Original subtitles

(rocket launching)

If the scientists, engineers,

and entrepreneurs are to be believed,

space will soon be buzzing with a new breed of spaceships,

piloted by a new generation of astronauts.

And many of these space scientists believe

that our nearest planetary neighbor, the moon,

will play a key role in these new initiatives.

To them, our moon offers everything

that the next phase in the development of space

is going to need.

And the good news is that, in astronomical terms,

it's right in our own backyard.

In a way, we're really lucky,

because we have this object orbiting the Earth

that's so close that we can get to.

You can go to the moon any time you want.

There's a launch window open 24/7.

It only takes three days to get there.

And, it has the materials that you need

to create space flight capabilities

and it has them in the form you need them in.

It will allow us to build a system

to let us go anywhere,

and I think that's really the ultimate goal

of space hearing.

You want the ability to go wherever you want to go

with whatever capability you need

to do whatever job you can imagine

for as long as you want to.

That's the real object of space flight.

(epic orchestral music)

It's been over four decades

since the last human boot print

was planted in the lunar dust.

The date was December 1972,

and the boot belonged to astronaut Gene Cernan.

As he prepared to join his colleague geologist Jack Schmitt

onboard the lunar module of Apollo 17

and head for home.

He had these carefully scripted words to say

as he mounted the access ladder.

As I take man's last step from the surface

back home, for some time to come

but we believe not too long into the future,

I'd like to just let

what I believe history will record

that America's challenge of today

has forged man's destiny of tomorrow.

And as we leave the moon at Taurus-Littrow,

we leave as we came,

and God willing, as we shall return.

With peace and hope for all mankind.

God speed the crew of Apollo 17.

Everyone in NASA and the space community

knew that this would be the last Apollo mission

and that new ventures such as Skylab,

the shuttle, and the space station,

were on the horizon.

But, like Gene Cernan,

most people also thought

that a man to return to the moon

would not be long in coming.

Few would of believed then

that mankind's return would be over half a century away

in the 2020's.

(rocket launching)

From its first flight in 1981,

the space shuttle transformed man's space flight

and enabled many new missions to be conducted

in low Earth orbit

about 400 kilometers or 250 miles above the Earth's surface.

Low Earth orbit,

also known as Leo,

is where the shuttle hosted 22 space lab missions.

Launched the Hubble Telescope

and played an essential role in constructing

the international space station.

In 2011, the last shuttle, Atlantis,

delivered a key module to the ISS

and return to Earth just before dawn on July 21st.

Landing here down in the lot.

It was the end of an era

of supreme achievements

by what had been originally conceived

as a reusable, cost-effective, space truck.

Shuttle was originally named STS

and it was called Space Transportation System.

And the idea was the shuttle,

the actual shuttle that we know and love,

was the first piece of a space transportation system,

it was never intended to be the ultimate end piece.

It's the first piece because it can transport

people and cargo from the Earth's surface to Leo.

And then from there on

you would have another vehicle that would transport them

to these other localities.

If we had kept with the original idea

of having an incremental system

that gradually expands our reach with time,

that would have been the next logical step,

to build a reusable vehicle that could go back and forth

between the station and higher points in Earth orbit.

The problem has been a combination

of cost and physics.

And until now, the two have been inseparable.

The physics problem is simple to state,

and it's called gravity.

The cost problem is equally simple to state.

To defeat or at least manage that gravity.

All objects that have mass

distort the space around them

and are attracted to each other as a result,

and the larger the object, the greater the distortion.

And the greater the attraction.

It's a fundamental law of nature

and for a rocket scientist,

overcoming and managing gravity poses

some of the most difficult design challenges of them all.

It directly effects the ease with which it is possible

to move around in space

because it determines the energy that needs to be spent

to travel from one place to another

or to escape the gravitational field of a planet

or a moon.

That gravitational field is often referred to

as a gravity well.

The more mass a planet or an object has,

the harder it is to escape from its pole.

So the bigger planets have very deep gravity wells.

As you go down the scale in size,

the escape and orbital velocities become

correspondingly smaller.

Finally, you come down to an object that's

small like the moon,

which has 1/6th the gravity

and 1% of the mass of the Earth,

and its escape velocity is much smaller than the Earth's.

Which is a crucially important fact

when you're trying to build a moon based

space transportation system.

The Earth's gravity well is the deepest

in the inner solar system.

A fact which leads to some startling statistics.

Over 85% of the weight of every rocket

launched from the Earth's surface

is the weight of the fuel required to lift itself

out of our gravity well

at an eye-popping $20,000 per kilogram.

For the shuttle, this meant that at launch

the combined weight of the solid fuel boosters,

the external fuel tank

and the orbiter

was typically 2,000 metric tons

of which only 100 metric tons

was the orbiter and its payload.

