[meteorite-list] Lunar and Martian Meteorites

From: Sterling K. Webb <kelly_at_meteoritecentral.com>
Date: Thu Apr 22 10:25:38 2004
Message-ID: <3EBEAFC7.CCF22001_at_bhil.com>

Hi, Bjoern, Bernd, List,

    It may be that that there is a limiting factor at work. The energy required to
blast a rock off the Lunar or Martian surface by impacting that surface with a much
larger rock increases as the mass of the rock to be removed increases. At a certain
point, the energy needed to get the rock off the Lunar or Martian surface is equal
to or greater than the energy required to shatter that rock into smaller fragments,
thus establishing an upper limit to the size of a rock that can be removed from the
Lunar or Martian surface.
    Somewhere (and I can no longer remember where or by whom) an estimate was
published of the largest possible Lunar and Martian escapee. It was not a large
mass (less than 50 kilos?). Also, since Lunar materials are very poorly
consolidated and much weaker than Martian basalts, the limit for Lunar lumps was
smaller than for Martian ones, despite the weaker Lunar gravity.


Sterling K. Webb
------------------------------------------------------------------
"Bjørn Sørheim" wrote:

> At 18:53 11.05.03 UT, Bernd wrote:
> >Hello Listees and Listoids,
> >
> >Something else that has always been a puzzle to me is the relatively small
> size of lunar and martian meteorites found to date. Why aren't there really
> big ones like the Jilin main mass (1770 kg), the 408 kg Paragould LL5 stone,
> or the 91 kg Juvinas eucrite? Does this have to do with orbital dynamics in
> the Earth-Moon and the Earth-Mars system? Are there tidal forces that
> literally disrupt martian or lunar meteorites somewhere on their way to Earth?
>
> Bernd,
> I think this is easy to answer, it has to do with statistics and size
> distribution:
> Think of the number of grains of sand on this planet (and others), compared to
> huge boulders, say 50 m or larger. There aren't many of the latter in proximity
> to your location, are there? On the other hand how many 'zillions' of grains
> of sand
> are there, whereever you might happen to live?
> So if you choose a small subset of a large population of rock fragments, this
> is bound to contain a large proportions of the small individuals, and none or
> very few of the large ones. If you then multiply the population by several
> orders
> of magnitude, then first the really large ones will pop up, I'm confident...
> You would agree, won't you??
>
> Regards,
> Bjørn Sørheim
Received on Sun 11 May 2003 04:17:11 PM PDT


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