Canceled Space Shuttle missions

During NASA's Space Shuttle program, several missions were canceled. Many were canceled as a result of the Challenger and the Columbia disasters or due to delays in the development of the shuttle. Others were canceled because of changes in payload and mission requirements.

Canceled due to the late development of the Space Shuttle

In 1972, NASA's planners had projected 570 Space Shuttle missions between 1980 and 1991. Later, this estimate was lowered to 487 launches between 1980 and 1992. The details of the first 23 projected missions, listed in the third edition of Manned Spaceflight and the first edition of the STS Flight Assignment Baseline, an internal NASA document published in October 1977, are:

Mission	Original launch date	Shuttle	Landing site	Mission details
STS-1A OFT-1	June 1979	Columbia	Edwards	Originally scheduled as the first orbital test. The crew was to consist of a commander and pilot, and the test flight was to last 2 days and 5 hours. The crew was not named at the initial announcement, but John W. Young and Robert L. Crippen were announced as the STS-1 crew in March 1978, when the shuttle was still scheduled for a 1979 launch.
STS-2A OFT-2	July 1979 6 March 1980	Columbia	Edwards	Originally scheduled as the third orbital flight test, then the second flight. The five-day mission was to have Fred Haise and Jack R. Lousma take the Teleoperator Retrieval System to the Skylab space station and boost it into a higher orbit. Vance D. Brand and C. Gordon Fullerton were their backups. By April 1979, when it was understood that the Shuttle could not be launched in time to rendezvous with Skylab, STS-2 was rescheduled for a 6 March 1980 launch, carrying the OSTA-1 payload and the Remote Manipulator System for the first time. This re-manifested STS-2 launched on 12 November 1981, with Joe Engle and Richard H. Truly in place of Haise and Lousma, respectively.
STS-3 OFT-3	September 1979	Columbia	Edwards	Originally scheduled as the third orbital flight test. The 7-day mission was to see the two-man crew test shuttle maneuvering and remote manipulator systems.
STS-4 OFT-4	December 1979	Columbia	Edwards	Originally scheduled as the fourth orbital flight test. The crew was to consist of a commander and pilot, and the mission was to last seven days.
STS-5 OFT-5	February 1980	Columbia	Kennedy	Originally scheduled as the fifth orbital flight test. The crew was to consist of commander Ken Mattingly, pilot Henry W. Hartsfield Jr. and one or two mission specialists. The mission was to last 7 days. First landing at Kennedy Space Center.
STS-6 OFT-6	March 1980	Columbia	Edwards	Originally scheduled as the sixth orbital flight test. The crew of four were to conduct the first test of operational payloads and conduct the first EVA from the shuttle. The mission was to last seven days.
STS-7	30 May 1980 27 February 1981	Columbia	Kennedy	First operational flight. The crew of three were to place the Long Duration Exposure Facility satellite into orbit and the mission was to last five days. The LDEF was eventually released in 1984 from Challenger during STS-41C. By 1979, when it became clear that the original launch schedule could not be kept, STS-7 was re-manifested with the TDRS-A satellite and scheduled to launch on 27 February 1981 with a crew of four and a duration of two days. This rescheduled STS-7 would also have landed at Kennedy Space Center.
STS-8	1 July 1980	Columbia	Edwards	The crew of three were to place the satellites TDRS-A and SBS-A into orbit during the 2-day mission. TDRS-A was sent into orbit on Challenger's maiden flight, STS-6, in April 1983.
STS-9	1 August 1980	Columbia	Edwards	The crew of three were to place the satellites GOES 4 and Anik-C1 into orbit during the 3-day mission. GOES 4 was launched atop a Delta 3914 a month after its originally scheduled launch on the shuttle. After this mission, Columbia would be returned to the Rockwell International plant at Palmdale, California for removal of the ejection seats and test instrumentation and would receive higher capacity fuel cells in preparation for the first Spacelab mission.
