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Asteroids are
the Earth's nemesis.
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00:00:06,026 --> 00:00:10,095
They've blitzed our world
for billions of years.
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This takes a few seconds
to create.
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00:00:14,268 --> 00:00:17,969
50,000 years ago was a very bad
day for anybody living nearby.
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00:00:17,971 --> 00:00:23,141
Yet asteroids are
also a valuable resource --
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00:00:23,143 --> 00:00:27,446
giant boulders
rich with valuable metals,
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00:00:27,448 --> 00:00:33,085
icy miniature worlds
with more freshwater than Earth.
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00:00:33,087 --> 00:00:36,388
Ultimately, asteroids
may be a stepping stone
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00:00:36,390 --> 00:00:39,825
by which we can one day leave
the entire solar system.
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00:00:39,827 --> 00:00:43,695
Asteroids are planet builders.
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00:00:43,697 --> 00:00:47,733
Without them,
our world would not be here.
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00:00:47,735 --> 00:00:49,868
We owe our very existence
to these things.
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00:00:49,870 --> 00:00:55,307
They are the givers
and takers of life.
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00:01:06,252 --> 00:01:09,588
The night sky is full of stars,
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00:01:09,590 --> 00:01:14,292
galaxies, planets,
and asteroids.
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00:01:14,294 --> 00:01:16,528
"Asteroid" actually
means "star-like."
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00:01:16,530 --> 00:01:18,263
Even in the very best
telescopes,
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they look like nothing more than
just points of light in the sky.
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00:01:21,301 --> 00:01:24,870
They're cosmic boulders,
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00:01:24,872 --> 00:01:27,472
and there are trillions of them,
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from the size of a car to giants
hundreds of miles across.
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00:01:33,547 --> 00:01:39,484
Together they tell the story
of how we came to be.
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00:01:39,486 --> 00:01:43,989
The Earth was made by asteroids.
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4.5 billion years ago,
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00:01:53,233 --> 00:01:56,802
the solar system is a vast,
cosmic whirlpool.
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00:01:58,404 --> 00:02:02,841
Dust sticks together
to create asteroids.
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00:02:04,210 --> 00:02:06,778
In our own solar system
and in every solar system,
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00:02:06,780 --> 00:02:09,614
the first objects to form --
the first large rocks --
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00:02:09,616 --> 00:02:12,184
before planets form,
are essentially asteroids.
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There are no planets yet.
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00:02:16,290 --> 00:02:20,692
Instead, trillions of rocks
and stones
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swirl around the newly born Sun.
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It would've been
a very strange place,
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00:02:27,267 --> 00:02:28,967
kind of like a merry-go-round
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00:02:28,969 --> 00:02:31,670
of all these objects orbiting
around the Sun.
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00:02:31,672 --> 00:02:33,872
And there are millions
of these asteroids
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that are just in different sizes
and different shapes.
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These ancient asteroids
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00:02:40,380 --> 00:02:43,215
will shape the solar system
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00:02:43,217 --> 00:02:46,484
and build the planet we live on.
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00:02:46,486 --> 00:02:50,155
Asteroids are so much more
than just rocks in space.
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00:02:50,157 --> 00:02:52,090
They're the building blocks
of our very own planet.
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Billions of small asteroids
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must clump together
to make a planet.
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00:03:01,935 --> 00:03:07,939
But asteroids move at thousands
of miles per hour.
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Getting them to stick is hard.
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We're here at the stock car race
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to see what the early solar
system may have looked like.
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00:03:23,557 --> 00:03:27,292
High-speed car
collisions cause damage.
50
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Parts smash off.
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00:03:30,330 --> 00:03:33,498
Asteroid collisions
are the same.
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00:03:34,800 --> 00:03:40,639
To join together, somehow
they must collide and stick.
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00:03:42,074 --> 00:03:45,176
Stock cars
show how this happens.
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00:03:45,178 --> 00:03:50,682
They move fast
but all in the same direction,
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just like the asteroids
in the early solar system.
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00:03:56,555 --> 00:04:01,192
When collisions happen,
they're relatively gentle.
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00:04:02,628 --> 00:04:07,365
Instead of smashing apart,
they join together.
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00:04:08,601 --> 00:04:11,770
These are planets in the making.
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00:04:11,772 --> 00:04:15,106
They're going around
almost at the same speed,
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00:04:15,108 --> 00:04:17,442
and they begin
to stick together,
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00:04:17,444 --> 00:04:20,278
and that's how planets
begin to form.
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Asteroids gather
into rock piles,
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like two cars locked together.
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As more asteroids collide,
the rock piles grow.
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00:04:37,663 --> 00:04:42,000
Building whole planets this way
would take billions of years.
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Yet the planets formed
in just a few million years.
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00:04:48,375 --> 00:04:50,008
How?
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00:04:50,010 --> 00:04:53,912
When the rock piles
reach mountain size,
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00:04:53,914 --> 00:04:56,881
gravity speeds up the process.
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Gravity started
to become important
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when they were about the size
of one of the Rocky Mountains,
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like Pikes Peak behind me.
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00:05:04,091 --> 00:05:06,524
It was when they were
several miles across
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00:05:06,526 --> 00:05:07,959
that they had enough mass
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00:05:07,961 --> 00:05:10,829
that their gravity could start
to draw material in.
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00:05:10,831 --> 00:05:12,564
Now, if the Earth weren't here,
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00:05:12,566 --> 00:05:15,667
and it were just Pikes Peak
over there a few miles away,
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00:05:15,669 --> 00:05:18,269
I would very slowly
start to drift toward it,
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faster and faster,
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accelerating the whole way
until I actually impacted it.
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The gravity would draw me in.
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It would pull on me
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until I actually hit
the mountain itself.
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00:05:30,383 --> 00:05:33,852
Large asteroids
are mountains in space.
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00:05:35,621 --> 00:05:39,090
The early solar system
is full of them.
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Their gravity pulls
other asteroids toward them.
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The larger an asteroid becomes,
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the more rocks it pulls in
and the faster it grows.
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00:05:55,175 --> 00:05:58,543
At that point,
the events happen very quickly.
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00:05:58,545 --> 00:06:01,279
It would actually draw that
stuff in and grow very rapidly.
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00:06:01,281 --> 00:06:07,018
One of these early
space mountains keeps on growing
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00:06:07,020 --> 00:06:11,089
until there are no rocks left
to pull in.
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It's no longer an asteroid.
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It's a young planet --
the Earth.
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All of the planets,
even the Earth,
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they owe their existence
to the fact
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00:06:26,339 --> 00:06:28,406
that there were asteroids
back then.
