A sweeping White House budget proposal for fiscal year 2026 would slash NASA’s funding by nearly a quarter, reshaping the agency’s exploration agenda, delaying or canceling flagship programs, and altering international partnerships that have shaped space science for decades. If enacted as written, the plan would reduce NASA’s budget from about $24.8 billion to roughly $18.8 billion, marking an inflation-adjusted milestone that would make the agency’s investment level the lowest since the early days of human spaceflight in 1961. The plan’s implications run across robotic science, technology development, the International Space Station, and critical human spaceflight capabilities, while signaling a clear tilt toward commercial transportation for Moon and Mars missions. The following analysis delves into five major cuts or cancellations highlighted by the proposal, unpacking what they mean for NASA’s long-term goals, industry partnerships, and U.S. leadership in space exploration.
Zeroing out nuclear propulsion
The most audacious and potentially far-reaching element of the budget proposal is the elimination of all funding for nuclear propulsion research and development, including the nuclear thermal propulsion (NTP) and nuclear electric propulsion (NEP) programs. The plan calls for canceling a nuclear propulsion demonstration project that had been conducted in partnership with the Department of Defense, a project commonly associated with the acronym DRACO. Although DARPA had already scaled back participation earlier in the year, the budget proposal takes the final step by removing NASA’s entire nuclear propulsion portfolio from its programmatic slate.
To understand the significance, it helps to recall why nuclear propulsion has long been viewed as a potential game-changer for deep-space missions. Nuclear thermal propulsion promises higher thrust and greater efficiency than conventional chemical rockets, enabling more ambitious cargo and crew missions to Mars and beyond within reasonable travel times. Nuclear electric propulsion, often discussed in the context of electricity generation and high-efficiency thrust, could further reduce transit times and broaden mission architectures for solar-system exploration. The absence of federal funding at NASA for these propulsion pathways would remove a critical lever in the agency’s long-range exploration strategy, potentially constraining future mission concepts that rely on heavy, energy-dense propulsion for crewed deep-space destinations.
Historical context underscores the stakes. NASA’s 2024 budget included a modest allocation—about $117 million—for nuclear propulsion work, up from roughly $91 million the prior year. While the numbers may appear small in the near-term, the cumulative effect of scrapping ongoing work and canceling the entire program portfolio is a signal about the administration’s priorities. Proponents of rapid, aggressive deep-space exploration have argued that nuclear propulsion is essential for enabling timely crewed missions to Mars, reducing one of the most challenging technical risks in long-duration spaceflight. Critics of the technology emphasize cost, safety, and the readiness of alternative propulsion concepts, arguing that the money might be better spent on proven systems or on accelerating commercial capabilities that could deliver similar capabilities down the line.
The budget’s approach to propulsion is not simply a matter of funding arithmetic; it reshapes NASA’s capacity to pursue a balanced, multi-path exploration program. By surrendering nuclear propulsion options, the agency would lean more heavily on conventional chemical propulsion, chemical-stage propulsion, and the development of surface systems for lunar and Martian activities. This shift could influence mission design for future Mars sample return campaigns, deep-space habitat concepts, and the feasibility of large crewed assembly in deep space. It also raises questions about how NASA would handle heavy-lift demands for stages, habitats, and cargo in future architectures. The broader space industry would be watching closely, since private-sector partners have long eyed nuclear propulsion as a potential enabler for more advanced and flexible mission opportunities. If Congress endorses the administration’s stance, the United States could lose a strategic option for enabling high-energy, low-iteration deep-space missions, which could in turn alter the tempo and cost structure of ambitious exploration plans.
In short, the decision to end funding for nuclear propulsion marks a deliberate pivot away from a long-considered technology path and toward other propulsion paradigms. The implications extend beyond technical capability to strategic posture, international competitiveness, and the resilience of NASA’s long-term exploration architecture. The policy choice would reset the baseline assumptions underpinning many mission concepts, affecting not only Mars timelines but also the potential for rapid response to emergent deep-space science opportunities.
