NASA ditches delayed SLS upper stage for ULA's Centaur V

"The space agency will use the Centaur V, currently flying as the upper stage of ULA's Vulcan rocket, for Artemis IV and V, both slated for 2028. A flight spare is also being ordered. The Interim Cryogenic Propulsion System (ICPS) currently used by Artemis is a modified Delta IV cryogenic second stage, always intended as a stopgap."

"However, the agency noted that alternatives, such as Blue Origin's New Glenn Upper Stage (NGUS), require "significant modifications" to Mobile Launcher 1, and ULA was already familiar with the steps needed to modify an upper stage for SLS. In addition, the Centaur V is a variant of the Atlas Centaur, used under the Commercial Crew Program, meaning that qualifying the stage for a human crew should not cause too many concerns."

"According to NASA's justification for the decision: "The NASA Kennedy Space Center (KSC) need date for processing is projected to be nine months prior to a launch. Award to another source would cause unacceptable delays to current launch schedules." Isaacman announced a shake-up of the delay-plagued, cost-bloated NASA's Artemis program at the end of February."

NASA chose United Launch Alliance's Centaur V upper stage for Artemis IV and V missions scheduled for 2028. The Centaur V, currently used on ULA's Vulcan rocket, will replace the Interim Cryogenic Propulsion System (ICPS) that was always intended as temporary. The Exploration Upper Stage (EUS) originally planned for these missions faces schedule delays and budget overruns. NASA administrator Jared Isaacman's plan to increase Space Launch System flight cadence prompted this decision. Alternative options like Blue Origin's New Glenn Upper Stage require significant modifications to Mobile Launcher 1. The Centaur V's heritage as an Atlas Centaur variant used in Commercial Crew Program supports crew qualification. Time constraints and processing requirements at Kennedy Space Center made sole-source selection necessary to maintain launch schedules.

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