Nova (1974–…): Season 40, Episode 24 - Asteroid: Doomsday or Payday? - full transcript

The asteroid that exploded over Siberia--injuring more than 1,000 and damaging buildings in six cities--was a shocking reminder that Earth is a target in a cosmic shooting range. From the width of a football field to the size of a...

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Our planet is under attack

Our solar system
is full of deadly missiles

that could strike at any time

It's like cosmic roulette

You can't go on
playing a game of chance

and expect to keep winning

Killer asteroids

Trillions of tons of rock,

hurtling through space at tens
of thousands of miles per hour

Some are on a collision course
with earth

An asteroid has
more damage potential



than a nuclear bomb
of the same energy

65 million years ago,

a huge asteroid wipes out
much of life on Earth

But strikes aren't all
ancient history

In 2013, a much smaller asteroid
terrorizes this Siberian city

For many, this really was
a wake-up event

Now the race is on
to understand the danger

We know they're out there

When and where
will the next one strike?

Will it hit on a city?

I don't know

The point is
we have to find that out

We really need to upgrade
the search capability

We stand at a crossroads



Only now do we have the ability
to identify the threat

and even the technology
to neutralize it

Boom!

That is just dangerous

Kapow!

But where some see danger,
others sense an opportunity

Asteroids contains
precious metals and water

Perhaps we can learn
to mine them for their wealth

There are millions and millions

of these objects
in the solar system,

and we've only just begun
to understand

their resource potential

Asteroids could be the biggest
threat humanity faces

or a great opportunity

"Asteroids: Doomsday or Payday?"

Right now on NOVA.

A rock tumbles through space:

material left over from when
the planets first formed

It has orbited the sun

for four-and-a-half
billion years

An asteroid

It's 30 meters,
or 90 feet, across,

half the size
of a small office building

Mass: 100,000 tons

It's on a collision course
with Earth

Ground-based telescopes spot it
just days before impact

In its sights: a large city

There's panic on the streets

Why didn't we see it sooner?

Perhaps then we could have
saved ourselves

Now it's too late

The asteroid strikes

It hits with the energy
of over 100 atom bombs

Everything from downtown to
the outer city limits and beyond

is completely obliterated

This nightmare scenario
is just fiction

We can only hope
it never happens

But asteroids
have struck Earth before

Wind back 65 million years

A rock approximately
ten kilometers wide

smashes into planet Earth

It helps wipe out the dinosaurs

and around 70% of species
on the planet

Our planet also bears the scars
from much smaller strikes

This one: 50,000 years ago

But the danger from asteroids
still hangs over us today

They can catch us
completely by surprise

Our challenge is to understand

these potentially
devastating objects

So what exactly is an asteroid?

Asteroids are rocks

left over from the birth
of the solar system

4 6 billion years ago

As Mars and Jupiter form,

they leave a ring of debris
between them:

the asteroid belt

Asteroids are rocks
that should form another planet,

but Jupiter's gravity
prevents them from coalescing

The asteroid belt ranges

from roughly 150 to nearly
500 million kilometers away

Out here, asteroids pose
no threat to Earth

There are millions of asteroids
and comets in the solar system

Fortunately for us, most of them
are on very stable orbits

They stay where they're
supposed to be

and they live their lives

and evolve through their part
of the solar system

without ever coming close
to the Earth

Today, we have the technology
to visit these remote objects

NASA's Dawn probe
approaches the Vesta,

the second-largest asteroid
in the solar system

It returns these detailed images

It's now en route
to an even larger body: Ceres

But not all asteroids stay
in the asteroid belt

A random collision,
a planet's gravity,

even heat from the sun

can knock them into a different
orbit closer to Earth

Many of these
near-Earth asteroids

cross our path time and again

If they enter our atmosphere,

they become potentially
deadly meteors

Any fragments
that reach the ground,

we call meteorites

With the experience
of three missions

and over 200 days in space,
former Astronaut Ed Lu believes

it's only a matter of time
before one strikes us again

It's like cosmic roulette

The entire city of Las Vegas
was built upon the concept

that the house always wins

And in this game,
we're not the house

Our asteroid knowledge
and detection technologies

have improved rapidly
in recent decades

Many now believe asteroids
are a problem we can solve

Asteroid impacts are actually
the first natural disaster

that humans have a hope
of really preventing

We can maybe try and model
where earthquakes happen,

we can try to predict how
frequently tornadoes happen

We can't stop them
from happening

Asteroid impacts,
we might actually be able

to do something about that
in the very near future

So how can we overcome
the asteroid threat?

