The Gusev crater on Mars may not be what NASA thinks it is, a planetary scientist reported last week. On Jan. 3, the first of NASA’s twin Mars Exploration Rovers will land inside Gusev crater. Among the spacecraft’s goals: to study evidence of a deep lake that NASA says lay there for millions of years. In such an environment, scientists think, Martian life – if it ever existed – may have taken root. But James Rice, a researcher at Arizona State University, says that the crater may never have been home to a lake.