------------- Original Message -------------- [meteorite-list] Re: Rubble pile asteroids Herbert Raab [EMAIL PROTECTED] <mailto:herbert.raab%40utanet.at> Wed, 25 Sep 2002 15:37:06 +0200 Bob Verish writes: > I have described it as being a loose rubble pile of > L6, L5, and L4 meteoroids; held together by the most > minimum of gravitational attraction. How else can you > explain a strewn field of stony meteorites with such
> a variation in metamorphic grade, yet NO EVIDENCE of > brecciation, meaning that each individual stone is > either all L6, or all L5, or all L4, but never a > combination of the three? I am not so sure if this is a strong indication that the Gold Basin meteorid was a rubble pile. If a rubble pile meteorid closes in on Earth, it will probably be disrupted by tidal forces *before* it enters the atmosphere. Maybe you would get a strewfield very similar to a strewfield produced by a compact meteorid that breaks up at in the atmosphere. Or maybe not, and the strewfield would be different (i.e., larger strewn field, no aerdynamic sorting of the meteorites by size, etc.). I don't know... ++++snip!++++ Best greetings, Herbert -------------- End of Original Message -------------- Ah, yes! Tidal forces! We are all familiar with how Jupiter's tidal forces broke apart the Shoemaker-Levi 9 Comet. So, to set the record straight, there is no meteoroid large enough that would have sufficient gravitational attraction to withstand Earth's tidal forces. But in Maurizio Eltri's recent post to this List, he has put forth a very interesting theory, in which he proposes that fine-grained friable debris from an asteroid/cometary collision would form a matrix around the more indurated, rocky fragments during the (re)accretion process! In effect, still forming a breccia, but one that is only sufficiently strong enough to withstand tidal forces, but too friable to withstand atmospheric ablation. Yeah, that would explain how you could get a "rubble pile" kind of strewn field like Gold Basin. And going back to what Herbert said about a rubble pile meteoroid possibly forming a "strewn field [that] would be different (i.e., larger strewn field, no aerodynamic sorting of the meteorites by size, etc.)" sure sounds like a description of Gold Basin. Certainly, there is nothing about the Gold Basin strewn field that would RULE OUT a rubble pile type of meteoroid. Clearly, our discussion will not prove one way over the other, but I would sure like to read the results from some serious study, or organized investigation into these possibilities. Bob V. __________________________________________________ Do you Yahoo!? New DSL Internet Access from SBC & Yahoo! http://sbc.yahoo.com ______________________________________________ Meteorite-list mailing list [EMAIL PROTECTED] http://www.pairlist.net/mailman/listinfo/meteorite-list