Observations have revealed
almost 1,000 asteroids

larger than a kilometer
in near-Earth orbits

These are potentially
large enough

to cause a global catastrophe

But we know where
most of them are

The chances of a strike
are vanishingly small

The immediate danger
comes from smaller asteroids,

less than one kilometer,
or about 3,000 feet, across

There are millions of these
in orbits that pass near Earth

We've discovered roughly
10,000 near-Earth objects

that can get fairly close
to the Earth

To put that in perspective,
only about 20 years ago,

we had less than 100

For every near-Earth asteroid
we have detected,

there are thousands
that we haven't

Ed Lu believes we need to locate
and track them

50 years ago, 100 years ago,

if we were wiped out
by an asteroid,

that was just bad luck

Today, if we are hit
by a major asteroid,

that is not bad luck anymore

That is negligence

We have the technology
to detect asteroids

long before they hit us

We've found many
of the big ones,

but smaller rocks could hit
at any time

The Minor Planet Center

at the Smithsonian
Astrophysical Observatory

is at the center of the mission

to track every asteroid
in the solar system

Gareth Williams is tasked
with deciding

which asteroids are a cause
for concern

The computers in this room
are really the nerve center

of the Minor Planet Center

The 103 million observations
and 600,000 orbits

that are stored
on the computers here

are the primary source
of information for the world

on the motions of minor bodies
in the solar system

Around 450 observer stations

feed information
to the Minor Planet Center

But most near-Earth
asteroid discoveries

come mainly from professional
optical telescopes

To date, we have found most of
the large main belt asteroids

Where we are lacking
in knowledge

are the smaller
near-Earth objects

Anything about
50 meters diameter,

we are very incomplete in our
knowledge of those objects

Every single asteroid the Minor
Planet Center knows about

was discovered using
the same basic principle

Optical telescopes capture
several images of the night sky

minutes, hours or days apart

Astronomers use computers
to compare the images

The stars stay still

Asteroids move

Once the computers identify
a new near-Earth asteroid,

further observations
are requested

The asteroid must be tracked
to decide if it's a threat

We can get an orbit from
three nights of observation

To get a good orbit,
we generally require

observations over an arc
of a month

The primary reason
we track asteroids

is to have some idea
of if and when an object

is going to approach the Earth
very closely or hit the Earth

To complete his risk assessment,
Gareth can request the help

of a different kind of telescope
to track the asteroid's orbit

This is NASA's
Goldstone Observatory

in the Mojave Desert

Standard optical telescopes
use reflective mirrors

to watch a patch of sky

Goldstone is different

It uses radar to zoom in on
and track an asteroid

This is a DSS-14,
a 70-meter radio telescope

It has a high-powered
radar transmitter on it

that we use for tracking
and imaging near-Earth asteroids

when they're close to the Earth

The Goldstone telescope
acts like a giant flashlight,

but instead of light,

it sends out a focused beam
of electromagnetic radio waves

toward the asteroid

By timing how long it takes
the radio waves

to hit the asteroid
and bounce back,

astronomers can verify
exactly where it is in space

And once locked onto it,

they can watch how it moves
over time

Radar is a very useful
instrument

in preventing newly discovered
asteroids from being lost

Usually, their orbits
are not well determined,

so if you get the radar
measurements,

you manage to extend

how far in future you know
where these objects are

This automatically provides you
with an early warning system

You know if there is
any chance of impact

many decades, maybe even
centuries in the future

The data Goldstone produces
is so precise,

it can predict an asteroid's
path years in advance

February 15, 2013:

