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Chelyabinsk Meteor Shockwave 2/15/2013

  1. Feb 15, 2013 #1
    Was today's Chelyabinsk meteor destruction from an accelerated, focused "superboom" or a sonic boom? I assume it was not an explosion boom. I am trying to understand if the boom destruction radiated from central point or traveled with the meteor as an aircraft's sonic boom continually travels with the airplane. Neither do I understand if the two types of booms would be mutually exclusive and, if not, could there be two audible booms? I am not a physics guy. Have fun with incomprehensible calculations if it interests you but please try to phrase a simple answer for this dummy. Thank you.
     
  2. jcsd
  3. Feb 15, 2013 #2

    Chronos

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    The meteorite was probably largely composed of iron allowing it penetrate relatively deep into earths atmosphere before exploding. Any supersonic body produces a sonic boom, but, that component was much less energetic than the shock wave from the explosion. It was probably a miniature version of the tungaska event.
     
  4. Feb 15, 2013 #3
    i agree with the above statement. that said, i don't think the shock wave from the explosion itself radiates from the blast location nearly as far as the sonic boom does. most of the damage was due to broken glass, and car alarms went off everywhere. that sounds more to me like the reverberation of a massive sonic boom than it does damage done by the explosion itself.

    i live in Sarasota on the west coast of FL, over 150 miles from the Space Shuttle's landing strip at Cape Canaveral. while none of the sonic booms caused by the shuttle upon atmospheric reentry shattered windows in my neighborhood, they've always been clearly audible from such a distance (maybe more or less, depending on where in the atmosphere the shuttle reenters), and i could always "feel" it in addition to hearing it. a quick google search revealed that scientists believe this object to have been approx. 50 feet in diameter and weighed approx. 7,700 tons (source is The Christian Science Monitor believe it or not LOL). its reentry speed was estimated at 19 mi/s, or ~68,000 mi/h (source is Digital Monitor). now considering 1) its cross section along its axis of motion is much larger than the shuttle's, 2) its almost certainly much less aerodynamic than the shuttle, and 3) its reentry speed was approx. 4 times faster than that of the shuttle's reentry speed, i can see how its sonic boom might be that much louder, energetic, and far-reaching than that of the shuttle's sonic boom upon reentry.

    now the blast supposedly released an amount of energy equivalent to a 300-500 kiloton nuclear weapon (source is The Christian Science Monitor), which is approx. 19 to 31 times as powerful as the 16-kiloton warhead that was dropped on Hiroshima in WWII...a large margin of error, i know. but if it exploded at an estimated altitude of 12-15 miles above the earth's surface (source is The Christian Science Monitor), and knowing that the Hiroshima bomb's blast radius was only ~1 mile, and assuming blast radius does not scale linearly w/ energy output, then i'm not so confident that the shock wave caused by the explosion itself (as evidenced by a blast radius) even reached the ground.

    granted this is speculation...what do you think?
     
  5. Feb 15, 2013 #4
    My theory is that the Chelyabinsk "meteor" was an old Russian military satellite being retired under cover of the passing asteroid, deliberately directed at the Chelyabinsk area so that local military teams could go out and rapidly collect the debris. I hope to see some discussion of whether the explosion and shockwave could be consistent with such a hypothesis.

    edit: Since the explosion was so big, it might be necessary to suppose a space weapon system with an actual bomb on board.
     
    Last edited: Feb 15, 2013
  6. Feb 15, 2013 #5

    russ_watters

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    We don't do conspiracy theory/crackpottery here, mitchell. There is no evidence whatsoever of anything more unusual than a once-a-century meteor explosion - and satellites don't explode with atomic bomb force.

    Anyway, It wasn't clear to me but it sounds like the primary blast was from the meteor exploding. I was surprised by the way it looked, but having seen too many movies I suppose I was expecting a stationary fireball. If the meteor is moving 30,000 mph, the fireball is also moving at 30,000 mph and looks like a streak instead of a ball.

    And incidentally, the shock wave from the explosion would combine with the shock wave from the sonic boom. They are both, after all, emanating from the same place and traveling at the same speed.
     
  7. Feb 15, 2013 #6
    indeed...i hadn't thought about the fact the both shocks were traveling at the same speed. still, the fact that the energy from the explosion itself probably emanated only a relatively short distance from the epicenter, and my own personal experience of hearing the shuttle's sonic boom upon atmospheric reentry on numerous occasions from much greater distances than the typical blast radius of a "small" nuclear weapon leads me to hypothesize that most of the damage was caused by the sonic boom (even if the explosion itself released much more energy than the sonic boom carried with it, albeit in a much more confined space).
     
