Viking 2

Viking 2 was the second of the two American Viking spacecraft that NASA sent to Mars, each an orbiter and a lander essentially identical to those of Viking 1. It was launched on a Titan IIIE rocket with a Centaur upper stage on 9 September 1975, although it had been planned as the first of the pair until a battery problem led NASA to swap the two and launch it second. It entered Mars orbit on 7 August 1976, and its lander touched down in Utopia Planitia on 3 September 1976, about 6,460 kilometres from the Viking 1 landing site. The lander was designed and built by contractors at Martin Marietta in Denver and carried cameras, a biology laboratory and a gas chromatograph mass spectrometer. It worked until its batteries failed on 12 April 1980, while the orbiter returned almost 16,000 images before it was turned off in July 1978.