Asteroid DA14 comes within
just 28,000 kilometers of Earth,

inside the orbit
of many satellites

But NASA and other telescopes
around the world

have already tracked
the asteroid for a year

They know its path
with great precision

They're 100% certain
that we're safe

The asteroid passes at exactly
the distance they predict

It was less than one-tenth
of the distance

between the Earth and the moon

In advance of the fly-by,

we expected that it would be
roughly 50 meters in diameter,

and this was the closest
approach by something that size

that we've ever known about
in advance

But our detection systems
don't always work this well

That becomes painfully clear
on the exact same day

that the world's telescopes
track DA14 passing by

Another asteroid approaches:

one our telescopes
fail to detect

It hits us

9:20 a m, Siberia, Russia

A fireball rips through the sky
over the city of Chelyabinsk

Smartphones and car dash cameras
provide an unprecedented view

A shockwave crashes down
on the city

Windows blow in

Doors are flattened

More than 1,000 are injured

The Chelyabinsk asteroid impact
was a game-changer

in the sense that
it makes it real for people

And that's important because
human psychology is such that

if something hasn't happened
in my lifetime,

I tend to discount it

NASA asks astrophysicist
Peter Brown

for an early estimate
of the size of the blast

He uses a highly sensitive
global system

of above-ground microphones

designed to detect
illegal nuclear bomb blasts

The system is part of the
nuclear weapons test ban treaty

We're listening to the very
lowest, very deep bass tones

reflecting the huge amount
of energy in this explosion

As the explosions get bigger,
the tone of the shockwave

or the tone of the sound
gets lower and lower and lower

until it's below the level that
human hearing is able to detect

Peter is shocked
by what he discovers

In this particular case,
the signal was very obvious

It was huge,

and the most startling
characteristic

was the fact that it was a very,
very low tonal frequency,

much lower than anything
I'd ever seen before

His official estimate
of the explosion's power

is nearly 500 kilotons...
More powerful than the blast

from a large nuclear bomb
from the American arsenal

The atomic bomb
dropped on Hiroshima

was about 15 to 20 kilotons,
so 15,000 to 20,000 tons of TNT

So this event, Chelyabinsk, is
about 20 to 30 times that event,

which is what makes it so
unusual but also so destructive

The event is huge

So why didn't we see it coming?

Physicist Mark Boslough
is one of the first scientists

to visit Chelyabinsk
after the meteor strike

He's convinced the answer
is tied up

with the asteroid's trajectory...
The direction it came from

He believes
he can calculate this

with the help
of amateur video footage

Using several key images,

he returns to the precise
locations where they were shot

He has to do this at night
when the stars are out

Well, I am doing
a stellar calibration

So we got

One of our videos
was from a dash cam,

from a car parked
in this parking lot,

and the fireball streaked
across the sky here

We're looking south,
it went from left to right

And what we really want to do

is determine the exact angles
to the fireball

as seen from this location

Mark's goal is to plot the exact
trajectory of the meteor

from where it appears in the sky

Standing where the eye-witness
video was originally taken,

Mark records its GPS coordinates

He then takes a picture of the
night sky with his own camera

He'll use the stars in his photo

to help him pinpoint
the meteor's path in the video

So if the stars show up
on the digital camera,

we can get those angles
and then calibrate that image

that was taken from the dash cam
and know exactly the angles

to the trajectory
of the fireball

By lining up his star field
photo against the video frame,

Mark can get a fix
on where the fireball appeared

relative to the stars

He repeats this process
at several locations

Finally, Mark uses
simple geometry

to locate the fireball
in three-dimensional space,

building a model
that shows exactly the angle

and direction of its approach

Mark's calculations explain
why our telescopes

fail to see
the Chelyabinsk meteor coming:

