[meteorite-list] Artificial Meteorite Shows Martian Impactors May Carry Traces of Life

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Thu, 25 Sep 2008 13:21:15 -0700 (PDT)
Message-ID: <200809252021.NAA15389_at_zagami.jpl.nasa.gov>


Artificial meteorite shows Martian impactors may carry traces of life
Thaindian News
September 25, 2008

Berlin, September 25 (ANI): An artificial meteorite designed by the
European Space Agency (ESA) has shown that traces of life in a Martian
meteorite could survive the violent heat and shock of entry into the
Earth's atmosphere.

The experiment's results also suggest that meteorite hunters should
widen their search to include white rocks if they want to find traces of
life in Martian meteorites.

The STONE-6 experiment tested whether sedimentary rock samples could
withstand the extreme conditions during a descent though the Earth's
atmosphere where temperatures reached at least 1700 degrees Celsius.
After landing, the samples were transported in protective holders to a
laboratory clean-room at ESTEC (European Space Research and Technology
Centre) and examined to see if any traces of life remained.
Recent missions have gathered compelling evidence for water and
sediments on early Mars. Potential traces of Martian life are more
likely to be found in sediments that have been formed in water.
However, although about 39 known meteorites from Mars have been
identified, all are basaltic rock-types and no sedimentary meteorites
have been found to date.

According to Dr Westall, "The STONE-6 experiment shows that sedimentary
martian meteorites could reach Earth. The fact that we haven't found any
to date could mean that we need to change the way we hunt for meteorites."

"In this experiment, we found that the sedimentary rocks developed a
white crust or none at all. That means that we need to expand our search
to white or light-coloured rocks," he added.

The STONE-6 experiment was mounted on a FOTON M3 capsule that was
launched from Baikonur on 14th September 2007.

Two samples of terrestrial sedimentary rock and a control sample of
basalt were fixed to the heat-shield of the return capsule, which
re-entered the atmosphere on 26th September after 12 days in orbit.
The basalt was lost during re-entry.

However, a sample of 3.5 billion year old volcanic sand containing
carbonaceous microfossils and a 370 million year sample of mudstone from
the Orkney Islands containing chemical biomarkers both survived.
On examination at ESTEC, the 3.5 billion year old sample of sand from
Pilbara in Australia was found to have formed a half-millimetre thick
fusion crust that was creamy white in colour.

About half the rock had ablated but the microfossils and carbon survived
at depth in the sample. Approximately 30 percent of the other sediment,
a lacustrine sand from the Orkney Islands, also survived, as did some of
the biomolecules.

The rocks also transported living organisms, a type of bacteria called
Chroococcidiopsis, on the back of the rocks, away from the exposed edge.
"The STONE-6 experiment suggests that, if Martian sedimentary meteorites
carry traces of past life, these traces could be safely transported to
Earth," said Dr Westall.
Received on Thu 25 Sep 2008 04:21:15 PM PDT

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