In pictures taken early in the Mariner 9 mission, this region, shows a dark mountain standing above the Martian dust storm. This higher resolution photograph shows that the area contains a complex crater, called Olympus Mons (Nix Olympica or Snows of Olympus), nearly 64 kilometers (40 miles) in diameter. The multiple crater form with scalloped margins, is characteristic of calderas--volcanic collapse depressions on Earth. In the Mariner 6 and 7 flights in 1969, an outer ring, 1600 kilometers (1,000 miles) in diameter, was seen. It is hidden by the dust in the oblique picture. Earth-based radar observations show that this is a high region on Mars and is usually covered by a white cloud when observed telescopically. This picture was taken on November 27, 1971.
Mariner 9 was the first spacecraft to orbit another planet. The spacecraft was designed to continue the atmospheric studies begun by Mariners 6 and 7, and to map over 70% of the Martian surface from the lowest altitude (1500 kilometers [900 miles]) and at the highest resolutions (1 kilometer per pixel to 100 meters per pixel) of any previous Mars mission.
Mariner 9 was launched on May 30, 1971 and arrived on November 14, 1971.