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00:06:28,408 --> 00:06:33,578
This is how all
rocky planets form --
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asteroids join together
until there are no more left.
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00:06:39,319 --> 00:06:43,388
Mercury, Venus,
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Earth, and Mars
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are all overgrown asteroids.
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But beyond Mars,
something went wrong.
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No rocky planets.
105
00:06:58,772 --> 00:07:03,041
Instead, billions of rocks
and boulders
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00:07:03,043 --> 00:07:08,079
that never joined together --
the asteroid belt.
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00:07:11,050 --> 00:07:14,652
Out here,
construction came to a halt
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00:07:14,654 --> 00:07:18,089
before a rocky planet
could form --
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00:07:18,091 --> 00:07:19,958
because of Jupiter.
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00:07:22,128 --> 00:07:26,965
The gas giant had already
formed nearby.
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Jupiter is humongous.
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It's the 800-pound gorilla.
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It dominates everything
gravitationally.
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4.5 billion years ago,
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Jupiter's gravity causes havoc.
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It flings asteroids
in every direction.
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Giant boulders scatter
from their regular orbits
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onto extreme chaotic paths.
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The stock car race ends,
and the demolition derby begins.
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00:08:04,970 --> 00:08:06,538
Once Jupiter got involved,
121
00:08:06,540 --> 00:08:09,874
the solar system began to look
like a demolition derby --
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00:08:09,876 --> 00:08:11,342
things colliding
with each other,
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00:08:11,344 --> 00:08:13,178
going in all sorts
of different directions.
124
00:08:15,181 --> 00:08:17,815
A cosmic pileup --
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00:08:17,817 --> 00:08:23,454
rocks smash into each other
from every direction,
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00:08:23,456 --> 00:08:25,757
violent, chaotic collisions.
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00:08:27,026 --> 00:08:31,029
These rocks
don't clump together.
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00:08:31,031 --> 00:08:33,765
They shatter...
129
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and create the asteroid belt.
130
00:08:38,438 --> 00:08:44,275
Violent collisions still rock
the asteroid belt today.
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00:08:44,277 --> 00:08:49,948
In 2010, the Hubble Space
Telescope captured this --
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the aftermath
of a hypervelocity collision.
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00:08:57,389 --> 00:09:01,893
Asteroids can both create
and destroy.
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00:09:01,895 --> 00:09:07,699
If many of them come together
gently, you get planets.
135
00:09:07,701 --> 00:09:13,771
Too much violence and you get
the asteroid belt --
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00:09:13,773 --> 00:09:17,208
billions of rocks and boulders,
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00:09:17,210 --> 00:09:22,146
a graveyard for a planet
that never formed.
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00:09:22,148 --> 00:09:27,485
The asteroid belt
is a mysterious realm,
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00:09:27,487 --> 00:09:32,257
full of danger
and full of promise,
140
00:09:32,259 --> 00:09:37,795
a new frontier just waiting
to be explored.
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00:09:49,438 --> 00:09:54,910
Asteroids are as
diverse as planets or moons.
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Some are metallic...
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00:09:58,515 --> 00:10:00,849
some rocky...
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00:10:00,851 --> 00:10:03,018
some icy.
145
00:10:05,454 --> 00:10:10,692
Some even have their own moons.
146
00:10:10,694 --> 00:10:15,964
They come in all shapes
and sizes...
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From boulders all the way
to miniature worlds.
148
00:10:24,607 --> 00:10:27,842
And they're everywhere.
149
00:10:27,844 --> 00:10:33,048
Distant solar systems have
their own asteroid belts.
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00:10:33,050 --> 00:10:39,754
The star Epsilon Eridani
is just 10 light-years away.
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It has not one
but two asteroid belts.
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00:10:44,828 --> 00:10:49,531
Another star has a belt
25 times larger
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than our own.
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00:10:51,668 --> 00:10:54,970
If you're actually living on
a planet in that solar system,
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the asteroid belt
would look like a --
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much brighter
than the Milky Way,
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00:10:58,642 --> 00:11:00,408
a big streak
across the night sky.
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00:11:00,410 --> 00:11:04,746
Asteroid belts
are the scraps left over
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00:11:04,748 --> 00:11:07,082
after plans have formed,
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00:11:07,084 --> 00:11:11,286
so they tell us a lot
about their solar system.
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00:11:12,922 --> 00:11:17,926
Our asteroid belt
is full of variety --
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millions of strange asteroids,
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each with a story to tell.
164
00:11:25,869 --> 00:11:29,270
Yet we have barely
explored it at all.
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00:11:31,641 --> 00:11:34,709
That's about to change.
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00:11:34,711 --> 00:11:40,281
The first mission to the
asteroid belt is under way --
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the Dawn Probe.
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00:11:42,919 --> 00:11:45,020
Its goal?
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To explore a mysterious,
distant realm.
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00:11:50,260 --> 00:11:53,094
We're gonna learn more
about the main belt asteroids
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from this one mission
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00:11:54,164 --> 00:11:55,430
than we will have
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00:11:55,432 --> 00:11:58,400
since we discovered the asteroid
belt in the first place.
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00:11:58,402 --> 00:12:01,036
In July 2011,
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00:12:01,038 --> 00:12:04,973
Dawn arrived at its first target
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00:12:04,975 --> 00:12:09,177
and sent back these pictures.
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Vesta is the second-largest
asteroid in the belt.
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It almost became a planet.
179
00:12:17,921 --> 00:12:24,359
Then Jupiter's massive gravity
stunted its growth.
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00:12:24,361 --> 00:12:28,830
Today it's a miniature world.
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00:12:28,832 --> 00:12:31,900
One of the common misconceptions
about the asteroid belt
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is that things are fairly small.
183
00:12:33,370 --> 00:12:35,036
But some of
the largest asteroids
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00:12:35,038 --> 00:12:37,539
are really more correctly
thought of as minor planets.
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00:12:37,541 --> 00:12:39,340
They're several hundred
miles across.
186
00:12:39,342 --> 00:12:43,645
Vesta even has a mountain
187
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three times higher than Everest.
188
00:12:47,250 --> 00:12:51,519
Mark Sykes is co-investigator
of the mission.
189
00:12:51,521 --> 00:12:54,189
It's just a real excitement
190
00:12:54,191 --> 00:12:56,591
because you're seeing a new
world for the first time,
191
00:12:56,593 --> 00:12:58,493
and you know just enough
to be dangerous
192
00:12:58,495 --> 00:13:00,829
in trying to explain what it is
that you're seeing.
193
00:13:00,831 --> 00:13:06,334
Vesta is like
a snapshot of the infant Earth
194
00:13:06,336 --> 00:13:10,271
when it was just as wide
as Arizona.
