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Re: More Martian Meteorites Coming this Way!

WBranchsb@aol.com schrieb:

> Hello Michael,
> Dear Walter,
> I know I am very concrete in my thought process & often mis "subtle">
> humor. Are you saying the article "clicked to" in your last posting
> is completely bogus & meant to be "funny?" - Michael
> The first thing that strikes me as being funny is the justaposition of
> the Martian meteorites (a very serious scientific subject) with a page
> devoted to UFOs (well, you know).
> Look at the following statement:
>  About 7 percent of Martian rocks knocked away from Mars eventually
> hit Earth, while more than 30 percent eventually burn up in the sun.
> The remainder strike other solar system neighbors.
> This sounds too authoratative with no range of percentages. Granted
> most meteorites land in the oceans but these figures sound too
> precise.
> And this one:
> Burns' research indicates that the rocks coming from Mars would take
> six months to reach Earth.
> Six months? Isn't this the figure often quoted as being the time it
> would take a manned mission to reach Mars?  Has analysis of SNC
> material indicated cosmic ray ages of 6 months (no, too short of a
> time span to calculate)?
> And this one:
> Studies have shown that microscopic life can survive in space for at
> least six months.
> What studies?  Are they analogue studies?  Has there been a shuttle
> mission which confirmed that  "microscopic life can survive in space
> for at least six months." (I am asking a serious question - if anyone
> know of these studies please let me know).
> Regards, Walter

Hello Walter, hello Michael, hello List!

Here is a copy of one of my posts (May 5th) concerning the topic
"Meteorites from Earth and Venus" - It may be of interest in this

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

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