Delta Cryogenic Second Stage

Delta Cryogenic Second Stage

A 4-meter DCSS from a Delta IV Medium
Manufacturer	Boeing IDS United Launch Alliance Mitsubishi Heavy Industries (Original Delta III design and manufacturing)
Country of origin	United States
Used on	Delta III Delta IV SLS Block I
Launch history
Status	Active
Total launches	44
Successes (stage only)	41 18 Delta IV 4 m 23 Delta IV 5 m
Failed	2 (Delta III)
Lower stage failed	1 (Delta III)
First flight	August 27, 1998
Last flight	TBD
Delta III second stage
P2048	8.8 meters (29 ft)
P2386	4 meters (13 ft)
Empty mass	2,480 kilograms (5,470 lb)
Gross mass	19,300 kilograms (42,500 lb)
P516	1 RL10B-2
P2228	110.1 kilonewtons (24,800 lbf)
Specific impulse	462 seconds (4.53 km/s)
Burn time	700 seconds
Propellant	LH2/LOX
Delta IV 4-meter stage
P2048	12.2 meters (40 ft)
P2386	4 meters (13 ft)
Empty mass	2,850 kilograms (6,280 lb)
Gross mass	24,170 kilograms (53,290 lb)
P516	1 RL10B-2
P2228	110.1 kilonewtons (24,800 lbf)
Specific impulse	462 seconds (4.53 km/s)
Burn time	850 seconds
Propellant	LH2/LOX
Delta IV 5-meter stage
P2048	13.7 meters (45 ft)
P2386	5 meters (16 ft)
Empty mass	3,490 kilograms (7,690 lb)
Gross mass	30,710 kilograms (67,700 lb)
P516	1 RL10B-2
P2228	110.1 kilonewtons (24,800 lbf)
Specific impulse	462 seconds (4.53 km/s)
Burn time	1125 seconds
Propellant	LH2/LOX

The Delta Cryogenic Second Stage (DCSS) is a family of cryogenic rocket stages used on the Delta III and Delta IV rockets, and which is planned to be used on the Space Launch System Block 1. The stage consists of a cylindrical liquid hydrogen (LH₂) tank structurally separated from an oblate spheroid liquid oxygen (LOX) tank. The LH₂ tank cylinder carries payload launch loads, while the LOX tank and engine are suspended below within the rocket's inter-stage. The stage is powered by a single Aerojet Rocketdyne-Pratt & Whitney RL10B-2 engine, which features an extendable carbon-carbon nozzle to improve specific impulse.

Delta III

The DCSS first flew on 3 Delta IIIs, failing two out of two times. A booster failed on the maiden flight and the rocket was destroyed by range safety, causing the loss of the DCSS before ignition. On its second flight, the stage tumbled uncontrollably, inserting the payload into an useless orbit. On the third flight, the stage performed the planned burn but fell short of the target orbit due to premature propellant exhaustion. The flight was deemed a failure. An un-flown example is on display outside the Discovery Cube Orange County.

Delta IV

Two different versions are flown, depending on variant. Composite interstages used to mate the first and second stages together accommodate the different configurations. For the Delta IV-M, a tapering interstage that narrows down in diameter from 5 meters to 4 meters is used on the 4-meter DCSS, while a cylindrical interstage is used on the 5-meter DCSS. Since the retirement of the Delta IV-M and Delta IV-M+ rockets, the DCSS is now used solely on the Delta IV Heavy in its 5-meter variation. As of September 2022, two missions remain before ULA retires the Delta IV Heavy.

Interim Cryogenic Propulsion Stage

The Interim Cryogenic Propulsion Stage, a minimally modified 5-meter DCSS, is used as the upper stage of the Space Launch System Block 1. The ICPS for Artemis I was mated to the SLS launch stack on July 6, 2021. The ICPS will be used for the first three Artemis missions before being retired in favor of the in-development Exploration Upper Stage for Artemis IV.

The Artemis 1 ICPS under construction