Mars Global Surveyor Mars Orbiter Camera: Interplanetary cruise through primary mission

More than 3 years of high-resolution (1.5-20 m/pixel) photographic observat ions of the surface of Mars have dramatically changed our view of that plan et. Among the most important observations and interpretations derived there from are that much of Mars, at least to depths of several kilometers, is la yered; that substantial portions of the planet have experienced burial and subsequent exhumation; that layered and massive units, many kilometers thic k, appear to reflect an ancient period of large-scale erosion and depositio n within what are now the ancient heavily cratered regions of Mars; and tha t processes previously unsuspected, including gully-forming fluid action an d burial and exhumation of large tracts of land, have operated within near- contemporary times. These and many other attributes of the planet argue for a complex geology and complicated history.