How to defend Earth from asteroids
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0:01 - 0:03I want to talk to you about something
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0:03 - 0:06kind of big.
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0:06 - 0:09We'll start here.
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0:09 - 0:1265 million years ago
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0:12 - 0:15the dinosaurs had a bad day.
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0:15 - 0:18(Laughter)
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0:18 - 0:21A chunk of rock six miles across,
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0:21 - 0:23moving something like 50 times
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0:23 - 0:25the speed of a rifle bullet,
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0:25 - 0:27slammed into the Earth.
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0:27 - 0:29It released its energy all at once,
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0:29 - 0:31and it was an explosion that was
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0:31 - 0:33mind-numbing.
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0:33 - 0:35If you took every nuclear weapon ever built
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0:35 - 0:37at the height of the Cold War,
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0:37 - 0:39lumped them together and blew them up
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0:39 - 0:41at the same time,
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0:41 - 0:43that would be one one-millionth
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0:43 - 0:47of the energy released at that moment.
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0:47 - 0:50The dinosaurs had a really bad day.
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0:50 - 0:52Okay?
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0:52 - 0:54Now, a six-mile-wide rock is very large.
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0:54 - 0:56We all live here in Boulder.
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0:56 - 0:58If you look out your window and you can see
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0:58 - 1:00Long's Peak, you're probably familiar with it.
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1:00 - 1:02Now, scoop up Long's Peak, and put it out
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1:02 - 1:04in space.
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1:04 - 1:06Take Meeker, Mt. Meeker. Lump that in there,
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1:06 - 1:08and put that in space as well,
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1:08 - 1:10and Mt. Everest, and K2,
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1:10 - 1:12and the Indian peaks.
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1:12 - 1:14Then you're starting to get an idea of
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1:14 - 1:16how much rock we're talking about, okay?
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1:16 - 1:18We know it was that big because of
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1:18 - 1:20the impact it had and the crater it left.
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1:20 - 1:22It hit in what we now know as Yucatan,
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1:22 - 1:24the Gulf of Mexico.
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1:24 - 1:26You can see here, there's the
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1:26 - 1:28Yucatan Peninsula, if you recognize Cozumel
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1:28 - 1:30off the east coast there.
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1:30 - 1:33Here is how big of a crater was left.
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1:33 - 1:35It was huge. To give you a sense of the scale,
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1:35 - 1:37okay, there you go. The scale here is
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1:37 - 1:3950 miles on top, a hundred kilometers
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1:39 - 1:41on the bottom. This thing was
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1:41 - 1:43300 kilometers across -- 200 miles --
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1:43 - 1:45an enormous crater that excavated out
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1:45 - 1:48vast amounts of earth that splashed around
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1:48 - 1:51the globe and set fires all over the planet,
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1:51 - 1:54threw up enough dust to block out the sun.
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1:54 - 1:56It wiped out 75 percent of all species
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1:56 - 1:58on Earth.
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1:58 - 2:01Now, not all asteroids are that big.
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2:01 - 2:03Some of them are smaller.
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2:03 - 2:06Here is one that came in
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2:06 - 2:08over the United States
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2:08 - 2:10in October of 1992.
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2:10 - 2:12It came in on a Friday night.
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2:12 - 2:14Why is that important?
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2:14 - 2:16Because back then, video cameras were
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2:16 - 2:18just starting to become popular, and people
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2:18 - 2:20would bring them, parents would bring them,
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2:20 - 2:22to their kids' football games to film their kids
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2:22 - 2:25play football. And since this came in on a Friday,
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2:25 - 2:27they were able to get this great footage
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2:27 - 2:29of this thing breaking up as it came in
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2:29 - 2:31over West Virgina, Maryland, Pennsylvania
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2:31 - 2:33and New Jersey until it did that
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2:33 - 2:35to a car in New York.
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2:35 - 2:37(Laughter)
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2:37 - 2:40Now, this is not a 200-mile-wide crater,
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2:40 - 2:42but then again you can see the rock
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2:42 - 2:44which is sitting right here,
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2:44 - 2:46about the size of a football, that hit
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2:46 - 2:48that car and did that damage.
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2:48 - 2:50Now this thing was probably about the size
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2:50 - 2:52of a school bus when it first came in.
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2:52 - 2:54It broke up through atmospheric pressure,
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2:54 - 2:56it crumbled, and then the pieces fell apart
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2:56 - 2:58and did some damage.
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2:58 - 3:00Now, you wouldn't want that falling on your foot
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3:00 - 3:02or your head, because it would do that to it.
