NASA’s Viking program was the first mission to return numerous images and scientific data from Mars. It comprised two identical spacecraft - Viking 1 and Viking 2 - each with an orbiter and a lander.
Both launched using a Titan IIIE/Centaur launch system. Viking 1 launched on 20 August 1975, reaching Mars after a ten-month journey. The orbiter took images and transmitted them to NASA, who used them to choose a site for the lander. On 20 July 1976 the lander separated from the orbiter and landed in an area called Chryse Planitia. For more than six years the lander took images and collected data from the surface. The orbiter’s fuel ran out on 7 August 1980, while the lander shut down on 13 November 1982 when a mistake during a software update caused its antenna to go down.
Viking 2 launched on 9 September 1975, reaching Mars orbit on 7 August 1976. The lander touched down in the Utopia Planitia on 3 September. Viking 2’s mission did not last as long as Viking 1; the orbiter shut down after a fuel leak about two years after arrival, while the lander had a battery failure after three-and-a-half years. Together Viking 1 and 2 provided more than 50,000 photographs of Mars.