Olympus Mons orbit around Mars in 1971 during a global dust-storm. The first objects to become visible as the dust began to settle, the tops of the Tharsis volcanoes, demonstrated that the altitude of these features greatly exceeded that of any mountain found on Earth, as astronomers expected. Observations of the planet from Mariner 9 confirmed that Nix Olympica was a volcano. Ultimately, astronomers adopted the name "Olympus Mons" for the albedo feature known as Nix Olympica. Olympus Mons is located between the northwestern edge of the Tharsis region and the eastern edge of Amazonis Planitia. It stands about from the other
Ascraeus Mons zone of knobby terrain outlined by a semicircular zone of concentric ridges. Similar deposits are also found at the northwestern edges of the other two Tharsis Montes, Pavonis Mons and Arsia Mons, as well as on Olympus Mons. The FSD at Ascraeus Mons is the smallest of those on the Tharsis Montes, covering an area of 14,000 km and extending outward from the volcano's base for about 100 km. The origin of these deposits has been debated for decades. However, recent geologic evidence suggests that FSDs are deposits left by glaciers, which covered portions of the volcanoes during a recent