Canceled Apollo missions wasn't going to have a flight for him". Another lunar landing was lost in April 1970 when Apollo 13 had its in-flight failure, and the Fra Mauro landing site was reassigned to Apollo 14. Then on September 2, 1970, NASA announced it was canceling the H4 and J4 missions, due to more budget cuts. Skylab was also pushed out to 1973, and the final landing schedule became: At the time, 35 of NASA's 49 active astronauts were waiting for a chance for a mission. In the closing days of the program, Apollo 17 LMP Harrison Schmitt aggressively lobbied for a
Apollo program landings. The S-IC first stage burned RP-1/LOX for a rated thrust of , which was upgraded to . The second and third stages burned liquid hydrogen, and the third stage was a modified version of the S-IVB, with thrust increased to and capability to restart the engine for translunar injection after reaching a parking orbit. NASA's Director of Flight Crew Operations during the Apollo program was Donald K. "Deke" Slayton, one of the original Mercury Seven astronauts who was medically grounded in September 1962 due to a heart murmur. Slayton was responsible for making all Gemini and Apollo crew assignments.