[meteorite-list] Prospecting for meteorites

From: Sterling K. Webb <kelly_at_meteoritecentral.com>
Date: Sat Nov 19 05:24:43 2005
Message-ID: <437EFD48.8143AE6_at_bhil.com>

Hi,

    Some decades ago, John S. Lewis calculated
that the largest IRON mass that could survive to reach
the surface of the Earth was under 100 tons. This was
making all the ideal assumptions: low entry velocity,
low entry angle, flattened shape. He suggested that
HOBA, which is about 60 tons, was originally that
mass. The soil surrounding it is rich red oxydized
shaley dirt and probably formed from the erosion
product of a larger HOBA than today's 60 tons.
    The largest STONE mass, by the same
calculation, would be only roughly 40 tons, but
since stones are poorly consolidated, they are
unlikely to be able to resist fragmenting, which
seems to be the case. If there was a 40 ton
stone meteorite, it would be a mass equivalent
to a sphere about 10 feet in diameter (3+ meters).
    Objects shatter if a shock wave (like a re-entry
shock wave) exceeds the speed of sound in the
material of the object. Stoney meteorites that have
been tested demonstrated a slow internal speed of
sound. Hence, it is likely that most large stoney
meteorites are shattered by their own re-entry
shock waves!

Sterling K. Webb
---------------------------------------------------------
michel FRANCO wrote:

> Hi,
>
> Thanks Sterling for the additionnal info about the Chinguetti meteorite
> story.
>
> I suggest to say that there is no more controversy about the existence
> of the huge mass and to stop spending time searching it. The dynamic of
> fall teaches that any mass larger than 200 tons will vaporize upon
> landing. The possible mass of the Chinguetti hill is over thousand of
> tons. For me it is physically impossible the find this huge mass.
>
> Then it is true that a meteorite was found nearby that hill and that the
> sun burnt rocks in the hot Sahara are covered with desert varnish, often
> very black and sometimes similar to slightly alterated fusion crust. The
> confusion was possible before we had knowledge of Eugene Shoemaker works
> about impact craters.
>
> My 2 cents.
>
> Best regards
>
> Michel FRANCO
>
Received on Sat 19 Nov 2005 05:24:08 AM PST