[meteorite-list] Re: Rubble pile asteroids

From: Robert Verish <bolidechaser_at_meteoritecentral.com>
Date: Thu Apr 22 10:08:32 2004
Message-ID: <20020925234445.46737.qmail_at_web80314.mail.yahoo.com>

------------- Original Message --------------
[meteorite-list] Re: Rubble pile asteroids
Herbert Raab herbert.raab_at_utanet.at
<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.



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Received on Wed 25 Sep 2002 07:44:45 PM PDT