Terminating operating missions
A second major set of cuts in the budget proposal targets NASA’s operating science missions that are currently active in space. The plan would cancel at least 19 NASA science missions that are already in operation, many of which are mature or approaching the end of their primary science phase. The rationale provided in the budget request is framed around reallocating resources to higher-priority Artemis initiatives and other Mars-forward programs, but the operational impact is significant and multi-faceted.
Several high-profile examples illustrate the breadth of the proposed terminations. The Juno mission, which is currently the only spacecraft sustaining a long-duration orbital study of Jupiter, is in the crosshairs. The New Horizons probe, famous for its Pluto flyby and continued voyage into the Kuiper Belt, would be shut down. OSIRIS-REx, NASA’s asteroid sample-return mission, currently in an extended phase as OSIRIS-APEX awaiting a rendezvous with the asteroid Apophis after a close Earth encounter in 2029, would be turned off. The Chandra X-ray Observatory, a flagship telescope renowned for decades of high-value observations of black holes, neutron stars, and the dynamic cosmos, would be decommissioned. In Earth science, NASA would roll back funding for missions that monitor greenhouse gas emissions, a critical capability for climate science and climate policy support.
Taken together, these cancellations would remove a broad swath of NASA’s scientific infrastructure that has delivered decades of fundamental discoveries, often at relatively modest annual costs when viewed against the agency’s overall budget. The implications for scientific communities and international partners are profound. The missions involved have produced a deep reservoir of data and a track record of near-continuous science return, enabling researchers to build upon findings across multiple disciplines—from planetary science to astrophysics and Earth system science. The immediate effect would be a reduction in NASA’s ability to maintain a continuous, comprehensive scientific leadership across space and Earth observation domains.
In the near term, these terminations would not only reduce scientific knowledge production but could also erode the continuity of long-running time-series data sets, a cornerstone of climate science and space weather research. The budget analysis notes that the missions slated for cancellation collectively represent many billions of dollars of taxpayer investment built up over decades, and that the cost of keeping them operational in a time of tighter budgets competes with the need to sustain other critical capabilities. The assessment also notes a relatively modest annual cost for these operating missions—on the order of less than 1–2 percent of NASA’s annual budget—and argues that the tradeoffs involved in their removal could be disproportionately large in terms of scientific return and international leadership.
From a programmatic perspective, terminating operating missions also signals a broader shift in NASA’s portfolio management. The agency would be privileging newer, Moon- and Mars-focused capabilities at the possible expense of maintaining a steady stream of robotic science outposts and long-standing observatories. The ripple effects would be felt not only by the projects’ science teams but also by international partners who depend on NASA’s ongoing contributions and data streams. The decision would also influence industrial and contractor ecosystems that provide scientific instruments, spacecraft parts, and operations support for these missions, creating a cascading impact across the broader space economy.
In considering these terminations, it is essential to weigh the opportunity costs—the potential scientific dividends foregone by canceling operating missions against the near-term fiscal relief and the strategic emphasis on Artemis and commercial Mars delivery. The budget proposal frames the cancellations as a temporary step toward a leaner portfolio designed to accelerate Moon and Mars exploration, but the long-term consequences for NASA’s scientific leadership and for the global scientific community would require careful management and strategic mitigation if these cuts were to be realized.
Ending support for Europe-led and international missions
A highly consequential element of the budget plan concerns international partnerships, particularly with the European Space Agency (ESA). The proposal would end U.S. contributions to several Europe-led missions, including the Rosalind Franklin rover—a central component of ESA’s ExoMars program—and a broader set of European-led initiatives such as EnVision, the LISA gravitational wave observatory, and the ARIEL mission to study exoplanetary atmospheres. Rosalind Franklin has been a symbol of close U.S.-European collaboration on Mars exploration, representing a multibillion-euro investment and a shared scientific objective of understanding Mars’ past habitability and potential for life.
