[meteorite-list] Metal Chunk on Mars Confirmed as Meteorite

From: Ron Baalke <baalke_at_meteoritecentral.com>
Date: Tue Jan 18 15:08:50 2005
Message-ID: <200501182008.MAA24045_at_zagami.jpl.nasa.gov>

http://www.newscientist.com/article.ns?id=dn6899

Metal chunk on Mars confirmed as meteorite
New Scientist
January 18, 2005

The Opportunity rover has found the first meteorite on the surface of
Mars, scientists confirmed to New Scientist on Tuesday.

Scientists first spotted the unusual pitted rock sitting by itself near
the rover's discarded heat shield earlier in January. An instrument that
measures thermal emissions scanned the rock from afar and it appeared to
be made from metal, suggesting it was a meteorite.

Then, on 15 January, Opportunity extended its instrument arm to the
rock. It used its Mossbauer spectrometer to confirm that the rock was
made of iron and nickel, showing that it must indeed be a meteorite that
had fallen from the sky.

"This is a wonderful surprise," says the rovers' lead scientist, Steve
Squyres, at Cornell University, New York, US. "I didn't see this one
coming."

Prior to the NASA mission, engineers had not foreseen the need to test
the rovers' grinding tools on meteorites. In recent days, Honeybee
Robotics, which made the grinding tool, conducted the first tests on an
iron-nickel meteorite borrowed from the American Museum of Natural
History in New York. After an hour of grinding, one-quarter of the
grinding head had worn away.

For that reason, Squyres said they would not use the real tool on the
Martian meteorite. The tool is usually used to remove the dust and outer
layers of rocks to unmask their underlying features.

Moving on

The concentration of meteorites on the Meridiani plains - where
Opportunity has roamed since January 2004 - will reflect how active the
surface processes are, as these would cover the rocks from space.

If researchers can find more meteorites, they may learn more about the
erosion and movement of surface materials. Opportunity will now head
south, where many small rocks litter the surface.

On the other side of Mars, Opportunity's twin rover, Spirit, has not
seen any rocks that appear to be meteorites. But only about 2% of the
meteorites found on Earth are made of iron and nickel - the rest are
made of rock, making them harder to discern against a background of
other rocks.

Squyres told New Scientist that the rovers may already have passed
meteorites without knowing it. "There're so many rocks there," Squyres
says, "I don't think we've really gone through our images."
Received on Tue 18 Jan 2005 03:08:39 PM PST