The

United States Air Force The United States Air Force (USAF) is the Air force, air service branch of the United States Department of Defense. It is one of the six United States Armed Forces and one of the eight uniformed services of the United States. Tracing its ori ...

's 4th Space Launch Squadron was a space launch unit located at

Vandenberg Air Force Base Vandenberg may refer to: * Vandenberg (surname), including a list of people with the name * USNS ''General Hoyt S. Vandenberg'' (T-AGM-10), transport ship in the United States Navy, sank as an artificial reef in Key West, Florida * Vandenberg S ...

, California. It was active at Vandenberg from 1994 to 1998 and again from 2003 to 2019. It launched various satellites into orbit from the complex of launch pads at Vandenberg.

Mission

The 4th Space Launch Squadron was the Air Force's

Evolved Expendable Launch Vehicle National Security Space Launch (NSSL) is a program of the United States Space Force (USSF) intended to assure access to space for United States Department of Defense and other United States government payloads. The program is managed by the Assure ...

(EELV) launch agency for the West Coast. The EELV system is a liquid-fueled first stage

Common Booster Core The Common Booster Core (CBC) was an American rocket stage, which was used on the Delta IV rocket as part of a modular rocket system. Delta IV rockets flying in the Medium and Medium+ configurations each used a single Common Booster Core as th ...

(CBC) that can be used alone, with strap-on solid fuel rocket boosters, or as a configuration of three CBCs acting as a more powerful booster.

History

The squadron was activated at

, California on 15 April 1994. Until it was inactivated in June 1998, it launched surveillance and meteorological satellites into

polar orbit A polar orbit is one in which a satellite passes above or nearly above both poles of the body being orbited (usually a planet such as the Earth, but possibly another body such as the Moon or Sun) on each revolution. It has an inclination of abo ...

. After reactivation in 2003, the squadron managed operations for EELVs. The EELV program was intended to develop provide alternatives to older and expensive heavy-lift launch vehicles, such as the Titan IV. EELVs include: : The Boeing

Delta IV Delta IV was a group of five expendable launch systems in the Delta rocket family. It flew 45 missions from 2002 to 2024. Originally designed by Boeing's Defense, Space and Security division for the Evolved Expendable Launch Vehicle (EELV) p ...

. There are different configurations for the Delta IV, which can lift payloads from 9,000 lb to over 13,000 lb into

Geosynchronous Orbit A geosynchronous orbit (sometimes abbreviated GSO) is an Earth-centered orbit with an orbital period that matches Earth's rotation on its axis, 23 hours, 56 minutes, and 4 seconds (one sidereal day). The synchronization of rotation and orbital ...

. : The Lockheed Martin

Atlas V Atlas V is an expendable launch system and the fifth major version in the Atlas (rocket family), Atlas launch vehicle family. It was developed by Lockheed Martin and has been operated by United Launch Alliance (ULA) since 2006. Primarily used to ...

. This system also has different available configurations, and can lift payloads between 10,000 lb and 30,000 lb to Geosynchronous Transfer Orbit. : The

Delta II Delta II was an expendable launch system, originally designed and built by McDonnell Douglas, and sometimes known as the Thorad Delta 1. Delta II was part of the Delta rocket family, derived directly from the Delta 3000, and entered service in ...

, a heritage vehicle smaller than the newer

. The Delta II can have up to nine external rockets strapped to its main stage, increasing lift capability. It can send approximately 4,000 lb into Geosynchronous Transfer Orbit.

Lineage

* Constituted as the 4th Space Launch Squadron on 29 March 1994 : Activated on 15 April 1994 : Inactivated on 29 June 1998 : Activated on 1 December 2003 : Inactivated on 31 May 2019 (in merger with 1st Air and Space Test Squadron as 2nd Space Launch Squadron)

Assignments

* 30th Operations Group, 15 April 1994 – 29 June 1998 * 30th Launch Group, 1 Dec 2003 – 20 July 2018 * 30th Operations Group, 20 July 2018 – 31 May 2019

Stations

* Vandenberg Air Force Base, California, 15 April 1994 – 29 June 1998 * Vandenberg Air Force Base, California, 1 December 2003 – 31 May 2019

Decorations

Launch Vehicles

Titan II The Titan II was an intercontinental ballistic missile (ICBM) developed by the Glenn L. Martin Company from the earlier Titan I missile. Titan II was originally designed and used as an ICBM, but was later adapted as a medium-lift space ...

(1997–1998) * Titan IV (1995–1997) * Delta IV (2003–2019) * Atlas V (2003–2019)

References

Notes

Bibliography

{{USAF Space Command Military units and formations in California Space Launch 0004