are especially vulnerable
because they are seldom used.

ln this world, the arms and hands
do most of the work...

to move the body around.

What would be
the toughest thing to get used to...

might very well be
just how you live in space...

where you can't walk
across the room.

You have to float
everywhere you're going.

The lack of gravity also slows
down the digestive tract...

which can cause
problems at mealtime.

Your digestive system stops.

You can't eat,
you can't drink...

until you can start
digesting again.

And that can take anywhere
from hours to days.

Worse still, zero gravity
and radiation can combine...

in an especially sinisterway.

ln space, the immune system
is not as effective as it normally is.

And many of the bacteria
and viruses...

that we normally can withstand
become more virulent.

Additionally, bacteria can
grow up to fifty times faster...

and any virus brought onboard...

could mutate into
a never-before-seen predator...

thanks to the ever-present radiation.

All these difficulties
prey on space travelers...

injust the first few hours
or days.

And what aboutjourneys
that need more time?

lt only gets tougher.

The universe
is an unforgiving place.

lt's open to only
the boldest adventurers...

those who have the mettle
to trek deep...

into an environment
swimming with toxic hazards...

and unafraid to stray far
from the safe and familiar.

We take it for granted
that clothing is flexible...

and machines work
in room temperature...

because, implicitly or explicitly,
they're designed for that.

You go into the depths of space,
ifyou're facing the Sun...

it could be hundreds
of degrees Fahrenheit.

lfyou're facing away
from the Sun...

it could be hundreds
of degrees below zero.

Down here on Earth,
you take so much for granted.

You know, we're out here...

the sunshine,
the fresh air all around you.

Up there,
you're in a closed ecosystem.

You have to supply
all the human needs...

that the Earthjust, you know,
automatically does for us.

You have to hope that
the integrity of the hull...

stays together so you don't have
rapid decompression...

quick suffocation.

The same reality
exists for a submarine...

gliding deep
through the ocean.

lt provides a life-preserving barrier
to protect its inhabitants...

from a surrounding alien world.

lf there's damage to the spaceship,
air leaks out, you die.

Damage to submarine,
water gets in, you die.

So the isolation,
both physically and personally...

between the two
seems quite parallel.

The potential
for a catastrophic mishap lurks.

When you're out
in the middle of the ocean...

you have only yourself and
your colleagues to rely on...

and the same thing
applies in space.

Things have to hold up.

You can't come back.

You can't run
to the hardware store.

You can't fix the thing with some part
that you didn't bring along.

And you're stuck
with human ingenuity...

the tools you brought with you.

And out there in space...

you truly arejust removed
from mankind.

lt is isolation
like l've neverfelt before.

Liftoff, we have liftoff...

Often our efforts to explore
space have been analogized...

to the great explorers
of the 15th and 16th century...

the first to cross the oceans,
going to unknown territory...

having to bring
all their supplies with them...

not knowing
if they'll ever return.

And l think there's a lot
to say about that analogy.

But there's a point
where it breaks down badly.

When Cortes
landed in South America...

when Columbus
hit the Caribbean...

there was still air there
for him to breathe, all right?

There was fruit on the trees.

Suppose the Apollo 11 astronauts,
Neil Armstrong and BuzzAldrin...

landed on the Moon
and, like, the engine broke.

Okay, Houston,
we've had a problem here.

What do you do?

Nothing. Youjust die.

There's not
sort of an engine tree...

that they can pluck parts from
to repair their ship.

So the hazards are
vastly greater to human health...

in space exploration than traveling
anywhere on Earth's surface.

There won't be
any service stations...

in case you break down,
run out of gas...

or need something to drink.

One of the challenges
of space exploration...

is either
carrying along with you...

all the supplies you need--
water, food, oxygen--

orfinding some way
to manufacture that...

en route or at your destination.

We're not there yet.

We don't know
how to do that yet.

And so one hazard is,
if something goes wrong...

and you run out offood and water
and shelter, that's bad.

You'll die.

Every sip,
every drop ofwater is precious.

On a space voyage, there
will be no such thing as a shower.

The only option
will likely be a wet cloth.

This is quite a change
from the 130 gallons ofwater...

each American consumes
injust one day.

The cuisine onboard would take
some getting used to as well.

For a few days, you can take
fresh fruits and fresh vegetables...

carrots and apples
and things like that.

For the longer missions, though,
you have to have storable foods...

that can, you know,
stay for long periods of time...

without spoiling and going bad.

