SpaceX chief says eight tankers will fuel lunar lander, not twenty-two

Elon Musk stated on Thursday that his company will require only six to eight Starship tanker launches to fuel the lunar lander for the 2028 Artemis IV mission. This figure directly contradicts the estimate of 22 flights cited by a NASA safety advisory panel earlier in the day. The discrepancy centers on the logistics of orbital refueling, a process essential for sending crewed Starships to the Moon.

The dispute began at the Aerospace Safety Advisory Panel's quarterly meeting. Panel member Charlie Precourt, a former NASA astronaut, identified the fueling process as a primary risk for the mission. He noted that current estimates suggest 22 flights are necessary. Precourt emphasized the need for close monitoring of these operations, saying, "We need to keep our eyes on numerous required fuelings for the lander."

Musk responded to the remark after Ars Technica reporter Eric Berger shared Precourt's comments on the social media platform X. Musk dismissed the 22-flight figure as "way too high" and proposed a range of six to eight launches instead. This lower count implies a more efficient transfer of propellant or a higher capacity for the vehicles involved.

The technical basis for the disagreement lies in Starship's performance. The rocket consumes most of its fuel reaching Earth orbit, leaving it unable to travel to the Moon without external refueling. SpaceX plans to use a depot in orbit as a storage tank. Tanker Starships will launch sequentially, dock with the depot, and transfer their remaining propellant. Once the depot is full, the lunar lander will launch, refuel, and depart for the Moon.

The total number of launches directly impacts the mission timeline and cost. Each tanker flight is a full rocket launch, adding time and potential points of failure. Eric Berger estimated that even with two Starship launches per week by the end of 2027, filling a depot according to the panel's 22-flight estimate would take approximately three months. A lower count would shorten this window.

Musk's estimate assumes a more capable version of the vehicle than the one currently in operation. NASA's higher figure appears based on current lift capabilities. Propellant losses due to boil-off in the cold vacuum of space and during transfers also affect the math. Musk has previously challenged high launch counts, calling a 2021 government estimate of 16 launches "extremely unlikely" and asserting that eight tankers would be the maximum needed.

Precourt noted that Artemis IV involves "a large number of firsts" for the hardware. SpaceX intends to use its upgraded V3 Starship for the refueling operations. Precourt also credited NASA Administrator Jared Isaacman with removing obstacles for both SpaceX and Blue Origin, whose Blue Moon lander does not rely on orbital refueling for its initial mission.