NASA has made a pointed hardware move for SLS, and it lands in the middle of Artemis turbulence. That choice presses harder on the lunar return timeline already clouded by delays.
Centaur V is not just a substitute for a lagging stage, it signals a cleaner, tougher reset. Behind that move sits a broader mission architecture shift, one that could reorder testing, cadence, and risk across the crewed moon program, while reviving doubts about how long SLS can hold its place there.
Why Centaur V replaced the Exploration Upper Stage
On Feb. 27, NASA’s Artemis reset dropped the road map for SLS Block 1B and Block 2. That change sidelined the Exploration Upper Stage, which had anchored the earlier plan for later moon missions.
The shift became official on March 6, when SAM.gov posted a sole-source notice from NASA’s Marshall Space Flight Center in Alabama covering Artemis IV and V. In that filing, NASA framed the move as a choice of upper stage shaped by capability and timing, with the adoption of Centaur V presented as the only product ready to satisfy both.
A standardized SLS takes shape after the Artemis reset
After years of talking about several SLS variants, NASA is steering the moon rocket toward one repeatable form. Under the reset, Artemis IV and V move to a common rocket configuration instead of following a separate Block 1B track.
That approach is meant to reduce custom changes between flights. NASA wants a steadier launch cadence after Artemis 2, and the Feb. 27 program redesign gives that shift a clearer shape as Artemis 3 changes purpose and the standardized SLS begins with the missions that follow.
What Centaur V brings over ICPS in performance and schedule
Compared with the Interim Cryogenic Propulsion Stage, Centaur V offers a larger step in capability for SLS. Its twin RL10 engines and higher propellant capacity give Orion more margin, and NASA said the stage can carry roughly twice the fuel loaded into ICPS.
Schedule mattered as much as raw performance. Vulcan flew for the first time in 2024, giving Centaur V some early flight heritage, and NASA’s March 6 filing said ULA alone could satisfy the procurement timeline for Artemis IV and V while matching the agency’s technical needs.
ULA’s Centaur (with minor modifications) is the only existing in-space propulsion stage capable of meeting the SLS upper stage design parameters and performance characteristics, while also meeting NASA’s schedule.
NASA
Artemis 2 stays on course while Artemis 3 gets a new role
For now, Artemis 2 keeps its place in NASA’s calendar and remains the mission that sends four astronauts around the moon before returning home. That profile still fits a 10-day lunar flyby mission, preserving Orion’s first crewed voyage beyond Earth orbit.
Artemis 3 no longer carries the first landing attempt under NASA’s revision. Instead, the flight shifts to low Earth orbit, where Orion would test links with one or more human landing systems. SpaceX’s Starship and Blue Origin’s Blue Moon are the names most directly tied to that new assignment.
Artemis 4 and Artemis 5 now carry the first landing effort
NASA’s revised manifest moves the first moon landing attempt to Artemis 4, not Artemis 3. That makes Artemis 4 the first crewed lunar landing bid under the new architecture, with 2028 still serving as the target year.
Artemis 5 follows in the same reshaped line, extending the new course rather than restoring the old one. In that revised mission sequence, the Orion spacecraft remains NASA’s crew vehicle, while Centaur V joins the SLS stack named for Artemis IV and V in the contract notice.
Critics still question SLS costs and the place of commercial launchers
Questions about SLS have not faded with this change. Years of development overruns, long gaps between launches, and a price tag measured in billions of dollars still feed criticism from lawmakers, analysts, and space advocates.
That criticism reaches beyond one rocket contract and into NASA’s longer-term strategy. It has revived a crew transport debate as SpaceX advances its Super Heavy booster, with opponents of SLS arguing that commercial launch options could one day move Orion, cargo, or crews at lower cost.
