By Robert Roy Britt
Mars Global Surveyor passed a milestone earlier this month when its 100,000th image was added to NASA's online image gallery for the mission. The total number of photographs is now more than twice the combined quantity supplied by the Viking orbiters in the 1970s.

More interesting is the detail included in the new images. One is said to be among the most detailed views ever provided of the Red Planet. Another reveals new clues about a mysterious "Inca City" on Mars.