HAMBURG, Germany — NASA is slowing down work on Mars Sample Return (MSR) amid uncertainty about its budget for next year and an ongoing review of alternative architectures for the program.

Speaking at a meeting of NASA’s Planetary Science Advisory Committee, or PAC, Nov. 13, Sandra Connelly, deputy associate administrator for science at NASA, said the agency directed three field centers working on MSR “to start ramping back on activities” related to that program.

That is driven in large part because of uncertainty about how much money MSR will receive when Congress completes its fiscal year 2024 appropriations bill. A House bill would provide $949.3 million, the full request by NASA, while a Senate version this summer would provide just $300 million, and included language directing NASA to descope or cancel MSR if its total cost exceeds $5.3 billion. A recent independent review concluded MSR will cost between $8 billion and $11 billion.

NASA is currently operating under a continuing resolution (CR) that funds programs at fiscal year 2023 levels, which for MSR is $822.3 million. The current CR expires Nov. 17, but another may extend that stopgap funding into early 2024. Connelly described the reductions in MSR work as a way to address a “worst-case scenario” where NASA receives only the funding in the Senate bill, months after the start of the fiscal year, and would need to sharply reduce work.

“It’s very unfortunate that we have to make this decision at this point. However, the intent is to enable sufficient funding to carry us throughout the year so we can continue working on and architecting this mission,” she said.

The letters went to the Goddard Space Flight Center, Jet Propulsion Laboratory and Marshall Space Flight Center, all working on different aspects of MSR. “It includes making reductions on contracts, ramping back where we can,” she said.

One element of MSR affected more than most is the Capture, Containment and Return System (CCRS), a NASA-provided element of the European Earth Return Orbiter that will capture the sample canister placed in Mars orbit and secure it for return to Earth.

“We’re going to carry it through PDR [preliminary design review] to make sure it’s well documented and at a place where we can pause,” Connelly said. “Basically, the direction is to not continue it at this point in time because we’re going to prioritize getting the samples into orbit.” She added it doesn’t preclude continuing CCRS later in the development of MSR.

That decision to slow down work on MSR coincides with an ongoing response by NASA to the independent review. That includes a reassessment of the MSR architecture that the agency hopes to complete by next March.

“The Senate language, I think, is pretty pointed and certainly acknowledging that, before we move forward, we need to make sure we have a clear and credible path,” Lori Glaze, director of NASA’s planetary science division, said at the meeting. That reassessment will provide that path, she argued.

Agency officials at the PAC meeting provided an overview of that work, but few specific details about the architectures under consideration. Steve Thibault, who is leading that technical team, said they are working through “architectural trade variants” for MSR. He said later some proposals are “time phased” to keep per-year costs down, suggesting that some elements of the architecture would be delayed.

However, Nicola Fox, associate administrator for science, said NASA had not yet decided to delay launches of MSR missions, including the Earth return orbiter sand sample retrieval lander, to some time after 2030. “It is in the trade space, but we’re not ready to do that yet,” she said of such delays. “The idea is to try to look for alternate architectures to preserve that date.”

Both Fox and Glaze emphasized the need for balance in NASA’s planetary science programs to avoid MSR from consuming an overwhelming part of the overall planetary budget. “We’re prioritizing getting those samples into orbit,” Fox said, “but making sure it’s not going to destroy the rest of the planetary portfolio.”

NASA’s work so far in reassessing MSR won the approval of the chair of that independent review board. “My sense is that they’re really doing the due diligence that’s necessary to address what we were recommending,” said Orlando Figueroa in brief comments at the PAC meeting. “We look forward to hearing from them when they’re ready.”

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...