Phil Plait: How to defend Earth from asteroids Phil Plait: Wie man die Erde vor Asteroiden schützen kann Phil Plait: Come difendere la Terra dagli asteroidi フィル・プレイト：小惑星から地球を守る方法 Phil Plait: Como defender a Terra dos asteróides

I want to talk to you about something kind of big. Eu quero falar com você sobre algo grande. We'll start here. 65 million years ago the dinosaurs had a bad day. (Laughter) A chunk of rock six miles across, moving something like 50 times the speed of a rifle bullet, slammed into the Earth. (Risos) Um pedaço de rocha de 10 quilômetros de diâmetro, movendo-se cerca de 50 vezes a velocidade de uma bala de fuzil, atingiu a Terra. It released its energy all at once, and it was an explosion that was mind-numbing. Ele liberou sua energia de uma só vez, e foi uma explosão que era entorpecente. If you took every nuclear weapon ever built at the height of the Cold War, lumped them together and blew them up at the same time, that would be one one-millionth of the energy released at that moment. Se você pegar todas as armas nucleares já construídas no auge da Guerra Fria, juntá-las e explodi-las ao mesmo tempo, isso seria um milionésimo da energia liberada naquele momento. The dinosaurs had a really bad day. Okay?

Now, a six-mile-wide rock is very large. Agora, uma rocha de seis milhas de largura é muito grande. We all live here in Boulder. Todos nós moramos aqui em Boulder. If you look out your window and you can see Long's Peak, you're probably familiar with it. Se você olhar pela janela e puder ver Long's Peak, provavelmente está familiarizado com ela. Now, scoop up Long's Peak, and put it out in space. Agora, pegue o Long's Peak e coloque-o no espaço. Take Meeker, Mt. Pegue Meeker, MT. Meeker. Lump that in there, and put that in space as well, and Mt. Coloque isso lá, e coloque-o no espaço também, e o Monte. Everest, and K2, and the Indian peaks. Then you're starting to get an idea of how much rock we're talking about, okay? We know it was that big because of the impact it had and the crater it left. It hit in what we now know as Yucatan, the Gulf of Mexico. You can see here, there's the Yucatan Peninsula, if you recognize Cozumel off the east coast there. Here is how big of a crater was left. Aqui está o tamanho de uma cratera deixada. It was huge. To give you a sense of the scale, okay, there you go. The scale here is 50 miles on top, a hundred kilometers on the bottom. This thing was 300 kilometers across -- 200 miles -- an enormous crater that excavated out vast amounts of earth that splashed around the globe and set fires all over the planet, threw up enough dust to block out the sun. It wiped out 75 percent of all species on Earth. Exterminou 75% de todas as espécies da Terra. Now, not all asteroids are that big. Some of them are smaller. Here is one that came in over the United States in October of 1992. It came in on a Friday night. Why is that important? Because back then, video cameras were just starting to become popular, and people would bring them, parents would bring them, to their kids' football games to film their kids play football. And since this came in on a Friday, they were able to get this great footage of this thing breaking up as it came in over West Virgina, Maryland, Pennsylvania and New Jersey until it did that to a car in New York. (Laughter)

Now, this is not a 200-mile-wide crater, but then again you can see the rock which is sitting right here, about the size of a football, that hit that car and did that damage. Now this thing was probably about the size of a school bus when it first came in. It broke up through atmospheric pressure, it crumbled, and then the pieces fell apart and did some damage. Ele quebrou devido à pressão atmosférica, desmoronou e, em seguida, os pedaços se separaram e causaram alguns danos. Now, you wouldn't want that falling on your foot or your head, because it would do that to it. Agora, você não gostaria que isso caísse no seu pé ou na sua cabeça, porque faria isso. That would be bad. But it won't wipe out, you know, all life on Earth, so that's fine. Mas não vai acabar com toda a vida na Terra, então está tudo bem. But it turns out, you don't need something six miles across to do a lot of damage. Mas acontece que você não precisa de algo de seis milhas de largura para causar muitos danos. There is a median point between tiny rock and gigantic rock, and in fact, if any of you have ever been to near Winslow, Arizona, there is a crater in the desert there that is so iconic that it is actually called Meteor Crater. Há um ponto médio entre rochas minúsculas e rochas gigantescas e, de fato, se algum de vocês já esteve perto de Winslow, Arizona, há uma cratera no deserto que é tão icônica que é na verdade chamada Meteor Crater.

