Viking 1 became the first spacecraft to land successfully on Mars in 1976.
NASA launched Viking 1 on August 20, 1975. Its lander reached the Martian surface on July 20, 1976, in Chryse Planitia, while the accompanying orbiter surveyed the planet from above. Viking 1 was the first mission to return clear, detailed images from the surface of Mars.
The lander analyzed Martian soil, measured weather conditions, and conducted biology experiments designed to test for microbial activity. Those experiments produced results that remain debated, but scientists did not accept them as conclusive evidence of life.
Viking 2 landed successfully in September 1976 at Utopia Planitia. Mars 3 had achieved a soft landing in 1971, but it stopped transmitting shortly afterward, so Viking 1 is commonly recognized as the first fully successful Mars landing mission. Viking 1 operated on the surface until 1982.