it approaches from the direction
of the sun

It's masked by the sun's glare

And the Chelyabinsk meteor
is not unusual

Any near-Earth asteroid
is completely invisible

at the point when its orbit

passes between the Earth
and the sun

That's a big gap
in our detection capability

And that's the issue right now

Our current surveys,
the current things

that we're doing right now
to find asteroids

are totally inadequate

We need to bump this up
by about a factor of 100

So we have a problem

Ground-based telescopes
can only detect asteroids

by looking away from the sun
into the night sky

But half the asteroids
that hit us

come from the other direction

There could now be a solution:
putting a telescope into space

Currently, all of the near-Earth
object discoveries

are made with ground-based
optical telescopes

If we could get
above the earth's atmosphere,

we could do a far more
efficient survey

NASA has already demonstrated

the capabilities
of space telescopes

to identify near-Earth objects

In 2010, the WISE mission
detects 135 near-Earth asteroids

before the telescope is retired

The problem is
there may be millions more

Many believe we now need
a longer-term mission

designed for asteroid detection

But the funds
haven't been allocated

Though NASA is rebooting
WISE as an asteroid-hunter,

a tailor-made asteroid
detection system from NASA

looks a long way off

So the private sector
is stepping in

B612, a non-profit foundation,

is financing a new infrared
space telescope

based on existing designs
like this one

Its sole aim: finding more
near-Earth asteroids

Former astronauts Ed Lu
and Rusty Schweikart

are leading the $400 million
fundraising drive

This is a public service

We're a non-profit corporation

We're not doing this
to make money

We're doing this, you know,

to help extend the domain
of life on Earth here

Codenamed Sentinel,
the telescope will orbit the sun

just like Earth
and the other planets

But with a similar orbit
to Venus,

it can look out towards Earth's
path with the sun behind it

Looking away from the sun
will enable it

to detect asteroids
we cannot see from Earth

Sentinel is an infrared
space telescope

that the B612 Foundation
is building,

and we're going to launch it
in 2018

As it moves around
the solar system,

it will scan Earth's orbit,

and we'll discover
just in its first year

200,000 near-Earth objects

Again, compare that
to our current discovery rate

of about a thousand

Sentinel will help
detect asteroids

between Earth and the sun

It will make it easier to find
that potentially dangerous group

of near-Earth asteroids:

not just those
over 140 meters wide,

but also millions
of smaller objects

Historically, these have been
hard to detect

Sentinel's technology
could change that

Sentinel will be built here
by Ball Aerospace,

who also helped design
and produce

the Spitzer and Kepler
Space Telescopes

Program Manager John Troeltzsch

is planning to use their proven
technology in the new telescope

So Sentinel has come in
at the right point in time

We've developed
a lot of technologies

over the last 20 years

in detectors,
in telecommunications systems,

in spacecraft, in solar power

All these things
are coming together today

to help produce
the Sentinel spacecraft

Sentinel's most important
technology

will be its infrared detector

This will find
the smaller asteroids

that most worry scientists

by searching for the heat
they emit

Asteroids are very hard to see

against the dark background
in deep space

Here's a piece of a meteorite

Same composition as an asteroid,

really hard to see
in visible light

However, when I take
my infrared camera,

wow, it shows right up

And I can see it clearly
against the background

This is the advantage
that Sentinel has

for infrared detection
of asteroids

Sentinel's infrared capability

is essential
for detecting small asteroids

Asteroids around a kilometer
across are easier to spot

Even though they're dark,
their size means

they reflect enough sunlight
for us to see them

Smaller dark asteroids
reflect less light,

but infrared detectors
will pick up the heat they emit

That gives Sentinel
a huge advantage

Our design for Sentinel
is designed to find 90%

of 140 meter or larger asteroids
that might threaten the Earth,

the things that can
really destroy

large areas of a continent,
really do major damage

The goal is to launch
Sentinel in 2018

Meanwhile, NASA is helping fund
a ground-based system

to complement existing
telescopes in Hawaii

Codenamed ATLAS, it will provide
a few weeks' warning,

enough for at least some people
to evacuate

Even this won't find every
asteroid that threatens us

Earth is still flying blind

through a solar system
full of undetected asteroids

The nightmare scenario
is still entirely possible

A small asteroid undetected
by our current technologies

could strike at any time

And we now know that the threat

is not just from rocks
140 meters across

Even far smaller asteroid
strikes can be devastating

When scientists use data
from the Chelyabinsk blast

to calculate
the asteroid's size,

they discover it's tiny:
20 meters across,

an asteroid so small,

no one thought
it could cause a problem

In fact, rocks this small

can do far more damage
than we saw at Chelyabinsk

It all depends on four factors:
the asteroid's composition,

its speed, angle of attack,
and where it strikes

In the immediate aftermath

of the Chelyabinsk strike
in Siberia,

physicist Mark Boslough
continues his research

He hunts through the snow
to find meteorites:

fragments of the asteroid

What's amazing to me, though,
when you think about it,

I mean, this is part
of an asteroid

that had been, you know,
floating through space,

orbiting the sun
for billions of years

And two weeks ago,
it exploded in the atmosphere,

dropped to the ground,

and here I am,
holding it in my hand

That's amazing

Mark takes the fragment
to a lab in Yekaterinburg

and studies it
under an electron microscope

There's a crack here

A crack?

Yes

What's the scale on that?