And yet astronauts agree that
enduring the myriad of risks...

is a small price to pay
for the chance...

to witness the wonder
of the cosmos in person.

l know how they felt
because they report things like...

well, you could
hold up yourfinger...

and you could block out
the Earth with your thumb...

and it kind of gave them
an entire new perspective...

of how amazing
this little blue marble, the Earth, is...

and how precious it is
in this vast solar system.

That experience
changed me forever...

and l think
it would change anyone...

that could possibly have
that experience in the future.

However,
the length offuture voyages...

might limit
the range of experiences...

available to space travelers.

Distances in ourvast universe
can defy comprehension.

lf our Sun were the size
of a basketball...

our Earth would be
the size of a pea.

lf they were placed
in Central Park...

the nearest starwould be
another basketball...

almost 5,000 miles away
in Hawaii.

One of the prerequisites
you might have for a space mission...

is that you're alive when
you arrive at your destination...

so you'd want your
space missions to be small...

compared with the life expectancy
of a human being.

And right now, that pretty much
limits us to the planets...

and possibly
comets and asteroids...

ifwe include those
as places we might visit.

The brutal, scathing landscapes
of the solar system's inner planets...

Mercury and Venus...

do not make for tempting
vacation destinations.

Temperatures on Venus can
exceed 900 degrees Fahrenheit.

And the crushing air pressure...

is equivalent to being submerged
in 3,000 feet ofwater.

That leaves all points further out
from the Sun for potential exploration.

But even trips
to our closest attractions...

will still take several months,
or even years.

About139 million miles separate
the orbits of Earth and Mars.

But since each body circles
the Sun at different speeds...

the distances, with respect
to each other, change continuously.

The problem with going to Mars is
that Mars and the Earth only line up...

about once every two years.

With current chemically
propelled rocket technology...

a flight leaving from Earth
for the Red Planet in 2018...

when the two bodies are
on the same side of the Sun...

could take 104 days,
less than four months.

After a forty-day stay...

the return trip would require
a little more than six months.

That's an entire year
to make one round trip.

But a voyage
departing in 2031...

when the Earth and Mars are
on the opposite sides of the Sun...

would demand about twenty months,
nearly two years oftravel time.

That's one to two years
away from any lifeline.

Comets, those oversized
dirty snowballs...

swoop close enough to Earth
to accommodate a round trip...

lasting as short as a few months.

Find some comet that's on its way
into the Sun and ride it.

And watch the coma grow
and the tail form...

and watch the Sun, first slowly,
but then rapidly...

get larger and larger and larger...

and you swing around
the backside and come out.

lt's got to be the most fun tour
of the solar system...

you can come up with.

lt'd be dangerous
because particles of the comet...

would fly up and hit
you in the face and things.

So, apart from all that,
which would kill you...

it would be a fun trip.

Just beyond the orbit of Mars...

asteroids flywithin range
of a fewyears' round trip from Earth.

Future travel agencies
might arrange...

cosmic versions
of extreme vacations...

by exploiting the unique environments
ofthese miniature planets.

They put you on a sled
and slingshot you into space...

in such a way that the weak
gravity ofthe asteroid...

will hold you in orbit, but
won't pull you back down again.

lt would be a great ride.

Three times farther away
than Mars...

the orbit of Jupiter,
with its crowded moon system...

offers dozens
of diverse visions.

lt may prove tempting
forfuture travelers...

but a round trip
could take five years.

Saturn is nearly twice
as far as Jupiter...

and the thought of decade-long trips
might be too much to bear.

But there are technologies...

that can slice the time it takes
to visit Mars tojust a few days.

For mankind ever to venture
into the depths of the cosmos...

endeavor to bathe in the light
of an exotic star...

or evenjust to voyage to the suburbs
of our own solar system...

we'll need to find a way
to travel much, much faster.

What's the fastest
we could travel?

Nothing yet observed
by science moves faster...

than the speed of light,
186,000 miles per second.

The speed of light is the ultimate
velocity in the universe.

lt's Einstein's
cop on the block.

The speed of light is so fast
that you could go around the Earth...

seven times injust one second.

Foryou tojump to the Moon,
at the speed of light...

you could reach the Moon
in about one second.

Compare that
to the three days it takes...

to get there
with current technology.

The problem is that we can't
travel at the speed of light...

or really anything
even approaching it.

Take the fastest thing
we have ever sent anywhere...

and ask how long will that take
to reach the nearest stars.

That would take 50,000 years.

And that is using
current chemical propulsion...

which maxes out
at about 40,000 miles per hour...

the same power source we use...

to lift our rockets
off ofthe planet.

