[meteorite-list] Mars Rover Spirt Finds Metallic Meteorites

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Tue Jun 13 12:22:14 2006
Message-ID: <200606131611.JAA29450_at_zagami.jpl.nasa.gov>

http://www.newscientistspace.com/article/dn9324-mars-rover-spirit-finds-metallic-meteorites.html

Mars rover Spirit finds metallic meteorites
Maggie McKee
New Scientist
13 June 2006

Two iron meteorites have been spotted by the Mars rover Spirit, mission
scientists have announced. The finds are the first meteorites identified
by Spirit, although its twin, Opportunity, discovered a similar space
rock on the other side of the planet in January 2005.

Spirit photographed the rocks in April 2006, just after it parked at Low
Ridge Haven, a northern-tilting slope that is serving as its home for
the six-month-long Martian winter.

The rocks appear smoother and lighter in tone than surrounding rocks.
They resemble the glossy, pitted meteorite - dubbed "Heat Shield Rock" -
that Opportunity found near its discarded heat shield.

Observations of that rock with Opportunity's miniature thermal emission
spectrometer (Mini-TES) showed it was very reflective - a telltale sign
of an iron meteorite (see Metal chunk on Mars confirmed as meteorite
<http://www.newscientistspace.com/article/dn6899>). Now, observations by
the Mini-TES on Spirit reveal the two suspect rocks are similarly
reflective.

"They're very good reflectors," says mission member Ray Arvidson of
Washington University in St Louis, US. "We're seeing the heat of the sky
being reflected to Mini-TES. I don't know how that can happen unless
it's a metal."

Drive-by meteorite

Iron meteorites make up just a few percent of the space rocks that would
be expected to litter the Martian surface. But their appearance and
spectral properties make them much easier to identify than the more
common "stony" meteorites.

The meteorites are fragments of larger space rocks nudged out of the
asteroid belt between Mars and Jupiter and into the Red Planet's path.
They survive on the surface because there are few geological processes
on Mars that would bury them after they fall to ground, says Arvidson.

"It's not surprising that we occasionally drive past a meteorite," he
told New Scientist. "Mars is a very old surface and the erosion rates
are relatively small, so we should expect these things to collect and be
exposed for our viewing."

Features observed at Spirit's winter haven are being named after
research stations and place names in Antarctica. So the two rocks have
been dubbed "Allan Hills" - for a site where many meteorites are found
in the Antarctic ice - and Zhong Shan, an Antarctic base established by
China in 1989.
Received on Tue 13 Jun 2006 12:11:51 PM PDT