195
00:13:11,941 --> 00:13:14,142
We're seeing perhaps
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00:13:14,144 --> 00:13:17,779
what an embryonic, early
terrestrial planet like Earth
197
00:13:17,781 --> 00:13:23,084
looked like in the first few
million years of its history.
198
00:13:23,086 --> 00:13:27,355
The Dawn Probe
has already found
199
00:13:27,357 --> 00:13:31,893
that Vesta has an iron core
like the Earth --
200
00:13:31,895 --> 00:13:34,763
evidence that
the Earth's core formed
201
00:13:34,765 --> 00:13:38,867
when the planet was still young.
202
00:13:38,869 --> 00:13:43,271
This stunted world
offers us a window
203
00:13:43,273 --> 00:13:46,407
on the Earth's distant past.
204
00:13:46,409 --> 00:13:51,813
We're seeing things that
we didn't necessarily expect,
205
00:13:51,815 --> 00:13:53,648
but that's what makes it fun.
206
00:13:53,650 --> 00:13:56,985
After Vesta,
207
00:13:56,987 --> 00:13:59,654
the Dawn mission will head
208
00:13:59,656 --> 00:14:03,658
into the asteroid belt's
outer reaches
209
00:14:03,660 --> 00:14:07,262
to explore an icy,
primeval world
210
00:14:07,264 --> 00:14:10,298
four times bigger than Vesta.
211
00:14:10,300 --> 00:14:17,205
There, Dawn aims to settle
another mystery
212
00:14:17,207 --> 00:14:20,875
about the Earth's past --
213
00:14:20,877 --> 00:14:25,747
where did our oceans come from?
214
00:14:36,026 --> 00:14:42,332
The asteroid belt is
ancient, violent, and remote --
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00:14:42,334 --> 00:14:47,337
hundreds of millions of miles
from Earth.
216
00:14:47,339 --> 00:14:52,809
But not all asteroids
stay in the asteroid belt.
217
00:14:52,811 --> 00:14:57,480
They can roam all over
the solar system.
218
00:14:57,482 --> 00:15:02,952
The Moon's surface records
a violent past --
219
00:15:02,954 --> 00:15:06,556
a massive, cosmic bombardment.
220
00:15:06,558 --> 00:15:10,493
We see evidence every night
when the Moon comes out.
221
00:15:10,495 --> 00:15:11,761
What do we see?
222
00:15:11,763 --> 00:15:13,963
A pockmarked, barren world --
223
00:15:13,965 --> 00:15:17,900
evidence that there was
an intense rain of asteroids
224
00:15:17,902 --> 00:15:20,937
and debris that came
from outer space,
225
00:15:20,939 --> 00:15:24,540
completely disfiguring
the surface of the Moon.
226
00:15:24,542 --> 00:15:29,112
Millions of craters
cover the Moon,
227
00:15:29,114 --> 00:15:33,616
including the largest
in the solar system --
228
00:15:33,618 --> 00:15:38,021
1,500 miles across,
229
00:15:38,023 --> 00:15:43,860
itself scarred by thousands
of smaller craters.
230
00:15:43,862 --> 00:15:48,264
A storm of asteroids
blasted the Moon
231
00:15:48,266 --> 00:15:51,401
4 billion years ago.
232
00:15:51,403 --> 00:15:55,138
And if that happened
to the Moon,
233
00:15:55,140 --> 00:15:59,208
it must also have happened
to Earth.
234
00:15:59,210 --> 00:16:03,846
The Earth is a much bigger,
more massive target in space.
235
00:16:03,848 --> 00:16:06,516
For every one of those craters
you see on the Moon,
236
00:16:06,518 --> 00:16:08,584
you've got to imagine
50 or 60 craters
237
00:16:08,586 --> 00:16:09,919
here on the planet Earth.
238
00:16:13,023 --> 00:16:17,393
The impacts back then
must have been horrendous.
239
00:16:17,395 --> 00:16:21,631
Every few weeks, a gigantic
object hurtling from outer space
240
00:16:21,633 --> 00:16:26,436
gouging out a huge chunk
of the planet Earth.
241
00:16:26,438 --> 00:16:30,573
We call it
the late heavy bombardment.
242
00:16:31,909 --> 00:16:38,181
For 200 million years,
fireballs rained from the sky.
243
00:16:42,519 --> 00:16:45,521
The impacts trigger earthquakes
244
00:16:45,523 --> 00:16:49,125
bigger than any
in recorded history.
245
00:16:50,894 --> 00:16:54,263
10,000-mile-per-hour hurricanes
246
00:16:54,265 --> 00:16:57,500
rip through
Earth's primitive atmosphere.
247
00:17:03,140 --> 00:17:09,212
But asteroids also bring
a new substance to Earth.
248
00:17:09,214 --> 00:17:13,683
Some asteroids contain ice --
249
00:17:13,685 --> 00:17:19,322
frozen water that melts
on impact.
250
00:17:19,324 --> 00:17:23,059
Each asteroid
brings a little more.
251
00:17:24,761 --> 00:17:29,198
But could asteroids
really bring enough water
252
00:17:29,200 --> 00:17:32,135
to cover 2/3 of our planet?
253
00:17:32,137 --> 00:17:35,104
One of the questions we have is
how did water get to the Earth.
254
00:17:35,106 --> 00:17:36,973
Because the original Earth,
we think,
255
00:17:36,975 --> 00:17:38,241
was very hot and very dry.
256
00:17:38,243 --> 00:17:45,047
NASA's Dawn Probe
aims to find out.
257
00:17:45,049 --> 00:17:51,454
The asteroid belt still contains
icy asteroids to this day
258
00:17:51,456 --> 00:17:55,558
in the coldest,
most distant part.
259
00:17:55,560 --> 00:17:57,894
In 2015,
260
00:17:57,896 --> 00:18:02,832
Dawn will arrive at the solar
system's largest asteroid --
261
00:18:02,834 --> 00:18:04,333
Ceres.
262
00:18:04,335 --> 00:18:08,504
Ceres is 1/3 the mass
of the entire asteroid belt
263
00:18:08,506 --> 00:18:11,641
and four times as large
as any other known asteroid.
264
00:18:11,643 --> 00:18:17,847
A lot of it
looks like pure ice.
265
00:18:17,849 --> 00:18:23,252
Ceres has a rocky
interior and ice-rich mantle.
266
00:18:23,254 --> 00:18:26,956
It's far enough away from
the Sun -- it's cold enough --
267
00:18:26,958 --> 00:18:28,224
that it's stable.