STS-10	14 November 1980	Columbia	Edwards	Originally scheduled for launch in 1980. The crew of three were to place the satellites TDRS-B and SBS-B into orbit during the 3-day mission. TDRS-B was rescheduled for STS-51E but became re-manifested on STS-51L, where it was destroyed along with Challenger on 28 January 1986.
STS-11	18 December 1980	Columbia	Edwards	Scheduled to carry the European Spacelab-1 science module. The crew of five were to consist of three NASA astronauts and two European payload specialists. The mission was to last seven days. This first Spacelab mission was later launched as STS-9 in November 1983.
STS-12	30 January 1981	Columbia	Edwards	The crew of three were to place the satellites TDRS-C and Anik-C2 into orbit during the 2-day mission. An alternate mission was also planned which replaced the TDRS-C with an Intelsat-V satellite, and would last five days instead of two. TDRS-C was eventually made as the replacement for the destroyed TDRS-B and launched from Discovery on STS-26 in September 1988.
STS-13	3 March 1981	Columbia	Edwards	The crew of three were to place the GOES-E satellite into orbit during the 5-day mission. GOES-E was eventually launched on a Delta 3914 over two months after its originally scheduled launch on the shuttle.
STS-14	7 April 1981	Columbia	Edwards	Scheduled to carry four Spacelab instrumentation pallets and a pressurized "igloo" used to support the payloads. The crew of five was to consist of two payload specialists. The mission was to last 12 days.
STS-15	13 May 1981	Columbia	Edwards	During this mission, the satellites TDRS-D and SBS-C would be placed into orbit. The Anik-C3 satellite could be substituted in place of SBS-C. TDRS-D was launched from Discovery on STS-29 in March 1989, with SBS-C being launched on Columbia's first operational mission, STS-5, in November 1982.
STS-16	16 June 1981	Columbia	Edwards	Originally scheduled for launch on 16 June 1981, carrying the Spacelab-3 science module. A "payload of opportunity" of 9 tons could accommodate a communications satellite. The crew of five was to include two payload specialists.
STS-17	16 July 1981	Enterprise	Edwards	Originally expected as the first spaceflight of the shuttle Enterprise, it was to place an Intelsat V satellite into orbit and retrieve the LDEF. Enterprise never launched, and instead its place as the second shuttle in the fleet was taken by Challenger.
STS-18	29 July 1981	Columbia	Edwards	Scheduled to carry a Spacelab pallet and pressurized "igloo". A military payload was planned for the Department of Defense, which would make it the first one flown on the Shuttle.
STS-19	2 September 1981	Columbia	Edwards	Was to carry a series of five Spacelab pallets.
STS-20	30 September 1981	Enterprise	Edwards	Originally scheduled for launch on 30 September 1981, carrying the Spacelab-4 life-science module and an unpressurized Spacelab pallet.
STS-21	14 October 1981	Columbia	Edwards	A crew of three was to retrieve the Solar Maximum Mission satellite and bring it back to Earth after a five-day mission. Columbia would have carried an "OMS Kit" which contained additional fuel for the shuttle's Orbital Maneuvering System, necessary to safely reach the SMM's orbit. The SMM, launched in February 1980, was eventually retrieved and repaired in orbit on STS-41-C in 1984, and continued operating until 1989.
STS-22	25 November 1981	Enterprise	Edwards	Was intended to carry an ESA-operated Spacelab module and additional pallet.
STS-23	5 January 1982	Columbia	Edwards	Was to launch the Galileo probe to Jupiter using a modified IUS booster. Galileo was eventually delivered to orbit by Atlantis during STS-34, launched 18 October 1989, after lengthy delays.

Later in the development process, NASA suggested using the first crewed Space Shuttle mission, STS-1, as a sub-orbital test of the Return to Launch Site flight profile devised for an emergency abort. Columbia would have launched from Kennedy Space Center, then executed a 180-degree turn at a speed of, or 6.7 times the speed of sound, in order to land at the Kennedy Space Center runway. The mission was canceled when astronauts refused to fly it, having deemed the plan to be too dangerous. STS-1 commander John W. Young recalled that "I said no. I said let's not practice Russian roulette, because you may have a loaded gun there. So we didn't."