THE WOODLANDS, Texas — NASA says its fiscal year 2025 budget proposal is constrained by the second year of a debt-ceiling agreement that caps overall spending, leading to delays, potential cancellations and broader uncertainty for many NASA science programs in particular.

NASA released its fiscal year 2025 budget proposal March 11, requesting $25.384 billion, the exact amount it received in fiscal year 2023. It is a little more than half a billion dollars more than what the agency received in the final fiscal year 2024 spending bill enacted last week.

However, NASA had requested nearly $27.2 billion in its original fiscal year 2024 budget request a year ago. That request projected seeking $27.73 billion in 2025, so the new fiscal year 2025 proposal reflects a reduction of more than $2.3 billion from those earlier ambitions.

In a call with reporters about the budget proposal, NASA Administrator Bill Nelson put the blame for those budget constraints on the debt ceiling agreement enacted last year. That agreement placed caps on non-defense discretionary spending, which includes NASA, for fiscal years 2024 and 2025.

He specifically singled out “a small handful of people in the House of Representatives” who would only agree to raising the debt ceiling if there were spending caps. NASA ended up with a 2% cut in 2024 versus 2023. “In a little agency that is doing an awful lot,” he said, “it makes a big difference.”

That carries over to the fiscal year 2025 request, where overall non-defense discretionary spending increases by only 1% over 2024 levels. “Naturally, we have to make hard choices,” he said.

Many of those hard choices come in NASA’s science programs. NASA requested $7.566 billion for science in 2025, a $231 million increase from the final 2024 spending bill. However, NASA anticipated spending more than $8.4 billion on science programs in 2025 in the projections included in last year’s budget proposal.

Among the changes included in the 2025 budget proposal is canceling the Geospace Dynamics Constellation mission, one of the top priorities of the previous heliophysics decadal survey. NASA had proposed pausing the mission’s development in its 2024 budget proposal, although the report accompanying the final 2024 spending bill directs NASA to provide Congress with a budget and schedule for launching it by the end of the decade.

The budget proposal also proposes restructuring the Earth System Observatory line of missions, preserving a partnership with the Japanese space agency JAXA on a mission they are leading while “assessing options” for implementing other aspects of the aerosols and cloud, convection and precipitation designated observables from the Earth science decadal survey. A future Surface Biology and Geology mission will be split into two projects “to maximize execution flexibility and reduce near-term budget requirements.”

NASA is also reducing spending on two of its existing space telescopes, the Chandra X-Ray Observatory and Hubble Space Telescope, as agency officials disclosed in the fall. NASA is proposing about a 5% cut in Hubble’s budget, realized primarily through cost savings from joint operations with the James Webb Space Telescope and reduced research grants.

The Chandra cuts, though, are more significant, from $68.3 million spent on it in 2023 to $41.1 million proposed for 2025. “The Chandra spacecraft has been degrading over its mission lifetime to the extent that several systems require active management to keep temperatures within acceptable ranges for spacecraft operations,” the agency’s budget request stated. “The reduction to Chandra will start orderly mission drawdown to minimal operations.” The proposal projects annual spending on Chandra to fall to just $5 million by 2029.

Mars Sample Return (MSR) remains a major uncertainty in the budget. The 2025 budget proposal includes more than $2.7 billion for planetary science overall but lists only “TBD” for MSR as the agency awaits the results of an architecture review for the program. That review is scheduled to be completed by the end of March, Nelson said in the call.

“We will report in April what then would be the spending in ’24 and ’25,” he said. “That’s why there is not a figure there in ’25.”

However, all of the planetary science funding included in the budget request is already allocated to other programs. “We’ll have to make some pretty tough choices,” said Nicola Fox, associate administrator for science. “We have to maintain a balanced portfolio overall.” She added that she did not expect the overall planetary science budget to go up once funding is allocated for MSR.

Commercial space stations and Artemis

Among other changes in the budget is a reduction in spending on NASA’s Commercial Low Earth Orbit Destinations, or CLD program to support work on commercial space stations to succeed the International Space Station. That program received $228 million in fiscal year 2024 and the agency had previously projected spending $229.6 million on it in 2025, but the new budget proposal instead requests $169.6 million.

Ken Bowersox, NASA associate administrator for space operations, said the decrease was an artifact of the awards in place for the ongoing first phase of CLD program. “The funding that we have here I think is very generous and is about the limit of what we can afford while we’re trying to work under these budget levels.”

NASA is continuing development of a U.S. Deorbit Vehicle (USDV) for the ISS, although the fiscal year 2025 budget proposal does not spell out a specific figure for it. Nelson said NASA is still hoping to secure funding for the USDV through a standalone domestic supplement spending bill yet to be considered by Congress.

Funding for NASA’s exploration programs, including those for the Artemis lunar exploration effort, are virtually unchanged from the final 2024 bill, with nearly $7.62 billion requested versus $7.67 billion received for 2024.

One minor change in a schedule included with the budget is a six-month slip in the Artemis 5 mission, from September 2029 to March 2030. That mission will be the first to use Blue Origin’s Blue Moon lunar lander, after SpaceX’s Starship lands on the Artemis 3 and 4 missions. Cathy Koerner, NASA associate administrator for exploration systems development, said the delay in Artemis 5 is linked to “budget levels anticipated over the next five fiscal years.”

The Coalition for Deep Space Exploration, an industry group, raised concerns about an increasingly irregular schedule of Artemis missions, with the agency’s plans for an annual cadence of missions now deferred to the early 2030s. It argued in a statement that “funding for a regular launch cadence will help develop and maintain the space industry workforce needed to preserve our place at the forefront of space exploration.”

Nelson said that any hope for stronger budgets will have to wait until at least fiscal year 2026, after the spending caps from the debt ceiling agreement expire. “We’re not going to get out of this hole until you finish both fiscal years, ’24 and ’25,” he said.

However, he said the current situation was not as bad for the agency as was the case a decade ago, when budget sequestration made deeper cuts. “Things were constrained considerably,” Nelson, at the time a senator, recalled. “So, I’d say this is mild by comparison to back then.”

NASA Fiscal Year 2025 budget proposal (in millions of $)

AccountFY24 enactedFY25 proposalDifference
Earth Science$2,195.0$2,378.7$183.7
Planetary Science$2,716.7$2,731.5$14.8
Biological and Physical Sciences$87.5$90.8$3.3
SPACE TECHNOLOGY$1,100.0$1,181.8$81.8
Space Launch System$2,600.0$2,423.2-$176.8
Exploration Ground Systems$758.8
Exploration Other$3,405.2
SPACE OPERATIONS$4,220.0$4,389.7$169.7
STEM ENGAGEMENT$143.0$143.5$0.5

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...