[meteorite-list] Martian Meteorite May Contain Water (NWA 817)

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Thu Apr 22 09:44:12 2004
Message-ID: <200106141553.IAA08236_at_zagami.jpl.nasa.gov>

http://news.bbc.co.uk/hi/english/sci/tech/newsid_1387000/1387399.stm

Martian meteorite may contain water
Dr. David Whitehouse
BBC News
June 13, 2001

A meteorite found in the Western Sahara may contain water that could have
come from below the surface of Mars, French researchers say.

Discovered last December, meteorite NWA 817 weighs 104 grammes (three and a
half ounces).

It is the fourth Martian meteorite to be classified as a nakhlite because of
its distinctive mineral composition.

A detailed analysis of various forms of hydrogen within the rock suggests it
was exposed to water from below the surface of Mars.

Possible contamination

The ratio of hydrogen and its isotope deuterium - another form of the atom -
can tell researchers if the rock was exposed to water and, possibly, where
that water came from.

"We detected a very low deuterium/hydrogen ratio, close to a reading for the
Earth," said Dr Phillipe Gillet, director of the National Institute for
Sciences of the Universe in France.

"Our interpretation is that this refers to a fluid that came from the
planet's interior, not its surface," he added.

Analysis of the three other known nakhlites shows that they have also been
exposed to water, but which came from the planet's surface. However, experts
are concerned that the water could be just the result of contamination after
the Martian rock landed on Earth.

Life questions

Dr Monica Grady of the Natural History Museum in London, UK, told BBC News
Online: "Desert meteorites are often badly weathered, and water exchanges
very easily during weathering so it could be contamination."

Dr Gillet admits that contamination is a possibility.

"However, if we are right, that means part of the water contained in the
Martian mantle did not rise to the surface of the planet," he said.

If it is confirmed that the water came from sub-surface rocks in Mars'
mantle it would add to the debate about how much water Mars had in the past.
Also, because life needs water, it would be pertinent to the question of
life on the planet.

Last year, the Mars Global Surveyor spacecraft in orbit around the planet
saw what might be evidence of recent running water on its surface.

Martian meteorites are believed to have been blasted off the planet by an
impact with a large object many millions of years ago. After wandering in
space for millions of years some of the chunks of rock fell down on to
Earth.
Received on Thu 14 Jun 2001 11:53:40 AM PDT