On February 27, 2026, NASA overhauled the mission sequence of its Artemis lunar program, converting the crewed Artemis III mission into a 2027 low-Earth-orbit systems demonstration and shifting the first crewed lunar South Pole landing to Artemis IV in 2028. Announced by NASA Administrator Jared Isaacman and Associate Administrator Amit Kshatriya at Kennedy Space Center ahead of the April 2026 Artemis II lunar flyby, the revised architecture models Artemis III on the March 1969 Apollo 9 mission. Instead of descending to the Moon, an Orion crew capsule launched aboard a standardized Block 1 Space Launch System rocket will rendezvous and dock in low Earth orbit with one or both commercial lunar landers under development by SpaceX and Blue Origin to test life support, propulsion, communications, and extravehicular activity spacesuits.
The principal technical driver behind adding an orbital demonstration flight before attempting a lunar landing is the requirement for large-scale cryogenic in-orbit refueling. Under the Human Landing System contract NASA awarded SpaceX in 2021 as part of the agency’s shift to commercial spaceflight, the Starship lunar lander cannot fly directly from Earth’s surface to the Moon with a full payload. Because Starship expends almost all of its propellant reaching low Earth orbit, the vehicle must dock with an orbiting propellant depot and refill its tanks with super-cooled liquid methane and liquid oxygen before firing its engines for trans-lunar injection.
Tanker Launch Cadence and Cryogenic Boil-Off Limits
Transferring hundreds of metric tons of cryogenic liquid between docked spacecraft in microgravity has never been performed at operational scale. In a November 2023 briefing to the NASA Advisory Council Human Exploration and Operations Committee, NASA Moon to Mars Program Office Assistant Deputy Associate Administrator Lakiesha Hawkins stated that executing a single Artemis lunar landing will require SpaceX to launch Starships in the high teens, with at least 15 launches needed when combining the uncrewed propellant depot, the succession of refueling tankers, and the Human Landing System lander itself.
The exact number of tanker flights depends on how much usable propellant each Starship tanker can deliver to the orbital depot and how much fuel evaporates during storage. A fully fueled Starship holds up to 1,500 metric tons of liquid propellant, and the fully reusable design targets a low-Earth-orbit payload capacity of 100 metric tons to 150 metric tons. However, flights using the Block 2 Starship prototype demonstrated a payload capacity of roughly 35 metric tons prior to the debut of the upgraded Block 3 configuration in 2026, and five out of 11 prototypes were lost during test flights prior to February 2026 due to fuel leaks and engine failures. Depending on final tanker payload performance and whether the lander requires a full or partial propellant load, filling the orbital depot requires between 10 and 15 dedicated tanker launches.
Because liquid oxygen boils at minus 183 degrees Celsius and liquid methane boils at minus 161 degrees Celsius at standard pressure, solar radiation and thermal conduction in low Earth orbit cause stored propellants to vaporize over time, a process known as cryogenic boil-off. To prevent boil-off losses from outpacing fuel delivery, SpaceX must launch tankers in rapid succession. Hawkins reported that NASA baseline planning assumes a six-day launch rotation alternating between two separate launch complexes: SpaceX’s expanding Starbase facility in Boca Chica, Texas, and Launch Complex 39A at Kennedy Space Center in Florida. The Starship lunar lander launches roughly halfway through that tanker sequence, docks with the filled depot to take on propellant, and travels to lunar orbit to await the crew arriving separately aboard NASA’s Orion spacecraft.
Standardized Ascent Hardware and Competing Lunar Architectures
To reduce concurrent engineering risks while SpaceX and Blue Origin mature their lunar landers and orbital refueling systems, NASA’s February 2026 architecture update canceled plans to switch the Space Launch System rocket to the upgraded Block 1B configuration with the four-engine Exploration Upper Stage immediately after Artemis III. Kshatriya stated that retaining a standardized Earth-ascent configuration close to the existing Block 1 vehicle and its Interim Cryogenic Propulsion Stage avoids introducing new rocket stage and launch-pad development risks during the initial landing missions.
Blue Origin, selected by NASA in 2023 to provide the Blue Moon Human Landing System beginning on Artemis V, also relies on in-space cryogenic refueling using liquid hydrogen and liquid oxygen, although its architecture transfers propellant near the Moon rather than in low Earth orbit. Meanwhile, China is developing a competing crewed lunar landing architecture targeting the lunar south pole by 2030 that avoids orbital propellant transfer altogether by launching its Mengzhou crew spacecraft and Lanyue lunar lander separately aboard two expendable Long March-10 super-heavy rockets for direct lunar-orbit rendezvous. Before NASA can commit a crew to the 2028 Artemis IV surface landing, SpaceX must complete an in-orbit ship-to-ship cryogenic propellant transfer demonstration, validate long-duration boil-off suppression in low Earth orbit, and execute an uncrewed Starship landing on the lunar surface.
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