Apollo 15 postal covers incident in the moon landings, the public's fascination with items flown in space increased, as did their value. Although it was not publicly known until September 1972, 15 of the men who entered space as Apollo Program astronauts, before Apollo 15, had agreed with a West German named Horst Eiermann to autograph 500 philatelic items (postcards and blocks of stamps) in exchange for $2,500. This included a member of each mission between Apollo 7 (1968) and Apollo 13 (1970). These items were not taken into space. Covers were prepared by the crews and flown on Apollo 11, Apollo 13 and Apollo
Apollo Applications Program of the Outer Solar System, and the original "Voyager program" of Mars Lander probes. The Apollo lunar base proposal saw an unmanned Saturn V used to land a shelter based on the Apollo Command/Service Module (CSM) on the Moon. A second Saturn V would carry a three-man crew and a modified CSM and Apollo Lunar Module (LM) to the Moon. The two-man excursion team would have a surface stay time of nearly 200 days and use of an advanced lunar rover and a lunar flier as well as logistics vehicles to construct a larger shelter. The isolation of the CSM