NASA’s Viking 1 lander reached the surface of Mars on July 20, 1976.
Viking 1 was the first American spacecraft to land successfully on Mars. Its landing occurred in Chryse Planitia, a broad plain in the planet’s northern lowlands. The spacecraft transmitted photographs and scientific measurements from the Martian surface, greatly expanding knowledge about Mars’s terrain, atmosphere, and soil.
NASA had originally planned the landing for July 4, 1976, the United States Bicentennial. Technical concerns led to a delay, and Viking 1 landed on July 20 instead. That date was still symbolically significant because it was the seventh anniversary of Apollo 11’s first crewed lunar landing.
Viking 1 is often confused with Viking 2, which landed later, on September 3, 1976. Both missions included orbiters and landers, but Viking 1 was the first of the pair to reach the Martian surface.