WASHINGTON — NASA Administrator Bill Nelson defended the cost and schedule performance of the agency’s Artemis lunar exploration effort even as officials hinted as the possibility for changes in one upcoming mission.

At a May 23 hearing, Sen. Jeanne Shaheen (D-N.H.), chair of the Senate Appropriations Committee’s commerce, justice and science subcommittee, pressed Nelson on costs associated with Artemis and suggested that the agency convene an independent review of those costs.

She asked Nelson to describe “what NASA is doing to hold contractors accountable for cost overruns and scheduling delays” including whether the agency withheld payments to contractors for those overruns. She did not cite specific cases with Artemis but rather past studies on the overall costs of the program, including one estimate by NASA’s Office of Inspector General (OIG) that each of the first four Space Launch System/Orion launches will cost $4.2 billion.

Nelson said that the companies are “docked” for award fee payments if their performance falls short. He also emphasized NASA’s use of commercial partnerships on Artemis, such as for the Human Landing System program that makes use of fixed-price contracts.

“Given the high cost, has NASA considered an independent review board for exploration?” Sheheen asked, citing the benefits of independent reviews on the James Webb Space Telescope program when it encountered additional overruns and delays late in its development.

Nelson argued such a review was not necessary. “We are constantly having other eyes” on Artemis, he said, citing reviews by OIG as well as the Government Accountability Office. “The fact is, when you go to the moon in order to go to Mars, it’s hard.”

NASA officials have, in fact, expressed some frustration with the level of outside scrutiny on Artemis. The agency’s response to the most recent OIG audit related to Artemis, regarding the agency’s readiness for the Artemis 2 mission, complained that OIG had not found any issues they were not already addressing and that working with the auditors caused “disruptions to ongoing workflow and priorities” for those working on the upcoming mission.

That Artemis 2 mission remains scheduled for launch in September 2025, a “realistic date,” Nelson told the subcommittee’s ranking member, Sen. Jerry Moran (R-Kan.), despite ongoing work on the Orion heat shield and other technical issues. Nelson emphasized, though, that “we don’t fly until it’s ready.”

That would be followed in September 2026 by Artemis 3, the first crewed landing. “Artemis 3, if you compare it to the Apollo program, is a combination of Apollo 9, 10 and 11,” he said. “It is a difficult task and, if we land, it is dependent on SpaceX having their lander ready.”

Nelson’s use of “if” regarding an Artemis 3 landing raised some eyebrows. Nelson said SpaceX has “hit all of their milestones” so far in development of the lunar lander version of their Starship vehicle that will be used on Artemis 3. Agency officials, though, have publicly questioned SpaceX’s ability to have the Starship lander ready in time, and have suggested that NASA might change the Artemis 3 mission if Starship is behind schedule. There have been more recent reports that NASA is examining options for Artemis 3 that fall short of a crewed lunar landing.

That issue came up during an online Lunar Surface Science Workshop session May 23. “We are fundamentally focused on Artemis 3 being a human lunar return mission,” said Mike Sarafin, NASA’s Artemis 3 mission manager, when asked questions about potential alternative mission profiles.

However, he acknowledged the agency was working on alternative concepts. “If we run into issues, we may choose an offramp,” he said. “We do what-if exercises internally” but he did not disclose what might trigger an offramp or what those alternatives would detail.

Sarafin did state that NASA was closely watching the “series of tests” ahead for Starship, including one projected for next year to demonstrate propellant transfer between two Starship vehicles, a key technology needed to refuel the lunar lander Starship. “Should any of those show results that are unsatisfactory,” he said of those tests, “we absolutely will take more time.”

Jeff Foust writes about space policy, commercial space, and related topics for SpaceNews. He earned a Ph.D. in planetary sciences from the Massachusetts Institute of Technology and a bachelor’s degree with honors in geophysics and planetary science...