transcript: We've all witnessed the beauty of a
shooting star, but what would happen if an asteroid was on a collision course
for earth? Could we detect it ahead of time? And more
importantly could we stop it? I believe I have an answer, now you see, asteroid
impacts are serious business, when I was in second
grade Ms. McGonigal told us that the dinosaurs the ancient dinosaurs
died out because they had small brains may be like my old boss. But even she knew that was
kinda lamethat theory was nothing. It turns out in my lifetime people found
this crater, off Chicxulub mexico. This crator was so
big, how big was it, it was so big that an asteroid hit the earth (or impactors hit the earth). Threw so much stuff into the
Earth's sky it was bigger in diameter than the earth itself so the earth was
surrounded by red hot rock for weeks at a time, it cooked everything. And just the
animals that lived in burrows and caves, our ancestors lead to us so serious
business you may recall Valentine's Day 2013? Chelyabinsk Russia (boom) air burst. See if you are an asteroid, and you are going 10 km /s or 20 km /s And you hit the Earth's atmosphere, the atmosphere is like concrete. you can't get out of the way so the
asteroid just explodes in air burst. So these asteroids are serious, most of
them are very small. If you're under 10 meters in
diameter you hit the Earth's atmosphere you burn up all Big Blue streak, green street white streak and then humans make wishes
upon you. (I don't know house efficacious those
wishes are but people do that), alright so, if ther asteroid starts to get bigger, starts to
get into the twenty-five meters and the 45 meters in diameter then you get
Meteor Crater Arizona (wham) huge thing. That would be like a city killer, or a county killer. And then when they get to be a 100 meters / 140 meters now you're into a country killer, and then they get bigger than that and it's a
continent killer, much bigger than that and you're taking out whole races of ancient species. So, what if we found an asteroid that
was headed our way, how would we find it? How would we find an asteroid headed our
way? That's a good question, well you can use telescopes. Skilled people
can point the cameras at the sky and look for fast-moving objects. Objects that are crossing the Earth's
orbit, but we're missing perhaps a hundred thousand of these things, of these county
killers, city killers and country killers. So, what we want to do is build a
spacecraft called The Sentinel, and as we say "it's like looking for a
charcoal briquette in the dark", these things are hard to
find. They are tiny compared to the vastness of space. But infrared light / heat bounces off them
so what you will do - you are a satellite, you are a surveying
spacecraft, you get your back to the Sun and look
out from about the orbit of Venus. And try to
find all these asteroids. And then you find one, what
do you do? Do you run in circles screaming? "AH" No, No No, we've got to deflect it, just a little, just a tiny amount.
Asteroid might be going 10 km/s we want to change its speed about 2 mm/s. So ten kilometers, that's ten times a
thousand meters, that's 10,000 meters. A millimeter that's a thousandth of a meter so that you take the one over
the thousand its a thousand times ten thousand, that's 10 million. You want to change its
speed a 10 millionth of its total. That's not very much, but if you're an asteroid that comes in at 10,000 tons / 100,000 tonnes, it does take quite a bit force to
change it a 10 millionth of its speed. Okay, how do we do that? Well, the easiest way is to get a rocket, just a big rocket, just go out there and smack into it. Except as an outer
space so it just goes (silence) like that. Okay, that would change its
speed a little, now notice everybody, what if it's not just a rock? What if its
a pile of rocks just loosely held together by primordial
gravity? And so if you hit them they will just spread out and you will have a shower of rocks. That would be bad. So, how about
this? We will get a big space craft that is massive, a massive spacecraft will go out there and just get nearer to the asteroid. Just get near it, and then the mutual
gravity of the you the asteroid and me the spacecraft will tug the asteroids just a
little bit just a tiny amounth or maybe get on the other side and tug this way. That might work but here's
the problem. We need a huge amount of fuel, for days and weeks and months and years. And what if it stops working, you can't
go out there and fix it. Okay, how about this? The Laser Bees? A swarm of sunlight powered lasers, that are zapping the surface of the
asteroid, for days, and weeks, and months,and years ZAP ZAP ZAP, so some asteroids, some rock is
vaporized so the ejecta, or the stuff ejected has
momentum just like rocket fuel, just like just
like standing on a skateboard and playing catch with a bowling ball... the way you do. And so it would then cause the asteroid to change its speed. And
so you send a swarm of these laser spacecraft, so that if one of them stops working
you can use the other one. And you can have them come in from all
different angles. And what if the asteroid is irregularly shaped (like this) you could beam it when the thing is
smooth and then when there's a pit or an
inefficient place to be beaming you turn off, you wait for the asteroid to turn,
then you turn it back on. You see everybody, just because it's unlikely, doesn't mean
it's not a big deal. You know if it only happens once every
few thousand years, well if it happens on my watch it would as the kids say "suck". Okay, so we
don't want that to happen, we want to avoid that. Asteroids are serious business, but
they're exciting. (Spaceship noise) Except we are in space so its (silence). Got a burning question? Well be sure to
subscribe asapscience, follow us on Twitter and Facebook, that's what all
the kids are doing. And if it's an asteroid it may not be a burning
question, it might be an impacting question, or even and ablating question.
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