Delta IV

Delta IV
	Delta IV Medium launch carrying DSCS III-B6.
Function	Orbital launch vehicle
Manufacturer	United Launch Alliance
Country of origin	United States
Cost per launch	US$164+ million
Size
Height	63–72 m (207–236 ft)
Diameter	5 m (16 ft)
Mass	249,500–733,400 kg (550,100–1,616,900 lb)
Stages	2
Capacity
Payload to LEO
Mass	11,470–28,790 kg (25,290–63,470 lb)
Payload to GTO
Mass	4,440–14,220 kg (9,790–31,350 lb)
Associated rockets
Family	Delta (rocket family)
Comparable	Atlas V; Falcon 9; H-IIA; Long March 5; Proton-M;
Launch history
Status	Delta IV Heavy is active; Delta IV Medium, and Medium+ (M+(4,2), M+(5,2), and M+(5,4)) retired.
Launch sites	SLC-37B, Cape Canaveral; SLC-6, Vandenberg SFB (formerly)
Total launches	44 Medium: 3; M+ (4,2): 15; M+ (5,2): 3; M+ (5,4): 8; Heavy: 15;
Success(es)	43 Medium: 3; M+ (4,2): 15; M+ (5,2): 3; M+ (5,4): 8; Heavy: 14;
Partial failure(s)	1 (Heavy)
First flight	Medium/M+: 20 November 2002 (Eutelsat W5); Heavy: 21 December 2004 (USA-181);
Last flight	Medium/M+: 22 August 2019 (USA-293/GPS III-2); Heavy: 22 June 2023 (NROL-68);
Type of passengers/cargo	GOES; GPS Block IIF; NRO classified payloads; WGS; Exploration Flight Test 1; Parker Solar Probe;
Boosters (Medium+) – GEM 60
No. boosters	Medium+ (4,2), Medium+ (5,2): 2; Medium+ (5,4): 4
Gross mass	33,638 kg (74,158 lb)
Powered by	off
Maximum thrust	826.6 kN (185,800 lbf)
Specific impulse	245 s (2.40 km/s) (sea level)
Burn time	91 seconds
Propellant	HTPB / Aluminum
Boosters (Heavy) – Common Booster Core (CBC)
No. boosters	2
Gross mass	226,400 kg (499,100 lb)
Powered by	1 RS-68A
Maximum thrust	3,140 kN (705,000 lbf) (sea level)
Specific impulse	Sea level: 360 s (3.5 km/s); Vacuum: 412 s (4.04 km/s)
Burn time	242 seconds
Propellant	LH2 / LOX
First stage – Common Booster Core (CBC)
Gross mass	226,400 kg (499,100 lb)
Powered by	1 RS-68A
Maximum thrust	3,140 kN (705,000 lbf) (sea level)
Specific impulse	Sea level: 360 s (3.5 km/s); Vacuum: 412 s (4.04 km/s)
Burn time	245 seconds (328 seconds in Heavy configuration)
Propellant	LH2 / LOX
Second stage – Delta Cryogenic Second Stage (DCSS)
Gross mass	4-m: 24,170 kg (53,290 lb); 5-m: 30,700 kg (67,700 lb)
Powered by	1 RL10-B-2
Maximum thrust	110 kN (25,000 lbf)
Specific impulse	462 s (4.53 km/s)
Burn time	850-1,125 seconds
Propellant	LH2 / LOX

Delta IV was 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 was primarily a launch vehicle for United States Air Force (USAF) military payloads, but was also 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 2023, the Heavy has flown its penultimate mission, NROL-68. Payloads that would have previously fly on Medium and Heavy are moving to either the Atlas V or Vulcan.

Delta IV vehicles were built in the ULA facility in Decatur, Alabama. Final assembly was completed at the launch site by ULA: at the horizontal integration facility for launches from SLC-37B pad at Cape Canaveral and in a similar facility for launches from SLC-6 pad at Vandenberg Air Force Base.

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