  8. Feb 16, 2013 #7
    Much like with the big bang the word "explosion" is missleading. The asteroid didn't explode, it broke up. By breaking up it presented many more fragments to the atmosphere with a much higher total surface area. That in turn generates more/stronger shockwaves than before.
     
  9. Feb 16, 2013 #8

    jimgraber

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    The meteor is thought to be rock, not iron. People "upstream" probably heard both the sonic boom and the explosion at different times. Also different "loudness".
     
  10. Feb 16, 2013 #9
    What were those secondary explosions? Were these perhaps multiple sonic booms produced by fragments?







    Also, I wonder if there were any aircraft in the vicinity when this happened, and if so, how would they have been affected?

    Scientists are saying this was a 30-Hiroshima blast.
     
    Last edited by a moderator: Sep 25, 2014
  11. Feb 16, 2013 #10

    Dotini

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  12. Feb 16, 2013 #11
    This one provides a pretty decent view of the flash too, from an opposite angle:




    I'd read that this object came in on an Earth-grazing trajectory. What would have happened if it was coming in on a surface-normal trajectory? Would it have impacted the ground?
     
    Last edited by a moderator: Sep 25, 2014
  13. Feb 16, 2013 #12

    Bandersnatch

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    No it wouldn't.
    Check this handy impact calculator to get a feel for various angles, velocities etc.,:
    http://www.purdue.edu/impactearth/
     
  14. Feb 16, 2013 #13
    Thank you, I also had the same question regarding this.
     
  15. Feb 16, 2013 #14
    Hey, that was pretty cool. I was disappointed that I didn't get to see anything go splat, however.

    Maybe that could be a good idea for an app.
     
  16. Feb 16, 2013 #15
    Why did the meteor explode? What specifically caused the fireball (the abrupt increase in brightness) for example? That is, what is the physics behind such a fireball versus one that just ablates and burns down to nothing? Meteors are made up of materials were normally consider explosive, so what produces the energy we see in such a fireball? What's the mechanism? Did the material of the meteor vaporize and the constituents burn?
     
  17. Feb 16, 2013 #16

    mfb

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    The energy is just the kinetic energy of the meteor. Space shuttles have to fight with that, too, and leave a similar (but much smaller) trace. Air drag is so extreme that it can break the object (if you hit a stone hard enough with anything, it will break - even if it is a single, massive block).
     
  18. Feb 16, 2013 #17
    Of course it's the kinetic energy but what specifically causes the fireball as opposed to the meteor just ablating down to nothing? Even if the meteor breaks up that doesn't mean that it will become a fireball. What the videos showed was an abrupt increase in the brightness of the fireball--what produced that light? Was it photons produced by breaking of the molecular bonds of many small particles of the meteor? Was it rapid combustion of the atomized material of the meteor? Or was it some other process?

    Kinetic energy + the material of the meteor are the inputs and the light (among others) is the output: what is the physical process that takes those inputs and produces that output?
     
    Last edited: Feb 16, 2013
  19. Feb 16, 2013 #18

    mfb

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    Many, fast particles flying through the atmosphere heat a lot of air. And a lot of hot air in some region is a fireball.

    A significant increase in air drag due to fragmentation.
    Hot air radiates, just as it does in a fire. Blackbody radiation, plus some parts due to internal transition in molecules.
     
  20. Feb 16, 2013 #19
    Is fragmentation alone enough to cause the rapid transition from a burning meteor streaking through the sky leaving something like a contrail to the rapid increase in size and brightness that we saw? The amount of light produced and the size of the "explosion" (variously estimated from 0.1 to 300 kilotons) suggests, at least to me, something more dramatic, such as abrupt vaporization and combustion. But that's just my guess.
     
  21. Feb 17, 2013 #20
    A fluid like water feels hard to someone jumping off the Golden Gate bridge, so they say, and I believe "them", although I've never tried this folly myself! If a poor little asteroid doing nothing but just falling freely is swatted by a great big planet and made to accelerate to relative rest at several tens of "gees", even the planetary atmosphere must seem much harder to it than the sea does to a jumper. Think tornadoes blowing at speeds of km/sec! The asteroid's presumed non-aerodynamic shape and heterogeneous make-up will then make the forces that accelerate it generate internal stresses that are both inhomogeneous and extreme, which are likely to cause very sudden fracture and a (small b's) big bang. Think of throwing a large diamond into a jet intake. Not that you would dream of actually doing this!

    Then glappkaeft's scenario (post #7) takes over.
     
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