Canceled Apollo missions  Several planned missions of the Apollo crewed Moon landing program of the 1960s and 1970s were canceled for a variety of reasons, including changes in technical direction, the Apollo 1 fire, 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 the Apollo 13 incident and further budget cuts. Two Skylab missions also ended up being canceled. Two complete Saturn Vs ended up going unused and are currently on display in the United States. In September 1962, NASA planned to make four crewed low-Earth-orbital test flights of partially equipped Block I Command/Service Modules (CSM) using the Saturn I launch vehicle, designated SA-11 through SA-14, in 1965 and 1966. However, the limited payload capacity of the Saturn I compared to the uprated Saturn IB would have severely limited the systems carried, and thus the testing value of these flights. Therefore, NASA canceled these flights in October 1963, and replaced them with two crewed Saturn IB missions, designated AS-204 and AS-205. These would be followed by the first uncrewed flight of the Lunar Module (LM) on AS-206, then the third crewed mission, designated AS-207/208, would use AS-207 to launch the crew in an improved Block II CSM, which would rendezvous and dock with the LM launched uncrewed on AS-208. The crew selected on March 21, 1966, for AS-204 consisted of Command Pilot Virgil "Gus" Grissom, Senior Pilot Ed White, and Pilot Roger Chaffee, who named their mission Apollo 1. AS-205 was to be named Apollo 2, and AS-207/208 would be Apollo 3. The AS-205 crew were Wally Schirra, Donn Eisele and Walter Cunningham. However, AS-205 was later deemed unnecessary and officially canceled on December 22, 1966. Schirra's crew then became the backup for Grissom's crew, and the crewed LM mission became the second crewed mission, redesignated AS-205/208 and crewed by Grissom's original backup crew: Command Pilot Jim McDivitt, CSM Pilot David Scott and LM Pilot Rusty Schweickart.