4 August

1969: On 4 August 1969, the US Mariner 7 encountered Mars (Mariner 6 had arrived a few days earlier). The Mariner 6 and 7 spacecraft were designed to fly over the equator and southern hemisphere of Mars.

The two spacecraft later returned a combined total of 143 approach pictures of the planet and 55 close-up pictures. The spacecraft also studied the Martian atmosphere and profiled its chemical composition. Closest approach to Mars for both spacecraft was approximately 3550 kilometres.