Rosalind Franklin’s ExoMars program has faced a long and complicated history. The mission was historically developed with ESA as the primary partner, with NASA contributing to the ascent and lander systems before a shift in partnerships and geopolitical events altered the alliance. In recent years, the program had been supported by U.S. commitments that helped secure a domestic launch vehicle and certain propulsion and landing technologies, with the rover intended to carry a suite of instruments to investigate the Martian environment and its geology. The budget proposal’s move to withdraw U.S. funding would precipitate a setback for ESA’s program timeline and could force ESA to reconfigure mission plans, seek alternative funding, or re-prioritize other instruments to maintain the project’s viability. The potential consequences extend beyond ExoMars; a broader wave of reductions toward European-led missions includes the EnVision mission (Venus orbiter), the LISA mission (gravitational wave observatory), and the ARIEL mission (exoplanet atmospheres), all of which have represented major collaborative ventures.
The rationale for these cuts often centers on reallocating finite resources toward U.S. domestic priorities, such as Artemis, and toward commercial spaceflight partnerships that are expected to deliver more frequent access to space for crewed and cargo missions to the Moon and beyond. However, the erosion of U.S. financial support for international collaborations can have longer-term geopolitical and scientific consequences. ESA and NASA have cultivated a collaborative ecosystem in which shared investments, joint missions, and synchronized science goals yield benefits that extend beyond astronomy and planetary science; they contribute to global scientific leadership, training of the next generation of space scientists and engineers, and the resilience of the international space science community. Reducing U.S. funding for these European partnerships could complicate future joint missions, slow scientific progress, and complicate ongoing efforts to maintain a robust, diversified, and inclusive space exploration program.
Beyond ExoMars, ending U.S. support for a suite of European-led activities—such as EnVision, LISA, and ARIEL—would send a signal about the administration’s approach to international collaboration in space science. While some policymakers argue that these programs should be funded through European channels or pursued via different international arrangements, others see the move as a setback for a global science ecosystem that has benefited from shared expertise, cross-border talent, and multi-national data-sharing standards. The net effect would be a shift in the balance of international partnerships, with potential consequences for the pace of discovery, the distribution of scientific infrastructure, and opportunities for U.S. researchers to access data, participate in joint analyses, and contribute to the development of next-generation space technologies through collaborative projects.
In sum, the proposed withdrawal of U.S. funding from Rosalind Franklin and related international missions would reshape the international science diplomacy landscape. It would influence ESA’s planning, affect NASA’s role as a global partner, and potentially alter the trajectory of joint science programs that have underpinned major planetary and astronomical discoveries for years. The broader implications touch on Europe-U.S. scientific cooperation, the health of the global space economy, and the shared ambition to push the frontiers of space exploration through coordinated, multinational efforts.
Scaling back International Space Station operations
The budget proposal also targets the International Space Station’s operations, including the plan to reduce funding for station operations and crew transportation by about 26 percent. This reduction would likely lead to a smaller crew on the ISS and a diminished research portfolio in the near term. The policy context notes that decommissioning the ISS by 2030 remains the long-range objective of U.S. space policy, but the White House’s fiscal plan would leave the station operating on a leaner and more limited basis through the remainder of the 2020s, with a focus on essential life-support and safety operations while deferring non-critical research activities.
Current policy discussions pre-dating the Trump administration had established a timeline in which the ISS would transition away from large-scale operations by 2030, to be replaced by commercial platforms for low-Earth orbit research. The budget request reiterates this framework, stating that NASA would pivot to maintain only minimal safe operations and a highly focused set of research activities necessary to support Moon and Mars exploration. This approach implies a gradual reduction in crew and cargo flights, a contraction of the ISS’s research portfolio, and a shift in the U.S. strategy for in-orbit research infrastructure.
From a strategic standpoint, the scaling back of ISS operations poses several challenges and opportunities. On the one hand, reducing the station’s activity could lower immediate operating costs and realign resources toward lunar surface programs, life-support system demonstrations, and long-duration mission readiness. On the other hand, the ISS has served as a critical testbed for life support systems, human factors research, and planetary protection protocols—capabilities that are essential for sustained human presence on the Moon and Mars. Critics of the proposal argue that a premature or abrupt scaling back could erode NASA’s leadership in human spaceflight research just as private companies and international partners move toward more ambitious, commercially enabled in-space platforms.
