On August 5, after a journey lasting more than 8 months, a carlike rover carefully settled down onto the surface of Mars. The vehicle is basically a science lab. Its mission: to search for evidence that the Red Planet might once have hosted life — even if the organisms were only one-celled microbes. The first stage of this mission — the landing — is “an amazing achievement,” observes Charles Bolden. He runs the National Aeronautics and Space Administration, or NASA, which built and delivered the vehicle to Mars.