About three microns

Mark's analysis reveals that
the fragment is mostly rock,

and it's shot through
with cracks

These are scars from previous
collisions in space

When it smashed
into our atmosphere

at 40,000 miles per hour,

and reaching more than
3,600 degrees Fahrenheit,

the cracks help break
the meteor apart

The way we understand it is

it hits the atmosphere
going so fast

that there's
so much stress on it

that it actually breaks
the asteroid

It exceeds the strength
of the asteroid,

and that can happen very,
very fast

The Chelyabinsk meteor
disintegrates

15 miles above the ground

It releases a shockwave

with the energy
of almost 30 atom bombs

It's this shockwave
that does the damage

The Chelyabinsk meteor explodes

because it's made
of fractured rock

But not all asteroids
are made this way

Some are made of metal

The Natural History Museum
in London

holds one of the world's largest
collections of meteorites

Caroline Smith studies them,

and it's clear to her that
not all meteorites are alike

Meteorites come in three
different flavors:

stones, stony irons, or irons

These two that I have here,

these are called
stony iron meteorites,

and these are a mixture
of rock and metal

Because they've got
so much metal in them,

they are much heavier than
a normal rock from Earth

I mean, that's a good
sort of 12, 15 kilograms

And this is an iron nickel
meteorite, and it's heavy

This is about
three times as heavy

as the one that
I've just shown you

It does put into context the
type of damage that you can get

from something of that size

Metallic asteroids are denser
and tougher than rocky ones,

so a metallic asteroid the size
of the Chelyabinsk rock

could punch through
the atmosphere

instead of breaking up,

hitting Earth's surface
more or less intact

And here's the proof:
Meteor Crater, Arizona

Over one kilometer across
and more than 150 meters deep,

yet the meteor that creates it
50,000 years ago

is only one-and-a-half times the
size of the Chelyabinsk meteor

The difference is that
it's metallic

It smashes into the ground with
the power of 500 atom bombs

An iron meteorite
slammed into the rock here

with most of its cosmic speed
still intact

at about 40,000 miles per hour

The energy released
in that impact

was something on the order

of ten megatons
of TNT equivalent,

and it's that energy
that was responsible

for excavating this
enormous hole in the ground

and spewing that rock
into the desert around us

Composition makes
a big difference

to the destructive power
of an asteroid

Metallic asteroids
stand the best chance

of surviving
the brutal atmosphere

But even stony asteroids
can still be devastating

Russia, 1908:

a meteor explodes in the sky
above Tunguska, Siberia

Calculations show
that the asteroid

is just twice the width
of the Chelyabinsk rock

But where the Chelyabinsk blast
knocks out windows,

the Tunguska strike flattens

hundreds of square miles
of forest

Its effects are similar
to this nuclear test blast

captured on film

Even 20 years later,
when these images were taken,

the effects are still evident

So why the difference
between the two meteors?

Video images show
the Chelyabinsk asteroid

approaches at a particularly
shallow angle

Mark Boslough feeds that
information into a computer

used to model the behavior
of nuclear weapons

This simulation shows
the effects

of the meteor's trajectory
on its destructive impact

And you get this enormous
fireball,

and that fireball continues
to move downward

and it pushes a shockwave
ahead of it

So these are like
mushroom clouds

with two big, giant nuclear
explosions at the bottom

The shock from the explosion
continues to push forward

and it starts to move downwards

You can see that it's descending

It's down to about
ten kilometers

above the surface here,
at ground zero

The simulation shows that

because the meteor enters
at a shallow angle,

much of the energy
is lost horizontally

The shockwave is destructive,
but it would have been far worse

if had been focused
more downward

and the explosion
had been closer to the ground

This is what Mark believes
happens in Tunguska in 1908

The Tunguska explosion
was much closer to the ground

and it was much more intense
in terms of energy release,

and therefore the blast wave
was much stronger,

and that's why
it blew down trees

over this wide area
almost a thousand square miles

No one dies
in the Tunguska blast,

but only because
no one lives here

Someday, a similar strike
could happen over a city

It could kill millions

I've seen maps
of the Tunguska blast area

overlaid with a map
of Washington, D C,

and it extends beyond
the Beltway in every direction

An asteroid has more damage
potential on the ground

than a nuclear bomb
of the same energy

Fortunately, most asteroids
are relatively small

and strikes are rare

Better detection will help,

but detection alone
is not enough

If we find an asteroid
heading toward Earth,

what can we do about it?

