Meteorite on Mars
By Ron Cowen
Opportunity, one of the twin rovers on Mars, has discovered the first meteorite on a planet other than Earth. Initial observations, taken from a distance with the rover’s thermal-emission spectrometer, indicated that the pitted, basketball-size body is a metal-rich meteorite. Driving close enough to use its X-ray and gamma-ray spectrometers, Opportunity confirmed the object’s meteorite status and revealed that it’s made mostly of iron and nickel, NASA announced on Jan. 19.
The metallic composition indicates that the rock came from an asteroid or planetary chunk large enough for its mixture of minerals to have separated into a dense, metallic core and a lighter, rocky mantle, notes rover researcher Steve Squyres of Cornell University.