VBefore Hope, detailed knowledge of Mars" thin atmosphere was patchy at best. Al Matroushi explains that earlier probes had discovered that some of its Earth-like atmosphere of hydrogen and oxygen was disappearing into space because of the planet"s weak magnetic field. "We"re paying attention to those two, because these are the basic components of water," Al Matroushi says. "So if we"re talking about life… this is something really important to understand."