[meteorite-list] Weird Meteorite May Be From Mars Moon

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Thu Apr 22 10:31:15 2004
Message-ID: <200404211921.MAA05926_at_zagami.jpl.nasa.gov>

http://www.newscientist.com/news/news.jsp?id=ns99994902

'Weird' meteorite may be from Mars moon
Jenny Hogan
New Scientist
April 21, 2004

A unique meteorite that fell on a Soviet military base in Yemen in 1980 may
have come from one of the moons of Mars. Several meteorites from the Red
Planet have been found on Earth, but this could be the only piece of Martian
moon rock.

Andrei Ivanov, who is based at the Vernadsky Institute of Geochemistry and
Analytical Chemistry in Moscow, Russia, spent two decades puzzling over the
fist-sized Kaidun meteorite before he decided that it must be a chip off
Phobos, the larger of the two Martian moons. "I can't find a better
candidate," Ivanov told New Scientist.

The Kaidun meteorite is like no other in the world - and 23,000 of them have
been catalogued. It is made of many small chunks of material, including
minerals never seen before.

Working with Michael Zolensky of the NASA Johnson Space Center in Houston,
Texas, Ivanov used an electron microscope to look at the space rock's
crystal structure, peered through its minerals using X-rays and vaporised
fragments to catalogue the elements inside. And every sample turned out to
be something "new and weird", says Zolensky.

Volcanic debris

Among the odd materials in the meteorite were two fragments of volcanic rock
- which only forms in massive, planet-like bodies with a core, mantle and
crust. But much of the meteorite is a kind of carbon-rich material that only
occurs in asteroids.

Zolensky thinks this paradox could be resolved if the meteorite comes from a
Martian moon. Both Phobos and Deimos are thought to be asteroids captured by
Mars as they wandered through space. That would explain the carbonaceous
material.

And the pieces of volcanic rock could be bits of Mars, thrown into orbit
when other asteroids crashed into the planet. Phobos is the more likely
candidate: it orbits only 6000 kilometres from the planet's surface, much
closer than Deimos, and so has probably mopped up a lot more fragments of
Mars rock.

The idea is plausible, if somewhat speculative, says Sara Russell, a
meteorite expert at the Natural History Museum in London. "There have been
no landers sent to Phobos and so almost nothing is known about the
composition and geology of this body."

Zolensky thinks that an unusual asteroid could have been the source. Hope of
resolving the mystery rests with the European Space Agency, which has been
asked by UK scientists to consider sending a mission to Phobos as part of
its Mars exploration programme.

Journal reference: Solar System Research (vol 38, p 97)
Received on Wed 21 Apr 2004 03:21:31 PM PDT