Space Launch Complex 6 at Vandenberg Space Force Base in California is a launch pad and support area. The site was originally developed starting in 1966, but no launches occurred until 1995, as it was repurposed sequentially for three programs that were subsequently cancelled. Initially to be used for Titan IIIM rockets and the Manned Orbiting Laboratory, these were cancelled before construction of SLC-6 was complete. The complex was later rebuilt to serve as the west coast launch site for the Space Shuttle, but went unused due to budget, safety and political considerations. The pad was subsequently used for four Athena rocket launches before being modified to support the Delta IV launch vehicle family, which used the pad for ten launches from 2006 until 2022. The last Delta IV launched in September 2022, and SpaceX leased SLC-6 in 2023 to convert it to launch Falcon 9 and Falcon Heavy starting in 2025.

The Space Shuttle Solid Rocket Booster (SRB) was the first solid-propellant rocket to be used for primary propulsion on a vehicle used for human spaceflight. A pair of these provided 85% of the Space Shuttle's thrust at liftoff and for the first two minutes of ascent. After burnout, they were jettisoned and parachuted into the Atlantic Ocean where they were recovered, examined, refurbished, and reused.