But getting us to Mars faster
than a few months' time...

would require
a different kind of propulsion.

There are a few ideas
for how to propel us...

to velocities closer
to the speed of light...

which would be fast enough...

to get us anywhere in
the solar system in under a day...

or even to the nearest stars
in less than a decade.

One such theory echoes...

an ancient earthly
propulsion device:

Wind pushing a sail.

lt was Kepler,
that great astronomer...

who first wrote
down in his notes...

the possibility of using sails
to sail in outer space.

Light streaming from the Sun...

mimics
gusts ofwind in outer space.

This solarwind is what creates
a comet's tail as it nears the Sun.

However, sunlight scatters
in all directions...

and as the distance
from the Sun doubles...

its power reduces
by a factor offour.

With a little help
from the Moon...

there is a manner in which light
could be focused in one direction.

lfwe have a battery
of laser cannons on the Moon...

firing in synchronization
at a solar sail...

we may be able to propel it...

to about perhaps
half the speed of light.

Now, lasers
do diffuse with space.

For example,
if l have a laser on the Earth...

and l shine it to the Moon...

it does not create
a spot on the Moon.

The spot is about five miles
across on the Moon.

These sails, however,
would be huge.

Nowwe're talking
about astronauts...

perhaps spending months
in outer space...

designing a sail hundreds...

maybe even thousands
of miles across...

sufficiently light and durable
in order to capture light...

from a battery of laser beams
on the Moon.

But solar sailing
limits space vessels...

to destinations
within our solar system.

One alternative gets
around this problem...

by tapping into hydrogen...

the most abundant element
in the universe...

as a propulsion source.

My favorite design
to take us to the stars...

is the ramjet fusion engine.

The ramjet engine
has a gigantic scoop...

in the forward direction...

that gobbles up hydrogen gas
as it moves in deep space.

lt collects the hydrogen gas...

and then fuses it
just like the Sun...

and shoots out a huge stream
of ions out the other end.

And on paper,
it looks fantastic.

On paper it looks
as if a ramjet fusion engine...

could go on forever,
simply using up the hydrogen...

that is found naturally
in outer space.

Unfortunately, scientists have
not yet been able to achieve...

a hydrogen fusion reaction
capable of propulsion in tests.

But another
potential fuel source...

one that seems to come
right out of science fiction...

has already been created
in laboratories.

lt's called anti-matter...

and it's the opposite
of all that we know.

For example,
think of the world...

on the other side
of the looking glass.

Just like in Lewis Carroll's
"Alice in Wonderland"...

we physicists have wondered,
is there another universe...

on the other end
of the looking glass...

a parity-reversed universe...

where left becomes right,
right becomes left?

ln an anti-universe,
charges are reversed...

so positive charges
become negative...

negative charges
become positive...

and when they meet,
they create a burst of energy.

So if this universe on the other side
of the looking glass...

were made out of anti-matter...

and l were to touch
this other universe...

l would destroy...

most of the NewYork City
metropolitan area...

in a burst of energy.

So the conversion of anti-matter
and matter to energy...

is one hundred percent efficient.

lt is the ultimate engine,
but there is a catch.

There's always a catch.

Even though we can create
anti-atoms in the laboratory...

the cost is stupendous.

lt would bankrupt
the United States ofAmerica...

to create a teaspoon
of anti-matter.

However, it would only take
a few grams of anti-matter...

to take us to Mars...

and perhaps several teaspoons
of anti-matter...

to take us to the nearby stars.

But for us to evervisit...

a distant star
or another galaxy...

we need something stranger...

than even Alice
could ever dream of...

peering through
her looking glass.

Scientists continue the quest
for a propulsion method...

to carry us ever deeper
into space.

But even achieving light-speed
won't allow us to get very far.

Light's fast,
but the universe is huge.

So, even ifwe could ride
on a beam of light...

ifwe wanted
to cross the galaxy...

the way they do in all
the science fiction programs...

it would take
100,000 years to do it.

And even at light-speed,
traveling to the nearest galaxy...

would take
several million years.

And if light-speed is the ultimate
speed limit of the universe...

it seems we are doomed
to confinement...

in our galactic neighborhood.

What we're desperate for...

is some new understanding
of the fabric of space-time...

that will allow us
to somehowwarp it...

distort it so that
you can take shortcuts...

and, of course, that's what
they do in "Star Trek"...

when they turn on
theirwarp drives.

They want to get from one side
of the galaxy to the other...

all they do
is invoke the warp drive...

that warps
the fabric of space...

and then they take
a little shortcut right there.

