An orbiting spacecraft has discovered a key mineral in bedrock on the Martian surface that suggests the planet might once have had an environment hospitable to life, scientists reported Thursday. The Mars Reconnaissance Orbiter detected carbonate mineral in rock outcrops in Nili Fossae, a region of valleys that have cut into the planet’s ancient crust, suggesting the area was not as harsh as other places on Mars. The mineral, which forms in the presence of water, had previously been detected in trace amounts in Martian dust and soil.