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3:02 - 3:04That would be bad.
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3:04 - 3:06But it won't wipe out, you know, all life
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3:06 - 3:08on Earth, so that's fine. But it turns out,
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3:08 - 3:11you don't need something six miles across
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3:11 - 3:13to do a lot of damage.
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3:13 - 3:15There is a median point between tiny rock
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3:15 - 3:17and gigantic rock, and in fact, if any of you
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3:17 - 3:20have ever been to near Winslow, Arizona,
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3:20 - 3:23there is a crater in the desert there that is
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3:23 - 3:27so iconic that it is actually called Meteor Crater.
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3:27 - 3:30To give you a sense of scale, this is about a mile wide.
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3:30 - 3:33If you look up at the top, that's a parking lot,
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3:33 - 3:36and those are recreational vehicles right there.
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3:36 - 3:39So it's about a mile across, 600 feet deep.
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3:39 - 3:42The object that formed this was probably about
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3:42 - 3:4530 to 50 yards across, so roughly the size
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3:45 - 3:48of Mackey Auditorium here.
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3:48 - 3:51It came in at speeds that were tremendous,
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3:51 - 3:53slammed into the ground, blew up,
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3:53 - 3:55and exploded with the energy of roughly
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3:55 - 3:57a 20-megaton nuclear bomb --
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3:57 - 3:59a very hefty bomb.
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3:59 - 4:01This was 50,000 years ago, so it may have
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4:01 - 4:03wiped out a few buffalo or antelope,
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4:03 - 4:06or something like that out in the desert,
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4:06 - 4:08but it probably would not have caused
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4:08 - 4:10global devastation.
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4:10 - 4:12It turns out that these things don't have to
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4:12 - 4:15hit the ground to do a lot of damage.
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4:15 - 4:17Now, in 1908, over Siberia, near the
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4:17 - 4:19Tunguska region -- for those of you who are
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4:19 - 4:21Dan Aykroyd fans and saw "Ghostbusters,"
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4:21 - 4:24when he talked about the greatest cross-dimensional rift
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4:24 - 4:27since the Siberia blast of 1909, where he got
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4:27 - 4:29the date wrong, but that's okay. (Laughter)
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4:29 - 4:32It was 1908. That's fine. I can live with that.
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4:32 - 4:35(Laughter)
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4:35 - 4:38Another rock came into the Earth's atmosphere
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4:38 - 4:40and this one blew up above the ground, several
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4:40 - 4:43miles up above the surface of the Earth.
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4:43 - 4:46The heat from the explosion set fire to the
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4:46 - 4:49forest below it, and then the shock wave
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4:49 - 4:51came down and knocked down trees for
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4:51 - 4:54hundreds of square miles, okay?
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4:54 - 4:56This did a huge amount of damage.
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4:56 - 4:58And again, this was a rock probably roughly
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4:58 - 5:00the size of this auditorium that we're sitting in.
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5:00 - 5:02In Meteor Crater it was made of metal,
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5:02 - 5:04and metal is much tougher, so it made it
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5:04 - 5:06to the ground.
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5:06 - 5:08The one over Tunguska was probably made
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5:08 - 5:10of rock, and that's much more crumbly, so it
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5:10 - 5:12blew up in the air. Either way, these are
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5:12 - 5:15tremendous explosions, 20 megatons.
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5:15 - 5:17Now, when these things blow up, they're not
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5:17 - 5:20going to do global ecological damage.
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5:20 - 5:22They're not going to do something like
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5:22 - 5:24the dinosaur-killer did.
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5:24 - 5:26They're just not big enough.
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5:26 - 5:28But they will do global economic damage,
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5:28 - 5:30because they don't have to hit, necessarily,
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5:30 - 5:32to do this kind of damage.
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5:32 - 5:34They don't have to do global devastation.
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5:34 - 5:36If one of these things were to hit
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5:36 - 5:38pretty much anywhere, it would cause a panic.
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5:38 - 5:40But if it came over a city, an important city --
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5:40 - 5:42not that any city is more important than others,
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5:42 - 5:44but some of them we depend on them more
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5:44 - 5:47on the global economic basis -- that could do
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5:47 - 5:50a huge amount of damage to us
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5:50 - 5:52as a civilization.
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5:52 - 5:55So, now that I've scared the crap out of you ...
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5:55 - 5:57(Laughter)
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5:57 - 5:59what can we do about this? All right?