Sci-fi movies
always have the answers

The hero flies up
and blows the asteroid apart

So this is the real
Hollywood way

of looking at an asteroid's
impact hazard mitigation

So they detect,
with just enough time,

that there's this giant asteroid
or comet or something

coming in towards the Earth,
and everyone decides,

"A-ha, well, we're gonna blow it
to kingdom come

We'll just nuke it"

Blowing an asteroid apart
sounds extreme,

but right now, scientists
are exploring ways

to harness technology

to save us from the next
big asteroid strike

We need to think about, "What is
the response of the object?"

"Are we going to fragment it?

"Is that okay?

"Are the fragments
going to recombine

"or fly off out of the way,

"or are fragments
going to hit the Earth

that we need to worry about?"

To learn how these fragments
might behave,

we can simulate a similar impact
here on Earth

And Peter Schultz is the man
who pulls the trigger

He operates one of the few guns
in the world

fast enough to model
an asteroid strike

This hydrogen-powered gun

is targeted into a reinforced
metal safety chamber

Inside this chamber is a small
resin replica of an asteroid

It's there to illustrate
two different approaches

to keeping Earth safe:
destruction and deflection

So today, we're going to do
two experiments

The first one will actually
destroy the asteroid

by using this projectile,
about a quarter inch across

And the second one,
we'll use this projectile:

it's about an eighth inch across

This will not destroy
the asteroid

but instead will form a crater,

and that's really intended
just to deflect it

without destroying it

The aluminum pellets
will hit the asteroid replica

at almost 12,000 miles per hour

That's over three miles
per second

High-speed cameras are needed

to record every millisecond
of the impact

Even this small simulation
will be violent

The team keeps a safe distance
in the control room

High voltage is good

We have ready lights

Oh, jeez!

We really busted the devil
out of this

The high-speed video
allows Peter to analyze

the impact of the larger
projectile in minute detail

Here's the projectile coming in,

you can actually see it
coming in

It's going to hit right there

Boom!

That is just dangerous

Kapow!

There's nothing left except for
something right in the center

The last piece, that core
still could be a threat,

but it's a lot smaller

We're way down
in terms of a threat

So this is one option we got:

we blow the whole thing
to smithereens

But we always have to wonder,
"Is there something left over?"

Scale this up
to blowing apart a real asteroid

and the problem is clear:

deadly fragments of rock
could still rain down on Earth

So the possible problems
with destroying an object,

or disrupting it, we say,

is that you need to have
enough time for the fragments

that are then flying off
in all kinds of directions

to get out of the way before
the Earth passes through there

Blowing an asteroid apart

could make the problem worse
instead of solving it

Luckily, there is another option

Rather than blast
the asteroid apart,

we could use an impact
to change its course

For a lot of objects, you don't
actually need to blow them up

to prevent them from hitting
Earth and making a crater

For me, the most realistic
are what we call

kinetic impactors
for small asteroids,

and that's basically
a cannonball

shot from a spacecraft
to knock it off course

That might reduce
the fragment problem,

but it still needs to be tested

Peter sets up the gun
with a smaller projectile

This shot should create
a crater, but not an explosion

Here we go

Okay, so let's see what we have

Whoa!

Oh, look at that!

This time, the asteroid
stays mostly intact

And this is the crater forming

So what's going to be
interesting is to see,

"Does it make it move?"

Boom!

Then we see that jet come out...

That's really hot gas,
it's a plasma...

And we can see
the ejecta forming,

and now it begins to move

The collision creates a blast
of super-heated impact material

spraying out from the simulated
asteroid

It acts like a rocket
firing out into space

The asteroid is nudged
off course

So the impact hit it,

its momentum
is now shoving this,

and with enough time,

maybe this would get it
out of our way

So I think we're illustrating

that we don't have to destroy
the whole thing to make it move;

we just have to have
enough energy and momentum

to give it a nudge

Could our planet and our lives
be saved by a mere nudge?

