Musk disputes Moon fuel count

Elon Musk rejected a recent estimate that 22 Starship launches are required to refuel a lunar lander.

The disagreement followed a public meeting of the Aerospace Safety Advisory Panel. Panel member Charlie Precourt, a former NASA astronaut, identified lander fueling as a primary risk for Artemis IV. That mission is scheduled to send a crew to the Moon in 2028. Precourt cited a previous estimate of approximately 22 flights. He stated, "We need to keep our eyes on numerous required fuelings for the lander."

Musk responded to Precourt's comments on X. The SpaceX chief wrote, "That's way too high. Actual number will be more like 6 to 8."

The technical issue involves the Starship's limited payload capacity. The rocket consumes nearly all its propellant to reach Earth orbit. It cannot proceed to the Moon without additional fuel. SpaceX plans to use a dedicated storage tank, or depot, in orbit. Tanker Starships will launch individually to dock with this depot and transfer their remaining propellant. Once the depot is full, the crewed lunar lander will launch, refuel, and depart.

Each tanker flight represents a full rocket launch. A higher number of flights increases time, cost, and potential failure points. Ars Technica reporter Eric Berger calculated that filling a depot with 22 flights would take about three months. This assumes SpaceX achieves a rate of two launches per week by the end of 2027.

The discrepancy stems from assumptions about vehicle capability. NASA's figure appears based on current Starship performance. Musk's lower range assumes an upgraded version. Propellant losses in orbit also affect the total. Fuel and oxygen are stored at very low temperatures. Some evaporates during the wait and during each transfer process.

Musk has challenged higher flight counts in the past. In 2021, he described a 16-launch estimate as "extremely unlikely" and predicted a maximum of eight tankers. Precourt noted that Artemis IV involves "a large number of firsts." He praised NASA Administrator Jared Isaacman for working to clear obstacles for SpaceX and Blue Origin. Blue Origin's lander does not require orbital refueling for its first mission.