Vandenberg Space Launch Complex 2

Space Launch Complex 2 is an active rocket launch site at Vandenberg Space Force Base, in California, USA. It consists of two launch pads: Space Launch Complex 2 East, used by the PGM-17 Thor missile and several of its derivatives from 1958 to 1972; and Space Launch Complex 2 West, which has been in use since 1959 to launch the Thor-Delta family and Delta II, and is currently used by the Firefly Alpha.
Space Launch Complex 2 was originally part of Launch Complex 75 and was known by designation LC 75-1 or just 75-1. The first launch out of the newly designated Space Launch Complex 2 was that of a Delta E with ESSA-3 on 2 October 1966 from SLC-2E.
SLC-2E and SLC-2W are located approximately apart.

SLC-2W

Thor and Thor-Agena (1959–1968)

Space Launch Complex 2 West was built in the late 1950s to launch the PGM-17 Thor for use in suborbital tests, being jointly operated by the United States Air Force and the Royal Air Force in accordance to the IRBM's stationing in Britain as part of Project Emily. It saw its first launch on September 17, 1959, with launches being held over the next four months and all but one being successful. Following the last flight on January 21, 1960, the pad underwent the conversion into an orbital launch complex, as the Thor got decommissioned from missile use and was replaced by ICBMs such as the LGM-25C Titan II.
As per its new use, LC 75-1-2 was subsequently designed to launch the Thor-Agena and the Thor-Ablestar to complement the nearby SLC-1E and 1W in its capabilities of putting satellites into polar orbit. Over the next seven years, it was put into use 21 times for nineteen Agena and two Ablestar launches, with the overwhelming majority of payloads being reconnaissance satellites such as the KH-4 for military customers like the National Reconnaissance Office.

Early Delta (1969–1989)

With the Department of Defense seeing its payloads grow in size throughout the late 1960s, both the Thor-Agena and Thor-Ablestar were retired and the pad received another modification under the SLC-2W name, this time to act as the west coast site of the Thor-Delta and its derivatives to complement LC-17 at Cape Canaveral. Throughout this period of the pad's history, 26 Delta launches were performed at the site, carrying various payloads for the DoD, NASA, NOAA, and a handful of international agencies such as ESA. During the late 70s, a mobile service tower was constructed at SLC-2W to help support the various Delta evolutions by creating an enclosed environment.
As the 1980s arrived and went along, the site gradually saw slowing use in the wake of the Delta family's expected replacement with the Space Shuttle, which was slated to have its own west coast launch site at SLC-6. Despite all California Shuttle plans getting axed following the Space Shuttle Challenger disaster in 1986, SLC-2W only saw one last liftoff in this configuration on November 18, 1989, with a Delta 5000 being used to launch the Cosmic Background Explorer for NASA.

Delta II (1995–2018)

After getting mothballed for a half decade, McDonnell Douglas revived SLC-2W in 1994 for use as the polar orbit site of their successor to the Thor-Delta rockets, the Delta II. The first launch in this new era was on November 4, 1995, carrying Radarsat-1 for the Canadian Space Agency and a Deep Space Network test satellite for NASA. Over the next 23 years, the pad saw 45 Delta II launches and delivered various payloads to polar orbit for numerous governmental agencies and commercial customers. Among the more notable payloads of this era are Aqua, Aura, Gravity Probe B, and the Wide-field Infrared Survey Explorer.
Additionally, SLC-2W followed the Delta II in changing hands regarding operation; it went from McDonnell Douglas to Boeing following their merger in 1997, and was subsequently passed to United Launch Alliance following the 2006 formation of the Boeing-Lockheed Martin joint venture. The site eventually wound down in use again throughout the 2010s following the Delta II's retirement from Cape Canaveral in 2011, and saw its last flight of a Thor-derived vehicle with the launch of ICESat-2 on September 12, 2018.

Firefly Aerospace (2019–present)

Following the Delta II's retirement, SLC-2W was leased out to Firefly Aerospace and repurposed to launch the Firefly Alpha. During the demolition process, a fire broke out inside the Delta II mobile service tower on October 15, 2020, though no injuries were reported. The maiden flight of Alpha took place on September 3, 2021, and resulted in a flight failure following an engine failure causing a range safety activation at transonic speeds. Firefly would not attempt a second flight until October 1, 2022, which was successful in reaching orbit. That same year, Firefly and Northrop Grumman announced their collaborative Medium Launch Vehicle was in development, and that it will also be using SLC-2W as a polar launch site.