The reason it's so easy

is because the Earth's
a moving target

The Earth's about
8,000 miles across,

and it's moving
65,000 miles an hour

So every eight minutes,

the Earth moves a distance
equal to its size

So all I'm really going to do is
upset the timing a little bit

If I make the asteroid show up
at the collision point

three minutes early
or three minutes late,

the Earth's gone,
and that's all it takes,

that's why it's so easy
at large distances

But this would be
a gradual process

The projectile
will have to be launched

many years before the asteroid
comes close to Earth

This is an urgent problem

because if there is
an asteroid out there

that is already on a trajectory
to hit the Earth

and we're not finding out
about it today,

then we're losing
valuable time it takes

to deflect that asteroid,

because what you really need
is time

You need a decade of warning,

and then it's actually
easy to do

But you need time

So there are two clear options
to prevent asteroid strikes:

Blast the asteroid apart
or deflect it

And there is another way

You could do something called
a gravity tractor,

which is something invented
by myself

and an astronaut named Stan Love

And you just hover
a small spacecraft near it

and you tow it

Even an object
as small as a space probe

has its own gravity

It's incredibly weak,
but over time,

it acts like a tow rope,
altering the asteroid's course

Now, it's not as effective
as a kinetic impactor,

but it's controllable

The purpose
of the gravity tractor

is really to fine tune
the deflection

So it appears that we have
the technical capability

to deflect an asteroid

But it will take
a major investment

to prevent the nightmare
scenario:

a small asteroid
we cannot detect

obliterating a major city

And now there's a new question:

could that same technology
be applied

to turn asteroids
from threat to opportunity?

To answer that question,

consider the birth of our planet

I think it's a fairly
widely-held consensus view

that asteroids' initial impacts
with the Earth

four-and-a-half
billion years ago

seeded the Earth
with a veneer of water

and carbon-based materials
that allowed life to form

These are the building blocks
of life

Asteroids probably dumped
organic compounds

onto the early Earth,

and alongside those
may have come

other beneficial materials:
platinum, gold and water,

all valuable resources on Earth

Could asteroids be a new source
of these materials in space?

Chris Lewicki is president
and chief engineer

of Planetary Resources,

a company that hopes to mine
asteroids for profit

We are mining asteroids today

Some of the most productive
metal mines on Earth

are the site of asteroid impacts

hundreds of millions
of years ago

So to go to space,
in some cases, to the source,

we can get these materials
in much more abundance

than they exist naturally
in the Earth's crust

A single asteroid
of between 200 and 500 meters

could contain as much platinum
as we have mined

in the whole of human history

But Planetary Resources
and other companies

are most interested
in another resource:

water locked up
in the asteroid's rock

I think water is the most
important resource

in developing space

because it enables everything
that follows,

and by taking the water

and breaking it
into hydrogen and oxygen,

we can create rocket fuel,
the same rocket fuel that we use

to launch space shuttles
and to explore space

According to Dale Boucher, CEO
of another space mining company,

producing rocket fuel from water
is simple

So now we're making rocket fuel

This is just water in here,

and we've got
a very simple process

run by a couple
of little batteries

passing electric current
through here

We're going to separate
this water into hydrogen,

hydrogen bubbling off this side

And on this side is oxygen

As you can see, there's twice
as much hydrogen as oxygen

because the formula is H20

Many rockets use liquid hydrogen
and oxygen as fuel

Mix them together
and add a spark,

and you get explosive thrust

Okay, so we're going to capture
the hydrogen in this tube,

we're going to bleed
this valve off

All of the hydrogen
that was bubbled off

is coming up in here

Because it's lighter than air,
it will float up

And what we're gonna do
is tilt it like this

and strike a match

We have lift off!

The weight of a rocket
at lift-off is almost all fuel

It burns almost all that fuel
just getting into orbit

If fuel could be produced
from asteroid water,

rockets could maneuver more
easily and even travel faster

This is something
that is abundant in space

On a single 75-meter asteroid,
we have enough water

to have fueled the entire
US space shuttle program

So how would the ability
to refuel in space

affect the future exploration
of our solar system?

