What’s next for NASA’s giant moon rocket?

“I think it would be the right call,” says Abhishek Tripathi, a former mission director at SpaceX now at the University of California, Berkeley. “It’s hard to point to SLS as being necessary.”

The calculations are not straightforward, however. Dumbacher notes that while SpaceX is making “great progress” on Starship, there is much yet to do. The rocket will need to launch possibly up to 18 times to transfer fuel to a single lunar Starship in Earth orbit that can then make the journey to the moon. The first test of this fuel transfer is expected next year.

SLS, conversely, can send Orion to the moon in a single launch. That means the case for SLS is only diminished “if the price of 18 Starship launches is less than an SLS launch”, says Dumbacher. SpaceX was awarded $2.9 billion by NASA in 2021 for the first Starship mission to the moon on Artemis III, but the exact cost per launch is unknown.

MICHAEL DEMOCKER/NASA

NASA is also already developing hardware for future SLS launches. “All elements for the second SLS for Artemis II have been delivered,” a NASA spokesperson said in response to emailed questions, adding that SLS also has “hardware in production” for Artemis III, IV, and V.

“SLS can deliver more payload to the moon, in a single launch, than any other rocket,” NASA said. “The rocket is needed and designed to meet the agency’s lunar transportation requirements.”

Dumbacher points out that if the US wants to return to the moon before China sends humans there, which the nation has said it would do by 2030, canceling SLS could be a setback. “Now is not the time to have a major relook at what’s the best rocket,” he says. “Every minute we delay, we are setting ourselves up for a situation where China will be putting people on the moon first.”

President-elect Donald Trump has given Musk a role in his incoming administration to slash public spending as part of the newly established Department of Government Efficiency. While the exact remit of this initiative is not yet clear, projects like SLS could be up for scrutiny.

Canceling SLS would require support from Congress, however, where Republicans will have only a slim majority. “SLS has been bipartisan and very popular,” says Forczyk, meaning it might be difficult to take any immediate action. “Money given to SLS is a benefit to taxpayers and voters in key congressional districts [where development of the rocket takes place],” says Forczyk. “We do not know how much influence Elon Musk will have.”