They cheat, basically.

Everybody knows
Einstein's famous dictum...

"You cannot go faster
than the speed of light."

However,
there's a footnote to it.

You see, Einstein left open
the possibility that you can...

rip, fold the fabric
of space and time itself...

so that you effectively take
a shortcut through the universe.

Think of a carpet.

lfyou want to go
across the carpet...

that's the old-fashioned way.

You can also get a lasso...

and lasso a table
on the other side of the carpet...

and then drag the table
toward you...

so that you collapse
the space in front ofyou.

ln a nutshell, Einstein says
the bigger the mass...

the bigger the bending
of space and time.

lfyou can concentrate...

enormous amounts of energy
at a single point...

comparable to that
of a black hole...

or a huge, gigantic star...

you are literallywarping
the fabric of space and time.

You simply hop across
to the nearby stars.

So, in otherwords,
you did not really go to the stars...

the stars came to you...

because you are compressing
the space in front ofyou.

The massive amount
of energy or mass needed...

to create such a warped
curvature of space...

seems beyond comprehension...

and perhaps
beyond human capability.

There may be an alternative.

Physicist John Brandenburg
is developing a theory...

in which a starship
ofthe future...

could achieve
faster-than-light travel...

not by manipulating
a vast area of the universe...

but rather by manipulating
only the area around the starship.

The trick is to have a starship
imitate a curious particle...

that, so far,
only exists in theory.

lt's called a tachyon.

lt's a particle
with a different twist.

Light itself always moves
at the same speed.

Tachyons, on the other hand,
can go infinitely fast.

Theyjust can't go slower
than the speed of light.

They look at the speed of light...

as a lower speed limit
that they cannot violate.

lf they do exist, tachyons
can outrun the speed of light...

because they have
what physicists recognize...

as imaginary mass.

An imaginary value
can be visualized...

in the spin
of a struck tennis ball.

lts spin can cause it
to bend and move...

in a manner that an observer
might not expect to see...

from its initial point
of contact.

ln the same way, a tachyon
is unseen by the universe...

and can break
its speed limits.

Brandenburg proposes...

altering the space-time
surrounding a starship...

with a powerful
electromagnetic field...

so that the ship moves
through space like a tachyon.

lt would operate
like a stealth aircraft...

invisible to radar,
unseen by radar operators.

So, if one can achieve
this control...

ofthe space-time
around this ship...

one can essentially make it
an imaginary object.

ln a technical way, that means
it's moving faster than light.

You're basically
disconnecting yourself...

from the rest of the cosmos.

lt could grant
the traveler the ability...

to go anywhere in the universe
in the blink of an eye...

as if a multitude of doorways
suddenly appeared.

A doorway you step into...

and then you step out
somewhere down the hall...

so fast that it didn't seem like you
had time to move anyplace.

That's an imaginary connection
in space-time.

And you've changed yourself,
not space-time.

No one may know howfast
or even where...

such a space vessel
could travel.

Which door to go into?
Which door to come out of?

That's the trick.

But voyaging through the hall
of the universe isn't possible...

without first overcoming
one of its fundamental forces...

the one that shackles us
to our home planet.

Getting away from the Earth's
gravitational field...

that's the first thing
that we have to do.

Ten, nine, eight...

seven, six...

For an object to break away
from Earth's gravitational pull...

...two, one.

We have ignition and liftoff
of NASA's new...

...it must achieve a velocity
of17,500 miles per hour.

That's fast enough to streak
from NewYork to Los Angeles...

in about eight minutes.

There's no otherway to do it...

at least that we have now,
other than brute force.

While a theoretical
space elevator...

can climb away from Earth's
gravitational pull...

a rocket must outrun it
with the brute force...

provided by the explosive chemical
reaction of burning fuel.

Chemical power is what drives
today's rocket engines.

Every time you burn something,
that's chemical power.

Every time
a rocket engine ignites...

that's chemical power.

Every time you start
your engine in your car...

you're using the chemical energy
stored in the gasoline.

The fuel alone can burden
a space-bound craft...

with up to ninety percent
of its total weight.

lfyou're carrying all the fuel
you'll ever need...

then most ofthe effort
of the first-ignited fuel...

is to lift
the unburnt fuel into orbit.

lt'd be like trying to drive from
NewYork City to Los Angeles...

on one tank of gas.

Well, you would need
a tanker truck behind you.

And most of the energy
to accelerate the tanker truck...

is going in tojust move the fuel
that's in the tanker truck.

