This is the first color picture ever transmitted from the surface of Mars. The Viking 1 lander beamed the image to Earth shortly after its landing, on July 20, 1976. For six years, the craft monitored the weather, analyzed the surface material, and hunted for evidence of life. The results of the life experiments were inconclusive, and are still hotly debated today. [NASA/JPL]
Find out more in our radio program entitled Viking 1.