Mars in fiction the past; Mars is a setting rather than a goal. Mariner 4 in July 1965 found that Mars—contrary to expectations—is heavily cratered, with a very thin atmosphere. No canals were found; while scientists did not believe that Mars was a moist planet, the lack of surface water surprised them. Science fiction had so influenced real explorations of the planet, however—Carl Sagan was among the many fans who became scientists—that after Mariner 9 in 1971-1972, craters were named after Wells, Burroughs, and other authors. The Mariner and Viking space probes confirmed that the Martian environment is extremely hostile to life. By
Mars 2 3 had completed their missions by 22 August 1972, after 362 orbits. The probe, combined with Mars 3, sent back a total of 60 pictures. The images and data revealed mountains as high as 22 km, atomic hydrogen and oxygen in the upper atmosphere, surface temperatures ranging from −110 °C to +13 °C, surface pressures of 5.5 to 6 mbar (0.55 to 0.6 kPa), water vapor concentrations 5,000 times less than in the Earth's atmosphere, the base of the ionosphere starting at 80 to 110 km altitude, and grains from dust storms as high as 7 km in the atmosphere.