Discovery and exploration of the Solar System Soviet "Lunokhod 1", which landed on the Moon in 1970. The first to visit another planet was Sojourner, which travelled 500 metres across the surface of Mars in 1997. The only manned rover to visit another world was NASA's Lunar rover, which traveled with Apollos 15, 16 and 17 between 1971 and 1972. Overview of some missions to the Solar System. See also the categories for missions to , , , and . Crewed exploration of the Solar System ended in 1972. The first human being to reach space (defined as an altitude of over 100 km) and to orbit
Olympus Mons - its flanks are shallower and extend farther from the summit in the northwestern direction than they do to the southeast. The volcano's shape and profile have been likened to a "circus tent" held up by a single pole that is shifted off center. Due to the size and shallow slopes of Olympus Mons, an observer standing on the Martian surface would be unable to view the entire profile of the volcano, even from a great distance. The curvature of the planet and the volcano itself would obscure such a synoptic view. Similarly, an observer near the summit would be