268
00:18:28,226 --> 00:18:32,528
Ceres is just 600 miles wide,
269
00:18:32,530 --> 00:18:37,233
yet there may be
more frozen water here
270
00:18:37,235 --> 00:18:40,670
than all the freshwater
on Earth.
271
00:18:40,672 --> 00:18:45,708
The Dawn mission will find out
for sure.
272
00:18:45,710 --> 00:18:50,680
If Ceres really does hold
so much ice,
273
00:18:50,682 --> 00:18:55,451
it could help explain why
the Earth has so much water.
274
00:18:57,354 --> 00:19:03,559
When asteroids bombarded
the Earth 4 billion years ago,
275
00:19:03,561 --> 00:19:07,096
massive icy bodies like Ceres
276
00:19:07,098 --> 00:19:12,101
could've brought vast amounts
of water.
277
00:19:12,103 --> 00:19:14,937
Water itself,
in the form of ice,
278
00:19:14,939 --> 00:19:16,772
came down from the heavens
279
00:19:16,774 --> 00:19:19,609
to create the lush oceans
of the Earth.
280
00:19:19,611 --> 00:19:23,446
And not just the oceans.
281
00:19:23,448 --> 00:19:27,883
Clouds, rivers...
282
00:19:27,885 --> 00:19:32,688
glaciers may all have come
from space.
283
00:19:34,658 --> 00:19:37,727
The Dawn mission
may uncover something
284
00:19:37,729 --> 00:19:41,097
even more significant on Ceres.
285
00:19:41,099 --> 00:19:46,869
It may find an ocean
underneath the ice --
286
00:19:46,871 --> 00:19:50,306
an inner mantle of liquid water,
287
00:19:50,308 --> 00:19:55,244
melted by heat from
the dwarf planet's core.
288
00:19:56,613 --> 00:20:00,916
Life as we know it
depends on water.
289
00:20:00,918 --> 00:20:06,889
Wherever we find water,
we may find the spark of life.
290
00:20:08,525 --> 00:20:11,127
If there is a liquid-water ocean
underneath the surface today,
291
00:20:11,129 --> 00:20:12,161
that begs the question
292
00:20:12,163 --> 00:20:13,796
of whether there could be
life there.
293
00:20:13,798 --> 00:20:18,200
Extraterrestrial life
could've started
294
00:20:18,202 --> 00:20:20,336
in the asteroid belt.
295
00:20:22,806 --> 00:20:27,310
Ceres could be home
to basic life-forms
296
00:20:27,312 --> 00:20:31,580
flourishing
in a subsurface ocean.
297
00:20:36,453 --> 00:20:41,290
If asteroids like Ceres
can support life,
298
00:20:41,292 --> 00:20:46,429
that could reveal how life
started on Earth.
299
00:20:46,431 --> 00:20:50,032
4 billion years ago,
300
00:20:50,034 --> 00:20:55,905
asteroids bombarded
the young Earth.
301
00:20:55,907 --> 00:21:01,544
They brought water,
and they may have brought life.
302
00:21:03,480 --> 00:21:06,782
From the asteroid belt
303
00:21:06,784 --> 00:21:10,353
to Earth's new oceans...
304
00:21:10,355 --> 00:21:13,756
Primitive organisms that thrived
305
00:21:13,758 --> 00:21:19,729
and ultimately evolved into all
the Earth's creatures --
306
00:21:19,731 --> 00:21:24,800
a planet that brims with life.
307
00:21:25,836 --> 00:21:30,206
Our earliest ancestors
may have arrived
308
00:21:30,208 --> 00:21:32,742
from the asteroid belt.
309
00:21:32,744 --> 00:21:36,212
Perhaps these little worlds
could be incubators of life
310
00:21:36,214 --> 00:21:38,013
throughout our solar system,
311
00:21:38,015 --> 00:21:41,384
maybe even in other solar
systems around other stars.
312
00:21:41,386 --> 00:21:45,154
Asteroids may bring life
313
00:21:45,156 --> 00:21:48,891
to worlds throughout
the Universe.
314
00:21:48,893 --> 00:21:52,628
They may also bring death.
315
00:22:00,266 --> 00:22:04,958
Asteroids are crucial
to life in the Universe.
316
00:22:05,452 --> 00:22:12,403
But once life gets started,
asteroids can also end it.
317
00:22:13,185 --> 00:22:15,252
Asteroids really have
two sides to them.
318
00:22:15,254 --> 00:22:17,220
They're sort of creation
and destruction
319
00:22:17,222 --> 00:22:18,555
all wrapped up together.
320
00:22:18,557 --> 00:22:23,226
Planet Earth is right
in the firing line.
321
00:22:23,228 --> 00:22:25,128
We've come to realize
in recent years
322
00:22:25,130 --> 00:22:27,798
that we live in this kind of
a cosmic shooting gallery.
323
00:22:27,800 --> 00:22:34,037
Astronauts
witness this firsthand.
324
00:22:34,039 --> 00:22:38,075
When I flew on Apollo 9 and I
went outside the spacecraft,
325
00:22:38,077 --> 00:22:40,277
it's very likely that I was hit
326
00:22:40,279 --> 00:22:43,347
by, you know,
a very, very small asteroid.
327
00:22:43,349 --> 00:22:48,018
And, you know, it will make
a hole in a space suit.
328
00:22:48,020 --> 00:22:52,789
Most objects in
the Earth's vicinity are tiny,
329
00:22:52,791 --> 00:22:56,727
but they move at thousands
of miles per hour.
330
00:22:56,729 --> 00:22:59,663
So, the suits
are very, very well-built,
331
00:22:59,665 --> 00:23:02,733
the result of which
is they're very heavy.
332
00:23:02,735 --> 00:23:06,269
But, you know, we've never had
one penetrated yet.
333
00:23:06,271 --> 00:23:11,074
The Earth, too,
has built-in protection
334
00:23:11,076 --> 00:23:16,279
from small asteroids --
the atmosphere.
335
00:23:16,281 --> 00:23:20,851
When asteroids hit
the atmosphere, they burn.
336
00:23:20,853 --> 00:23:22,319
I can remember,
337
00:23:22,321 --> 00:23:25,756
one night when we were looking
down at the dark Earth,
338
00:23:25,758 --> 00:23:29,259
and I kept thinking I saw
an occasional flash of light,
339
00:23:29,261 --> 00:23:30,594
but I wasn't sure.
340
00:23:30,596 --> 00:23:34,064
And then suddenly, we're
realizing, of course, you know,
341
00:23:34,066 --> 00:23:36,400
we're looking at shooting stars.
342
00:23:41,372 --> 00:23:44,241
Most people don't
realize that on a given night,
343
00:23:44,243 --> 00:23:46,977
if you lie in the grass
and look up at the night sky,
344
00:23:46,979 --> 00:23:50,313
you'll see shooting stars,
many of them each hour.
