It has been half a century since NASA landed on Mars with the Viking 1 lander. Viking 1, one of a pair of Viking spacecraft, landed on Mars on July 20, 1976. Launched on August 20, 1975, Viking 1 arrived in orbit around Mars on June 19, 1976. The Viking program is, when adjusted for inflation, one of the most expensive robotic missions ever attempted by NASA. The spacecraft consisted of an orbiter, which was eventually shut down on August 7 as its attitude control gas was depleted, and a lander,