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The
discovery of a new Martian meteorite was announced by Dr. Jutta Zipfel
from the Max Planck Institute for Chemistry in Mainz. Members of the institute
staff classified this meteorite based on results from mineralogy, chemistry,
and inert gas analyses. An official announcement was made during the 61st
Meteoritical Society meeting in Dublin 1998.
Several
observations make this finding exciting news and are an enrichment of
meteoritical sciences. This meteorite is the first Martian meteorite found
in the hot desert climate of the Sahara. It is the first one found since
1994 and also the first since the discussion whether there is life on
Mars began two years ago. Now, the number of Martian meteorites has increased
to a total of 13, a small number if compared to the total of more than
20,000 meteorite specimens known so far. A fragment of the meteorite was
given to the Max Planck Institute for Chemistry in Mainz by a private
finder for scientific purposes. The rock weighs a little over 2 kg and
is shaped like a loaf of bread.
During a five-minute speech, Zipfel presented results from inert gas,
chemical and mineralogical studies. The inert gas inventory of the atmosphere
of Mars is very characteristic and well known from the Viking mission
measurements on the surface of Mars in 1976. This is, so far, the strongest
evidence that meteorites having this inert gas fingerprint must come from
Mars. Inert gases present in this meteorite clearly puts it in the group
of Martian meteorites. Typical elemental ratios obtained by bulk chemical
analyses of a chip of the new meteorite soon confirmed this finding. In
addition, mineral chemistry and petrographic observations, such as the
presence of feldspathic glass, rounded out the picture. We had no
doubt that this was a Martian meteorite, said Zipfel, who made the
announcement at the MSM in Dublin.
During the meeting, Zipfel gave British scientists from the Open University
a 150 mg sample for analysis of the oxygen isotopic composition of the
meteorite. These measurements were carried out one week after the Dublin
announcement and their results are consistent with findings obtained by
the Max Planck scientists.
Inert gas analyses show that this meteorite was ejected from Mars about
1 million years ago, marking an ejection event unknown from other Martian
meteorites, said Zipfel in her presentation. After that, the meteorite
took its time to travel through space before it was captured by the gravity
of the Earth and landed in Northern Africa. It was collected there in
May of this year and immediately brought to the German Max Planck Institute
for classification. The meteorite is the first find of its group in a
hot desert environment. Clearly, it carries along with it its desert history,
in that it is penetrated throughout by veins filled with terrestrial weathering
products. The search for past evidence of life in this meteorite
will be severely impeded because it was lying in the hot desert for probably
thousands of years and not in a relatively sterile environment such as
Antarctica, said Zipfel. However, it will give scientists the opportunity
to gain further knowledge about geochemical processes on Mars and new
insights into its evolution as a planet.
The chemical study of Martian meteorites and their implications for the
bulk composition of Mars has a long tradition with scientists from the
Max Planck Institute for Chemistry in Mainz. Their development of the
APXS instrument was selected by NASAs Mars "Pathfinder Mission".
Measurements with this instrument made it possible for the first time
to analyze rocks sitting on the surface of Mars.
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