SpaceX’s lunar lander has run into a snag and may not be ready for a mission to the moon that was scheduled for 2027, according to a report by Space News. The company’s Starship Human Landing System (HLS) is a variant of the typical Starship spacecraft that has been designed to transport astronauts between lunar orbit and the surface of the moon.

“The HLS schedule is significantly challenged and, in our estimation, could be years late for a 2027 Artemis 3 moon landing,” said NASA safety analyst Paul Hill following a visit to SpaceX’s Starbase facility.

The underlying issue seems to be regarding cryogenic propellant transfer, as the SpaceX team has yet to figure out a way to refuel Starship in low Earth orbit before it heads to the moon. This will be the first version of the vehicle capable of such transfers and the work has been slowed down by ongoing engine redesigns.

There’s no timetable as to when the team will get this sorted. SpaceX president Gwynne Shotwell recently expressed hope that the project won’t be “as hard as some of my engineers think it could be.”

This delay has caused some to speculate that it could give China the upper-hand when it comes to manned lunar missions. The country has developed its own lunar vehicle called Lanyue that could land on the surface by 2030.

Also, this isn’t the first time the Elon Musk-owned SpaceX has missed deadlines regarding a return to the moon. The company said in 2023 that it would attempt in-orbit refueling by early 2025. That didn’t happen. Musk said earlier this month that SpaceX will “demonstrate fuel reusability next year” which also isn’t happening.

The Artemis 2 launch, however, is still on track for early 2026. This mission will send four astronauts around the moon, but not onto the surface. It has been over 50 years since the US put boots on the lunar surface. The last manned mission to the moon was in 1972.