Launched on May 30, 1971 and reached Mars on November 14, 1971. It was the first spacecraft from earth to go into orbit around another planet. Mariner 9 took over 7000 pictures of the planet and studied what the atmosphere and surface was composed of as well as Mars gravity and typography. It also took close up pictures of Mars’ moons Phobos and Deimos.
Launched on November 28, 1964, Mariner 4 was the first spacecraft to fly by Mars (flyby on July 14, 1965). It also provided us with the first close up look at the planet. The mission confirmed that Mars has a thin atmosphere composed largely by carbon dioxide.