A flight was planned for the summer of 1986 to mark the beginning of the Air Force's shuttle program, which aimed to place large spy satellites into polar orbits. Bob Crippen, a veteran astronaut who had led three other missions, was set to command this flight from Vandenberg, California. However, the shuttle never launched. The launch site, Space Launch Complex 6 (SLC-6), had cost between 3.3 and 4 billion dollars to build and prepare for the space shuttle. The Challenger disaster in January 1986 led to the cancellation of the Vandenberg shuttle program just four months before the planned first launch. The site was placed in caretaker status in 1989 and later used for smaller launch vehicles like the Athena and Delta before its demolition in 2026. The history of SLC-6, nicknamed "Slick Six," dates back to before the shuttle era. Construction started in March 1966 at Vandenberg South for the Manned Orbiting Laboratory (MOL), a program that combined a Titan III rocket with a modified Gemini capsule connected to a space laboratory. The U.S. Air Force had acquired the land for this project around 1966. However, the MOL program was canceled in June 1969, before any launches occurred. In 1972, the site was chosen for the shuttle program and was officially approved as a launch complex in 1975. The reconstruction of SLC-6, which began in January 1979 and ended in July 1986, involved major changes. The original mobile service tower was removed, and two new flame trenches were built to accommodate the shuttle's solid rocket motors. A 35 km stretch of road was also constructed to transport the shuttle using a 76-wheel transporter built in Italy. The total cost of the project was estimated at between 3.3 and over 4 billion dollars. According to The Washington Post, the cost was 3.3 billion by 1988 when the Air Force announced the site would be placed in caretaker status. Wikipedia later reported the cost as over 4 billion for the complex modifications and related infrastructure. SLC-6 was declared operational on October 15, 1985, with the prototype Enterprise assembled for alignment tests, though many tasks remained unfinished. On January 28, 1986, the Challenger disaster occurred, leading to a major shift in the space program. On July 31, Air Force Secretary Edward Aldridge announced that the Vandenberg shuttle program would be placed in "operational caretaker status." The transition took three years, with the site falling into "minimum caretaker status" on February 20, 1987. On May 13, 1988, Aldridge ordered the transfer of shuttle equipment to the Kennedy Space Center by September 30, 1989. The work was completed ten days earlier, on September 20, 1989, when SLC-6 was officially placed in caretaker status. The project, one of the largest of its kind, had waited years for a flight that never happened. On December 26, 1989, the Air Force officially closed the Vandenberg shuttle program. Despite its original purpose being unfulfilled, SLC-6 found a second life with smaller launch vehicles. The first launch took place on August 15, 1995, with an Athena I carrying the GemStar-1 satellite. A Delta IV rocket launched on June 27, 2006, and the last launch, a Delta IV Heavy for NROL-91, occurred on September 24, 2022. However, not all projects succeeded; a planned modification for the Titan IV/Centaur was abandoned in 1991 due to low demand. On June 16, 2026, the site was demolished, with the access tower, mobile service tower, and parts of the assembly building brought down by explosives. SLC-6 is now planned to accommodate SpaceX's Falcon 9 and Falcon Heavy rockets. The structures built for the shuttle will thus disappear without ever hosting a shuttle launch.