345
00:23:51,516 --> 00:23:56,920
Most shooting stars
are the size of grains of sand.
346
00:23:56,922 --> 00:23:59,356
These burn up.
347
00:24:01,626 --> 00:24:03,894
But larger space rocks
348
00:24:03,896 --> 00:24:07,831
can punch right through
to the ground.
349
00:24:07,833 --> 00:24:10,500
Here's the proof --
350
00:24:10,502 --> 00:24:13,804
meteor crater in Arizona,
351
00:24:13,806 --> 00:24:17,741
gouged out by an asteroid
352
00:24:17,743 --> 00:24:21,144
just 150 feet across.
353
00:24:21,146 --> 00:24:25,615
You can see the huge
force that excavated this,
354
00:24:25,617 --> 00:24:28,819
and you can also see
the layers of material
355
00:24:28,821 --> 00:24:33,490
that were turned over
as the crater was excavated,
356
00:24:33,492 --> 00:24:36,259
and so some of these rocks
around here
357
00:24:36,261 --> 00:24:39,629
are kind of upside-down
from where they started.
358
00:24:39,631 --> 00:24:43,800
There have been
millions of impacts like this
359
00:24:43,802 --> 00:24:46,203
in Earth's past.
360
00:24:46,205 --> 00:24:48,939
There will be more.
361
00:24:48,941 --> 00:24:53,777
Imagine a city
where meteor crater is now.
362
00:24:53,779 --> 00:24:57,414
You can see a fireball coming
through the sky very quickly.
363
00:24:57,416 --> 00:25:00,350
You know, this thing is moving
at eight miles a second,
364
00:25:00,352 --> 00:25:02,285
and so it wouldn't take
very long
365
00:25:02,287 --> 00:25:05,088
for it to move across the sky
and strike the ground.
366
00:25:05,090 --> 00:25:09,659
Heat from the fireball
scorches the surface.
367
00:25:09,661 --> 00:25:13,930
But most damage comes
after the impact.
368
00:25:16,100 --> 00:25:17,968
Once it strikes the ground,
369
00:25:17,970 --> 00:25:20,570
this takes a few seconds
to create.
370
00:25:20,572 --> 00:25:24,074
So, a very short time,
very large amount of energy,
371
00:25:24,076 --> 00:25:26,076
and very devastating effects.
372
00:25:26,078 --> 00:25:30,146
The asteroid is obliterated.
373
00:25:30,148 --> 00:25:34,050
A mighty shock wave
generates winds
374
00:25:34,052 --> 00:25:38,522
six times more powerful
than a hurricane.
375
00:25:38,524 --> 00:25:41,057
You have the blast
that comes out,
376
00:25:41,059 --> 00:25:43,026
probably for several miles,
377
00:25:43,028 --> 00:25:47,731
and large debris that would
crush buildings and homes.
378
00:25:47,733 --> 00:25:51,101
If it hit today,
379
00:25:51,103 --> 00:25:57,741
the asteroid from meteor crater
would be a city killer.
380
00:25:57,743 --> 00:26:01,978
But the meteor crater asteroid
was small.
381
00:26:01,980 --> 00:26:08,518
It was likely a fragment
from a much larger asteroid.
382
00:26:08,520 --> 00:26:12,222
Whatever it is that hit in
meteor crater wasn't very big.
383
00:26:12,224 --> 00:26:14,324
It was probably 50 yards across,
384
00:26:14,326 --> 00:26:17,027
so not even as big
as a football field.
385
00:26:17,029 --> 00:26:23,033
There are millions
of much larger asteroids.
386
00:26:23,035 --> 00:26:27,537
These would cause
even more carnage --
387
00:26:27,539 --> 00:26:30,507
country killers and worse.
388
00:26:31,876 --> 00:26:35,345
Asteroids over a half mile wide
389
00:26:35,347 --> 00:26:38,648
could end our civilization --
390
00:26:38,650 --> 00:26:42,018
worldwide killers.
391
00:26:42,020 --> 00:26:45,655
We know because
it happened already.
392
00:26:50,194 --> 00:26:53,597
There are traces everywhere.
393
00:26:55,733 --> 00:26:58,802
There's evidence of giant
impacts all over the world,
394
00:26:58,804 --> 00:27:01,104
and it's right underneath
your feet.
395
00:27:01,106 --> 00:27:04,341
And in fact, in some places,
it's pretty easy to spot.
396
00:27:08,145 --> 00:27:12,682
Like here in Southern Colorado.
397
00:27:16,220 --> 00:27:20,991
So, this layer of light-colored
rock, that's the KT boundary.
398
00:27:20,993 --> 00:27:24,661
And it's called a boundary
because it marks the boundary
399
00:27:24,663 --> 00:27:26,630
between two different
time periods.
400
00:27:26,632 --> 00:27:28,498
Everything that was
put down here
401
00:27:28,500 --> 00:27:31,901
underneath the KT boundary
had dinosaurs in it.
402
00:27:31,903 --> 00:27:34,638
Everything above it --
no dinosaurs.
403
00:27:34,640 --> 00:27:37,407
So it really marks
that point in time
404
00:27:37,409 --> 00:27:39,476
when the dinosaurs went away.
405
00:27:39,478 --> 00:27:45,882
The layer is rich
in an element called iridium.
406
00:27:45,884 --> 00:27:52,255
It's rare on the Earth's surface
but common in asteroids.
407
00:27:52,257 --> 00:27:55,625
So, if a giant asteroid came in,
smacked into the Earth,
408
00:27:55,627 --> 00:27:57,160
blew out dust everywhere,
409
00:27:57,162 --> 00:27:59,029
the iridium inside the asteroid
410
00:27:59,031 --> 00:28:02,065
would've settled down
into a layer all over Earth,
411
00:28:02,067 --> 00:28:04,501
and that's exactly
what we see right here.
412
00:28:06,871 --> 00:28:10,874
The clear fingerprint
of an asteroid.
413
00:28:10,876 --> 00:28:13,677
There must have been
some perfect morning
414
00:28:13,679 --> 00:28:15,145
before the asteroid impact
415
00:28:15,147 --> 00:28:17,847
when the land of the dinosaurs
was still very much
416
00:28:17,849 --> 00:28:19,949
as it had been
for millions of years.
417
00:28:19,951 --> 00:28:22,719
Then there would be something
sighted up in the sky,
418
00:28:22,721 --> 00:28:24,421
something very bright, very hot.
419
00:28:24,423 --> 00:28:28,591
The asteroid
is six miles long,
420
00:28:28,593 --> 00:28:32,262
big enough
to devastate the planet.
