Every year, Congress rescues NASA’s science programs from the budget axe. And every year, the rescue comes a little later, costs a little more political capital, and leaves a little more scar tissue on the institution it’s supposed to protect. Scientists leave for more stable careers. International partners hedge their commitments. Early-career researchers look at mission timelines measured in decades and funding horizons measured in months, and choose another field. The damage doesn’t show up in any appropriations table — but it is accumulating, and it may already be approaching a point of no return.

That backdrop is what makes the FY2027 budget fight different from the usual annual appropriations jockeying. The Trump administration has proposed dropping NASA’s top-line budget from $24.4 billion to $18.8 billion, with a 47% cut to the Science Mission Directorate — nearly identical to the proposal Congress just rejected for FY2026. This isn’t a negotiating posture. It’s a siege strategy, and the question is whether the institution being besieged can hold together while the cavalry keeps arriving just in time.

What the FY2026 Cuts Actually Mean

Congress rejected the steepest proposed reductions for FY2026, which would have slashed NASA’s overall budget by nearly 25% and its science funding by close to half. But rejecting the steepest cuts is not the same as holding the line. Planetary science, which received roughly $2.7 billion in FY2025, came out of the process with reduced funding — enough to force real choices about which missions continue and which get shelved.

One concrete consequence: Congress cancelled the Mars Sample Return mission. The program, which would have brought Martian rock and soil samples collected by the Perseverance rover back to Earth, had already been troubled by ballooning cost estimates. Its cancellation removes what was once considered a flagship mission from NASA’s planetary science portfolio entirely.

Extended missions at Mars are also under pressure. The typical approval cycle for continuing operations runs two to three years, but current planning suggests missions may only get one additional year. For long-running programs that depend on continuity of data collection, this shortened horizon creates uncertainty about staffing, instrument operations, and scientific output. It also makes it harder for international partners to coordinate joint observations. The question of what to do about aging but productive missions is perennial — but shrinking budgets compress the decision timeline and raise the threshold for what counts as productive enough to justify continued spending.

Three Venus Missions, Not Enough Money

NASA currently has three Venus missions in various stages of development: DAVINCI, VERITAS, and the European Space Agency’s EnVision (on which NASA is a partner). Officials have indicated it will be a challenge to maintain funding for all three.

DAVINCI would send a probe through Venus’s thick atmosphere to measure its composition on the way down. VERITAS would map the planet’s surface with radar. EnVision, led by ESA with a NASA-provided instrument, would study Venus’s geology and atmosphere. Each addresses different scientific questions, but all three draw from the same shrinking pool of money.

If one or more of these missions gets delayed or downscoped, it doesn’t just affect NASA. It complicates ESA’s planning and weakens the kind of international scientific cooperation that has historically been one of NASA’s strongest institutional assets. A partner agency that can’t guarantee its contribution to a joint mission is a partner agency that gets planned around rather than planned with.

The Impoundment Risk

Budget numbers on paper are one thing. Whether agencies actually receive their appropriated funds is another. There have been reports of delays in the release of FY2026 funding to other federal science agencies. If OMB exercises similar discretion over NASA appropriations, the agency could face effective spending reductions even beyond what Congress authorized.

The president proposes, Congress disposes — that’s true as a matter of legislative procedure. But when the same severe cuts get proposed year after year, the political energy required to fight them off doesn’t come free. Advocacy organizations, NASA center directors, and program managers all spend time and capital defending programs that have already been funded. The process itself has costs, even when the worst outcomes are avoided.

FY2027: The Same Fight, Reloaded

The FY2027 request closely mirrors the FY2026 proposal that Congress rejected. Major projects in development — the Nancy Grace Roman Space Telescope, the Dragonfly mission to Saturn’s moon Titan, the NEO Surveyor asteroid-hunting telescope — would all face potential delays or cancellation.

The one area the administration wants to grow is human exploration. The Exploration account would see an increase, reflecting continued support for NASA’s Artemis program, which continues to generate high-visibility milestones. But budget documents that celebrate Artemis achievements have also described the Space Launch System as expensive and delayed, calling for more cost-effective alternatives. The tension between praising a program’s achievements and proposing its replacement is the kind of contradiction that only makes sense when the numbers don’t add up and the administration is signaling priorities without specifying alternatives.

Congressional Response: How Big Is the Coalition?

A significant number of House members have reportedly signed letters requesting increased NASA science funding — enough to restore what supporters have described as a trajectory from the president’s first term, adjusted for inflation. The existence of broad bipartisan support signals that the coalition which rejected deep cuts in FY2026 remains intact.

But maintaining that coalition across two consecutive budget cycles requires sustained political effort, and the backdrop has shifted. Rising defense spending, which accounts for a growing share of discretionary outlays, will further reduce the money available for non-defense programs. Hope has recent precedent behind it, but the question is whether Congress can maintain flat or near-flat science funding for a second consecutive year while defense spending grows and the administration applies pressure in the opposite direction.

The Real Cost: Institutional Erosion

This is where the budget numbers stop telling the full story. NASA administrator Jared Isaacman has reportedly called on the workforce to find efficiencies and focus resources amid budget constraints. The language of efficiency is standard for budget squeezes. But there is a difference between asking an agency to find 5% savings through better procurement and asking it to absorb a 47% cut to its science portfolio. The first is management. The second is dismantlement.

The Planetary Society has characterized the proposal as a serious threat to US leadership in space science and exploration, pointing out the contradiction between the president’s stated desire for NASA to remain the world’s premier space agency and the budget office’s proposed spending levels.

That contradiction will be resolved, as always, on Capitol Hill. But the resolution will take months, and during those months every NASA program manager has to plan for multiple possible outcomes. Some will slow-walk hiring. Others will delay procurement decisions. Industry contractors price risk into their bids. The uncertainty itself becomes a cost, paid in lost time and institutional friction that doesn’t show up in any budget table.

The FY2027 fight has just begun, and it will look a lot like the one that just ended. For NASA’s planetary science program, the relevant question isn’t whether Congress will reject the worst-case scenario. It’s how many years of repeated budget brinkmanship a scientific enterprise can absorb before the damage becomes permanent — and whether anyone in a position to stop it recognizes that the clock is already running.

Photo by Phil Evenden on Pexels