Moreover, the policy recognizes market uncertainty surrounding the emergence of new commercial stations in low Earth orbit. A robust ISS replacement ecosystem might not materialize at the pace envisioned, and the international space community would face a transitional period in which there might be limited in-space research capacity outside of the U.S. domestic program. In such a scenario, other nations, including China, could become the dominant players in low-Earth orbit research, potentially altering the global leadership dynamics in space science and engineering. The decision to scale back ISS operations, therefore, becomes a strategic bet about the timing and feasibility of commercial alternatives, the readiness of private-sector capacity to absorb research needs, and the ability of NASA to maintain a steady pipeline of experiments and data collection during a period of transition.
In sum, the scaling back of ISS operations would reframe NASA’s role in in-orbit research, lifecycle management of the station, and the transition to future commercial platforms. It would require careful planning for continuity of science, data stewardship, and international collaboration during a period in which the United States seeks to reorient its space architecture toward Moon and Mars exploration.
Cuts to human research and health in spaceflight
A fifth major element of the budget plan focuses on human health and performance research—an area central to ensuring astronaut safety and mission success on long-duration journeys to the Moon and Mars. The proposal would reduce funding for human research by a substantial margin, cutting the budget from $151 million to $40 million in fiscal year 2026. This reduction would represent a drastic downscaling of an area that NASA scientists describe as critical for understanding how the human body responds to extended exposure to radiation, microgravity, confinement, and other adverse spaceflight conditions.
NASA’s Human Research Program has long identified several health risks that crews would face during deep-space missions, particularly the three-year-plus durations anticipated for Mars journeys. Key risks include exposure to high radiation levels, cognitive and mental health effects from isolation and confinement, challenges related to operating in a closed, autonomous environment far from Earth, and the physiological and mission-performance implications of long-term microgravity and altered living conditions. The agency’s leaders have repeatedly indicated that a comprehensive understanding of these hazards must evolve from high-risk to medium- or manageable-level risk through systematic research, experimentation, and data collection. This progress is viewed as essential for safe, feasible long-duration exploration missions.
The budget request asserts that most of these health and performance studies occur on the ISS, and the proposed cuts would thus reduce NASA’s capacity to characterize and mitigate the risks associated with deep-space travel. The plan notes that NIH collaboration would also be affected, as the administration signals a broader goal of reducing interagency research commitments. The implications extend to Artemis and future crewed missions, since robust human health data and evidence-based countermeasures are foundational to mission planning, life-support design, habitat configurations, and medical readiness for crewed lunar and Martian expeditions.
Critics warn that slashing this research undermines the safety framework for future exploration and could drive up mission risk, insurance costs, and mission timelines if critical health data is scarce or delayed. Proponents of reallocation might argue that the funds could be redirected toward more immediate near-term technologies and infrastructure, including life-support system demonstrations and habitat technologies that can be tested on the Moon or in lunar analogs. The debate centers on the balance between investing in robust human factors research and accelerating hardware development for the Moon and Mars, and the budget plan posits that the highest-priority, mission-critical work will be preserved while other research programs are preserved or terminated in support of Artemis.
In short, the proposed reduction in human health and performance research marks a significant shift in NASA’s portfolio and risk management for human spaceflight. The long-term consequences of this decision would depend on how Congress2 balances safety, mission readiness, and the broader aim of advancing Moon and Mars capabilities within a constrained budget.
The broader political context and potential consequences
The White House’s Office of Management and Budget leads most of the language in the spending plan, and the office is overseen by a key political figure central to the administration’s broader cost-cutting and reform agenda. The plan’s framework reflects a strategy associated with a broader effort to restructure the federal government’s science, technology, and space programs. Critics argue that the budget’s emphasis on trimming NASA’s portfolio—especially in areas like nuclear propulsion, robotic and human health research, and international partnerships—reflects a political philosophy that prioritizes shorter-term fiscal savings over long-term strategic investments in science and technology leadership.
