The formal contract award came on March 6 2026 through a sole-source justification published the following day. This move locks in a proven design already flying on ULA’s Vulcan rocket to power future SLS missions instead of continuing development of Boeing’s more powerful Exploration Upper Stage. The change aligns perfectly with the February 27 architecture overhaul that keeps the rocket in a standardized near-Block 1 configuration for the rest of the decade.
Artemis II in April 2026 and the revised Artemis III test flight in 2027 will still use the existing Interim Cryogenic Propulsion Stage. From Artemis IV onward the Centaur V takes over. It delivers the performance needed to send Orion plus attached commercial landers into lunar orbit while avoiding the major redesigns and new certifications that the Block 1B upgrade would have required. Engineers at Kennedy Space Center can rely on familiar interfaces and ground support systems with only minor modifications.
The decision stems from practical realities. Development of the Exploration Upper Stage had pushed costs toward 2.8 billion dollars and slipped delivery well past original targets. Production of the current ICPS stage had already ended because its design ties back to the retired Delta IV. NASA evaluated the Blue Origin New Glenn upper stage as an alternative but rejected it over extensive infrastructure changes required to fit the Vehicle Assembly Building and meet height constraints. The Centaur V offered the fastest path with the least risk thanks to its RL10 engine heritage and ongoing manufacturing at ULA facilities.
This standardization supports the new goal of one SLS launch roughly every 10 months. Consistent hardware across missions reduces processing time at Kennedy and builds operational experience faster. It also frees up resources for the commercial lander tests in low Earth orbit during Artemis III and the surface operations planned for 2028. The contract covers stages for Artemis IV and V plus a flight spare so the cadence can hold steady even if minor issues arise.
The shift marks a clear trade-off. The Centaur V does not match the payload capacity the full Block 1B with Exploration Upper Stage would have provided but it gets the program to the Moon sooner and more reliably. Later missions may need to accept slightly lighter cargo manifests to the lunar surface yet the overall architecture gains momentum from fewer moving parts.
Whether this exact configuration can scale to more ambitious follow-on objectives beyond 2028 stays an open question for now. Early analysis suggests it works well for the initial annual landings but planners will watch performance data closely once flights begin. For the near term the choice reinforces the realistic path laid out last month.
United Launch Alliance stands ready to deliver. Its teams already support SLS ground systems and have human-rating experience from past programs. The partnership between NASA Boeing and Lockheed Martin through ULA brings continuity while injecting fresh production capacity into the rocket line. This step keeps the entire Artemis sequence on track for the first crewed south pole landing under Artemis IV without introducing new unknowns at the critical upper stage level.
