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Meteorites from Earth and Venus

Hello List,

There is a very interesting abstract in METEORITICS which touches both
on the current topic of meteorites found in lunar samples, the Venus
topic we had some days ago, and Ron's contribution:

> It is also interesting to note that no Earth meteorites have been
> found (stony rocks), though there should be some that exist.  I'd
> assume they haven't been found yet because an Earth meteorite would
> have to be a very recent fall, as once it loses its fusion crust due
> to exposure to weather and the elements, it would be indistinguishable
> from a regular Earth rock.




MELOSH H.J. et al. (1993) Swapping rocks: Ejection and exchange of
surface material among the terrestrial planets (Meteoritics 28-3, 1993,
A398, Excerpts):

The discovery of meteorites originating from both the Moon and Mars has
led to the realization that major impacts can eject material from
planet-sized objects. Although there is not yet any direct proof, there
appears to be no reason why such impacts cannot  eject material from the
surfaces of Earth and Venus as well.

Mercury ejecta is nearly all reaccreted by Mercury or erodes in space
... ( a few percent impact Venus).

Venus ejecta is mostly reaccreted by Venus, but a significant fraction
(about 30%) falls on the Earth ...

Earth ejecta is also mainly reaccreted by the Earth but about 30% strike
Venus ...

The larger planets, Venus and Earth,thus readily exchange ejecta. Mars
ejecta largely falls on Venus and Earth, but Mars only receives a small
fraction of their ejecta. A substantial fraction of ejecta from all the
terrestrial planets (except Mercury) is thrown out of the solar system
by Jupiter ...

... we should expect someday to find meteorites from Earth itself and
from Venus.

Best wishes, Bernd