Astronomy:List of Delta IV Medium launches

**Delta 4 Medium**
	Delta 4 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	550,000 lb (250,000 kg)
Stages	2
Capacity
Payload to LEO	25,287 lb (11,470 kg)
Payload to GTO	9,799 lb (4,445 kg)
Associated rockets
Family	Delta Delta 4 Medium
Comparable	Atlas 5; Falcon 9; H-2A; Long March 3B; Proton-M;
Launch history
Status	Retired
Launch sites	SLC-37B, Cape Canaveral Air Force Station ; SLC-6, Vandenberg Air Force Base
Total launches	29 Medium: 3; M+ (4,2): 15; M+ (5,2): 3; M+ (5,4): 8;
Successes	29
First flight	20 November 2002 (Eutelsat W5)
Last flight	22 August 2019 (USA-293/GPS III-2)
Notable payloads	GOES; GPS Block IIF; NRO classified payloads; WGS;
First stage – CBC
Gross mass	226,400 kg (499,100 lb)
Engines	1 RS-68A
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)
Fuel	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)
Engines	1 RL10-B-2
Thrust	110 kN (25,000 lbf)
Specific impulse	462 s (4.53 km/s)
Burn time	850-1,125 seconds
Fuel	LH2 / LOX

Since November 2002, rockets from the Delta 4 Medium family have been launched 29 times, all of which were successful. Its last flight was with a 3rd generation GPS satellite in August 2019.

About the Delta 4 Medium

The Delta 4 Medium (also referred to as 'single stick'^[1]^[2]) was available in four configurations: Medium, Medium+ (4,2), Medium+ (5,2), and Medium+ (5,4).^[3]

The Delta 4 Medium (Delta 9040) was the most basic Delta IV. It featured a single CBC and a modified Delta 3 second stage, with 4-meter liquid hydrogen and liquid oxygen tanks (called a Delta Cryogenic Second Stage (DCSS)) and a 4-meter payload fairing. The Delta 4 Medium was capable of launching 4,200 kg to geostationary transfer orbit (GTO). From Cape Canaveral, GTO is 1804 m/s away from GEO. The mass of fairing and payload attach fittings have been subtracted from the gross performance.^[4]

The Delta 4 Medium+ (4,2) (Delta 9240) had the same CBC and DCSS as the Medium, but with the addition of two Orbital ATK-built 1.5-m (60-in) diameter solid rocket booster Graphite-Epoxy Motors (GEM-60s) strap-on boosters to increase payload capacity to 6,150 kg to GTO.^[4]

The Delta 4 Medium+ (5,2) (Delta 9250) was similar to the Medium+ (4,2), but had a 5-m–diameter DCSS and payload fairing for larger payloads. Because of the extra weight of the larger payload fairing and second stage, the Medium+ (5,2) could launch 5,072 kg to GTO.^[4]

The Delta 4 Medium+ (5,4) (Delta 9450) was similar to the Medium+ (5,2), but used four GEM-60s instead of two, enabling it to lift 6,882 kg to GTO.^[4]

To encapsulate the satellite payload, a variety of different payload fairings were available. A stretched Delta III 4-meter diameter composite payload fairing was used on 4-meter Medium versions, while an enlarged, 5-meter diameter composite fairing was used on 5-meter Medium versions.

The Medium (4,2) version last flew on 22 August 2019, marking the retirement of the Delta 4 Medium variants.^[3]^[5]