NASA panel put lunar lander refueling at 22 launches; Musk says 6 to 8

SpaceX chief executive Elon Musk put the number of tanker flights needed to fill a Starship lunar lander at six to eight on Thursday, hours after a NASA safety panel said the figure was about 22. The exchange followed a quarterly public meeting of the Aerospace Safety Advisory Panel, where member Charlie Precourt, a former NASA astronaut, flagged refueling of the lander as a risk for Artemis IV, the mission set to carry a crew to the Moon in 2028. "We need to keep our eyes on numerous required fuelings for the lander," Precourt said, adding, "I think the last estimate is around 22 flights." Ars Technica's Eric Berger posted the remark on X. Musk replied, "That's way too high. Actual number will be more like 6 to 8."

Starship burns nearly all its propellant reaching Earth orbit, so it cannot reach the Moon without refilling in space. SpaceX's plan calls for launching a Starship configured as a depot, then flying tankers one at a time to dock with it and transfer propellant. When the depot is full, the lander launches, docks, fills up and departs for the Moon. Each tanker flight is a full rocket launch, which adds schedule and cost. Berger estimated that even at two Starship launches per week by the end of 2027, filling a depot at the panel's figure would take about three months.

The gap between the two estimates turns on propellant performance. The number of tankers depends on how much each delivers to orbit and how much is lost. Starship's fuel and oxygen are kept at extremely low temperatures, some of it boils off in orbit, and more is lost during each transfer. NASA's figure reflects what Starship can lift now, while Musk's range assumes a more capable vehicle. SpaceX plans to conduct refueling with its upgraded V3 Starship.

Musk has challenged higher counts before. In 2021, after a government document described 16 launches, he called that "extremely unlikely" and said eight tankers would be the maximum. Precourt called Artemis IV "a large number of firsts" and commended the team of NASA Administrator Jared Isaacman for removing obstacles for SpaceX and Blue Origin. Blue Origin's Blue Moon lander does not require orbital refueling for its first mission. Artemis IV is planned for 2028.

Boil-off and transfer losses during propellant loading remain the variable that separates the two counts. The upgraded V3 Starship, which SpaceX plans to use for refueling, has not yet flown the depot-and-tanker sequence.