Updated 10 p.m. Eastern with additional comments.
DENVER — The White House is proposing steep cuts in NASA’s science program that, if implemented, would cancel several major missions, contradicting claims by the administration’s nominee to lead the agency.
A draft of the White House’s budget proposal sent to NASA April 10 by the Office of Management and Budget (OMB) would cut about 20% from the agency’s overall spending levels but reduce spending for the agency’s science programs by nearly 50%.
The document, known as a passback, is not publicly released but is sent to agencies like NASA to allow them to make final appeals before the formal rollout of the budget proposal. Ars Technica first reported on the passback.
According to sources familiar with the details of the passback, the budget would reduce NASA’s topline, or overall, budget to about $20 billion. NASA received about $25 billion for fiscal year 2025 in a continuing resolution (CR) that kept it and other agencies at 2024 spending levels.
That CR sets funding for NASA’s Science Mission Directorate at about $7.3 billion. However, the passback would provide just $3.9 billion for the directorate in 2026, a cut of nearly 50% from 2025.
The biggest hit would be to NASA’s astrophysics division, which received about $1.5 billion in 2024 (NASA has not completed allocations to its science divisions for 2025 based on the levels in the continuing resolution) but would get less than $500 million in 2026. It would propose canceling the Nancy Grace Roman Space Telescope, which had been on budget and schedule for a launch in late 2026.
Earth science would be cut by a little more than 50% to just over $1 billion, while heliophysics would see a nearly 50% cut to about $450 million.
The budget would provide $1.9 billion for planetary science, about a third less than what it received in 2024. It would, though, cancel the Mars Sample Return program, which has suffered cost and schedule overruns that led to an agency decision in January to study two alternative approaches to it. It would also cancel DAVINCI, a Venus mission selected as part of the Discovery program nearly four years ago.
The passback appears to confirm rumors swirling for weeks in the space community that the Trump administration would seek to make major cuts to NASA science. At an April 6 event, Rep. George Whitesides (D-Calif.), vice ranking member of the House Science Committee, said he had learned that NASA Earth science missions still in their early formulation phase, as well as those in extended operations, had been instructed to prepare termination plans for fiscal year 2026.
In an April 7 interview during the 40th Space Symposium, NASA Acting Administrator Janet Petro said she was not aware of any direction to prepare termination plans for those missions, adding that reports of major cuts were “rumors from really not credible sources.” However, an industry source later shared documents showing that those missions had indeed been given direction to prepare termination plans.
The OMB passback contradicts comments made by Jared Isaacman, the White House’s nominee for NASA administrator, at his April 9 confirmation hearing. “I’m an advocate for science,” he said, citing his public support last year for NASA’s Chandra X-Ray Observatory, which had been threatened with budget cuts in NASA’s fiscal year 2025 budget proposal.
“NASA will be a force multiplier for science,” he said. “We will leverage NASA’s scientific talent and capabilities to enable academic institutions and industry to increase the rate of world-changing discoveries. We will launch more telescopes, more probes, more rovers and endeavor to understand our planet and the universe beyond.”
The passback has alarmed both advocates of science programs and some key members of Congress. “The proposed budget from within the White House — which cuts NASA science by 47% — would plunge NASA into a dark age,” The Planetary Society said in a statement. It argued the budget would result in “premature termination of dozens of active, productive spacecraft” and “halt the development of nearly every future science project at NASA.”
“The impacts of these proposed funding cuts would not only be devastating to the astronomical sciences community, but they would also have far-reaching consequences for the nation,” said Dara Norman, president of the American Astronomical Society, in a statement by the group. She noted the cuts would likely affect not just missions but also grant funding for scientists. “These cuts will certainly result in the loss of American leadership in science.”
Sen. Chris Van Hollen (D-Md.), ranking member of the commerce, justice and science subcommittee of the Senate Appropriations Committee, which funds NASA, raised concerns about the effect of the proposed cuts on NASA’s Goddard Space Flight Center, which is located in Maryland.
“To gut NASA Goddard and the NASA Science Mission Directorate is not just shortsighted, it’s dangerous,” he said in a statement. He called the passback a “wholly unserious” proposal and would “fight tooth and nail against these cuts and to protect the critical work being done at NASA Goddard.”
“Donald Trump’s attack on NASA amounts to a form of national self-destruction and will have untold effects on the country’s scientific efforts, research objectives, and our standing around the globe,” said Sen. Adam Schiff (D-Calif.), in a statement late April 11.
He cited specific concerns with the proposed cancellation of the Mars Sample Return program, which is run by the Jet Propulsion Laboratory in California. “It’s a gift to China, and a slap in the face to those that have dedicated years to making the American space program the best in the world.”
“Effectuating these absurd cuts would destroy NASA’s ability to carry out its fundamental objectives, cut off their societal benefits, and spell catastrophe for the U.S. Earth and space science enterprise by throwing billions in already-made taxpayer investments into the trash heap,” said Rep. Zoe Lofgren (D-Calif.), ranking member of the House Science Committee, in a statement.
Even Elon Musk, chief executive of SpaceX and a close adviser to President Trump, appeared dismayed by the NASA budget passback. “Troubling,” he posted on social media in response to one report on the proposed science cuts. “I am very much in favor of science, but unfortunately cannot participate in NASA budget discussions, due to SpaceX being a major contractor to NASA.”
