40 years ago, November 14th 1971 the Mariner 9 became the first spacecraft to orbit another planet. It wasn’t supposed to be the first; Mariner 8 was supposed to have that honor. But Mariner 8’s engine cut out soon after launch on May 8th, 1971 and it crashed to Earth. Mariner 9, the survivor of the pair was launched on May 30th, 1971 and went on to orbit Mars as well as send back large amounts of data. Mariner 9 was able to confirm that Earth basesd assumptions that there were sand-storms on Mars were a reality. because these storms were obscuring the view Mariner was kept in orbit longer than originally planned. When the dust cleared the first images of canyons, craters, and volcanos were obtained.
Mariner was shut down in October of 1972 having used all of its altitude control gas. Its orbit around Mars will fail on or after 2022.