I have to respectfully disagree Doug. I'd agree more with you had I not witnessed it myself. I believe there might be an unconsidered chemical source to drive an explosion.
The Maryville Bolide(1983), which I was lucky to observe may have been an aberration from the norm on several levels( e.g. calculations indicate it was still incandescent between 3-4 miles when conventional wisdom places the max altitude for incandescence at 5 miles above sea level)but none-the-less it expanded explosively in all directions formaing a slightly squat turnip-shapped fire/smoke ball. This meteorite was likely still traveling 1-2 or more kilos per second when it first appeared in front of me. When it "bolided", there was a visible smoke trail of a fragment that was ejected up and out at 45-60° leaving 3 distinct doglegs of smoke trails as it went up, out, then started down. An area of secondary crust was found on the only recovered mass suggesting that may have been the source of the wayward fragment. Many questions remained about this fall. Owing to an early morning entry with both cosmic velocity and meeting Earth's 15kps(?) orbital velocity combined, it was screaming fast. The size of the bolide/smoke sphere was estimated between 400-1200 ft in diameter. This seems rather large for the approx. 1kg stone which was recovered. The fall was very close to a large lake so we could never be confidant if the recovered stone was truly the surviving/main mass or if it was the fragment observed ejected from the upper hemisphere of the bolide. In that we know factually little and only weakly theoretically-- about the actual expansion mechanism aka explosive disruption, I believe that there is a case to be made for an "explosion"--i.e. rapidly expanding, gas-driven, wave front which is moving at or near shock wave velocities of chemical explosives or propellant burn speeds-- even if we are unsure of the mechanism that expands the fireball to many diameters of the original smoke/incandescent trail. Be it recalled that when air suspended, combustible particles such as coal dust or wheat flour are ignited, they act as explosives and can collapse large structures or mine shafts. The nano-gram sized particles of a extensive disruption when suddenly exposed to oxygen might be a sufficient chemical explosive mechanism. For example, metallic iron, shearing at apart at plasma temperatures, might be literally burned in the higher oxygen levels of the lower atmosphere and the rapid expansion of the fireball could be driven by a burning iron fog--meeting the definition of explosive. Regards, Elton --- [EMAIL PROTECTED] wrote: > Pete wrote: > "Some will be blown up and some will be blown down." > > I believe this is a common misconception for many in the meteorite > community and common thought. I don't think anything is "blowing > up". > Simply fragmenting. Each part of the original whole maintains its > portion of momentum upon fragmentation. The direction of the > momentum is along the angle of entry. There is no blowing up in that sense of a bomb which propells fragments in all directions as there is no internal source of energy (like in a chemical explosive). ______________________________________________ http://www.meteoritecentral.com Meteorite-list mailing list Meteorite-list@meteoritecentral.com http://six.pairlist.net/mailman/listinfo/meteorite-list