Country of origin United States Total launches 21 | Status Active | |
 | ||
Manufacturer Boeing IDS
United Launch Alliance Used on Delta III
Delta IV
SLS Block I Successes
(stage only) 18
11 Delta IV 4m
7 Delta IV 5m | ||
The Delta Cryogenic Second Stage (DCSS) is a family of cryogenic rocket stages used on the Delta III & Delta IV rockets, and which is planned to be used on the Block I Space Launch System. The stage consists of a cylindrical LH2 tank structurally separated from an oblate spheroid 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 Pratt & Whitney RL10B-2 engine, which features an extendable carbon-carbon nozzle to improve specific impulse.
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Delta III
The first DCSS variant flown was on the Delta III, performing on 2 out of 3 flights. An un-flown example is on display outside the Discovery Cube Orange County.
Delta IV
On the Delta IV, depending on variant, two different versions are flown. Composite interstages used to mate the first and second stages together accommodate the different configurations. For the Delta IV-M, a tapering interstage 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.
ICPS
The Interim Cryogenic Propulsion Stage (ICPS), a modified DCSS, will be used as a second stage on the debut flight of NASA's Space Launch System, Exploration Mission 1 (EM-1), scheduled for December 2017.