Viking program: Viking 1 takes the famous Face on Mars photo.

The Viking program consisted of a pair of identical American space probes, Viking 1 and Viking 2 both launched in 1975, and landed on Mars in 1976. The mission effort began in 1968 and was managed by the NASA Langley Research Center. Each spacecraft was composed of two main parts: an orbiter spacecraft which photographed the surface of Mars from orbit, and a lander which studied the planet from the surface. The orbiters also served as communication relays for the landers once they touched down.

Viking 1 was the first of two spacecraft, along with Viking 2, each consisting of an orbiter and a lander, sent to Mars as part of NASA's Viking program. The lander touched down on Mars on July 20, 1976, the first successful Mars lander in history. Viking 1 operated on Mars for 2,307 days or 2245 Martian solar days, the longest extraterrestrial surface mission until the record was broken by the Opportunity rover on May 19, 2010.

Cydonia is a region on the planet Mars that has attracted both scientific and popular interest. The name originally referred to the albedo feature that was visible from earthbound telescopes. The area borders the plains of Acidalia Planitia and the highlands of Arabia Terra. The region includes the named features Cydonia Mensae, an area of flat-topped mesa-like features; Cydonia Colles, a region of small hills or knobs; and Cydonia Labyrinthus, a complex of intersecting valleys. As with other albedo features on Mars, the name Cydonia was drawn from classical antiquity, in this case from Kydonia, a historic polis on the island of Crete. Cydonia contains the "Face on Mars", located about halfway between the craters Arandas and Bamberg.