PhobosThe Viking 1 orbiter, observing Mars from orbit while relaying data from the Viking 1 lander to Earth, snaps a close-up view of the Martian moon Phobos from within 5,000 miles. Though more distant from Phobos than Mariner 9’s closest pass in 1972, the Viking cameras are vastly superior, revealing greater detail even at greater distances; craters as small as 13 miles across can be seen in the images. JPL scientists and mission planners are already developing ideas for future Mars missions, including unmanned landers with wheeled rovers.