The space shuttle, its rockets,
and the fuel they're carrying...

weigh a staggering
four million pounds.

And nothing short
of a bone-rattling eruption...

could push it up
and away from Earth.

Well, Grant, looks like
your long wait is over.

We wish you all the best luck
in the world, Godspeed...

and we'll see you back in here
in about two weeks.

Ajourney into space today
means that space travelers...

must ride a controlled
detonation into the sky.

Whatever the vehicle weighs,
we have to generate...

about one and a half
to two times that thrust...

in order to get it off
the surface of the Earth.

To get the space shuttle
up to speed...

demands seven million
pounds ofthrust.

To put that into perspective...

lfyou can imagine me...

holding a one-pound ball
in my hand.

lf l'm holding it here,
and l'm holding it steady...

l am exerting
a pound of thrust on that ball.

So, if l lower it down, l'm
clearly not exerting the one pound.

lf l pick it up,
l'm exerting more than a pound.

So you have to have
a little more thrust...

than you do the weight, obviously,
oryou won't go anywhere.

How a rocket moves can be
illustrated with a blown-up balloon.

This works almost
like an engine nozzle.

Now, l can hold it in place...

and you can control it,
you can let it go.

And what we do is,
we try to eject as much mass...

through that throat as we can.

And as it expands out
the back end...

that expansion or that pressure
pushing that way...

pushes the vehicle this way.

When today's astronauts
climb aboard...

for theirjourneys
on the space shuttle...

they're hitching to giant containers
housing that necessary mass.

Millions of pounds of highly
combustible hydrogen and oxygen...

wait to be ejected.

lt only takes a spark.

The main engine starts
six seconds before takeoff.

The whole shuttle shakes.

lt feels like it wants tojust rip
itself out of the launch pad.

Liftoff of Space Shuttle
"Endeavour"'...

lt shudders, and you think,
"Oh, my gosh...

"that's an awful lot offorce."

About a million
and a half pounds of thrust.

lt's kind of surreal.

lt's like, "This can't
really be happening."

lt's something
you've been wanting to do...

for years and years,
and it's really happening.

lt's like riding
a manmade Earthquake.

You've spent several million
pounds worth offuel...

to get to the first
two minutes offlight...

and then the solid rocket
boosters come off.

And that's like a train wreck
when those things come off.

lt almost feels like
you'rejust accelerating...

faster and faster and faster...

as you burn all the fuel
out of the big main tank.

So for the next six minutes,
you're accelerating up to a point...

where you're finally feeling
about three gs...

three times the force of gravity
of acceleration.

And so now it almost feels
like there's a big gorilla...

sitting on your chest.

A drag racerwho accelerates
from zero to 100 miles per hour...

in two seconds
will feel g forces...

similar to those
experienced by astronauts.

As the vehicle
keeps accelerating...

and you're watching
the speed tick by...

in thousands offeet per second...

until you get to twenty-five times
the speed of sound.

Then there's a cut-off,
and then everything's floating...

and nowyou're in space.

So space isn't very far away.

lt only takes about eight minutes
and thirty seconds to get there.

The next model forventuring
into the great beyond...

and reaching newworlds...

will begin first with a visit
to an old friend.

Although not quite yet
a space elevator...

NASA's mission
to return to the Moon...

builds on the idea of Earth orbit
as a base forfarthervoyages.

NASA's Constellation Program...

a successor to the legendary
Apollo Program...

aims to plant boots
on the Moon by 2020.

Two separate rockets
form the foundation of the plan.

The unmanned Ares V rocket...

towering taller than a football
field standing on its end...

will carry
the lunar lander, supplies...

and an Earth departure rocket
into orbit...

where it will wait
for the astronauts.

The Ares l rocket will deliver
the crew to orbit aboard a capsule.

lt then will rendezvous with
the Earth departure rocket...

and blast to the Moon.

We can take more supplies...

more commodities
to the Moon.

That's what this tandem system
provides for us, instead ofApollo...

which only allowed us to go
for one or two days at a time...

and then come back.

Will we everfind a way
to surpass...

the bold achievements
of the Apollo program?

Will we ever cross the vast
expanse ofthe cosmos...

as quickly and effortlessly
as we travel...

to another city
or another continent?

We must ifwe are to survive
as a people.

lfwe stop exploring...

we have learned time and time
again throughout history...

that those societies, basically,
tend to wither up and die.

lt's a part ofwhat we are...

it's a part of what we
leave to our children...

and their children.

lt's who we are,
and it's what we do.