In my mind, it makes sense

to go to an asteroid,
mine water, produce rocket fuel

and hold it there

in an orbital station,
let's say,

so that ships or equipment
or robotic missions can stop in,

have a sandwich, have a coffee,
refuel the rocket ship

and go on to Mars

Imagine driving
your car somewhere

without the opportunity
to stop by and gas it up

This is what we've been doing
in exploring space to date

We now have the potential

of being able to refuel
a spaceship on its way

not only from Earth
into outer space

but to refuel
for farther destinations

in the solar system

The rocket fuel is out there

The challenge is to find
the right asteroids,

get to them,
and then extract the water

All of this demands
new technology,

and several companies are
working on that right now

Planetary Resources plan to use

a newly designed telescope
called Arkyd

to find suitable asteroids

Mining in space starts

much the same as mining does
here on Earth

We start with prospecting
and identifying the resource

And we will survey
maybe dozens of asteroids

until we find the one
that has the most interesting

and most economically viable
combination of features

Assuming they find
an asteroid to mine,

the next challenge is
to reach it

Here, the technology for this
is still on the drawing board

NASA is studying ways
to grab an asteroid

and tow it nearer to Earth

This is a very ambitious
engineering project

So the idea is
to send a spacecraft

out to a near-Earth asteroid...

Not to the asteroid belt
outside of Mars,

but to one that actually
on its own comes near Earth

and is small enough...

And then take the asteroid
with a Kevlar bag

And the asteroid, of course,

is spinning relative
to the spacecraft,

and so it would tangle itself up
in the Kevlar,

which would slow it down

and give the spacecraft
something to hold on to

They would then haul it back

and put it into orbit
around the moon

and have someplace
for scientists to go

to look at this large piece
of space rock still in space

For now, it's unclear whether
this program will go forward

But even if the right asteroid
can be found and captured,

the next challenge will be
extracting the resources

Mining expert Dale Boucher

believes there are lessons
from mining on Earth

that will help with the much
tougher task of mining in space

Terrestrial mining is a brute
force type of activity

You know, when we're drilling,

we've got huge 100-pound drills
driving into the rock

with massive air pressure
behind it, trying to excavate

The excavator itself is massive,
weighs many tons

It's using that dead weight
to its advantage

That's what it needs
to get the traction

to push its bucket
into that rock

and pull that rock out of there

None of this will work in space

There's very little gravity,
and the rocks can be cold:

hundreds of degrees below zero

Mining in space demands
whole new technologies

The big difference is gravity,

which means that
we have more problems

with trying to push enough force
on a drill bit, let's say,

or on an excavator bucket

to try and make that
do our work for us

So we have to start thinking
about how we anchor ourselves

to these very virtually
weightless bodies

Dale has been involved
in developing

specialized mining
and drilling technology

to meet these
extraterrestrial challenges

This drill bit
has been designed for use

in the lower temperatures
of the moon

The same technology
might possibly be adapted

for mining asteroids

So this drill is trying to drill

through this simulated
lunar material

that's got water in it,

and we've cooled it down
to liquid nitrogen temperatures

to simulate the temperature
on the surface of the moon,

near the south pole,

where this drill
is supposed to end up

This is different
from the mining drills

used here on Earth

To save energy and weight,

it uses less power
and is much slower

So the drill runs on

about less than
100 watts of power

It takes a very long time
to drill:

it's like watching paint dry

To do a full meter sample

would take about an hour
to an hour-and-a-half,

depending on how hard
the material actually is

Even if the technology
is within reach,

it would be extremely costly
to find suitable asteroids,

relocate them
and extract their resources

Is there a big enough payoff?

If we're going to exploit
asteroids,

I think we need to really do
a cost benefit

It's expensive to get up there

It's plausible

We can do this... after all,
we've been to the moon...

But I think this requires
some very serious study

We know it's possible

to reach an asteroid
and bring samples to Earth

because the Japanese Hayabusa
probe has already done it

But the samples it brought back
in 2010 were microscopic

To mine significant quantities

is an entirely different
challenge

So is the idea of mining
asteroids premature?

Some believe there's no point
in trying to exploit asteroids

until we are safe from them

Well, I can tell you that
you can't mine an asteroid

if you don't know where it is

in the same way you can't
deflect an asteroid

or protect the Earth
from an asteroid

if you don't know where it is

So the first step to all of this
is building Sentinel,

because Sentinel will find the
asteroids in our solar system

We can deal with the threat
of asteroids

and the opportunity that
they present simultaneously

As we develop the technology
to detect, characterize

and ultimately mine asteroids,

it's that very same technology
that will allow us to identify

potentially hazardous asteroids
and take action

This will drive expansion and
exploration of the solar system,

enabling humanity to eventually

live and work and play
in space permanently

A paradox

Are asteroids the biggest threat
humanity faces

or a new opportunity?

As our knowledge
and technology improve,

could it be that they are both?

Captioned by
Media Access Group at WGBH
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