Mars rover's rock exam yields surprises

The first martian rock examined by NASA's Curiosity rover has a more varied composition than expected from previous missions, the space agency reported. The rover team used two instruments on Curiosity to study the chemical makeup of the football-size rock, with such examinations being a major emphasis of the mission because rock compositions can reveal clues to unseen environments and planetary processes, NASA's Jet Propulsion Laboratory in Pasadena, Calif., said in a release Thursday. The examination yielded some surprising results, scientists said. "This rock is a close match in chemical composition to an unusual but well-known type of igneous rock found in many volcanic provinces on Earth," said Edward Stolper of the California Institute of Technology, a Curiosity co-investigator. "With only one martian rock of this type, it is difficult to know whether the same processes were involved, but it is a reasonable place to start thinking about its origin." On Earth, rocks with such a composition typically come from processes in the planet's mantle beneath the crust, from crystallization of relatively water-rich magma at elevated pressure, researchers said. During a two-year prime mission researchers will use Curiosity's 10 instruments to assess whether the study area ever has offered environmental conditions -- including water -- favorable for microbial life.