Early science fiction is littered with explorations of dry, barren Mars, or brave adventurers battling the jungles of Venus. We now know these depictions of the planets for the fantasies they are, as one unmanned probe after another stripped layers of hope from our dreams of other planets close to home where mankind would walk without artificial aid, and perhaps meet other intelligent beings. Yet somehow, the romance of these far-distant worlds persists. NASA's first goal after putting a man into space was to land a man on the moon, and an intense theoretical debate began on the best method of accomplishing this task. Once the basic theoretical concepts were completed, however, the theorists kept on thinking. The moon was one target, yes. But the planets, Mars and Venus – these also drew their interest, and fairly soon after the birth of Apollo, in 1962, NASA began to commission studies for the program that would follow it; using the lessons, techniques and equipment developed for the lunar landings for flights to the planets.
