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 program management costs; construction expenses for facilities and their upgrading, and costs for flight operations. This was based on a Congressional Budget Office report, "A Budgetary Analysis of NASA's New Vision for Space", September 2004. "The Space Review" estimated in 2010 the cost of Apollo from 1959 to 1973 as $20.4 billion, or $109 billion in 2010 dollars. ($ in dollars) Looking beyond the manned lunar landings, NASA investigated several post-lunar applications for Apollo hardware. The Apollo Extension Series ("Apollo X",) proposed up to 30 flights to Earth orbit, using the space in the Spacecraft Lunar Module Adapter (SLA) to house