[meteorite-list] Giant Asteroid Fragment Makes Impact
From: Larry Lebofsky <lebofsky_at_meteoritecentral.com>
Date: Thu May 11 20:23:15 2006 Message-ID: <1147393392.4463d57006fd1_at_hindmost.LPL.Arizona.EDU> Hi, Why does the impactor need to have been one piece when it hit or even before it entered the atmosphere? Larry Quoting Ron Baalke <baalke_at_zagami.jpl.nasa.gov>: > > > > Hi, > > > > The rational for survivor fragments of an impactor is > > that they are from the far back side of the impactor. The > > transformation of the impactor's mass from a solid to a > > plasma proceeds from the "front" or impacting surface. > > A shock wave from this explosive vaporization preceeds > > the actual transformation, traveling at the impact speed > > of the body plus the rate of expansion of the vaporization. > > If this shock wave speed exceeds the speed of sound in > > the impacting body, the shock wave will fracture, pulverize > > and even vaporize (if it's fast enough) the body of the > > impactor ahead of it. > > Another possibility is the meteorite fragment they found was from > another fall, and not from the impactor that created the crater. > > > The models say the transient crater is deep, but it would > > shallow up dramatically from rebound and ends up as > > an extremely shallow crater for its size. If there was > > little shock melting, is it possible that rebound melting > > occured? Or the release of local vulcanism? I don't know > > if we know enough about this crater to be sure. > > > Bear in mind a lot can happen geologically in 144 million years since > the crater was formed, not to mention erosion effects. The depth > the crater is at today is probably not the depth it was when it was > created. > > Ron Baalke > ______________________________________________ > Meteorite-list mailing list > Meteorite-list_at_meteoritecentral.com > http://six.pairlist.net/mailman/listinfo/meteorite-list > Received on Thu 11 May 2006 08:23:12 PM PDT |
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