Mariner 9 was a NASA spacecraft. It was the ninth spacecraft in the Mariner programme. It was sent to study and orbit the planet Mars. It was the first spacecraft to orbit another planet. Mariner 9 was launched on May 30, 1971 from Cape Canaveral Air Force Station. Mariner 9 reached Mars on November 13, 1971, after a ~170 day flight. The spacecraft was sent to map 70 % of the surface of Mars and to study the temperature changes of the Martian atmosphere and surface. When it arrived, a dust storm hid the surface of Mars. After a few months the dust settled and Mariner 9 discovered the Valles Marineris.