Viking 1 became the first successful lander on Mars in 1976, during the U.S. Bicentennial year.
NASA’s Viking 1 spacecraft entered Mars orbit on June 19, 1976. Its lander touched down in Chryse Planitia on July 20, 1976, after the planned July 4 landing date was postponed because the original site looked too rough for a safe landing.
The mission consisted of an orbiter and a lander. From the Martian surface, Viking 1 transmitted photographs, weather observations, and results from experiments that examined the soil for possible signs of biological activity. Its landing was a major achievement in planetary exploration.
Viking 2 followed later in 1976 and also landed successfully. Mariner 9 had orbited Mars earlier but was not a lander, while Mars Pathfinder arrived decades later. The Bicentennial connection is especially notable because Viking 1 was originally intended to land on July 4.