This simple in balance between fuel and payload

is the reason why lofting a single kilogram of mass

into orbit has traditionally been so expensive.

There's two kinds of mass that you launch.

There's smart mass and there's dumb mass.

Smart mass are things that have high information density

like a computer.

But dumb mass is a ton of water

or a ton of liquid hydrogen.

The rocket doesn't care.

It has to lift it up against the gravity field of the Earth.

What we're trying to do is to move to a template

where we're getting most of the dumb mass

from sources other than the Earth.

And at the top of the dumb mass shopping list

for space engineers is propellant, rocket fuel,

and this is where the moon enters the picture.

If it were possible to generate liquid oxygen

and liquid hydrogen,

the two most powerful rocket fuels knows to science

on the moon,

then here would be a source of propellant

that would be conveniently sitting at the bottom

of a very weak, very shallow gravity well,

at the heart of the Earth, Moon transportation system.

Homegrown, locally available, and cheap,

all powered by the moon's water.

Intriguingly, this would also enable

future space engineers

to take advantage of a theory first proposed

in late 18th century France

by astronomer and mathemetician Joseph Louis Lagrange,

who suggested that there could be a few

rather unique gravitational locations

in the space between suns, their planets, and their moons.

Whenever you have two gravitational bodies,

there are places around those

where the gravity kind of cancels out

the effect of each other.

These points are effectively the neutral

buoyancy points of the

they call them weak stability boundaries

but they're places in the Earth-Moon system

that are easy to get to other places from

and that's why they're of strategic importance.

So, depending on these locations,

you can potentially set up

a space station or a depot or whatever the case may be,

and it will stay in space at that location

with very minimal amounts of propellant to keep it there.

When you factor in

propellant manufacturing on the moon

and the strategic use of the Lagrange points,

the space transportation system

starts to look much more feasible

and affordable

and that, the space scientists suggest,

is going to require a family of transport vehicles.

Each, specifically tailored to their individual missions.

Do you want something that goes

from the Earth's surface to the Moon's surface

and back again.

The answer is no, you're gonna break that up into chunks.

I want something that goes from the Earth's surface

to maybe some orbit around Earth,

whether it's low Earth orbit

or geosynchronous or whatever the case may be.

Now I'm gonna wanna have something that goes from

Earth's orbit towards the Moon.

Do I want to go all the way to the moon,

like we did in Apollo and break,

or do I want to go to a midpoint,

such as a Lagrange point,

and then have that transportation system just go

from Earth orbit to Lagrange point and back,

and then have another transportation go

from the Lagrange point down to low Earth

low lunar orbit or to the lunar surface,

so you kind of breaking up your system

So, at that Lagrange point, if I take this approach

where it is now the hub

of my two transportation systems or railroads,

well, I'm gonna probably wanna put a fuel depot there.

My gas station.

I'm not taking everything with me to come home.

I'm only taking half of what I need

which makes my launch vehicle

and transportation system smaller.

(rocket launching)

Part of this new multi-part

transportation system

is likely to see the introduction

of a wholly new propulsion technology.

It's a form of ion drive,

known as solar electric propulsion.

You take an element or a molecule,

and you accelerate it using magnetic fields

and electrical fields.

Here, you can get extremely high velocities

of these particles

but you don't really throw a lot of these particles

at the same time.

So, you have two ways of going to the moon now.

With chemical propulsion, it's a fast trip,

maybe not as efficient,

so you probably would use that for your crew.

For cargo, you'll probably want to take

the slow approach, high efficiency,

where the amount of propellant that you use

is not that great,

but it may take months to a year to transfer something

from Earth orbit to the moon.

You have this balancing act

and maybe you might combine the two.

Maybe you use chemical propulsion to get you

mostly out of the gravity well of Earth,

and then you use electric propulsion

to move around the vicinity of the moon.

To go to the moon's surface,

here again you'll need chemical propulsion

because of the high thrust you need coming down

and getting off the planetary surface.

So, it'll probably have a combination

of these types of transportation systems.

Extrapolated from its logical conclusion,

this view of tomorrow's moon

foresees permanently manned habitats

where water mining operations are in full swing

and the associated rocket propellant plants

are almost making a profit.

Elsewhere, exotic metals are being mined robotically

for shipment back to Earth

and on the far side of the moon

where they will be shielded

from the Earth's electromagnetic noise.

Astronomers will be setting up shop

to probe the cosmos.

The colonization of our nearest celestial neighbor

will have begun

and in the space between the moon and the Earth,

fuel depots will hover at the gravity neutral

Lagrange points.

Gateway space stations will be preparing

for the journey to Mars

and asteroids are being mined for their precious metals.

And the key to it all depends

on one single, simple verification

that there is enough water on the moon

to manufacture rocket fuel

from its hydrogen and oxygen atoms

because if there is,

the sky is quite literally the limit.

(epic orchestral music)