Several dynamic factors surround the budget’s prospects. First, while the White House has laid out a detailed blueprint, congressional actors in both chambers will fashion their own versions of the fiscal plan. Lawmakers will craft budget bills that determine the funding levels for NASA, potentially restoring or adjusting some of the proposed cuts as they see fit. A Senate bill released during consideration includes language to claw back funding for SLS and Orion costs to support Artemis IV and Artemis V missions, signaling the possibility of partial reversal from the administration’s plan but not a wholesale reinstatement of all cuts. It is common for Congress to modify executive budget proposals, and the final appropriations can diverge significantly from the original plan.
Second, political dynamics such as party priorities, regional interests, and committee control will shape the outcome. Senators and representatives who favor commercial spaceflight and private-sector competition may push for different allocations than those who emphasize traditional NASA mission architectures or international collaborations. The status of NASA leadership and advocacy within the administration—such as influence from political appointees and industry leaders—will also shape the debate. The absence of a strong, empowered advocate at the highest level of NASA due to the withdrawal of certain leadership figures can affect morale, staffing, and the ability to articulate a persuasive case for retaining core programs.
Third, the plan’s emphasis on commercial Mars transportation and a Mars-forward approach could redefine the agency’s relationship with private industry. The budget proposes shifting toward purchasing transportation services for Mars missions and relying more on commercial partners for lunar access, potentially reducing NASA’s role in direct development of certain heavy-lift capabilities in favor of procurement of services. This would align with a broader policy trend toward “buying capabilities” rather than building them in-house, but may also require NASA to maintain a robust domestic industrial base and ensure a predictable demand signal to private companies for sustained investment and risk-taking.
The combination of these political dynamics and programmatic implications raises questions about the long-term health of U.S. space leadership. A plan to scale back NASA in key areas while prioritizing Artemis and commercial partnerships could strengthen a Moon-first architecture but risk eroding in-house capabilities in fundamental science, space technology, and deep-space exploration research. International partnerships could be affected as well, given the potential for reduced U.S. financial commitments to European and other partners, complicating joint missions and data-sharing arrangements.
As the budget process unfolds, observers will watch for signals about the administration’s intent to support or contest the agency’s strategic direction. The interplay between exploration, science, and international collaboration remains a central question for the U.S. space program, and the final funding decisions will shape NASA’s ability to pursue a balanced approach that preserves scientific leadership, fosters innovation in the private sector, and maintains a credible and ambitious plan for Moon and Mars exploration.
Conclusion
The proposed fiscal year 2026 budget presents a watershed moment for NASA, its partners, and the wider space science community. The plan’s near-25-percent reduction in funding would trigger a cascade of consequences across core missions, research priorities, and international collaborations. By zeroing nuclear propulsion funding, terminating a substantial portion of operating missions, withdrawing U.S. support for European-led projects, scaling back ISS operations, and making deep cuts to human health and performance research, the administration signals a fundamental reorientation of how the United States approaches space exploration in the coming decade. The result would be a NASA that must navigate a tightened portfolio, a potential shift toward commercial service procurement for some lunar and Martian objectives, and a redefined role in international space partnerships.
The long-term implications hinge on how Congress responds, how private industry adapts to a shifting funding landscape, and how international partners recalibrate their own programs in light of U.S. policy. If countervailing funding or targeted restorations are enacted, NASA could preserve essential capabilities while pursuing Artemis with renewed focus and efficiency. If the plan moves forward largely as proposed, the agency and its partners may need to embrace a more market-driven and modular approach to exploration—one that emphasizes service procurement, rapid technology demonstrations, and a leaner portfolio—while managing risk across science, human spaceflight, and planetary science domains. The coming months will determine whether this budget philosophy becomes the blueprint for a redefined era of space exploration or whether strategic adjustments will be made to safeguard scientific leadership, international cooperation, and the resilience of the United States’ space program.
