RS-68A
RS-68A is the uprated, single-chamber LOX/LH2 gas-generator derivative of RS-68, developed for higher Delta IV Heavy performance. NASA records about 705,000 lbf (3,123 kN) thrust, first flight in June 2012, and three RS-68A engines on the Delta IV Heavy Common Booster Cores; status remains retired.
Identity
- Domains
- spaceflight
- Identity Level
- variant
- Kind
- liquid-rocket-engine
- Name
- RS-68A
- Status
- retired
Details
- Description
- RS-68A is the uprated, single-chamber LOX/LH2 gas-generator derivative of RS-68, developed for higher Delta IV Heavy performance. NASA records about 705,000 lbf (3,123 kN) thrust, first flight in June 2012, and three RS-68A engines on the Delta IV Heavy Common Booster Cores; status remains retired.
- Developers
- Dry Mass Kg
- 6747.64
- Family
- First Flight Date
- 2012-06-29
- Length M
- 5.1816
- Lineage
- Note
- ULA identifies RS-68A as an upgrade of the original RS-68 for higher Delta IV Heavy performance.
- Related Propulsion System
- Relationship
- direct-derivative-of
- Sources
- Accessed Date
- 2026-07-29
- Publisher
- United Launch Alliance
- Title
- First RS-68A hot-fire engine test
- Manufacturers
- Propellants
- liquid hydrogenliquid oxygen
- Rocket Specs
- Chamber Count
- 1
- Cycle
- gas generator
- Sea Level Thrust Kn
- 3,137
- Vacuum Specific Impulse S
- 411.9
Links
Assets & Meta
- Creation Time
- July 29, 2026 at 09:31:33 UTC
- Updated Time
- August 22, 2026 at 01:20:02 UTC
Other
- Sources
- Accessed Date
- 2026-07-29
- Publisher
- United Launch Alliance
- Title
- Final Delta IV Heavy launch
- Accessed Date
- 2026-07-29
- Publisher
- United Launch Alliance
- Title
- First RS-68A hot-fire engine test
- Accessed Date
- 2026-07-29
- Publisher
- United Launch Alliance
- Title
- Delta IV Launch Services User's Guide
- Accessed Date
- 2026-08-14
- Note
- NASA records the evolved RS-68A at 705,000 pounds of thrust, first test firing in September 2008, and first flight in June 2012; the same source documents the three-engine Delta IV Heavy application.
- Publisher
- NASA
- Title
- NASA Stennis, Aerojet Rocketdyne Closes Historic Commercial Test Partnership
- Accessed Date
- 2026-08-15
- Note
- ULA identifies 29 June 2012 as the inaugural flight of the upgraded RS-68A engine on Delta IV Heavy.
- Publisher
- United Launch Alliance
- Title
- United Launch Alliance Upgraded Delta IV Heavy Rocket Successfully Launches Second Payload in Nine Days for the National Reconnaissance Office
- Accessed Date
- 2026-08-21
- Note
- ULA lists the RS-68A at 204 in length and 14,876 lb weight on its Delta IV heritage propulsion page.
- Publisher
- United Launch Alliance
- Title
- Delta IV