The number of launches required to fuel a Starship lander has been a moving target for years, and NASA has long declined to commit to a precise figure. In 2023, then director of NASA’s Human Landing System, Lisa Watson-Morgan, said she was reluctant to state the number exactly, later describing it as in the high single digits to the low double digits. Other officials have cited high teens. The hope had been that SpaceX would improve Starship’s lift capacity enough to reduce the number of tanker flights, but some NASA officials now have concerns that this may not be happening quickly enough for Starship to play a meaningful role in Artemis this decade.
The 22 figure surfaced Thursday at the quarterly meeting of NASA’s Aerospace Safety Advisory Panel. Panel member Charlie Precourt, a former NASA astronaut, discussed risks tied to Artemis IV. “With respect to Artemis IV, however, we’ve got a large number of firsts that reduce the likelihood of mission success,” Precourt said. “We need to keep our eyes on numerous required fuelings for the lander. I think the last estimate is around 22 flights.” Precourt did not name Starship, but NASA’s other lunar lander, Blue Origin’s Blue Moon, will not use orbital refueling in its initial mission design.
After the estimate was posted on X, Musk replied that the figure was inaccurate. “That’s way too high,” Musk said. “Actual number will be more like 6 to 8.” Significant uncertainty remains in how much cryogenic methane and liquid oxygen will boil off in orbit and how efficient the transfer of propellants between vehicles will be. SpaceX is working to increase Starship’s flight rate, but even if the company achieves twice weekly launches by the end of 2027, it would still need about three months to fuel a depot for a Starship landing.
The estimate bears directly on the Artemis timeline. A campaign of roughly two dozen launches per landing implies a launch cadence and refueling reliability that has never been demonstrated. Precourt described the problem as a challenging one for NASA and praised agency chief Jared Isaacman and his team for working to help both SpaceX and Blue Origin succeed. “With respect to schedule, I personally really appreciate the focus the administrator and the leadership team is putting on how to press schedule by bringing in resources to enable it to look for places where there are barriers,” he said.
NASA is still working toward a human lunar landing in 2028. The outstanding questions center on how much propellant boils off in orbit, how efficient ship-to-ship transfers prove to be, and whether SpaceX can reach the launch cadence needed to fuel a depot on the required schedule.
