Vandenberg AFB Space Launch Complex 4

Space Launch Complex 4 (SLC-4) is a launch site at Vandenberg Air Force Base, with two pads one of which is currently used by SpaceX to launch the Falcon 9 rocket. The complex was previously used by Atlas and Titan rockets between 1963 and 2005. It consisted of two separate launch pads, SLC-4W and SLC-4E, which were formerly designated PALC2-3 and PALC2-4 respectively. Both pads were originally built for use by Atlas-Agena rockets, but were later rebuilt to handle Titan rockets. The designation SLC-4 was applied at the time of the conversion to launch Titans.

Space Launch Complex 4E is currently used by SpaceX as a launch site for the Falcon 9 rocket, which first flew from Vandenberg on 29 September 2013. A 24 month refurbishment program started in early 2011.

Atlas-Agena
The first launch to use what is now SLC-4 occurred on 12 July 1963, when an Atlas LV-3 Agena-D launched the first KH-7 Gambit reconnaissance satellite, from PALC2-3. Twelve Atlas-Agenas launches were conducted from PALC2-3, with the last occurring on 12 March 1965.

Titan IIIB
Following this, it was rebuilt as SLC-4W, a Titan launch complex. The first Titan launch from SLC-4W was a Titan IIIB, on 29 July 1966. All 70 Titan IIIB launches occurred from SLC-4W, with the last on 12 February 1987.

Titan 23G
Subsequent to the retirement of the Titan IIIB, it became a Titan 23G launch site, and twelve Titan II launches, using the 23G orbital configuration, were conducted between 5 September 1988 and 18 October 2003. Following the retirement of the Titan 23G, SLC-4W was deactivated. 93 rockets were launched from SLC-4W.

SLC-4W was the site of the launch of Clementine, the only spacecraft to be launched from Vandenberg to the Moon, which was launched by a Titan 23G on 25 January 1994.

Atlas-Agena
The first launch from PALC2-4 occurred on 14 August 1964, when a KH-7 satellite was launched by an Atlas-Agena D. After 27 Atlas-Agena launches, the last of which was on 4 June 1967, the complex was deactivated.

Titan IIID
During 1971 the complex was reactivate and refurbished for use by the Martin Marietta Titan III launch vehicles. The Titan IIID made its maiden flight from SLC-4E on 15 June 1971, launching the first KH-9 Hexagon satellite. The first KH-11 Kennan satellite was launched from the complex on 19 December 1976. All 22 Titan IIIDs were launched from SLC-4E, with the last occurring on 17 November 1982.

Titan 34D
The complex was then refurbished to accommodate the Martin Marietta Titan 34D. Seven Titan 34Ds were launched between 20 June 1983, and 6 November 1988. On 18 April 1986, a Titan 34D exploded less than nine seconds after launch, showering debris over the launch pad.

Titan IV
The last type to use the complex was the Titan IV, starting on 8 March 1991, with the launch of Lacrosse 2. On 19 October 2005, the last flight of a Titan rocket occurred, when a Titan IVB was launched from SLC-4E, with an Improved Crystal satellite. Following this launch, the complex was deactivated, having been used for 68 launches.

Falcon
SpaceX refurbished SLC–4E for Falcon 9 and Falcon Heavy launches, in a 24-month process that began in early 2011. The draft environmental impact assessment with a finding of "no significant impact" was published in February 2011. Demolition began on the pad's fixed and mobile service towers in summer 2011.

In April 2011, company plans had projected Falcon Heavy hardware arriving at Vandenberg in 2012, with launch "soon thereafter" and an initial Falcon Heavy launch from SpaceX' Cape Canaveral launch complex in 2014.

By late 2012, SpaceX continued to anticipate that the initial launch from the Vandenberg pad would be in 2013, but would be a Falcon 9 launch—actually, a heavily modified and much larger Falcon 9 v1.1. As the pad was nearing completion in February 2013, the first Falcon 9 launch was scheduled for summer 2013, but was ultimately launched on 29 September 2013, and was the maiden flight of the Falcon 9 v1.1 configuration, carrying Canada's CASSIOPE satellite.