the real Mars: heavily cratered, dotted with extinct volcanoes, colder than Antarctica and drier than the Sahara desert.

Many of the gully systems look extraordinarily recent -- sharply carved and crossing older, wind-scoured features. Their appearance is so fresh, in fact, that it has excited planetary geologists such as MOC designer Mike Malin to think that Mars "may have experienced massive, short-term climate changes, where water could come and go in hundreds of years." Indeed, Garvin said, scientists wonder whether liquid water might exist on Mars now, buried in some areas perhaps 500 meters underground, and that "there might be a dynamic cycling of the atmosphere going on even today."