Launched 1975
Decommissioned 1983

The success of the Mariner 9 mission in orbiting Mars in 1972 led American scientists to conceive of the Viking program with the aim of landing a spacecraft on the Red Planet. The mission was named for Scandinavian explorers of the ninth and tenth centuries who discovered North America.

Life possible on Mars

The fourth planet from the Sun with an orbit next in line after Earth, Mars has a period of revolution at 687 days, almost double that of Earth. When the Sun, Earth, and Mars are aligned, the distance of Mars from Earth is 35 million miles; this alignment takes place every 15 to 17 years. When Mars is at its greatest distance from the Sun, it is about 63 million miles from Earth. Scientists believed the dark-colored patches on the planet might be simple forms of life. This could be determined by collecting samples and conducting experiments.

Viking designed to explore Mars