Original subtitles

(upbeat music)

- [Narrator] Scientists have made a staggering discovery.

A planet circling the sun's nearest neighbor

with temperatures that could allow liquid water to flow.

What will it take to go there,

to explore it?

The answer is speed.

Laser driven spaceships.

Anti-matter engines.

Warp drive, right out of science fiction.

How far,

how fast can our technology to take us?

(upbeat music)

(moves in to light music)

It's a journey that has lasted a century.

A spacecraft approaches its destination,

a planet beyond our solar system

and a future beyond our imagination.

Touchdown will mark a milestone in our eternal quest

to expand our horizons,

to explore and to survive.

It's not the first time we've struck out

into the void against all odds.

For much of our history, the oceans were the great unknown.

Several thousand years ago, a seafaring culture emerged

in the Southwest Pacific.

Riding ocean and wind currents,

the Polynesians sailed East,

navigating by the stars, the Moon and the Sun.

Over centuries of time,

they claimed the Pacific Ocean island by distant island.

It was one of the most expansive migrations

in human history.

Their furthest reach, Easter Island,

was over 2000 kilometers from the nearest land.

(upbeat music)

Today we have begun to reach beyond

our planetary shores,

across distances so vast,

we measure them in light years.

That's how far light travels in a year,

almost 10 trillion kilometers.

Our roadmap leads us out into the southern sky.

There, a little over four light years away

you'll find our sun's nearest neighbors,

a dim red dwarf star called Proxima Centauri.

And a pair of Sun-like stars called Alpha Centauri.

Go beyond them and you've entered

the local bubble, a giant empty region cleared

of gas by a star that exploded long ago.

Within this bubble, 50 light years from Earth,

are 150 stars bright enough

to be seen with the naked eye.

(light music)

Nestled among them are 2000 smaller stars

visible only with a powerful telescope.

How many have planets?

Could any serve as stations

on our way out to explore the galaxy?

(upbeat music)

Our first stop, no doubt,

is a planet orbiting around the star nearest to Earth,

Proxima Centauri.

About one third larger than Earth,

it's a very different kind of planet.

One side facing away from its star is dark and freezing.

The other side facing inward, is forever bright and warm.

Did life flourish here?

Could humans survive?

The key is whether there's an atmosphere

and water on the surface.

These would be signs that there's a climate

and temperatures moderate enough to support life.

If Proxima B or any other planet in the solar neighborhood

proves to be habitable, the call will certainly be heard

to mount an expedition to see and explore it up close.

But to get there in the short course of a human lifetime

will take whole new types of spacecraft

we have yet to build,

whole new designs that can propel us to extreme speeds.

The discovery of Proxima B was part of an intensive campaign

to find worlds like Earth

in the neighborhood of our Sun.

Increasingly, the hunt for planets combines the enormous

light gathering power of giant new observatories

on the ground with a growing fleet of telescopes in space.

More than just identifying the presence of planets,

these instruments allow us

to measure surface temperatures, detect atmospheres,

and look for the chemical signatures of life.

Astronomers are devising whole new tests of habitability.

One group used the Hubble Space Telescope

to probe a series of seven planets recently

found orbiting an ultra cool dwarf star

40 light years away called Trappist I.

Each of these planets is roughly the size of Earth.

Three orbit within the habitable zone.

At just the right distance from the parent star

and with the right temperature to support liquid water.

What are the chances

they actually harbor oceans and rivers and lakes?

Red dwarf stars like Trappist I are known

to emit large and violent flares.

Over time, solar radiation acts to split molecules

of water in a planet's atmosphere.

Hydrogen atoms liberated in the split

then waft into space,

leaving the oxygen to bind with rocks on the surface.

This same process has been documented on the planet Mars.

In its early years,

there is thought to have been enough water

to carve networks

of river and lake beds.

Over time, these stores of water disappeared

along with Mars' chance of nurturing life.

To find out whether the planets

of Trappist I have been stripped of their water,

astronomers measured the amount

of ultraviolet light striking them,

an indication of their exposure to solar flares.

They found that the innermost planets are bathed

in ultraviolet light and are most likely bone dry.

By contrast,

the outermost planets have been spared the radiation.

It's possible they have kept the stores

of water acquired during their birth, whether liquid or ice.

(light music)

Based on a statistical analysis

of solar systems discovered so far,

one study estimates that there is at least

one planet like Earth within 20 light years.

(upbeat music)

Astronomers may have already found it.

Each night in this control room

at the La Silla Observatory in Chile,

astronomers conduct the world's most intensive hunt

for planets in the neighborhood of the Sun.

They work with an older telescope,

commissioned in the year 1977.

It has a relatively small mirror at 3.6 meters in diameter

but it's outfitted with a spectrographic technology

that allows astronomers to finally parse

the light of nearby stars.

