United Launch Services LLC, Centennial, Colorado, has been awarded a $10,050,485 firm-fixed-price modification to contract for Delta IV heavy launch services. The modification is for Space Launch Complex-6 non-routine facility expenses. Work will be performed at Vandenberg Air Force Base, California, and is expected to be completed Sept. 17, 2021. The total cumulative face value of the contract is $1,038,054,046. Space and Missile Systems Center, Lost Angeles Air Force Base, California, is the contracting activity.
The Delta IV is a group of five expendable launch systems in the Delta rocket family introduced in the early 2000s. Originally designed by Boeing’s Defense, Space and Security division for the Evolved Expendable Launch Vehicle (EELV) program, the Delta IV became a United Launch Alliance (ULA) product in 2006. The Delta IV is primarily a launch vehicle for United States Air Force (USAF) military payloads, but has also been used to launch a number of United States government non-military payloads and a single commercial satellite.
The Delta IV originally had two main versions which allowed the family to cover a range of payload sizes and masses: the retired Medium (which had four configurations) and Heavy. As of 2019, only the Heavy remains active, with payloads that would previously fly on Medium moving to either the existing Atlas V or the forthcoming Vulcan. Retirement of the Delta IV is anticipated in 2023.
Delta IV vehicles are built in the ULA facility in Decatur, Alabama. Final assembly is completed at the launch site by ULA.
The Delta IV Heavy (Delta 9250H) combines a 5 m (16 ft) diameter DCSS and payload fairing with two additional CBCs. These are strap-on boosters which are separated earlier in the flight than the center CBC. As of 2007, a longer 5 meter diameter composite fairing was standard on the Delta IV Heavy, with an aluminum isogrid fairing also available. The aluminum trisector (three-part) fairing was built by Boeing and derived from a Titan IV fairing. The trisector fairing was first used on the DSP-23 flight. The Delta IV with the extended fairing is over 62 m (203 ft) tall.