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 landing gave information on the Martian gravity and magnetosphere. In 1973, the Soviet Union sent four more probes to Mars: the Mars 4 and Mars 5 orbiters and the Mars 6 and Mars 7 fly-by/lander combinations. All missions except Mars 7 sent back data, with Mars 5 being most successful. Mars 5 transmitted 60 images before a loss of pressurization in the transmitter housing ended the mission. The Mars 6 lander transmitted data during descent, but failed upon impact. Mars 4 flew by the planet at a range of 2200 km, returning one swath of pictures and radio occultation data, which