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 Block II space suits, and would be designated by the Block II titles, regardless of whether a LM was present on the flight or not. On April 24, 1967, Mueller published an official Apollo mission numbering scheme, using sequential numbers for all flights, manned or unmanned. The sequence would start with Apollo 4 to cover the first three unmanned flights while retiring the Apollo 1 designation to honor the crew, per their widows' wishes. In September 1967, Mueller approved a sequence of mission types which had to be successfully accomplished in order to achieve the manned lunar landing. Each step