[meteorite-list] meteorites ON mars

From: Robert Woolard <meteoritefinder_at_meteoritecentral.com>
Date: Wed, 18 Jul 2007 08:25:36 -0700 (PDT)
Message-ID: <393027.74819.qm_at_web38907.mail.mud.yahoo.com>

Hello Rob,

  This article might be of interest to you. I am
sending a link to the abstract, and a copy of a
portion of the abstract. As you will see, this
originally appeared in the Oct 1999 issue of Sky $
Telescope magazine.

  I hope you find this helpful, and interesting.

  Best wishes,
  Robert Woolard
       
          *****************************

Meteorites on Mars
Sky & Telescope (Archives); Oct 1999; 18;

     ************************************
 
http://pqasb.pqarchiver.com/skyandtelescope/access/886341691.html?dids=886341691:886341691&FMT=CITE&FMTS=CITE:PAGE&date=Oct+1999&author=&desc=Meteorites+on+Mars

      ***************************************


Meteorites on Mars
 
Date: Oct 1999
 
 Abstract (Document Summary)
 
When astronauts finally set foot on the red planet,
looking for meteorites will not be a high-priority
task. But they'll likely stumble across them anyway,
according to British researchers Phil A. Bland
(Natural History Museum) and Thomas B. Smith (Open
University). At the Lunar and Planetary Science
Conference last March, Bland explained that rocky
debris from the asteroid belt encounters Mars more
often, and at slower average speeds, than it does
Earth. He and Smith calculate that meteoroids in the
narrow mass range of 20 to 50 grams have a good chance
of surviving their atmospheric passage and landing
intact if they strike the Martian surface no faster
than about 2 kilometers per second. Once on the ground
the meteorites should remain recognizable as such for
upward of a billion years because chemical weathering
occurs thousands of times more slowly on Mars than it
does on Earth. Meteorites 1 to 2 centimeters across
should accumulate in sizable numbers, and future
astronauts can expect to find a handful of small
specimens in any given area the size of a baseball
diamond. "That little Sojourner rover should have
rolled over one or two of them," Bland notes. In some
locales even more meteorites will lie exposed because
the surface dust that once buried them is now gone, a
situation analogous to the gradual removal of ice in
parts of Antarctica. Nothing in the rock-strewn
landscapes recorded by the Viking and Mars Pathfinder
landers looks unmistakably like a meteorite. But
Friedrich H?rz and Mark J. Cintala (NASA/ Johnson
Space Center) see signs that the surface has indeed
been peppered from above. In particular, the rock
dubbed ...
 
--- Rob McCafferty <rob_mccafferty at yahoo.com> wrote:

> I'm not thinking of doing an expedition to Mars or
> anything but I was wondering if anyone has published
>
> any work regarding meteorites on Mars? I know a
> couple
> have been spotted by the rovers already having
> looked
> at just a very small area of the surface.
>
> With Mars being much colder and drier than even
> Antarctica, it seems to me that they could lie
> preserved for millions of years. Contamination would
> happen due to the ultra fine nature of the dust but
> otherwise they'd remain pristine almost forever.
> With the meteors hitting Mars' atmosphere slower due
> to increased distance from the sun AND the lower
> escape velocity of Mars both contributing to
> increase
> the odds, how is this offset by the reduced
> atmospheric pressure, similar to earth's at
> 100,000ft.
>
> Since most meteorites on earth stop at around
> 30,000ft, where the air is still 30% surface
> pressure,
> what are the threshold limits for Mars?
> I have them for earth but not a method for
> determining
> it. I don't even know if the earth thresholds are
> determined emprically or theorhetically.
> If these are known for Mars and the density of
> meteorites on Mars' surface deduced, it would give
> us
> a far better idea of how much stuff is floating
> around
> out there and also, how much is likely lying on the
> earth.
>
> I know this is a tough call but I'm sure someone
> will
> be better connected than I am.
>
> I'd love to take a look at any data, if you have it
> or
> access to it.
>
> Regards
>
> Rob McC
>
>
>
>
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Received on Wed 18 Jul 2007 11:25:36 AM PDT