Mars Global Surveyor (MGS) (U.S.)

Destination: Mars. Launched: Nov. 7, 1996. Arrival: Sept. 11, 1997. Mission: To provide detailed maps of the planet's surface and distribution of minerals, and to monitor the Martian weather. Six instruments on the orbiting spacecraft are studying Martian surface, atmosphere, and gravitational and magnetic fields. Surveyor's cameras are able to distinguish features as small as 10 ft across.

The primary mapping mission was delayed until March 1999, due to problems with the craft's solar panels. MGS completed its primary mission in Jan. 2001, and is currently in an extended mission phase. Having studied the planet's entire surface, atmosphere, and interior, MGS has returned more Mars data than all other Martian missions combined. Its most significant results include photographs of gullies and debris flow that suggest the presence of water at or near the planet's surface. MGS is collecting and transmitting data from the Mars Exploration Rovers.