The White House’s fiscal year 2026 budget request proposes a dramatic 24 percent cut to NASA’s funding, slashing it from $24.8 billion to $18.8 billion—the largest single-year reduction in the agency’s history, per The Planetary Society.
The request takes aim at projects it describes as “grossly expensive and delayed.” But many programs in the crosshairs are hitting their cost and schedule targets. Some are actively exploring outer space.
The budget—which, if approved by Congress, will take effect October 1—boosts human space exploration, increasing funding for those missions to the tune of $647 million. It proposes allocating $7 billion toward lunar exploration and $1 billion for “Mars-focused programs.”
But that comes at the expense of science and other programs. The Science Mission Directorate (SMD), for example, faces a 47 percent cut. Earlier this week, all living former heads of the SMD sent a joint letter urging Congress to reject the move.
“This proposed budget ends nearly all future investments for both new missions and advanced technology for science,” they wrote. “It walks away from dozens of current, extraordinarily successful and productive science missions in extended operations.”
Per a July Government Accountability Office (GAO) assessment of major NASA projects, several candidates for downsizing are struggling to meet their initial targets. Several others, though, remain on track—and a few have even reached the final frontier.
On the Chopping Block
NASA’s Orion crew capsule is the major culprit behind the agency’s budget woes.
A key component of the Artemis moon mission program, Orion flew without crew on 2022’s Artemis I and will carry astronauts on Artemis II and Artemis III. But according to the GAO, Orion alone accounted for $363 million of the more than $500 million in cost overruns NASA has recorded in 2025.
Cumulatively, Orion has exceeded its original baseline by $3.2 billion, accounting for nearly three-quarters of the cost overruns attributed to NASA’s 18 major projects in development. The White House budget proposes phasing out Orion after Artemis III.
NASA’s Space Launch System (SLS) similarly faces cancellation following that mission. Per the GAO, development of SLS Block 1—the configuration that will launch Artemis II and Artemis III—cost $2.7 billion more than expected. A future iteration, Block 1B, is meeting cost and schedule estimates. But concerns remain over its readiness for Artemis IV, its intended debut.
Per the budget, NASA would fund replacements for Orion and SLS using “more cost-effective commercial systems” such as SpaceX’s Starship or Blue Origin’s New Glenn.
Also at risk is the Mars Sample Return mission, which seeks to retrieve samples from NASA’s Perseverance rover by the 2030s. Perseverance has been exploring the Red Planet since 2021. But NASA was forced to abandon its initial return plans due to projected cost and schedule delays.
The agency in 2024 announced a revised mission architecture, soliciting proposals from commercial firms that it believes can greatly reduce the mission’s cost. The White House, despite President Donald Trump’s emphasis on Mars missions over lunar exploration, wants to axe it and other key science projects.
“Cutting NASA’s overall Science budget by 50 percent…would result in mass layoffs of the same people we need to get us to Mars,” wrote James Burk, executive director of The Mars Society. “I join all my colleagues in opposing this draconian proposal.”
At the same time, several programs meeting their baselines face cuts.
The Lunar Gateway space station, another Artemis component, could be canceled despite sticking to initial estimates, though concerns remain about the readiness of its Habitation and Logistics Outpost (HALO) module. The Nancy Grace Roman Space Telescope, meanwhile, faces a more than 50 percent budget cut despite 90 percent of its budget having already been spent. Per The Planetary Society, Roman is “on time, on schedule, and nearly ready to launch.”
Two other projects, Mars Atmosphere and Volatile EvolutioN (MAVEN) and the Juno probe, face cancellation despite ongoing space missions. The spacecraft are orbiting Mars and Jupiter, respectively, beaming valuable data and imagery back to Earth. Both met baseline estimates at launch—MAVEN, for example, cost $90 million less than expected.
A third active science project on the chopping block, the OSIRIS-APEX mission, is en route to the asteroid Apophis, which is expected to pass near Earth in 2029. The mission is a follow-on to the completed OSIRIS-REx, which like MAVEN and Juno hit its targets. The Planetary Society called it “as close to a ‘freebie’ as space missions get.”
Wiggle Room
Trump has made Mars a strategic priority. The budget, for example, directs $864 million to fund a new “Commercial Moon and Mars Infrastructure & Transportation” program and $350 million to support “Mars technology.”
But U.S. officials on both sides of the aisle have been hesitant to get on board. Canceling key projects could jeopardize NASA’s international partnerships, such as its collaboration with the European Space Agency on Gateway. Per the budget, doing so would reduce the agency’s workforce by nearly one-third, costing jobs in both Democratic and Republican states. Neither of those outcomes has universal appeal.
“We must stay the course,” Senator Ted Cruz (R-Texas), chairman of the Senate Committee on Commerce, Science, and Transportation, said during a hearing in March. “An extreme shift in priorities at this stage would almost certainly mean a red moon, ceding ground to China for generations to come.”
Cruz spearheaded the inclusion of nearly $10 billion in funding for SLS, Orion, and Gateway in the recently passed Republican-led reconciliation bill. The move funds SLS and Orion through the Artemis V mission, in sharp contrast to Trump’s proposal. With the money allocated, canceling those projects becomes a steeper challenge for the White House.
Representative Brian Babin (R-Texas), who leads House oversight of NASA and whose district contains Johnson Space Center in Houston, said at the Paris Air Show that the budget is “not set in stone.”
Still, NASA is already feeling the impact of the new administration. Keith Cowing, who runs the blog NASAWatch, last week reported that more than 2,600 employees—including center directors—have accepted buyout offers that would provide continued pay and benefits in exchange for early resignation. Combined with an expected 350 non-buyout departures, about 17 percent of NASA’s workforce of nearly 18,000 civil servants is planning to leave the agency.
At the same time, the White House is tightening the noose around projects slated for cuts. Digital media outlet Ars Technica reported that NASA leadership directed mission leaders to prepare “closeout” plans for certain projects, with the goal for them to be in place by October 1—the day FY 2026 begins. Per Ars Technica, personnel within the agency believe the directive is an effort to shutter projects before Congress approves the budget, rather than a simple “planning exercise,” as the memo states.
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