United Launch Alliance (ULA) is developing an enlarged Centaur V upper stage for NASA’s Space Launch System (SLS), with qualification and flight hardware intended to support an Artemis mission in 2028.
The company announced the collaboration on October 23, 2026, confirming that NASA has prioritized development of the 180K Centaur V Exploration stage.
The new upper stage will have approximately 50% more propellant capacity than the existing Centaur V design, along with changes to its structural materials, propellant tanks, avionics, and flight software.
According to ULA’s official announcement, the development program includes a qualification test unit and a flight unit intended for a 2028 Artemis launch.
The new stage is part of NASA’s revised lunar transportation architecture, which replaces plans for the larger SLS Block 1B configuration and its Boeing-developed Exploration Upper Stage.
Why NASA Is Developing an Enlarged Centaur
The SLS upper stage provides propulsion after the rocket’s main core stage completes its portion of the launch.
For lunar missions, the upper stage must accelerate Orion onto a trajectory that carries it beyond Earth orbit.
This maneuver is called trans-lunar injection. It requires the rocket to increase the spacecraft’s velocity enough to place it on a path toward the Moon.
The original SLS Block 1 configuration used an Interim Cryogenic Propulsion Stage developed by ULA. It successfully supported the Artemis I and Artemis II missions.
NASA previously intended to replace that stage with Boeing’s Exploration Upper Stage, introducing the larger Block 1B version of SLS.
The agency changed its approach in 2026, abandoning the planned Block 1B upgrade in favor of a more standardized rocket configuration.
The revised SLS upper-stage strategy established Centaur V as the basis for later Artemis missions.
The October 23 announcement provides additional technical details about how the stage will be modified to support the revised lunar mission requirements.
The enlarged Centaur is intended to help NASA deliver Orion to lower lunar orbits than previously planned, potentially reducing the propulsion requirements imposed on commercial lunar landers.
The 180K Centaur V Design
ULA’s existing Centaur V is the upper stage used by the company’s Vulcan launch vehicle.
Centaur V uses liquid hydrogen and liquid oxygen to produce thrust. These cryogenic propellants provide high efficiency for missions requiring substantial changes in spacecraft velocity.
For the SLS application, ULA will develop a larger version with increased propellant storage capacity.
The company identified several principal modifications.
The propellant tanks will be lengthened, increasing overall storage capacity by approximately 50%.
The tanks will also use alloy 718 rather than the stainless steel used in the current Centaur V baseline. Alloy 718 is a nickel-based, high-strength material used in aerospace applications.
ULA plans to install larger hydrazine tanks and update the upper stage’s avionics and software.
The avionics control and monitor vehicle operations, process flight information, and support the commands needed to execute the mission.
These changes are intended to provide the performance and systems compatibility required for the SLS and Orion lunar transportation architecture.
ULA also confirmed that the Centaur Exploration stage will undergo human-rating activities. Human-rating is the engineering and certification process used to establish that a spacecraft or launch system satisfies applicable crew safety requirements.
The development program will include a qualification test unit to demonstrate the design’s required performance and a separate flight unit for an Artemis mission.
How the Stage Supports the Revised Lunar Mission Architecture
NASA’s October 23 lunar lander architecture announcement describes a transition away from the previously planned near-rectilinear halo orbit.
That orbit was part of the original Artemis architecture involving the planned Lunar Gateway station.
NASA now intends to use different rendezvous arrangements for SpaceX and Blue Origin.
For Blue Origin’s Blue Moon lander, the revised mission plan uses an elliptical polar orbit around the Moon, with NASA examining options for operations in lower lunar orbits.
Moving Orion closer to the lunar surface can reduce the amount of propulsion needed for a lander to travel between the surface and the crew spacecraft.
That is important because a lander must carry enough propellant to descend, land, and return its crew to orbit.
During NASA’s October 23 briefing, agency officials identified the enlarged Centaur as part of the effort to provide Orion with access to lower lunar orbits.
The Centaur modification and the new lunar rendezvous arrangements are connected engineering changes. Together, they influence the amount of propulsion required from the SLS upper stage, Orion, and the commercial landers.
Manufacturing and Transportation
ULA will manufacture the Centaur Exploration stage at its 2.4-million-square-foot production facility in Decatur, Alabama.
The factory already manufactures launch vehicle hardware for the company’s rocket programs.
After assembly, the stage will be transported aboard ULA’s purpose-built RocketShip vessel to Cape Canaveral Space Force Station in Florida.
It will then be delivered to NASA’s Kennedy Space Center for integration with SLS.
ULA says the stage will be positioned above the SLS core stage and below the Orion spacecraft.
That arrangement preserves the general relationship between the major rocket components while introducing a new upper-stage design.
Centaur’s Previous Lunar Mission Experience
Centaur has an extensive history in lunar and planetary exploration.
The upper-stage family originated in the early 1960s and has supported more than 280 missions, according to ULA.
Centaur stages launched spacecraft associated with the Surveyor, Lunar Orbiter, Ranger, and Lunar Reconnaissance Orbiter programs.
ULA also identifies Centaur missions supporting major planetary spacecraft, including Mars Science Laboratory’s Curiosity rover and the Mars 2020 Perseverance rover.
The underlying propulsion technology has consequently been used for decades in missions requiring precise spacecraft trajectories.
The SLS application will extend that heritage through a substantially modified stage designed for crewed lunar exploration.
Development Milestones for 2028
ULA’s October 23 announcement establishes 2028 as the target for supporting an Artemis mission with the new upper stage.
The company has identified the required qualification and flight hardware but has not announced completion of either unit.
Development work includes the longer propellant tanks, new structural materials, updated control systems, and human-rating activities.
The modified Centaur is intended for later Artemis lunar missions, not the low-Earth-orbit Artemis III demonstration planned for summer 2027.
NASA’s revised program includes a mission-specific SLS configuration for Artemis III and the enlarged Centaur-based configuration for subsequent lunar flights.
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