To give you a sense of scale, this is about a mile wide. If you look up at the top, that's a parking lot, and those are recreational vehicles right there. So it's about a mile across, 600 feet deep. The object that formed this was probably about 30 to 50 yards across, so roughly the size of Mackey Auditorium here. O objeto que o formou provavelmente tinha cerca de 30 a 50 metros de diâmetro, aproximadamente o tamanho do Mackey Auditorium aqui. It came in at speeds that were tremendous, slammed into the ground, blew up, and exploded with the energy of roughly a 20-megaton nuclear bomb -- a very hefty bomb. Chegou a velocidades tremendas, bateu no chão, explodiu e explodiu com a energia de aproximadamente uma bomba nuclear de 20 megatoneladas - uma bomba muito pesada. This was 50,000 years ago, so it may have wiped out a few buffalo or antelope, or something like that out in the desert, but it probably would not have caused global devastation. Isso foi há 50.000 anos, então pode ter destruído alguns búfalos ou antílopes, ou algo assim no deserto, mas provavelmente não teria causado devastação global.

It turns out that these things don't have to hit the ground to do a lot of damage. Acontece que essas coisas não precisam atingir o chão para causar muitos danos. Now, in 1908, over Siberia, near the Tunguska region -- for those of you who are Dan Aykroyd fans and saw "Ghostbusters," when he talked about the greatest cross-dimensional rift since the Siberia blast of 1909, where he got the date wrong, but that's okay. Agora, em 1908, sobre a Sibéria, perto da região de Tunguska - para aqueles que são fãs de Dan Aykroyd e viram "Caça-fantasmas", quando ele falou sobre a maior fenda interdimensional desde a explosão da Sibéria em 1909, onde ele conseguiu o encontro errado, mas tudo bem. (Laughter) It was 1908. That's fine. I can live with that. (Laughter) Another rock came into the Earth's atmosphere and this one blew up above the ground, several miles up above the surface of the Earth. (Risos) Outra pedra entrou na atmosfera da Terra e esta explodiu acima do solo, vários quilômetros acima da superfície da Terra. The heat from the explosion set fire to the forest below it, and then the shock wave came down and knocked down trees for hundreds of square miles, okay? O calor da explosão incendiou a floresta abaixo dela, e então a onda de choque desceu e derrubou árvores por centenas de quilômetros quadrados, ok? This did a huge amount of damage. Isso causou uma enorme quantidade de dano. And again, this was a rock probably roughly the size of this auditorium that we're sitting in. In Meteor Crater it was made of metal, and metal is much tougher, so it made it to the ground. The one over Tunguska was probably made of rock, and that's much more crumbly, so it blew up in the air. Either way, these are tremendous explosions, 20 megatons. Now, when these things blow up, they're not going to do global ecological damage. They're not going to do something like the dinosaur-killer did. They're just not big enough. But they will do global economic damage, because they don't have to hit, necessarily, to do this kind of damage. Mas eles causarão danos econômicos globais, porque não precisam atingir, necessariamente, esse tipo de dano. They don't have to do global devastation. If one of these things were to hit pretty much anywhere, it would cause a panic. Se uma dessas coisas acontecesse praticamente em qualquer lugar, isso causaria pânico. But if it came over a city, an important city -- not that any city is more important than others, but some of them we depend on them more on the global economic basis -- that could do a huge amount of damage to us as a civilization. Mas se surgir uma cidade, uma cidade importante - não que uma cidade seja mais importante que outras, mas em algumas delas dependemos mais delas da base econômica global - isso poderia causar uma enorme quantidade de danos a nós como uma civilização.

So, now that I've scared the crap out of you ... (Laughter) what can we do about this? Então, agora que te assustei ... (Risos), o que podemos fazer sobre isso? All right? This is a potential threat. Esta é uma ameaça em potencial. Let me note that we have not had a giant impact like the dinosaur-killer for 65 million years. They're very rare. The smaller ones happen more often, but probably on the order of a millennium, every few centuries or every few thousand years, but it's still something to be aware of. Well, what do we do about them? The first thing we have to do is find them. This is an image of an asteroid that passed us in 2009. It's right here. But you can see that it's extremely faint. Mas você pode ver que é extremamente fraco. I don't even know if you can see that in the back row. These are just stars. This is a rock that was about 30 yards across, so roughly the size of the ones that blew up over Tunguska and hit Arizona 50,000 years ago.