421
00:28:34,131 --> 00:28:37,133
The asteroid that came in
and formed this layer here
422
00:28:37,135 --> 00:28:39,636
was very massive
and was moving very fast,
423
00:28:39,638 --> 00:28:41,738
and so when it impacted
the Earth,
424
00:28:41,740 --> 00:28:45,041
that energy was turned into
boom -- a very, very big boom.
425
00:28:48,212 --> 00:28:53,683
It has the force
of 5 billion Hiroshima bombs.
426
00:28:53,685 --> 00:28:59,289
Large pieces of Earth blow out
into space,
427
00:28:59,291 --> 00:29:05,428
then rain back down --
a storm of fireballs.
428
00:29:05,430 --> 00:29:10,533
Wildfires rage across the globe.
429
00:29:14,572 --> 00:29:19,042
In the KT boundary layer
is a layer of soot,
430
00:29:19,044 --> 00:29:22,278
and that's an indication
that there were global fires,
431
00:29:22,280 --> 00:29:25,115
that everything on Earth
was basically on fire
432
00:29:25,117 --> 00:29:26,416
after this happened.
433
00:29:26,418 --> 00:29:32,489
The Earth plunges
into darkness --
434
00:29:32,491 --> 00:29:36,326
an impact winter --
435
00:29:36,328 --> 00:29:38,161
mass extinction.
436
00:29:38,163 --> 00:29:40,597
Basically
you can think of this
437
00:29:40,599 --> 00:29:42,866
as every environmental
catastrophe
438
00:29:42,868 --> 00:29:44,734
all happening at the same time.
439
00:29:44,736 --> 00:29:47,604
It was an incredibly bad day
for planet Earth.
440
00:29:47,606 --> 00:29:53,843
A chilling reminder
of the threat from space.
441
00:29:53,845 --> 00:29:59,182
Asteroids this big
will hit us again.
442
00:29:59,184 --> 00:30:02,085
We will go
the way of the dinosaurs.
443
00:30:02,087 --> 00:30:03,653
We will be survived,
444
00:30:03,655 --> 00:30:06,723
most likely by the bugs,
the cockroaches.
445
00:30:06,725 --> 00:30:10,393
They will be the ones
who will inherit this Earth.
446
00:30:10,395 --> 00:30:12,829
But hopefully that's gonna be
a long time from now.
447
00:30:12,831 --> 00:30:17,467
Is mankind doomed?
448
00:30:17,469 --> 00:30:21,638
Or can we dodge fate?
449
00:30:28,276 --> 00:30:33,714
Asteroids built our world.
450
00:30:33,716 --> 00:30:37,050
They brought water.
451
00:30:37,052 --> 00:30:40,521
They killed the dinosaurs
452
00:30:40,523 --> 00:30:44,791
and made room for new species.
453
00:30:47,061 --> 00:30:50,931
But asteroids are also a threat.
454
00:30:53,768 --> 00:30:55,936
We know absolutely
for certain
455
00:30:55,938 --> 00:30:58,338
that there will be large impacts
in the future,
456
00:30:58,340 --> 00:31:01,875
so it's not a question of "if,"
it's only a question of "when."
457
00:31:01,877 --> 00:31:06,613
Large meteor impacts happen once
every 60 to 100 million years.
458
00:31:06,615 --> 00:31:08,682
We're due for one soon perhaps.
459
00:31:08,684 --> 00:31:14,855
If we want to survive,
we need to prepare.
460
00:31:14,857 --> 00:31:18,292
We must find the asteroids,
461
00:31:18,294 --> 00:31:21,795
determine if they're heading
for Earth,
462
00:31:21,797 --> 00:31:24,131
then stop them.
463
00:31:24,133 --> 00:31:26,900
That's not easy.
464
00:31:26,902 --> 00:31:29,436
But it may be possible.
465
00:31:29,438 --> 00:31:32,873
Happily, there's a difference
between us and dinosaurs.
466
00:31:32,875 --> 00:31:34,141
We have telescopes,
467
00:31:34,143 --> 00:31:36,944
and we can get advance notice
of an impact.
468
00:31:39,814 --> 00:31:45,018
Asteroids are much smaller
than stars and planets.
469
00:31:45,020 --> 00:31:47,254
It's hard to see them coming.
470
00:31:49,424 --> 00:31:52,492
To track asteroids,
471
00:31:52,494 --> 00:31:56,463
you need a giant telescope
472
00:31:56,465 --> 00:32:01,602
like the Arecibo Observatory
in Puerto Rico.
473
00:32:01,604 --> 00:32:05,172
Right now I'm on top of the
largest telescope in the world,
474
00:32:05,174 --> 00:32:07,407
and this place may actually be
our best defense
475
00:32:07,409 --> 00:32:10,010
against getting hit by one
of these near-earth asteroids.
476
00:32:10,012 --> 00:32:15,816
The vast bowl
is 1,000 feet across.
477
00:32:18,486 --> 00:32:21,888
And it's not only the world's
biggest telescope,
478
00:32:21,890 --> 00:32:26,426
it's also the world's
biggest radar dish.
479
00:32:26,428 --> 00:32:27,694
When you think about using radar
480
00:32:27,696 --> 00:32:29,162
to keep track
of all the airplanes
481
00:32:29,164 --> 00:32:30,163
that are up in the sky,
482
00:32:30,165 --> 00:32:32,032
well, this one is so powerful,
483
00:32:32,034 --> 00:32:35,969
it can actually track near-earth
objects millions of miles away.
484
00:32:35,971 --> 00:32:39,206
Unlike a telescope,
485
00:32:39,208 --> 00:32:44,011
radar can directly measure
an object's distance
486
00:32:44,013 --> 00:32:47,080
and reveal exactly where it is.
487
00:32:47,082 --> 00:32:51,952
That's perfect
for tracking asteroids.
488
00:32:51,954 --> 00:32:54,688
In 2004,
489
00:32:54,690 --> 00:32:58,892
astronomers spot
a stadium-sized asteroid
490
00:32:58,894 --> 00:33:01,094
heading toward Earth.
491
00:33:01,096 --> 00:33:02,763
Its name --
492
00:33:02,765 --> 00:33:07,934
"Apophis," after the Egyptian
God of destruction.
493
00:33:09,504 --> 00:33:12,205
The day it might hit us --
494
00:33:12,207 --> 00:33:16,343
April 13, 2029,
495
00:33:16,345 --> 00:33:20,180
Friday the 13th.
496
00:33:20,182 --> 00:33:22,516
Apophis was the first
near-earth object
497
00:33:22,518 --> 00:33:25,118
of the modern era that had
astronomers honestly scared.
