From Artemis IV onward, the new upper stage will be used instead of the existing interim cryogenic propulsion stage.
By Jon Martindale March 10, 2026
https://www.extremetech.com/aerospace/n ... re-artemisNASA has selected the United Launch Alliance's Vulcan Centaur upper stage to replace the existing Space Launch System second-stage for Artemis IV and beyond, per a procurement filing spotted by SpaceNews. With similar dimensions and specific impulse ratings, Centaur is a near-drop-in replacement and will enable more Artemis missions to fly with the SLS in the future. With the procurement filing on March 6, NASA secures the SLS as a viable launch vehicle for many more years to come.
NASA announced in late February that it would be halting development of the Block 1B (and Block 2) version of the SLS. This version was initially planned to begin flying on Artemis III and use the planned Exploration Upper Stage (EUS) as a replacement for its existing Interim Cryogenic Propulsion Stage (ICPS). Because the existing ICPS is built by the ULA and based on its retired Delta 4 rocket, a new upper stage was required, and Centaur fits the bill.