Posted: Sat, Apr 17, 2004, 1:13 PM ET (1713 GMT)
The Mars rover Opportunity has discovered a rock on the Martian surface that appears similar in composition to a class of meteorites found on Earth that scientists believed to have come from Mars. Scientists compared data from spectrometers on Opportunity to compare "Bounce Rock" to analyses of a class of Martian meteorites on Earth called shergottites. The comparison led scientists to conclude that Bounce Rock is similar in composition to several shergottites, notably one called EETA79001 that was found in Antarctica in 1979. Previous research linked shergottites to Mars through an analysis of bubbles of gas trapped in the meteorites, but previous studies had failed to turn up rocks on the Martian surface similar to those meteorites. Bounce Rock, so named because the airbag-encapsulated spacecraft bounced on the rock when it landed, appears to be made primarily of pyroxene, a volcanic mineral not seen elsewhere on the planet. The rock may have been ejected from an impact crater about 50 kilometers from the landing site.

Related Links:

•  UPI article
•  Florida Today article
•  NASA/JPL press release