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5:59 - 6:01This is a potential threat.
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6:01 - 6:03Let me note that we have not had
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6:03 - 6:05a giant impact like the dinosaur-killer
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6:05 - 6:08for 65 million years. They're very rare.
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6:08 - 6:11The smaller ones happen more often, but
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6:11 - 6:13probably on the order of a millennium,
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6:13 - 6:15every few centuries or every few thousand
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6:15 - 6:18years, but it's still something to be aware of.
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6:18 - 6:20Well, what do we do about them?
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6:20 - 6:22The first thing we have to do is find them.
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6:22 - 6:24This is an image of an asteroid that passed
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6:24 - 6:26us in 2009.
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6:26 - 6:28It's right here.
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6:28 - 6:30But you can see that it's extremely faint.
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6:30 - 6:32I don't even know if you can see that
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6:32 - 6:34in the back row. These are just stars.
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6:34 - 6:36This is a rock that was about 30 yards across,
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6:36 - 6:38so roughly the size of the ones that blew up
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6:38 - 6:41over Tunguska and hit Arizona 50,000 years ago.
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6:41 - 6:43These things are faint.
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6:43 - 6:45They're hard to see, and the sky is really big.
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6:45 - 6:47We have to find these things first.
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6:47 - 6:49Well the good news is, we're looking for them.
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6:49 - 6:51NASA has devoted money to this.
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6:51 - 6:53The National Science Foundation, other
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6:53 - 6:55countries are very interested in doing this.
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6:55 - 6:57We're building telescopes that are looking
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6:57 - 6:59for the threat. That's a great first step,
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6:59 - 7:01but what's the second step? The second step
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7:01 - 7:03is that we see one heading toward us,
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7:03 - 7:05we have to stop it. What do we do?
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7:05 - 7:07You've probably heard about the asteroid
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7:07 - 7:10Apophis. If you haven't yet, you will.
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7:10 - 7:12If you've heard about the Mayan 2012
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7:12 - 7:14apocalypse, you're going to hear about Apophis,
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7:14 - 7:16because you're keyed in to all the doomsday
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7:16 - 7:18networks anyway.
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7:19 - 7:22Apophis is an asteroid that was discovered in 2004.
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7:22 - 7:25It's roughly 250 yards across, so it's
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7:25 - 7:27pretty big -- big size, you know,
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7:27 - 7:29bigger than a football stadium -- and it's going to
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7:29 - 7:32pass by the Earth in April of 2029.
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7:32 - 7:34And it's going to pass us so close that it's
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7:34 - 7:36actually going to come underneath
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7:36 - 7:38our weather satellites.
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7:38 - 7:40The Earth's gravity is going to bend the orbit
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7:40 - 7:43of this thing so much that if it's just right,
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7:43 - 7:46if it passes through this region of space,
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7:46 - 7:48this kidney bean-shaped region called
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7:48 - 7:50the keyhole, the Earth's gravity will bend it
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7:50 - 7:52just enough that seven years later
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7:52 - 7:54on April 13, which is a Friday, I'll note,
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7:54 - 7:57in the year 2036 ... (Laughter)
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7:57 - 8:00-- you can't plan that kind of stuff --
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8:00 - 8:02Apophis is going to hit us. And it's
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8:02 - 8:04250 meters across, so it would do
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8:04 - 8:06unbelievable damage.
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8:06 - 8:08Now the good news is that the odds of it
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8:08 - 8:10actually passing through this keyhole and
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8:10 - 8:12hitting us next go-around are one in a million,
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8:12 - 8:14roughly -- very, very low odds, so I personally
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8:14 - 8:16am not lying awake at night worrying about this at all.
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8:16 - 8:18I don't think Apophis is a problem.
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8:18 - 8:20In fact, Apophis is a blessing in disguise,
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8:20 - 8:22because it woke us up to the dangers
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8:22 - 8:24of these things.
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8:24 - 8:26This thing was discovered just a few years
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8:26 - 8:28ago and could hit us a few years from now.
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8:28 - 8:30It won't, but it gives us a chance to study
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8:30 - 8:32these kinds of asteroids. We didn't really
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8:32 - 8:34necessarily understand these keyholes, and
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8:34 - 8:36now we do and it turns out
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8:36 - 8:38that's really important, because how do you
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8:38 - 8:40stop an asteroid like this?
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8:40 - 8:42Well, let me ask you, what happens if you're
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8:42 - 8:44standing in the middle of the road and a car's
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8:44 - 8:46headed for you? What do you do? You do this.