It does this by recording subtle shifts in their light

caused by the gravitational tug of planets.

Among their targets is a star that lies

just below the constellation of Leo,

11 light years from Earth.

Ross 128 is a red dwarf star like Proxima Centauri.

Orbiting this star, within the habitable zone,

astronomers have found a planet

slightly larger than Earth.

(light music)

Because the star is relatively quiescent,

the planet may not have endured

destructive blasts of radiation.

In the coming years,

astronomers will use powerful ground telescopes

to probe the planet's atmosphere.

They are looking for the presence

of biomarkers such as oxygen,

and other evidence of a habitable climate.

They'll also look for clues

to the early evolution of our own planet

and ultimately for an answer to the age old question,

are we alone in the universe?

- Should we ever decide it's worth

going there for a closeup look, we might want to wait.

Ross 128 is actually moving toward us,

in the blink of a cosmic eye,

79,000 years from now,

it will become our son's nearest neighbor.

Proxima Centauri,

Trappist I and Ross 128

are among the first targets

in what is shaping up to be

the golden age of planet hunting.

The Transit Exoplanet Satellite, TES,

has found evidence of over

5,000 planets orbiting nearby stars

that astronomers hope to scan in the coming years.

(light music)

Many are like those found around the star HD 20749,

slightly smaller than our Sun, and 53 light years away.

The surface of Planet C likely hovers

around 400 degrees Celsius.

It's so close to the star that it whips

around it every eight Earth days.

Planet B is a gas giant,

23 times the mass of Earth, within a deep layer of clouds

temperatures average around 150 degrees Celsius.

The sun-like star Pi Mensa hosts

a planet twice the size of Earth.

Its surface temperature is over 900 degrees Celsius.

Then there's this planet,

around the red dwarf star TOI0-00

roughly the size of Earth,

it's tucked just inside the habitable zone

of its parent star.

Following up on data from TES,

planet hunters used the powerful detectors

of the James Webb Space Telescope

to confirm its first planet.

At 99% the size of Earth,

it orbits the Red dwarf star LHS-475.

This planet will no doubt be the subject

of intensive study in coming years.

(light music)

Inevitably, the discovery of planets

around nearby stars has spurred debate

about the imperatives of interstellar missions.

The physicist Stephen Hawking, was one of a growing number

of scientists concerned about a cloud

of uncertainties surrounding Earth's future.

- Pollution.

Overpopulation.

War.

Climate change and ecological collapse.

We have no choice, they say,

but to develop the technologies needed to not only travel

to other solar systems, but to survive in alien realms.

The dream of settling distant worlds

is as old as the rocket itself.

Back in the early years of the 20th century

the Russian space visionary Konstantin Sulkovsky

believed humans would one day ascend to the stars.

They would evolve into a whole new species

he called homo cosmicus.

Sulkovsky laid out the physics of the rocket.

His famous rocket equation describes

the basic principle of acceleration.

It's the force of mass expelled

at high velocity out the back of a rocket.

Versus the overall mass of the rocket.

(light music)

Decades later in the 1960s with the space age

in full swing another Russian scientist,

Nikolai Kardashev,

described space faring civilizations

as the product of a long range technological evolution.

He defined level one as a planetary civilization

with the ability to tap into energy equivalent

to that of the sun striking our planet.

At this basic level,

a planetary civilization would exceed

our current energy generating capacity

by five orders of magnitude.

It may take us centuries to advance that far.

It may take thousands or even millions

of years to reach level two,

the ability to harness the energy equivalent

of a star, or level three, the energy of a galaxy.

In theory, a civilization with that degree of

sophistication could wander the galaxy mining raw materials

from planetary bodies while generating energy

from technologies we can scarcely imagine.

Advancing that far does not mean

we can afford to abandon Earth.

According to a recent rethinking

of Kardashev's theories,

maintaining the health of our biosphere

will be crucial to the development

of interstellar technologies.

In this view,

interstellar flight will flow from successful efforts

to solve humanity's growing energy needs,

with technologies that are more efficient,

powerful, and safe.

Indeed, radically more potent fuels

and engines could even pose serious dangers

to the very environments that allow us

to develop and test them.

(dramatic music)

In this way of thinking,

to advance toward a planetary civilization

means producing energy in ways

that actually safeguard Earth.

What leaps in science and engineering

will interstellar technologies depend upon?

How far, and how fast can they take us.

The speeds we can reach depend on the technologies

we employ and the power that drives them.

Power is often measured in joules.

The amount needed to lift a 100 gram object

one meter against Earth's gravity.

The metabolism of an average person

at rest produces 100 joules per second or 100 watts.

That's the same as a light bulb.

An elite runner traveling

at almost 40 kilometers per hour generates 1500 watts.