SLC-2E

Space Launch Complex 2 East, originally built as Launch Complex 75–1–1, was similar to its western counterpart through its use by the USAF and RAF for Thor missile tests. During this initial period, the pad hosted its first launch on December 18, 1958, and saw three additional flights throughout the next year. Following the retirement of the Thor, LC 75-1-1 got modified in 1960 to launch the Thor-Agena and Thor-Ablestar to increase launch cadence for the military at the base, and each rocket saw 23 and 6 launches from there respectively. Among the most notable launches of that era includes Alouette 1, the first Canadian satellite. In 1966, the pad got renamed to SLC-2E.
As the Thor-Agena and Thor-Ablestar got phased out from use in the late 1960s, SLC-2E likewise saw a gradual conversion for use by the Thor-Delta and Thorad-Agena. During this era, the pad witnessed a total of 19 launches of various government satellites, with fourteen being from the Delta line and five being from the Thorad family. The last launch from SLC-2E came on March 12, 1972, seeing a Delta N propel TD-1A into orbit for ESRO. Much like SLC-1E and 1W, SLC-2E got mothballed to concentrate launches in the area at SLC-2W.
In the years following its deactivation, most structures at SLC-2E have been demolished.

Launch statistics

SLC-2W

Thor and derivatives

All launches operated by the United States Air Force.

No.	Date	Time	Launch vehicle	Configuration	Payload	Result	Remarks
1	17 September 1959	21:09	PGM-17 Thor	Thor DM-18A	Suborbital test		First launch from LC-75-1-2. Test conducted with the Royal Air Force.
2	12 November 1959	19:24	PGM-17 Thor	Thor DM-18A	Suborbital test		Test conducted with the Royal Air Force.
3	15 December 1959	02:14	PGM-17 Thor	Thor DM-18A	Suborbital test		Test conducted with the Royal Air Force. Flight control failure led to missile breakup 60 seconds after launch.
4	21 January 1960	20:10	PGM-17 Thor	Thor DM-18A	Suborbital test		Test conducted with the Royal Air Force. Final missile test at LC-75.
5	29 August 1962	01:00	Thor-Agena	Thor DM-21 / Agena-D	FTV 1153		First orbital launch and first Thor-Agena flight from LC-75-1-2.
6	29 September 1962	23:34	Thor-Agena	Thor DM-21 / Agena-D	FTV 1154
7	26 October 1962	16:14	Thor-Agena	Thor DM-21 / Agena-D	STARAD		Radiation monitoring satellite, designed to monitor the artificial Van Allen belt created by the nuclear test Starfish Prime.
8	4 December 1962	21:30	Thor-Agena	Thor DM-21 / Agena-D	FTV 1155
9	27 June 1963	00:37	Thor-Agena	TAT SLV-2A / Agena-D	OPS-0999		Carried Hitchhiker 1 as a secondary payload.
10	31 July 1963	00:00	Thor-Agena	TAT SLV-2A / Agena-D	OPS-1370
11	23 September 1963	23:00	Thor-Agena	TAT SLV-2A / Agena-D	OPS-1353
12	9 November 1963	20:27	Thor-Agena	TAT SLV-2 / Agena-D	OPS-2268		Heat shield failure led to high temperatures at thrust sections, leading to eventual control loss 119 seconds after launch.
13	21 December 1963	21:45	Thor-Agena	TAT SLV-2A / Agena-D	OPS-2268		Carried Hitchhiker 3 as a secondary payload.
14	19 January 1964	10:59	Thor-Agena	TAT SLV-2A / Agena-D	OPS-3367		Two weather satellites, designated OPS-3367A and B.
15	13 June 1964	15:47	Thor-Agena	TAT SLV-2A / Agena-D	OPS-3236
16	21 August 1964	15:45	Thor-Agena	TAT SLV-2A / Agena-D	OPS-2739
17	6 October 1964	17:04	Thor-Ablestar	Thor DSV-2A / Ablestar	OPS 5796		Part of the Transit Satellite System. First Thor-Ablestar flight from LC-75-1-2.
18	13 December 1964	00:08	Thor-Ablestar	Thor DSV-2A / Ablestar	OPS 6582		Part of the Transit Satellite System. Second and final Thor-Ablestar flight from LC-75-1-2.
19	9 March 1965	18:29	Thor-Agena	TAT SLV-2A / Agena-D	Rideshare payload		Consisted of eight separate satellites, including SOLRAD and POPPY probes.
20	17 July 1965	05:55	Thor-Agena	TAT SLV-2A / Agena-D	OPS-8411
21	9 February 1966	19:45	Thor-Agena	TAT SLV-2A / Agena-D	OPS-1439
22	29 December 1966	12:00	Thor-Agena	TAT SLV-2A / Agena-D	OPS-1584		First launch under the name SLC-2W.
23	14 January 1967	21:28	Thor-Agena	TAT SLV-2A / Agena-D	OPS-1664
24	22 February 1967	22:02	Thor-Agena	TAT SLV-2A / Agena-D	OPS-4750
25	30 March 1967	18:54	Thor-Agena	TAT SLV-2A / Agena-D	OPS-4779
26	31 May 1967	09:30	Thor-Agena	Thor DM-21 / Agena-D	Rideshare payload		Consisted of nine separate satellites, including POPPY and Calsphere probes.
27	25 July 1967	03:48	Thor-Agena	TAT SLV-2A / Agena-D	OPS-1879
28	17 January 1968	10:12	Thor-Agena	TAT SLV-2A / Agena-D	OPS-1965		Final flight of the Thor-Agena.