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8:46 - 8:48Right? Move. The car goes past you.
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8:48 - 8:50But we can't move the Earth, at least
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8:50 - 8:52not easily, but we can move a small asteroid.
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8:52 - 8:54And it turns out, we've even done it.
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8:54 - 8:57In the year 2005, NASA launched a probe
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8:57 - 9:00called Deep Impact, which slammed into --
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9:00 - 9:03slammed a piece of itself into the nucleus of a comet.
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9:03 - 9:05Comets are very much like asteroids.
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9:05 - 9:07The purpose wasn't to push it out of the way.
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9:07 - 9:09The purpose was to make a crater to excavate
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9:09 - 9:11the material and see what was underneath
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9:11 - 9:13the surface of this comet, which we learned
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9:13 - 9:15quite a bit about.
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9:15 - 9:17We did move the comet a little tiny bit,
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9:17 - 9:19not very much, but that wasn't the point.
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9:19 - 9:21However, think about this.
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9:21 - 9:23This thing is orbiting the sun at
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9:23 - 9:2510 miles per second, 20 miles per second.
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9:25 - 9:27We shot a space probe at it and hit it. Okay?
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9:27 - 9:30Imagine how hard that must be, and we did it.
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9:30 - 9:33That means we can do it again.
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9:33 - 9:35If we need, if we see an asteroid that's coming
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9:35 - 9:37toward us, and it's headed right for us,
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9:37 - 9:40and we have two years to go, boom! We hit it.
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9:40 - 9:42You can try to -- you know, if you watch
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9:42 - 9:44the movies, you might think about,
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9:44 - 9:46why don't we use a nuclear weapon?
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9:46 - 9:48It's like, well, you can try that, but the problem is timing.
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9:48 - 9:50You shoot a nuclear weapon at this thing,
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9:50 - 9:52you have to blow it up within a few milliseconds
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9:52 - 9:54of tolerance or else you'll just miss it.
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9:54 - 9:56And there are a lot of other problems
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9:56 - 9:58with that. It's very hard to do.
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9:58 - 10:00But just hitting something? That's pretty easy.
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10:00 - 10:02I think even NASA can do that,
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10:02 - 10:04and they proved that they can. (Laughter)
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10:04 - 10:06The problem is, what happens if you hit
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10:06 - 10:08this asteroid, you've changed the orbit,
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10:08 - 10:10you measure the orbit and then you find out,
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10:10 - 10:12oh, yeah, we just pushed it into a keyhole,
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10:12 - 10:14and now it's going to hit us in three years.
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10:14 - 10:16Well, my opinion is, fine. Okay?
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10:16 - 10:18It's not hitting us in six months. That's good.
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10:18 - 10:21Now we have three years to do something else.
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10:21 - 10:23And you can hit it again. That's kind of
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10:23 - 10:25ham-fisted. You might just push it into a third
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10:25 - 10:27keyhole or whatever, so you don't do that.
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10:27 - 10:31And this is the part, it's the part I just love.
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10:31 - 10:33(Laughter)
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10:33 - 10:35After the big macho "Rrrrrrr BAM! We're
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10:35 - 10:37gonna hit this thing in the face,"
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10:37 - 10:40then we bring in the velvet gloves.
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10:40 - 10:43(Laughter)
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10:43 - 10:45There's a group of scientists and engineers
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10:45 - 10:47and astronauts and they call themselves
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10:47 - 10:49The B612 Foundation. For those of you
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10:49 - 10:51who've read "The Little Prince,"
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10:51 - 10:53you understand that reference, I hope. The little prince
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10:53 - 10:55who lived on an asteroid, it was called B612.
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10:55 - 10:57These are smart guys -- men and women --
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10:57 - 10:59astronauts, like I said, engineers.
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10:59 - 11:01Rusty Schweickart, who was an Apollo 9
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11:01 - 11:03astronaut, is on this. Dan Durda, my friend
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11:03 - 11:05who made this image, works here at
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11:05 - 11:07Southwest Research Institute in Boulder,
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11:07 - 11:09on Walnut Street. He created this image for this,
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11:09 - 11:11and he's actually one of the astronomers
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11:11 - 11:13who works for them. If we see an asteroid
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11:13 - 11:15that's going to hit the Earth and we have
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11:15 - 11:18enough time, we can hit it to move it into
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11:18 - 11:21a better orbit. But then what we do is we launch
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11:21 - 11:23a probe that has to weigh a ton or two.