Using the technology of a bicycle

we use that same wattage

to top 66 kilometers per hour.

On the ground, this is our speediest machine,

a race car can reach speeds of 350 kilometers per hour

with an engine that converts

the potential energy packed into gasoline,

about 40 million joules per kilo,

into the kinetic energy of motion.

It's held back by friction from the road and the air.

One way to fight friction, soar into the upper atmosphere.

The SR-71 Blackbird flies at 3,500 kilometers per hour,

10 times faster than a race car.

As much power as a jet can muster

a full tank buys only a few hours of flight.

Rocketing into space is even less efficient.

To rise into Earth orbit,

a giant Saturn V rocket must

hit 28,000 kilometers per hour,

almost 10 times faster than a jet

But the faster it goes, the more fuel it burns,

the more it has to carry.

To get Apollo astronauts into space

and on their way to the moon.

A Saturn five rocket had to lug 16 times its weight in fuel.

As inefficient as chemical rockets are,

they have served the vast imperatives of the space age.

Since the 1960s,

we've used them to launch thousands

of satellites for communications and military purposes,

for studying the Earth and peering into space.

And we've used rockets

to send a succession of astronauts into Earth orbit.

The now retired Space Shuttle served

as a platform for research,

for launching and servicing the Hubble Space Telescope,

and for building the International Space Station,

a successor to the Russian Mir,

and American Skylab stations.

The International Space Station began to take shape in 1998.

It has become the largest collaborative

engineering project in human history.

This sprawling structure posts a complex arrangement

of modules and nodes and a network of labs and living areas.

Here astronauts are learning

to live for extended periods of time

apart from the gravity, climate systems,

and comforts of our home planet.

From Earth,

rockets deliver resupply missions up to six times each year.

These unmanned capsules from Russia and the United States

carry hundreds of meals,

new equipment and scientific experiments.

The International Space Station has become

a hub for zero gravity science.

At any given time,

the crew is conducting pointed research

into life support systems and preparing data

for publication in science journals.

(upbeat music)

Proponents of this work see it laying the groundwork

for longer and more ambitious manned missions.

There are a host of challenges to overcome.

Beyond recycling waste and the internal atmosphere,

life support systems must include

the ability to grow food.

On missions far beyond Earth,

living compartments must protect

against solar radiation and cosmic rays.

Once these problems are solved,

some proponents envision the construction

of bases in orbit around the sun,

with factories or supply hubs

to support a network of remote colonies.

Whether we send people to explore Mars

or to mine rare minerals on asteroids,

we'll have to overcome the power

and speed limits of the space age.

Right now, because of the amount of fuel needed just

to get into space, most long distance spacecraft

can only coast to their destinations.

The Twin Voyager spacecraft got

around this by using the pole of Jupiter's gravity

as a planetary slingshot.

Racing out at 62,000 kilometers per hour,

more than double the speed of a Saturn V,

Voyager 2 became the first spacecraft

to exit the solar system.

But as fast as it's going

it will need another 73,000 years to reach Proxima Centauri.

To make long distance space travel efficient,

whether it's humans or robots making the journey,

we'll have to reinvent the rocket.

(suspenseful music)

The search for faster, more advanced spacecraft began

in the 1960s in the shadow of the nuclear arms race.

Nuclear bombs release energy by splitting the atom.

Imagine if that potential

could be harnessed to propel a spacecraft.

Scientists tested a whole new type of rocket,

a vehicle propelled by small nuclear explosions.

They envision an orbiting space station

as the launchpad for the Orion spacecraft.

(upbeat music)

A series of controlled nuclear blasts

set off behind the craft

would accelerate it to 10% the speed of light.

Orion would've been able to reach Proxima B

in just over four decades of Earth time.

Plans for this spacecraft never got off the ground.

The technology was unproven, and perhaps unsafe.

In the 1970s with interstellar flight

still in their sights, a group of British engineers

designed a 200 meter long craft called Daedalus.

It would use another type of nuclear power - fusion.

That's the energy that lights up the sun,

generated when gravity forces atoms together

under immense heat and pressure.

Just a gram of fusion fuel could yield energy

in the range of 200 billion joules.

The idea was to produce an extremely hot gas

that would propel the craft by blasting it out the back.

After accelerating through two stages,

it could cruise along at 12% the speed of light,

but this required Daedalus

to carry more than 40,000 tons of fuel

and there'd be nothing left to slow it down.

Once it approached its destination.

As it flew past its target

at 129 million kilometers per hour

it would deploy a fleet of robotic explorers

to go in for a look.

Daedalus was never built,

but the completeness of the design

has inspired new generations of dreamers.

(light music)

Today, one group of scientists believes it may have

a way to reach Proxima B more efficiently.

The concept begins with a solar power

generating station orbiting Earth.

