On the heels of the revelation that Boeing is planning to lay off as many as 400 workers from its Space Launch System program, NASA has called the SLS mega-rocket “essential” to its Artemis moon landing program — sowing confusion about what, exactly, may change for both the launch vehicle and Artemis in the days and weeks ahead.

The statement from NASA comes amid widespread speculation that SLS — which made its debut flight test in 2022 — may be on the chopping block.

The moon rocket has been a major point of controversy in the space community for years, as detractors have called the launch system — which is billions of dollars over budget — wasteful. Development of the rocket cost $23.8 billion between 2011 and its first flight two years ago, while initial projections expected that number to be more around $18 billion. And one oversight official in 2022 estimated that the vehicle would cost more than $4 billion per launch for the first four Artemis missions.

Those critics often argue that Elon Musk’s company, SpaceX, would be able to accomplish moon missions at a far cheaper price point with Starship, the most powerful launch system ever constructed, which is still in the early stages of development.

Former NASA administrator Bill Nelson, the Biden-era head of the agency, was asked in December whether he was concerned about speculation that the next administration would restructure Artemis or consider canceling the SLS rocket.

“I have not been concerned,” Nelson said at a news conference. “Are they going to axe Artemis and insert Starship? First of all, there is one human-rated spacecraft that is flying and has already flown beyond the moon — further than any other human-rated spacecraft — and that’s the SLS combined with (NASA’s moon spacecraft) Orion.”

Canceling SLS has also seemed politically intractable, as key lawmakers on Capitol Hill have continued to fund and throw their support behind the program. Supporters also argue that SLS has already been tested in space, having flown around the moon on its inaugural 2022 flight. The Starship launch system, meanwhile, has yet to fly a mission to orbit, and the spacecraft explosively broke apart midair during a flight test in January.

On Friday, however, Boeing — the primary NASA contractor for the SLS rocket — signaled that changes are afoot. The company issued a warning about “the potential for approximately 400 fewer positions (in the SLS program) by April 2025.”

The layoffs will be made to “align with revisions to the Artemis program and cost expectations,” a statement from Boeing reads.

‘Evaluate and align budget’

In its statement responding to the move, NASA did not acknowledge what potential changes may be coming to the Artemis program, which began under the previous Trump administration and aims to return astronauts to the lunar surface as soon as mid-2027, according to the latest schedule estimates from the space agency.

“NASA and its industry partners continuously work together to evaluate and align budget, resources, contractor performance, and schedules to execute mission requirements efficiently, safely, and successfully in support of NASA’s Moon to Mars goals and objectives,” the space agency said Monday in a statement. “NASA defers to its industry contractors for more information regarding their workforces.”

Boeing did not respond to a request for additional comment.

NASA has long said it plans to use the SLS rocket to power 10 or more Artemis missions, which will aim to return humans to the moon’s surface as well as set up a permanent lunar outpost.

SpaceX’s Starship is also set to play a role in the project. NASA has agreed to pay the company nearly $4 billion to carry astronauts on the final leg of the mission. The space agency is aiming to use the Starship spacecraft, the upper stage of SpaceX’s launch system, as a moon lander that would ferry them from the Orion spacecraft — which launches atop SLS — down to the lunar surface.

SpaceX’s deals with NASA, however, are fixed-price, meaning the company will not receive additional investment for Starship if funds run out. But SpaceX will also maintain ownership of the vehicle and can use it for commercial purposes.

Boeing, meanwhile, is developing NASA’s SLS under a “cost-plus contract” which has allowed the space agency’s expenses to balloon as the project experienced delays and development setbacks. Nelson at one point even called cost-plus contracts a “plague.”