These things are faint. Essas coisas são fracas. They're hard to see, and the sky is really big. We have to find these things first. Well the good news is, we're looking for them. NASA has devoted money to this. A NASA dedicou dinheiro a isso. The National Science Foundation, other countries are very interested in doing this. We're building telescopes that are looking for the threat. That's a great first step, but what's the second step? Esse é um ótimo primeiro passo, mas qual é o segundo passo? The second step is that we see one heading toward us, we have to stop it. What do we do? You've probably heard about the asteroid Apophis. If you haven't yet, you will. If you've heard about the Mayan 2012 apocalypse, you're going to hear about Apophis, because you're keyed in to all the doomsday networks anyway. Se você já ouviu falar sobre o apocalipse maia de 2012, vai ouvir sobre o Apophis, porque está conectado a todas as redes do dia do juízo final. Apophis is an asteroid that was discovered in 2004. It's roughly 250 yards across, so it's pretty big -- big size, you know, bigger than a football stadium -- and it's going to pass by the Earth in April of 2029. And it's going to pass us so close that it's actually going to come underneath our weather satellites. The Earth's gravity is going to bend the orbit of this thing so much that if it's just right, if it passes through this region of space, this kidney bean-shaped region called the keyhole, the Earth's gravity will bend it just enough that seven years later on April 13, which is a Friday, I'll note, in the year 2036 ... (Laughter) -- you can't plan that kind of stuff -- Apophis is going to hit us. A gravidade da Terra dobrará tanto a órbita dessa coisa que, se estiver correta, se passar por essa região do espaço, essa região em forma de feijão-rim chamada buraco da fechadura, a gravidade da Terra dobrará apenas o suficiente para que sete anos mais tarde, em 13 de abril, que é uma sexta-feira, observarei, no ano de 2036 ... (Risos) - você não pode planejar esse tipo de coisa - Apophis vai nos atingir. And it's 250 meters across, so it would do unbelievable damage. Now the good news is that the odds of it actually passing through this keyhole and hitting us next go-around are one in a million, roughly -- very, very low odds, so I personally am not lying awake at night worrying about this at all. I don't think Apophis is a problem. In fact, Apophis is a blessing in disguise, because it woke us up to the dangers of these things. De fato, Apophis é uma bênção disfarçada, porque nos despertou para os perigos dessas coisas. This thing was discovered just a few years ago and could hit us a few years from now. It won't, but it gives us a chance to study these kinds of asteroids. We didn't really necessarily understand these keyholes, and now we do and it turns out that's really important, because how do you stop an asteroid like this? Well, let me ask you, what happens if you're standing in the middle of the road and a car's headed for you? Bem, deixe-me perguntar: o que acontece se você estiver no meio da estrada e um carro estiver indo em sua direção? What do you do? You do this. Right? Move. The car goes past you. But we can't move the Earth, at least not easily, but we can move a small asteroid. And it turns out, we've even done it. E acontece que até fizemos. In the year 2005, NASA launched a probe called Deep Impact, which slammed into -- slammed a piece of itself into the nucleus of a comet. No ano de 2005, a NASA lançou uma sonda chamada Deep Impact, que bateu com um pedaço de si mesma no núcleo de um cometa. Comets are very much like asteroids. The purpose wasn't to push it out of the way. The purpose was to make a crater to excavate the material and see what was underneath the surface of this comet, which we learned quite a bit about. We did move the comet a little tiny bit, not very much, but that wasn't the point. However, think about this. This thing is orbiting the sun at 10 miles per second, 20 miles per second. We shot a space probe at it and hit it. Atiramos uma sonda espacial e atingimos. Okay?

Imagine how hard that must be, and we did it. That means we can do it again.

If we need, if we see an asteroid that's coming toward us, and it's headed right for us, and we have two years to go, boom! We hit it. You can try to -- you know, if you watch the movies, you might think about, why don't we use a nuclear weapon? It's like, well, you can try that, but the problem is timing. You shoot a nuclear weapon at this thing, you have to blow it up within a few milliseconds of tolerance or else you'll just miss it. Você atira uma arma nuclear nessa coisa, tem que explodi-la dentro de alguns milissegundos de tolerância ou senão vai sentir falta dela. And there are a lot of other problems with that. It's very hard to do. But just hitting something? That's pretty easy. I think even NASA can do that, and they proved that they can. (Laughter) The problem is, what happens if you hit this asteroid, you've changed the orbit, you measure the orbit and then you find out, oh, yeah, we just pushed it into a keyhole, and now it's going to hit us in three years. (Risos) O problema é: o que acontece se você acertar este asteróide, você mudou a órbita, mede a órbita e depois descobre, oh, sim, nós apenas o colocamos no buraco da fechadura, e agora ele vai bater nós em três anos. Well, my opinion is, fine. Okay?