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11:23 - 11:26It doesn't have to be huge -- couple of tons,
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11:26 - 11:29not that big -- and you park it near the asteroid.
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11:29 - 11:31You don't land on it, because these things are
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11:31 - 11:33tumbling end over end. It's very hard to land on them.
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11:33 - 11:35Instead you get near it.
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11:35 - 11:37The gravity of the asteroid pulls on the probe,
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11:37 - 11:40and the probe has a couple of tons of mass.
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11:40 - 11:42It has a little tiny bit of gravity, but it's enough
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11:42 - 11:44that it can pull the asteroid, and you have your
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11:44 - 11:46rockets set up, so you can -- oh, you can barely
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11:46 - 11:48see it here, but there's rocket plumes -- and you
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11:48 - 11:50basically, these guys are connected by their
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11:50 - 11:53own gravity, and if you move the probe very
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11:53 - 11:57slowly, very, very gently, you can very easily
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11:57 - 12:00finesse that rock into a safe orbit.
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12:00 - 12:02You can even put in orbit around the Earth
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12:02 - 12:04where we could mine it, although that's a
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12:04 - 12:06whole other thing. I won't go into that.
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12:06 - 12:08(Laughter)
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12:08 - 12:10But we'd be rich!
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12:10 - 12:15(Laughter)
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12:15 - 12:17So think about this, right?
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12:17 - 12:19There are these giant rocks flying out there,
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12:19 - 12:21and they're hitting us, and they're doing
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12:21 - 12:23damage to us, but we've figured out how to do
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12:23 - 12:26this, and all the pieces are in place to do this.
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12:26 - 12:28We have astronomers in place with telescopes
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12:28 - 12:30looking for them. We have smart people,
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12:30 - 12:32very, very smart people, who are concerned
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12:32 - 12:34about this and figuring out how to fix the
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12:34 - 12:37problem, and we have the technology to do this.
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12:37 - 12:39This probe actually can't use chemical rockets.
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12:39 - 12:41Chemical rockets provide too much thrust, too
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12:41 - 12:43much push. The probe would just shoot away.
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12:43 - 12:45We invented something called an ion drive,
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12:45 - 12:48which is a very, very, very low-thrust engine.
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12:48 - 12:50It generates the force a piece of paper would
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12:50 - 12:52have on your hand, incredibly light,
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12:52 - 12:55but it can run for months and years,
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12:55 - 12:58providing that very gentle push.
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12:58 - 13:00If anybody here is a fan of the original "Star Trek,"
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13:00 - 13:02they ran across an alien ship that had
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13:02 - 13:04an ion drive, and Spock said,
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13:04 - 13:06"They're very technically sophisticated.
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13:06 - 13:08They're a hundred years ahead of us with this drive."
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13:08 - 13:10Yeah, we have an ion drive now. (Laughter)
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13:10 - 13:12We don't have the Enterprise, but
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13:12 - 13:14we've got an ion drive now.
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13:14 - 13:17(Applause)
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13:17 - 13:19Spock.
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13:19 - 13:22(Laughter)
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13:22 - 13:24So ...
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13:24 - 13:26that's the difference, that's the difference
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13:26 - 13:28between us and the dinosaurs.
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13:28 - 13:30This happened to them.
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13:30 - 13:32It doesn't have to happen to us.
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13:32 - 13:35The difference between the dinosaurs and us
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13:35 - 13:37is that we have a space program
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13:37 - 13:39and we can vote,
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13:39 - 13:42and so we can change our future.
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13:42 - 13:43(Laughter)
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13:43 - 13:46We have the ability to change our future.
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13:46 - 13:4865 million years from now,
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13:48 - 13:50we don't have to have our bones
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13:50 - 13:52collecting dust in a museum.
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13:52 - 13:54Thank you very much.
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13:54 - 13:55(Applause)
- Title:
- How to defend Earth from asteroids
- Speaker:
- Phil Plait
- Description:
-
What's six miles wide and can end civilization in an instant? An asteroid - and there are lots of them out there. With humor and great visuals, Phil Plait enthralls the TEDxBoulder audience with all the ways asteroids can kill, and what we must do to avoid them.
- Video Language:
- English
- Team:
- closed TED
- Project:
- TEDTalks
- Duration:
- 13:56
Krystian Aparta commented on English subtitles for How to defend Earth from asteroids | ||
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Krystian Aparta edited English subtitles for How to defend Earth from asteroids | ||
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Krystian Aparta
The English transcript was updated on 5/23/2017.