page_title: List of uncrewed NASA missions
section_title: Viking program (1975)
hierarchical_section_title: List of uncrewed NASA missions / List of missions / Viking program (1975)
caption_attribution_description: Artist's impression of the Viking Orbiter spacecraft. Artist's description: "The Viking Orbiter spacecraft releases the aeroshell clad lander near the 'high point' of it's orbit around Mars. The planet is shown based on Mariner 9 photography, oriented as it should appear during separation. Oil on canvas panel for NASA Headquarters."
context_page_description: Since 1958, NASA has overseen more than 1,000 uncrewed missions into Earth orbit or beyond. It has both launched its own missions and provided funding for private-sector missions. A number of NASA missions, including the Explorers Program, Voyager program, and New Frontiers program, are ongoing.
context_section_description: The Viking program consisted of a pair of American space probes sent to Mars—Viking 1 and Viking 2. Each vehicle was composed of two main parts, an orbiter designed to photograph the surface of Mars from orbit, and a lander designed to study the planet from the surface. The orbiters also served as communication relays for the landers once they touched down. Viking 1 was launched on August 20, 1975, and the second craft, Viking 2, was launched on September 9, 1975, both riding atop Titan III-E rockets with Centaur upper stages. By discovering many geological forms that are typically formed from large amounts of water, the Viking program caused a revolution in scientific ideas about water on Mars.
  The primary objectives of the Viking orbiters were to transport the landers to Mars, perform reconnaissance to locate and certify landing sites, act as communications relays for the landers, and to perform their own scientific investigations. The orbiter, based on the earlier Mariner 9 spacecraft, was an octagon approximately 2.5 m (8.2 ft) across. The total launch mass was 2,328 kilograms (5,132 lb), of which 1,445 kilograms (3,186 lb) were propellant and attitude control gas.
caption: Viking at Mars releasing the descent capsule, artist concept
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