<Tr> <Th> First launch </Th> <Td> Viking 1 August 20, 1975 </Td> </Tr> <Tr> <Th> Last launch </Th> <Td> Viking 2 September 9, 1975 </Td> </Tr> <P> The Viking program consisted of a pair of American space probes sent to Mars, Viking 1 and Viking 2 . Each spacecraft 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 . </P> <P> The Viking program grew from NASA's earlier, even more ambitious, Voyager Mars program, which was not related to the successful Voyager deep space probes of the late 1970s . 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 . Viking 1 entered Mars orbit on June 19, 1976, with Viking 2 following suit on August 7 . </P>

On what planet did viking 1 and 2 land what robotic feature did they have
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