Musk Cuts Lunar Fuel Flight Count to Six or Eight

NASA’s Aerospace Safety Advisory Panel met quarterly on Thursday to review risks for upcoming space missions. During the session, the panel flagged the orbital refueling process for the Moon landing as a primary concern.

Charlie Precourt, a former NASA astronaut serving on the panel, stated that fueling SpaceX’s lunar lander represents a major risk for Artemis IV. The mission is scheduled to put a crew on the Moon in 2028. Precourt cited the most recent internal estimate, which requires approximately 22 Starship tanker flights to fill the orbital depot.

Elon Musk responded to the remark after Eric Berger, a journalist for Ars Technica, shared Precourt’s comments on social media. Musk called the panel’s figure “way too high.” He proposed a range of six to eight launches instead, arguing that the higher count fails to account for vehicle improvements.

The discrepancy arises from the physical limitations of the Starship rocket. The vehicle consumes nearly all its propellant reaching Earth orbit, preventing it from reaching the Moon without external fuel. SpaceX’s design relies on a storage tank, or depot, launched first. Tanker Starships then fly one at a time to dock and transfer their remaining propellant to the depot. Once full, the lander launches, docks, refuels, and departs for the Moon.

The total number of launches determines the timeline and cost of the mission. More launches create additional windows for technical failures. Eric Berger estimated that even with a launch rate of two Starships per week by late 2027, filling a depot at the panel’s 22-flight estimate would take about three months. A lower count would shorten this window.

The fuel calculation depends on how much propellant each tanker delivers to orbit and how much is lost during transfer. Starship fuel is stored at extremely low temperatures, causing some to boil off while waiting in orbit. NASA’s estimate appears based on current Starship lift capacity, while Musk’s lower figure assumes a more capable vehicle.

Musk has previously disputed higher launch counts. In 2021, he rejected a government suggestion of 16 launches, calling the figure “extremely unlikely” and predicting a maximum of eight. Precourt noted that Artemis IV involves a “large number of firsts.” He also acknowledged efforts by NASA Administrator Jared Isaacman to clear path dependencies for both SpaceX and Blue Origin.