Vandenberg's southward launch trajectory is advantageous for deploying satellites into high-inclination polar and Sun-synchronous orbits, needed for weather forecasting, Earth observation, and reconnaissance missions as they enable comprehensive and regular global coverage.

After purchase of south base, the Air Force started construction of the SLC-6 facility on 12 March 1966, to support launches of a Titan IIIM for the Manned Orbiting Laboratory (MOL).

With plans of launching civilian and military equatorial space shuttle flights from Kennedy Space Center (KSC) and military polar orbit flights from Vandenberg, NASA and the Air Force looked at different sites for launching the shuttle, finally deciding upon SLC-6, due to its dedicated crewed spaceflight role that was left over from the canceled MOL/Titan program.

[8] There were several reasons for using SLC-6:[7] A Senate report summarized: "The Air Force originally justified the expenditure of such SLC-6 funding on the basis of a need to launch high-priority military payloads into polar orbits.

After Defense Department officials testified that polar orbits could not be achieved by launching from Kennedy Space Center in Florida, the Congress initiated construction of ...

The original Mobile Service Tower (MST) was lowered in height and two new flame ducts were added for the shuttle's solid rocket boosters.

Additional modifications or improvements included liquid hydrogen and liquid oxygen storage tanks, a payload preparation room, payload changeout room, a new launch tower with escape system for the shuttle crew members, sound suppression system and water reclamation area and a Shuttle Assembly Building were added to the original complex.

[7]Between November 1984 and May 1985, the Space Shuttle Enterprise was mated with External Tank and SRBs in boilerplate configuration for a series of fit checks like those conducted at LC-39.

However, the Challenger disaster of 28 January 1986 grounded the Shuttle fleet as efforts were concentrated on recovery and returning the program to flight after a two-year hiatus.

Previously, the orbiters were trucked to Armstrong Flight Research Center at Edwards Air Force Base, about 36 miles (58 km) away, which took about 10 hours.

In the early 1990s, Lockheed Missiles and Space Company began studies on the prospect of a new family of small launch vehicles for commercial and other users.

[24] After another contract was issued in 1994 by the Air Force, modification work began on the existing SLC-6 shuttle launch mount for a small "milkstool" platform to be located over one of the two exhaust ducts originally intended for one of the large solid rocket boosters.

The payload on board was GEMstar 1, a small communications satellite manufactured by CTA, Inc. for the Volunteers in Technical Assistance (VITA), a non-profit organization.

[25] After some hardware redesign and testing, a newly rechristened Athena I successfully launched NASA's Lewis satellite into orbit from SLC-6 on 22 August 1997.

The launch vehicle's Common Booster Core and associated flight hardware was transported from the Boeing factory in Decatur, Ala., to Vandenberg aboard the MV Delta Mariner cargo vessel that docked just south of SLC-6 at the same location originally constructed for receiving and offloading space shuttle external tanks.

After sitting on the pad since late-2003 and enduring technical issues with both the booster and the payload, the first of the Delta IV launch vehicles to fly from SLC-6 successfully lifted off at 8:33 p.m. PDT on 27 June 2006.

Another Delta IV Medium vehicle flew a mission for the Air Force Defense Meteorological Satellite Program, orbiting DMSP-17, on 4 November 2006.

[38][39] Prior to its leasing, there was interest among other companies for control over the pad thanks to its large size, most notably by Blue Origin for their New Glenn orbital launch vehicle.