Several planned missions of the Apollo crewed Moon landing program of the 1960s and 1970s were canceled, for reasons which included changes in technical direction, the Apollo 1 fire, the Apollo 13 incident, hardware delays, and budget limitations. After the landing by Apollo 12, Apollo 20, which would have been the final crewed mission to the Moon, was canceled to allow Skylab to launch as a "dry workshop" (assembled on the ground in an unused S-IVB Saturn IB second stage). The next two missions, Apollos 18 and 19, were later canceled after Apollo 13 and further budget cuts. Two Skylab missions also ended up being canceled. Two complete Saturn V rockets remained unused and were put on display in the United States.
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Canceled Apollo missions in the context of List of Apollo astronauts
As part of the Apollo program by NASA, 24 astronauts flew nine missions to the Moon between December 1968 and December 1972. During six successful two-man landing missions, twelve men walked on the lunar surface, six of whom drove Lunar Roving Vehicles as part of the last three missions. Three men have been to the Moon twice, one orbited once and took a circumlunar trajectory the second time, while the other two landed once apiece. Apart from these 24 men, no human being has gone beyond low Earth orbit. As of December 2025, five of the 24 remain alive. A number of non-human animals have circled or orbited it, including two tortoises, several turtles, and five mice.
Apollo missions 8 and 10–17 were the nine crewed missions to the Moon. Apollo 4–6 and AS-201 and AS-202 were uncrewed, while AS-203 is considered a test flight. The Apollo program included three other crewed missions: Apollo 1 (AS-204) did not launch and its crew died in a ground-based capsule fire, while Apollo 7 and Apollo 9 were low Earth orbit missions that tested spacecraft components and docking maneuvers. Apollo missions 18, 19, and 20 were canceled. Twelve astronauts later flew unused Apollo command modules in the Apollo Applications Program's Skylab and Apollo–Soyuz Test Project. Of the 24 astronauts who flew to the Moon, two went on to command a Skylab mission, one commanded Apollo–Soyuz, one flew as commander for Approach and Landing Tests of the Space Shuttle, and two commanded orbital Space Shuttle missions.
View the full Wikipedia page for List of Apollo astronautsCanceled Apollo missions in the context of Apollo–Soyuz
Apollo–Soyuz was the first crewed international space mission, conducted jointly by the United States and the Soviet Union in July 1975. Millions watched on television as an American Apollo spacecraft docked with a Soviet Soyuz capsule. The mission and its symbolic "handshake in space" became an emblem of détente during the Cold War.
The Americans referred to the flight as the Apollo–Soyuz Test Project (ASTP), while the Soviets called it Experimental flight "Soyuz"–"Apollo" (Russian: Экспериментальный полёт «Союз»–«Аполлон», romanized: Eksperimentalniy polyot "Soyuz"–"Apollon") and designated the spacecraft Soyuz 19. The unnumbered Apollo vehicle was a leftover from the canceled Apollo missions program and was the final Apollo module to fly.
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