SLS to use ULA's Centaur V as new upper stage, NASA posts

A March government posting shows NASA pursuing United Launch Alliance's Centaur V as the upper stage for the Space Launch System on Artemis IV and V under a sole-source contract; the revised Artemis plan also repurposes missions and accelerates the launch cadence. Plans for missions beyond Artemis 5 are not specified.

NASA has moved to specify an existing commercial upper stage for the Space Launch System (SLS) in its revised Artemis plan. A March 6 posting on the federal SAM.gov site described a sole-source contract from NASA's Marshall Space Flight Center for a "Vulcan Centaur V Upper Stage for Space Launch System." The change follows a Feb. 27 announcement that reworked the Artemis mission lineup and called for a standardized SLS configuration. The contract posting links Centaur V to Artemis IV and Artemis V, while missions beyond Artemis 5 are not addressed in the document. Key points: - SAM.gov listed a sole-source contract from NASA Marshall for a "Vulcan Centaur V Upper Stage for Space Launch System," described as supplying next-generation upper stages for Artemis IV and Artemis V. - The posting stated that no other supplies or services would satisfy agency requirements due to the specialized nature of the need and schedule constraints. - Centaur V is ULA's upper stage for the Vulcan rocket; Vulcan debuted in 2024 and the stage has flown successfully on several missions. - Centaur V uses two RL10 engines, holds roughly twice the propellant of the Interim Cryogenic Propulsion Stage (ICPS), and is nearly the same diameter as Orion and its service module. - Under the revised Artemis architecture, Artemis 2 remains unchanged, Artemis 3 is repurposed as a 2027 test flight in low Earth orbit, and Artemis 4 is the next planned lunar landing mission; only Artemis 4 and 5 are specified to use the standardized SLS with Centaur V, and later missions are not mentioned. Summary: The contract posting signals NASA's short-term choice to use an existing ULA upper stage for SLS missions IV and V, aligning vehicle selection with a stated schedule and available hardware. Undetermined at this time.