In this image released Tuesday, Jan. 18, 2005, by NASA taken by the Mars rover Opportunity, a basketball-size metal meteorite can be seen in the upper right of the image while part of the rover's heatshield is seen to the upper left. Opportunity came upon the meteorite last week while it was taking a look at a spacecraft shell that was jettisoned before landing after protecting the rover during its plunge through the Martian atmosphere.(AP/NASA Photo)

    BEIJING, Jan. 19 -- The Mars rover Opportunity has discovered a basketball-size nickel-iron meteorite, which NASA hopes can provide clues to wind and erosion on the martian plains.

    Principal investigator Steve Squyres says the discovery is a surprise. But he says if more meteorites are found, they may help determine whether the surface is being covered by wind-blown materials or whether it's being stripped away.

    After landing on the the Meridiani plains on Jan. 24, Opportunity, a six-wheeled robot geologist, quickly discovered rocks showing that its area of Meridiani was once soaked in water. Opportunity came upon the meteorite last week while it was taking a look at a spacecraft shell that was jettisoned before landing.

    After being examined with infrared spectrometer, the meteorite looked like the martian sky, which is really weird, said Squyres. He explained that The metal surface was reflecting sky radiation instead of emitting much of its own.

    Scientists are not interested in the meteorite itself. Rather, they want to see if other objects spotted out on the Meridiani plains are also meteorites and what that might tell them about Mars.

    Squyres likened the fall of meteorites on the martian surface to a steady rain at a very slow rate. He says the meteorites accumulate over time.

    If few are seen, that would indicate sand is continually being deposited on the surface, burying things and building up terrain. But if the wind is continually stripping away surface material, more meteorites should be found.

    "So whether you're seeing a net accumulation or a net burial of the meteorites is going to tell you something about what the erosion or deposition rates are out on the plains," Squyres said. Enditem

(Agencies)