Viking 1 was launched by a Titan-Centaur rocket from Complex 41 at Cape Canaveral Air Force Station at 5:22 p.m. EDT on Aug. 20, 1975, to begin a half-billion mile, 11-month journey through space to explore Mars. The 4-ton spacecraft went into orbit around the red planet in mid-1976 and landed on Mars on July 20, 1976.