498
00:33:25,120 --> 00:33:26,987
There seemed to be
a one in 30 chance
499
00:33:26,989 --> 00:33:28,822
of something catastrophic
happening.
500
00:33:28,824 --> 00:33:32,793
Arecibo springs into action
501
00:33:32,795 --> 00:33:38,131
against the biggest threat
from space ever detected.
502
00:33:38,133 --> 00:33:43,070
Apophis could devastate
entire countries.
503
00:33:43,072 --> 00:33:47,607
But the asteroid's path
is still uncertain.
504
00:33:47,609 --> 00:33:52,379
It might hit,
or it might just miss.
505
00:33:52,381 --> 00:33:57,017
Only Arecibo
can tell us for sure.
506
00:33:57,019 --> 00:33:58,752
The Arecibo telescope
507
00:33:58,754 --> 00:34:01,488
was able to reduce the
uncertainty of Apophis by 98%.
508
00:34:01,490 --> 00:34:03,457
It told us that there was
no chance
509
00:34:03,459 --> 00:34:05,092
this thing would hit us in 2029.
510
00:34:09,430 --> 00:34:12,532
It will be close.
511
00:34:12,534 --> 00:34:18,405
Apophis will pass closer
to the Earth than the Moon,
512
00:34:18,407 --> 00:34:23,910
closer even than some
communications satellites.
513
00:34:27,048 --> 00:34:33,053
We have powerful tools
to detect asteroids.
514
00:34:33,055 --> 00:34:37,190
Someday, we'll find one
that will hit the Earth.
515
00:34:38,392 --> 00:34:43,029
How can we protect ourselves?
516
00:34:43,031 --> 00:34:47,100
The obvious strategy
is to destroy the asteroid
517
00:34:47,102 --> 00:34:49,069
before it destroys us.
518
00:34:49,071 --> 00:34:52,205
But that could be risky.
519
00:34:52,207 --> 00:34:54,841
You don't want to blow it up
520
00:34:54,843 --> 00:34:57,144
because you may end up
breaking it up
521
00:34:57,146 --> 00:34:59,212
into two or three
or five pieces,
522
00:34:59,214 --> 00:35:01,948
which then end up hitting
all around the Earth
523
00:35:01,950 --> 00:35:05,118
and wiping out
many, many people.
524
00:35:05,120 --> 00:35:10,791
Exploding an asteroid
could cause more harm than good.
525
00:35:10,793 --> 00:35:14,728
Better to make it
miss completely.
526
00:35:14,730 --> 00:35:18,031
When an asteroid is headed
for Earth,
527
00:35:18,033 --> 00:35:21,668
their future paths cross.
528
00:35:21,670 --> 00:35:26,706
And they'll both reach
that point at the same time.
529
00:35:28,843 --> 00:35:32,546
Imagine the Earth
is a freight train
530
00:35:32,548 --> 00:35:35,849
and the asteroid is a car,
531
00:35:35,851 --> 00:35:40,053
both heading
for a railroad crossing.
532
00:35:40,055 --> 00:35:43,623
If they reach that crossing
at the same time,
533
00:35:43,625 --> 00:35:46,092
they will collide.
534
00:35:46,094 --> 00:35:49,029
The best way to avoid the impact
535
00:35:49,031 --> 00:35:52,699
is not to swerve away
from the train,
536
00:35:52,701 --> 00:35:56,136
it's to hit the gas
or the brakes.
537
00:35:56,138 --> 00:35:59,606
If you can cross the tracks
before the train gets there
538
00:35:59,608 --> 00:36:02,442
or wait for the train to pass
and then cross them --
539
00:36:02,444 --> 00:36:04,511
that's what we want to do
with asteroids,
540
00:36:04,513 --> 00:36:06,913
just to make sure that
the asteroid and the Earth
541
00:36:06,915 --> 00:36:09,049
aren't at the same place
at the same time.
542
00:36:16,324 --> 00:36:19,826
By simply slowing down the car,
we're gonna miss.
543
00:36:19,828 --> 00:36:22,529
That's the way to avert
a collision.
544
00:36:25,032 --> 00:36:29,703
But asteroids
don't come with brakes.
545
00:36:29,705 --> 00:36:33,974
We need another way
to change their speed.
546
00:36:33,976 --> 00:36:40,080
One approach is to use
the asteroid's gravity.
547
00:36:40,082 --> 00:36:41,915
For a small enough asteroid,
548
00:36:41,917 --> 00:36:44,818
all you need to do is park
a large spacecraft
549
00:36:44,820 --> 00:36:46,419
next to the asteroid.
550
00:36:46,421 --> 00:36:51,691
A spaceship would hover above
the asteroid's surface.
551
00:36:51,693 --> 00:36:53,727
You can thrust
with your spacecraft
552
00:36:53,729 --> 00:36:56,830
to keep it from falling onto
the surface of the asteroid,
553
00:36:56,832 --> 00:36:59,132
and so it's like a little
gravity tractor --
554
00:36:59,134 --> 00:37:00,867
using gravity as the tow line
555
00:37:00,869 --> 00:37:02,969
to move the asteroid
out of the way.
556
00:37:02,971 --> 00:37:06,640
Over time,
the gravity between them
557
00:37:06,642 --> 00:37:10,010
would slow down the asteroid
just enough
558
00:37:10,012 --> 00:37:11,978
for it to miss the Earth.
559
00:37:14,348 --> 00:37:19,753
Asteroids could shape our future
in another way.
560
00:37:19,755 --> 00:37:23,456
We could turn them
from a deadly threat
561
00:37:23,458 --> 00:37:27,060
into a precious resource.
562
00:37:40,343 --> 00:37:45,047
Asteroids are a creative force.
563
00:37:45,049 --> 00:37:47,283
They build planets.
564
00:37:47,285 --> 00:37:49,985
They bring water.
565
00:37:49,987 --> 00:37:53,422
But they're also destructive.
566
00:37:53,424 --> 00:37:55,991
Asteroids are both a boon
and a threat.
567
00:37:55,993 --> 00:37:58,794
Early on, they bring
the materials for life.
568
00:37:58,796 --> 00:38:00,763
Later on, they can destroy life.
569
00:38:00,765 --> 00:38:05,501
Asteroids bring
violence and death.
570
00:38:05,503 --> 00:38:09,538
But life may not always
be in danger.
571
00:38:09,540 --> 00:38:14,076
Ultimately, if life
becomes intelligent enough,
572
00:38:14,078 --> 00:38:15,244
it can send objects out
573
00:38:15,246 --> 00:38:17,146
to deflect or destroy
the impending asteroids.
