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Clinton Siebert

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meteors and the earth

I was watching a show on the discovery channel about earth being hit and they were trying to come up with solutions. Well one solution that was rejected was blowing it up they say blowing it up would be more disastrous than the meteor it self plus we don't have the capability of sending a missile that far into space yet. Now this is where I'm puzzled there's no gravity in space and everything is weightless so a bomb exploding say 500 feet away from it should creat enough force to push the meteor in a completely different direction. Now about sending a missile there we can land a probe on a asteroid, and send robots to mars but we can't send a missal with a bomb into space so I guess what I want to know is am I an idiot or are these shows on the discovery channels a bunch of hog wash?

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    Sep 6 2011: Hi Clinton,

    I've done some study on this and the danger from meteor impact is very real. The Space Guard Program has a handful of telescopes searching for Near Earth Objects and are finding them at an increasing rate as more effort is brought to bear. NEO's are hard to see and we may have only a matter of weeks warning. Richard Firestone's "Younger Dryas" event evidence concludes that most life was wiped off of North America only 10,000 years ago. His evidence is compelling. 20 years ago, only a handful of large impact craters were known on Earth. Today there are hundreds.

    The only defense we currently have is our ICBM nuclear arsenal. That's it. Would it be effective? Maybe. It depends on a couple of things. #1 problem is that there is no atmosphere in space, so a nuclear warhead would not compress air which makes for 99% of it's blast effectiveness. So a warhead exploding near an asteroid would have little effect. The warhead would have to hit and possibly bury itself, even a little bit, into the asteroid, and it would then have a good chance of fracturing it into smaller bits IF it were a rocky meteorite. If it was iron/nickel of any size, it's game over.

    An ICBM could easily reach a meteorite that is a week or so away, so we could send many to do the job. A hardened nose cone would be necessary. The argument that blowing a big meteor into smaller pieces would just mean that more asteroids would hit the planet is idiot. Yes, there would be more incoming, BUT they would be smaller, offering more surface area to be heat ablated. Surface area ablation geometrically increases with the more surface area that is created by making little ones out of big ones. Ten one ton meteorites would inflict an order of magnitude less damage than one ten ton meteorite.

    The BIG problem with using nuclear tipped ICBM's for the job is that it would justify the entire Cold War nuclear arsenal as a savant technology, which is an anathema.
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      Sep 6 2011: who is the idiot here? let us consider. the destruction a meteor does lies within its energy content. the energy content is, at the moment of impact, kinetic energy. what happens to the kinetic energy if you cut the mass in half, but count both halves in? yep. exactly nothing. the kinetic energy is proportional to the mass, so it helps not. even if you grind the mass into small grains, the delivered total energy is the same.

      there are some differences though. if the mass is in one piece, and large enough, it can penetrate the crust causing even more devastation. broke up mass has its effect spread out more. on the other hand, multiple impacts means larger total blast area, ejecta coverage, heat radiation coverage. in the theoretical case of fine dust, almost the entire energy will be absorbed by the atmosphere, which can be even more devastating, making the air escape the earth in large amounts.

      it might be the case that. 10 x 1ton is better than 1 x 10ton, but this is a small small problem. the big problem starts with million or even billion ton sizes.
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    Sep 7 2011: 1. The Sunday Horoscope will tell you exactly when to launch
    2. You'd only need one warhead IF the delivery vehicle was painted to look like a red firecracker. A green firecracker won't do the job.
    3. The nations of the world would have to unite to donate all their rubber bands.
    4. An orbiting public ale house would be a very good facility.
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    Sep 6 2011: Ok I guess maybe the bomb theory might not work if the force from the explosion can not go anywhere, but what about the probe we landed on that one asteroid couldn't we do that only put a jet pack on it like I said it would not take much force to move one even one the size of a city considering it don't weigh nothing in space anyway.
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    Sep 6 2011: The imaginary opponent you refer to is the uncritically thinking news media that parrot certain "scientists" or their mouthpieces to tell us that our nuclear weapons stockpiles are useless against meteors. This is done for ideological reasons to not justify our ICBMs as savant technology.

    I call them "idiot" because they refuse to apply simple rules of physics and logic to the peril of great destruction- they would have us die rather than exploit the only tool we have for our defense. That sort of thinking is, in fact, the thinking of an idiot, and believe, there are many such idiots in positions of power, as you well know.

