Mars Science Laboratory due to land on Mars on Aug. 6
Rather than hunt for microbes like the Viking missions of the 1970s, NASA's Mars ScienceLaboratory, nicknamed Curiosity, will look for places that could have hosted and preserved life.
"The term 'life-detection' is so ill-defined and so hard to ascertain it doesn't make a goodstarting point," said geologist John Grotzinger, with the California Institute of Technology.
Instead, NASA's new Mars mission, scheduled for landing on Aug. 6, is primarily a geologicalexpedition to an intriguing piece of real estate called Gale Crater, located just south of theMartian equator.
Scientists believe the crater formed some 3.5 billion to 3.8 billion years ago when Mars, Earthand the rest of the planets in the inner solar system were regularly bombarded by meteorites.
Gale's most striking feature is not the 96-mile (154-km) wide pit in the ground, but a 3-mile-high a(5-km-high) mound of debris rising from the crater's floor. Scientists believe themountain, located in the center of the basin, is the layered remains of sediment that once filledthe crater.
Over time and by a process not well understood, the sediment was carried away, leaving whatis now known as Mount Sharp, which scientists hope will reveal the geological history of Marslike no similar formation can do on Earth.
"There is no place on Earth you can go to get the whole history at once," Grotzinger toldjournalists during field trip last month to California's Death Valley, one of the few places wherechunks of Earth's geologic record are exposed.
“At Gale you don't need to reconstruct the layers. You can see how they go from older toyounger. You've got time's arrow always pointed in the right direction. It's all laid out verysimply," Grotzinger said.