|Volume: 03, Issue: 02||01/26/2005|
Opportunity Observes Unprecedented Mars MeteoriteNASAís Opportunity rover has made a fascinating discovery: the first meteorite found on Mars, or on any planet other than Earth. The Mars Exploration Rover recently found the pitted iron meteorite, which is about the size of a basketball.
According to readings from the roverís spectrometer, the meteorite is composed of mostly iron and nickel. Only a small fraction of the meteorites fallen on Earth are similarly metal-rich; most are more heavily composed of rock.
"This is a huge surprise, though maybe it shouldn't have been," said Dr. Steve Squyres of Cornell University, principal investigator for the science instruments on Opportunity and its twin, Spirit.
The meteorite, dubbed "Heat Shield Rock," sits near debris of Opportunity's heat shield on the surface of Meridiani Planum. The site is a cratered flatland that has been Opportunity's home since the roverís landing on Mars nearly one year ago.
Scientists are intrigued by the composition of the meteorite, as it lends questions about where it came from. Typically iron meteorites would have come from a destroyed planet or larger body that had a metallic core, according to Squyres. Rover-team scientists are now wondering whether some rocks that Opportunity has seen atop the ground surface are rocky meteorites.
"Mars should be hit by a lot more rocky meteorites than iron meteorites," Squyres said. "We've been seeing lots of cobbles out on the plains, and this raises the possibility that some of them may in fact be meteorites. We may be investigating some of those in coming weeks. The key is not what we'll learn about meteorites -- we have lots of meteorites on Earth -- but what the meteorites can tell us about Meridiani Planum."
The numbers of exposed meteorites could be an indication of whether the plain is gradually eroding away or being built up. According to NASA Chief Scientist Dr. Jim Garvin, these findings open a great number of new research possibilities on Mars.
Opportunity and Spirit successfully completed their primary three-month missions on Mars in April 2004. NASA has extended their missions twice because the rovers have remained in good condition to continue exploring Mars longer than anticipated. They have found geological evidence of past wet environmental conditions that might have been hospitable to life.
Opportunity has driven a total of 2.10 kilometers (1.30 miles). Minor mottling from dust has appeared in images from the rover's rear hazard-identification camera since Opportunity entered the area of its heat-shield debris, said rover project manager Jim Erickson of NASA's Jet Propulsion Laboratory. The rover team plans to begin driving Opportunity south toward a circular feature called "Vostok" within about a week.
Spirit has driven a total of 4.05 kilometers (2.52 miles). It has been making slow progress uphill toward a ridge on "Husband Hill" inside Gusev Crater.
JPL, a division of the California Institute of Technology in Pasadena, has managed NASA's Mars Exploration Rover project since it began in 2000. Images and additional information about the rovers and their discoveries are available on the Internet at http://www.nasa.gov/vision/universe/solarsystem/mer_main.html and at http://marsrovers.jpl.nasa.gov .
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