NASA’s Viking 1 spacecraft landed on Mars on July 20, 1976, during the United States Bicentennial.
NASA had originally planned for Viking 1 to land on July 4, the Bicentennial date. The landing was delayed until July 20, which coincided with the seventh anniversary of Apollo 11’s lunar landing. Viking 1 then became the first spacecraft to successfully land on Mars and carry out its mission from the Martian surface.
The spacecraft was part of NASA’s Viking program, which included an orbiter and a lander. Viking 1 transmitted photographs and scientific measurements, including data about the Martian atmosphere, soil, and surface environment.
Viking 2 followed with a successful landing on September 3, 1976. The two missions are often confused because both landed on Mars in the same Bicentennial year, but Viking 1 arrived first.