NASA's Aerospace Safety Advisory Panel calculates that a single Starship lunar lander would require fully 22 in-orbit refuelings to reach the surface of the Moon, per Ars Technica as reported by Jalopnik.

That plan calls for one Starship to launch into orbit as a fuel depot, many more tanker Starships to fill it, and a final crewed Starship to take on that propellant before heading Moonward. The total number of times any rocket has ever refueled in orbit is zero.

With NASA targeting a crewed lunar landing in 2028, the feat would rank among the most complicated endeavors any space agency has ever attempted.

Elon Musk publicly disputed the panel's figure, posting on X, which SpaceX owns, that the actual number of refuelings "will be more like 6 to 8."

space.com reports that the uncertainty is longstanding: a 2021 Government Accountability Office audit estimated as many as 16 launches, and a panel member this month suggested up to 22 before Musk's rebuttal.

The estimate is fuzzy because Starship burns liquid oxygen and methane, which boil off in the vacuum of space, so how much fuel survives transfer depends on the efficiency of technology that has never been tested in orbit.

space.com describes NASA's Artemis IV mission outline: SpaceX would first launch a depot ship to low Earth orbit, then send "(multiple)" tanker Starships to fill it.

The lunar lander would then dock for a pit stop, undock, and raise its orbit to what NASA labels the "final tanking orbit," where the depot would rendezvous again after more tanker flights for a final fuel transfer. Only then would Starship ascend to high Earth orbit to meet Orion.

NASA says the staggered choreography gives flexibility on when the SLS can launch astronauts and reduces total fuel needs by taking Orion directly to low lunar orbit.

SpaceX plans its first orbital refueling test in early 2027, just over a year before it would theoretically need to do it for real, according to Jalopnik.

Starship currently launches once every few months, and Musk claims a weekly cadence by early 2027 and twice-weekly by year's end — even then, 22 refueling launches plus the depot would take about three months. Delays led NASA to reopen the lander contract, letting Blue Origin bid.

Jalopnik reports Blue Origin's proposal needs just four New Glenn launches to park booster stages in orbit and a Blue Moon lander to stack with them, requiring no fuel transfer at all.

The stakes are high: if SpaceX cannot demonstrate orbital refueling works, or fails to pull off an uncrewed lunar landing by the end of next year, space.com reports NASA could still select Blue Origin's Blue Moon lander for Artemis IV.

Either way, astronauts ride the SLS rocket in an Orion capsule to high Earth orbit, dock with whichever lander wins, and two of the four crew descend to the surface while two remain aboard Orion. Jalopnik notes that NASA wants to move faster than Apollo did, with less testing runway.

As space.com puts it, the refueling question remains open, but answers should come as the launch date nears.