Mars 6, also known as 3MP No.50P was a Soviet spacecraft launched to explore Mars. A 3MP bus spacecraft launched as part of the Mars program, it consisted of a lander, and a coast stage with instruments to study Mars as it flew past.

Viking 1 was the first of two spacecraft, along with Viking 2, each consisting of an orbiter and a lander, sent to Mars as part of NASA's Viking program. The lander touched down on Mars on July 20, 1976, the first successful Mars lander in history. Viking 1 operated on Mars for 2,307 days or 2245 Martian solar days, the longest Mars surface mission until the record was broken by the Opportunity rover on May 19, 2010.