574
00:38:17,148 --> 00:38:23,652
We now have the
technology to divert asteroids.
575
00:38:23,654 --> 00:38:28,457
That means we can treat them
not as a threat
576
00:38:28,459 --> 00:38:30,626
but an opportunity.
577
00:38:30,628 --> 00:38:33,595
We could mine them.
578
00:38:33,597 --> 00:38:35,631
Many of them are
just ripe for the taking
579
00:38:35,633 --> 00:38:37,266
in these wonderful
mineral resources.
580
00:38:37,268 --> 00:38:38,834
And so the asteroids,
in some ways,
581
00:38:38,836 --> 00:38:40,436
are literally gold mines
in the sky.
582
00:38:40,438 --> 00:38:44,473
They're not just gold mines.
583
00:38:44,475 --> 00:38:46,542
They're zinc mines,
584
00:38:46,544 --> 00:38:48,243
aluminum mines,
585
00:38:48,245 --> 00:38:50,813
platinum mines.
586
00:38:50,815 --> 00:38:54,917
Just one average-sized asteroid
587
00:38:54,919 --> 00:38:56,885
could contain minerals
588
00:38:56,887 --> 00:39:00,356
worth thousands of billions
of dollars.
589
00:39:03,660 --> 00:39:08,764
But first, we have to reach
the asteroids.
590
00:39:12,035 --> 00:39:15,904
On April 15, 2010,
591
00:39:15,906 --> 00:39:20,242
President Obama
announced a new plan.
592
00:39:20,244 --> 00:39:22,111
By 2025,
593
00:39:22,113 --> 00:39:25,381
we expect new spacecraft
designed for long journeys
594
00:39:25,383 --> 00:39:28,650
to allow us to begin the first
ever crewed missions
595
00:39:28,652 --> 00:39:30,686
beyond the Moon into deep space.
596
00:39:32,655 --> 00:39:35,858
We'll start by sending
astronauts to an asteroid
597
00:39:35,860 --> 00:39:37,693
for the first time in history.
598
00:39:39,196 --> 00:39:42,564
Ironically,
599
00:39:42,566 --> 00:39:44,933
the easiest asteroids to reach
600
00:39:44,935 --> 00:39:48,404
are the same ones
that threaten the Earth.
601
00:39:48,406 --> 00:39:50,372
As they pass by,
602
00:39:50,374 --> 00:39:55,611
a spaceship could rendezvous
with the asteroid.
603
00:39:55,613 --> 00:39:59,982
Yet even when asteroids
come so close,
604
00:39:59,984 --> 00:40:04,853
asteroid mining may be too good
to be true.
605
00:40:04,855 --> 00:40:09,291
The reason why we're not
mining the asteroid belt today
606
00:40:09,293 --> 00:40:12,261
and letting the space program
pay for itself
607
00:40:12,263 --> 00:40:13,662
is because of cost.
608
00:40:13,664 --> 00:40:17,232
It takes an enormous amount
of rocket fuel and expertise
609
00:40:17,234 --> 00:40:20,135
to bring back an asteroid
from outer space.
610
00:40:20,137 --> 00:40:23,605
But perhaps we don't need
611
00:40:23,607 --> 00:40:28,177
to bring the minerals back
to Earth.
612
00:40:28,179 --> 00:40:32,147
We could use the resources
of asteroids
613
00:40:32,149 --> 00:40:35,684
to build settlements
out in space.
614
00:40:35,686 --> 00:40:38,954
You don't have to build
a space station.
615
00:40:38,956 --> 00:40:40,389
It's already there.
616
00:40:40,391 --> 00:40:41,990
You don't need shielding
617
00:40:41,992 --> 00:40:45,127
because you can simply drill
right into the soil
618
00:40:45,129 --> 00:40:47,796
and use the rocky material
as shielding
619
00:40:47,798 --> 00:40:50,432
against radiation
and micro-meteorites.
620
00:40:50,434 --> 00:40:51,733
So, in some sense,
621
00:40:51,735 --> 00:40:54,870
think of an asteroid
as a ready-made space station.
622
00:40:54,872 --> 00:41:00,275
Low gravity makes it
easy to come and go.
623
00:41:00,277 --> 00:41:02,911
There's plenty of water,
624
00:41:02,913 --> 00:41:06,782
and all the construction
materials
625
00:41:06,784 --> 00:41:10,119
that colonizers could ever need.
626
00:41:13,189 --> 00:41:17,226
So, one day, when we have
colonies in the asteroid belt,
627
00:41:17,228 --> 00:41:19,695
and we need
to build cities there,
628
00:41:19,697 --> 00:41:22,898
that's where we're gonna
find valuable deposits
629
00:41:22,900 --> 00:41:25,567
of metals
in the asteroid belt itself.
630
00:41:25,569 --> 00:41:30,305
A vast band of cities in space
631
00:41:30,307 --> 00:41:33,675
strung across a billion miles.
632
00:41:34,844 --> 00:41:39,348
And not just cities
but factories
633
00:41:39,350 --> 00:41:45,154
to turn metal from the asteroids
into spaceships.
634
00:41:45,156 --> 00:41:48,023
Perhaps asteroids could actually
provide the metal --
635
00:41:48,025 --> 00:41:50,559
the real structure --
to build our spacecraft.
636
00:41:50,561 --> 00:41:53,162
So somewhere up there,
between Mars and Jupiter,
637
00:41:53,164 --> 00:41:55,898
there may be the makings
of our future spaceships.
638
00:41:55,900 --> 00:41:58,767
Ultimately, asteroids
may be a stepping stone
639
00:41:58,769 --> 00:42:02,204
by which we can, one day,
leave the entire solar system.
640
00:42:03,940 --> 00:42:07,843
Asteroids made the Earth.
641
00:42:07,845 --> 00:42:11,847
Perhaps they even
brought life here.
642
00:42:11,849 --> 00:42:13,882
And in the future,
643
00:42:13,884 --> 00:42:18,554
asteroids could help humans
escape the Earth
644
00:42:18,556 --> 00:42:21,690
and colonize the galaxy.
645
00:42:23,193 --> 00:42:27,863
So, in a way, asteroids
are drawing us out into space,
646
00:42:27,865 --> 00:42:31,833
whether to protect ourselves
or to expand where we live.
647
00:42:35,238 --> 00:42:40,175
Advanced civilizations
all over the Universe
648
00:42:40,177 --> 00:42:45,781
may use asteroids as
stepping stones to the stars.
649
00:42:48,685 --> 00:42:53,789
Mankind may soon enter the age
650
00:42:53,791 --> 00:42:56,391
of asteroids.
50621
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