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Space Earth Science

Why Meteoroids Explode Before Hitting the Earth (qz.com) 58

Posted by BeauHD from the behind-the-scenes dept.
According to a new study from Purdue University, scientists have figured out why meteoroids explode before hitting the Earth. "The research, published in the December issue of the journal Meteoritics & Planetary Science, shows that as meteoroids plunge, the high-pressure air they push against find its way into the objects' pores and cracks, forcing their bodies apart from the inside," reports Quartz. "The result is a kind of detonation that looks like an explosion." From the report: To explain the astrophysics, researchers focused their work on a widely viewed February 2013 meteoroid explosion place over Chelyabinsk, Russia, a city of 1.1 million north of the Kazakhstan border. Researchers ran a computer program that allowed for them to simulate what happened to the meteoroid in the atmosphere. "Our simulations reveal a previously unrecognized process in which the penetration of high-pressure air into the body of the meteoroid greatly enhances the deformation and facilitates the breakup of meteoroids similar to the size of Chelyabinsk," the study states. The researchers added that while the air pressure is effective at breaking apart small meteoroids, larger ones would likely withstand the force as they come to Earth.
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Why Meteoroids Explode Before Hitting the Earth More

Why Meteoroids Explode Before Hitting the Earth

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  • Missile Command (Score:4, Funny)

    by xxxJonBoyxxx ( 565205 ) on Wednesday December 13, 2017 @02:19AM (#55730353)
    >> Why Meteoroids Explode Before Hitting the Earth

    I'm not saying it's Missile Command, but it's Missile Command.
    https://www.youtube.com/watch?v=nokIGklnBGY

  • So, aliens are basically bombarding us with meteoroids armed with the old "pull my finger" gag. The gall of them! Can't we build a space wall to keep these stinking meteoroids out?

    "Memo to the engineering team on the dark side of the moon, building the blimps that will be used to conquer the Earth:"

    "Avoid pores and cracks in the outer skin of the weapon. These could lead to premature explosion, which would be a major bummer for the Führer,"

    "-- Donald Zuckerberg, Reich Minister of Armaments and

    • So, aliens are basically bombarding us with meteoroids armed with the old "pull my finger" gag. The gall of them! Can't we build a space wall to keep these stinking meteoroids out?

      Dyson Corp. has sent Trump a proposal for building a space wall, but the cost would be in the quintillions of dollars. Just to fund a project of that size, we would have to cancel the F-35 program.

  • I called it firework.

    I mean, look at the number of cars [youtu.be] stop to stare at it when it comes!

  • I swear I read "Why Metroids Explode Before Hitting the Earth"

  • Hang On... (Score:2, Interesting)

    by ytene ( 4376651 )
    Something about the OP doesn't make sense.

    And no, not the fact that there isn't much in the way of "high-pressure air" at the outermost fringes of our atmosphere...

    The part which seems a little odd is to suggest that altering the apparent pressure [i.e. by the velocity of entry] can in some way "force" air into the cracks within a meteorite/meteorid to induce some form of break-up.

    Isn't it much more likely to be induced by the coefficient of expansion of the material concerned? If you take a meteor

    • Re: (Score:3, Interesting)

      by DrTJ ( 4014489 )

      You're on to something.

      As far as I know, there are two ways for something to explode (not merely "break up", or "burn"). Either the object is made out of a high explosive, in which the chemical reaction occurs faster than the disintegration, or there is a hard shell surrounding a "low explosive" which reacts "slowly" and builds up a pressure within the shell and explodes when the shell bursts.

      Clearly, the meteoroids are not made out of high explosives (I think and hope), but I have a hard time to view them

      • Re:Hang On... (Score:4, Insightful)

        by burtosis ( 1124179 ) on Wednesday December 13, 2017 @09:51AM (#55731525)
        Have you ever used a pressure washer? I own a mid grade entry level one with 3500 psi. You have to be very careful not to spray too hard into a crack or it will rip whatever it is apart. 3500 might not sound like a lot, but square area is deceptive. Say 300 psi gets into the crack, but the crack is 6 inches deep and 12 inches wide that's 21,600 lbs pushing on each side. But it gets worse, the stress has to flow from one side to the other of the crack, around the propagating crack tip. The sides of the crack act as a lever to concentrate the force many times higher if the crack tip is sharp and enough force is used to slightly bend the material. It's similar to fracking, the pressure may be moderate to high but the surface area is very large and it creates a super large force through several different effects that is capable of breaking rock.
        • Forgot to add that this fracturing would cause an explosion. Take a steel brick and hold a lighter under it, nothing happens. Create a dust and properly disperse it in the air and you can get a sizable explosion, this was a real problem for storing things like flour. So if it were to suddenly break up into small enough pieces it would react orders of magnitude faster with the atmosphere.

    • It's been a while since I studied CFD [computational fluid dynamics - which is the science that would show how atmospheric gases would "flow" around an meteorite as it entered the atmosphere - but I think it's fair to say that a "boundary layer" would form that might in fact make it ridiculously difficult for "high pressure air" to be "forced" into tiny cracks in the surface.

      Try thinking of it this way.

      The meteor is stationary and it is being hit by a 20 km/s stream of gas (far into the hypersonic range, so this gas cannot "flow" around it). When the gas hits the surface of the meteor it comes to a dead halt. All that kinetic energy is converted into internal energy of the gas - extremely high pressure as well as extremely high temperature. This pressure at the very least exerts intense force on the meteor accelerating it (in this frame of reference) and subjecting it to powerf

    • Re:Hang On... (Score:4, Funny)

      by crunchygranola ( 1954152 ) on Wednesday December 13, 2017 @12:19PM (#55732515)

      Something about the OP doesn't make sense. And no, not the fact that there isn't much in the way of "high-pressure air" at the outermost fringes of our atmosphere... The part which seems a little odd is to suggest that altering the apparent pressure [i.e. by the velocity of entry] can in some way "force" air into the cracks within a meteorite/meteorid to induce some form of break-up. Isn't it much more likely to be induced by the coefficient of expansion of the material concerned? If you take a meteorite and then flash-heat the outer surface very, very, very quickly - like for example by slamming it into an atmosphere at several thousand kph - then the outer layer will become very, very hot very quickly - and start to expand. The interior, meanwhile, simply won't have had time to warm up and thus will remain space-cold... As the outer layer warms, it expands. This would easily be enough to cause cracks in the material [think of the way that you can split a rock by pouring water into a crack and then waiting for the water to freeze...]. It's been a while since I studied CFD [computational fluid dynamics - which is the science that would show how atmospheric gases would "flow" around an meteorite as it entered the atmosphere - but I think it's fair to say that a "boundary layer" would form that might in fact make it ridiculously difficult for "high pressure air" to be "forced" into tiny cracks in the surface.

      Interesting how you imagine tossing around some dimly remembered terms like "boundary layer" invalidates the detailed physics of these researcher's model.

      If they had access to your brilliance they would have know the answer without even examining the problem!

      This should a Slashdot "law":

      "If, with just a few minutes of thought about a scientific topic you have only slight familiarity with, you believe you have identified a fatal error that a team of highly trained professional researchers have failed to detect, you can be certain that you are wrong."

  • Do asteroids or comets have "tails' outside of the atmosphere in the vacuum of space -- ie, plumes of particulates given off? Are they "burning"?

    Or is this just what happens when they cross into an atmosphere and experience friction?

    I guess maybe I could see solar heating causing them to erode, but at the same time is there enough solar heating much outside Earth's orbital distance?

  • duh.
  • And are willing to die to destroy us.

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