    I'm from the 1960's generation when many of us became exceedingly "obnoxious" in protest of an unjust war and other rightful causes. I have no problem with being obnoxious in the face of idiocy or calling an idiot policy an idiot policy.

    The protection of Earth from meteor and comet impacts is a matter of life and death for all of us and can serve to unite humanity with a common goal far more compelling than global warming or an invasion of UFO aliens.
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      Sep 6 2011: please mister Highly Trained Physicist, enlighten us about the following problem.

      let's suppose we have an asteroid in collision course with earth. the size of the asteroid is 5 km in diameter, and has a density of 3000 kg / m3 (apologies for the metric system, but even NASA uses it). the asteroids next fly-by will be in 2013, the distance is 900000 km. then the asteroid and the earth will next meet in 2019, and this is the time of the impact.

      questions:
      1, when to approach the asteroid? in 2013, in 2019, or somewhere in between, when it is far away? if it is in 2019, what is the appropriate distance of intervention?
      2, how many nuclear warheads of what size must be detonated on its surface to knock it out of the collision course, depending on the first answer.
      3, what method we can use to deliver the payload. bear in mind that the ICBMs does not have enough fuel to carry the warheads to orbit, let alone to a higher energy trajectory. the maximum altitude they can reach is something like 1500 km.
      4, in case we don't have the necessary delivery mechanism, what facilities are required, and how much resources of each kind?

      thank you for your time.
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    Sep 6 2011: Yes, Krisztian, the kinetic energy is the same, but it is applied over a greater area and hence less of it exists per area of impact. At 100 yards a rifle is far more deadly than a shotgun.

    There may be, however a greater problem than kinetic energy. That is the electric potential that the meteor may carry. The Tunguska impact of 1907 in Siberia leveled 60 square miles of forest but left barely any crater. It may have been blown apart by arcing to the Earth before impact. If arcing destroyed the Tunguska meteor, it might do the same for any other potential impactor. But then, that electric potential may also cause arcing to any sort of missile we send and destroy the missile before it hits. What we are doing is guessing about a matter of life and death. Never a happy situation.
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      Sep 6 2011: let's not forget that the original statement of yours was that ten impacts of tenth size means tenth the effects. you also called those who disagree with it "idiots". so i'm not going to pretend that we have some kind of constructive conversation here, but actually i feel like lecturing an obnoxious person. i recommend to go back to school, and be less self confident about the issue. but at least stop calling your opponent "idiot".
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    Sep 5 2011: If we see an asteroid coming I think our best bet is undoubtedly to knock it off course with a series of nukes. Given a few months notice.

    Anything we see well ahead of time we could send a fleet of ships to gently nudge off course. For anything 1-3 miles wide this should work. One rocket per space-capable country should do the trick. Given at least six years notice.

    If we only see it a few days in advance we'll have to bomb-proof our homes! If crocodiles & small mammals could survive I'm sure we could too! We'd just need a safe place to stay for 3-4 months. Then the surface would be survivable again.
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    Sep 5 2011: Hitting an asteroid with a missile will only break it into large chunks that will still fall to Earth. At worse it'll just leave a crater on the face of it. I'm not sure the shockwave typically created by an explosion could propagate in the void of space either, although somebody with more experience on the matter than me should confirm this.
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      Sep 5 2011: The shockwave from the blast should cause plenty of force if a star explodes it obliterates any planets close to it so the explosive force should be able to travel in the vacuum of space. We should be able to do the same thing with a meteor without blowing it up just push it on another course. They also mentioned we would probably not be able to see it in time, we can see planets in other galaxies so we should be able to see it days before it got here even just a mile wide one and we should only need a few hours warning to launch a missile.
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        Sep 5 2011: We observe planets indirectly through their gravitational effect on their stars. This is the work of months. Besides, we aren't looking for a specific planet, there are a few we happen to find at some time. Thus asteroids can escape our scrutiny (and they have). Thankfully, sometimes we do see them like the one who will pass near us in 2029 and might be back in 2035 depending on its trajectory.

        I have now checked my previous intuition, shock waves don't propagate in space because they have no medium to displace; like air, so as I said the shock wave wouldn't do it. What's likely to come into contact when stars explode is the gases they expound (although the planet should be close enough that the gases are not scattered enough on impact).
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      Sep 5 2011: depends on the missile. currently, our most mighty nuclear warheads would not surely be able to break a huge asteroid or comet apart. those things are really really big in an impressive way.