It's lined with lasers each aimed at a tiny spacecraft

a futuristic version of that Polynesian sailboat.

The force exerted by each laser beam is small,

but together in frictionless space

they can propel a space sale

with staggering success,

to 20% the speed of light.

In just 20 years,

a fleet of laser powered craft approaches Proxima B,

they send their data bouncing from one craft

to the next on a four year return journey to Earth.

If Proxima B proves a worthy destination

there are technologies

on the drawing board that promise an even faster ride.

- What if we could tap into

the stuff of science fiction - anti-matter?

It's the product of high energy radiation

that rips through our solar system.

When cosmic rays smash into atoms in our upper atmosphere

they create a spray of particles of the opposite charge.

If we can't capture anti-matter particles

in orbit we may find a way to produce them on Earth.

(light music)

Down at CERN, the giant physics lab on the border of France

and Switzerland, scientists have been creating anti-matter

as a way of studying the underlying nature of our universe,

and how it emerged in the earliest moments of time.

Using the Large Hadron Collider,

they accelerate atoms to nearly the speed of light

and blast them together

to release their fundamental constituents.

But the anti-matter yield is so small that the cost

of producing just a gram's worth is estimated

to be upwards of $100 trillion,

and the stuff is so volatile

that storing more than a few atoms at a time

remains a significant challenge.

Our ability to produce such an energy dense fuel

raises basic questions

about whether interstellar flight is even possible.

One thing's for sure,

more Earth-friendly alternatives such as geothermal,

solar and wind won't transform us

into a planetary civilization,

and they simply don't pack enough explosive power

to get us to Proxima Centauri.

Anti-matter might, provided we can learn

to control and produce it in enough quantity.

It is the most powerful fuel known,

with about two billion times more energy

per volume than conventional rocket fuel.

In contemporary spacecraft designs,

protons and antiprotons are isolated with magnetic fields.

They're channeled in parallel

to a propulsion chamber.

Where they collide the streams annihilate each other.

The blast creates a high energy beam

that pushes on a magnetic field within the crack.

Accelerating it forward.

Though it would take only

a thousandth of a gram to fly to Saturn

the craft would need to carry tons more

to get up to interstellar speeds

and reach Proxima Centauri within a human lifetime.

Such a potent fuel brings serious hazards.

The high temperatures produced

by an anti-matter engine

would be enough to destroy the spacecraft.

It would have to be made of materials

not yet invented that can radiate that heat into space.

(upbeat music)

Setting out on its journey,

the spacecraft must navigate

an obstacle course of interstellar objects.

If it meets a meteor, it uses a battery

of shields to pulverize the object.

(loud booms)

And whisk it away.

If the craft plows through a cloud of dust

it's buffered by a protective magnetic field.

As it finally closes in on its target, it releases a probe.

Our cosmic envoy,

powered by its own anti-matter engine,

firing in reverse, the probe would need

to spend years even decades slowing down.

Even at these speeds,

the mission is probably too long

for any human to go along.

(dramatic music)

Imagine for a moment,

a future in which time and distance

are not so daunting, and the stars

are literally at our fingertips.

(upbeat music)

The spacecraft maneuvers

into an orbital station in preparation for launch.

It's a testament to science conceived

on a stunning theoretical frontier

with engineering far beyond what we know today.

This craft is based on a mind boggling discovery

by Albert Einstein that gravity

is the distortion of space by massive objects.

What if a spaceship could manipulate this strange cosmic

trait to pass between the folds of space and time?

Such a spacecraft would run on exotic forms

of matter not yet discovered, and use the equivalent

of all the electric power generated by the United States.

Welcome to Warp Drive.

In theory, this ship could go faster than light

as it traverses the galaxy in a cosmic bubble.

But don't book your flight just yet,

building a spacecraft like this will take

breathtaking advances in science and technology.

As far off as this may be,

who can say what challenges human ingenuity

will one day overcome,

what ideas or technologies will propel us forward.

(light music)

when, or if, we do reach for the stars,

the impulse will no doubt come not

from a struggle to survive,

but from a sense of wonder

at the limitless variety of a living universe.

The scene is hundreds or thousands of years in the future,

a Starship arrives at Proxima B or a similar destination.

Whether the craft carries humans or not,

we'll likely send an unmanned probe down

to give us our first up close look.

(upbeat music)

It may well land using technologies

we've perfected in our day.

At the dawn of planetary exploration.

Sensors will probe the alien landscape.

Artificial intelligence that evolved

and was updated during the journey will interpret the scene.

What's the makeup of the planet's soil?

It's atmosphere.

Has life established a foothold?

Steadily a new world surrenders its secrets.

With each revelation we reflect

on the odyssey that brought us here,

and how it began in the discoveries

and dreams of generations long past.

(upbeat music)

(upbeat music continues)