It's not hitting us in six months. That's good. Now we have three years to do something else. And you can hit it again. That's kind of ham-fisted. Isso é uma espécie de punhos de presunto. You might just push it into a third keyhole or whatever, so you don't do that. Você pode simplesmente empurrá-lo para um terceiro buraco da fechadura ou o que quer que seja, para não fazer isso. And this is the part, it's the part I just love. (Laughter) After the big macho "Rrrrrrr BAM! We're gonna hit this thing in the face," then we bring in the velvet gloves. Nós vamos acertar essa coisa na cara ", depois trazemos as luvas de veludo. (Laughter) There's a group of scientists and engineers and astronauts and they call themselves The B612 Foundation. For those of you who've read "The Little Prince," you understand that reference, I hope. The little prince who lived on an asteroid, it was called B612.

These are smart guys -- men and women -- astronauts, like I said, engineers. Rusty Schweickart, who was an Apollo 9 astronaut, is on this. Dan Durda, my friend who made this image, works here at Southwest Research Institute in Boulder, on Walnut Street. Dan Durda, meu amigo que criou essa imagem, trabalha aqui no Southwest Research Institute, em Boulder, na Walnut Street. He created this image for this, and he's actually one of the astronomers who works for them. If we see an asteroid that's going to hit the Earth and we have enough time, we can hit it to move it into a better orbit. But then what we do is we launch a probe that has to weigh a ton or two. Mas o que fazemos é lançar uma sonda que pesa uma tonelada ou duas. It doesn't have to be huge -- couple of tons, not that big -- and you park it near the asteroid. Não precisa ser enorme - algumas toneladas, não tão grande - e você estaciona perto do asteróide. You don't land on it, because these things are tumbling end over end. Você não pousa nele, porque essas coisas estão caindo de ponta a ponta. It's very hard to land on them. É muito difícil pousar neles. Instead you get near it.

The gravity of the asteroid pulls on the probe, and the probe has a couple of tons of mass. A gravidade do asteróide puxa a sonda, e a sonda tem algumas toneladas de massa. It has a little tiny bit of gravity, but it's enough that it can pull the asteroid, and you have your rockets set up, so you can -- oh, you can barely see it here, but there's rocket plumes -- and you basically, these guys are connected by their own gravity, and if you move the probe very slowly, very, very gently, you can very easily finesse that rock into a safe orbit. Tem um pouquinho de gravidade, mas é suficiente para poder puxar o asteróide, e você tem seus foguetes montados para poder - oh, você mal pode vê-lo aqui, mas há plumas de foguete - e você basicamente , esses caras são conectados por sua própria gravidade e, se você mover a sonda muito lentamente, muito, muito gentilmente, poderá facilmente arrastar a rocha para uma órbita segura. You can even put in orbit around the Earth where we could mine it, although that's a whole other thing. I won't go into that. (Laughter) But we'd be rich! (Laughter)

So think about this, right? There are these giant rocks flying out there, and they're hitting us, and they're doing damage to us, but we've figured out how to do this, and all the pieces are in place to do this. We have astronomers in place with telescopes looking for them. We have smart people, very, very smart people, who are concerned about this and figuring out how to fix the problem, and we have the technology to do this. This probe actually can't use chemical rockets. Na verdade, essa sonda não pode usar foguetes químicos. Chemical rockets provide too much thrust, too much push. Foguetes químicos fornecem muito impulso, muita pressão. The probe would just shoot away.

We invented something called an ion drive, which is a very, very, very low-thrust engine. It generates the force a piece of paper would have on your hand, incredibly light, but it can run for months and years, providing that very gentle push. If anybody here is a fan of the original "Star Trek," they ran across an alien ship that had an ion drive, and Spock said, "They're very technically sophisticated. Se alguém aqui é fã do "Star Trek" original, eles se depararam com uma nave alienígena que tinha um íon e Spock disse: "Eles são tecnicamente sofisticados. They're a hundred years ahead of us with this drive." Yeah, we have an ion drive now. (Laughter) We don't have the Enterprise, but we've got an ion drive now. (Risos) Não temos a Enterprise, mas agora temos um íon. (Applause) Spock. (Aplausos) Spock. (Laughter)

So ... that's the difference, that's the difference between us and the dinosaurs. Então ... essa é a diferença, é a diferença entre nós e os dinossauros. This happened to them. It doesn't have to happen to us. The difference between the dinosaurs and us is that we have a space program and we can vote, and so we can change our future. (Laughter) We have the ability to change our future. (Risos) Temos a capacidade de mudar nosso futuro. 65 million years from now, we don't have to have our bones collecting dust in a museum. Daqui a 65 milhões de anos, não precisamos ter nossos ossos coletando poeira em um museu. Thank you very much. (Applause)