Trump’s NASA Budget Cuts Nuclear Propulsion: A Deeper Look

Picking favorites — the draconian cuts

On June 2, 2025, the White House released President Trump’s fiscal year (FY) 2026 budget request for NASA, proposing a 24% reduction in total funding—from $24.8 billion in FY 2025 to $18.8 billion. Among the most controversial elements are deep cuts to NASA’s Space Technology Mission Directorate (STMD), slicing its budget almost in half from $1.1 billion to $568 million, and full termination of nuclear thermal propulsion (NTP) and nuclear electric propulsion (NEP) development.

“The reductions also scale back or eliminate technology projects that are not needed by NASA or are better suited to private sector research and development.”
—White House technical supplement, May 2025

Key program cancellations

• DRACO (Demonstration Rocket for Agile Cislunar Operations): End of NASA’s participation despite DARPA completing its knowledge transfer.
• Future NTP and NEP efforts: Zero funding, though NTP offers ~900 s specific impulse (Isp) versus ~450 s for chemical.
• Space Launch System (SLS) and Orion crew vehicle: Proposed cancellation, shifting human exploration to commercial landers.
• Multiple robotic science missions: Mars Sample Return, Venus probes, and potential space telescopes.

DRACO’s design and potential

DRACO, a joint NASA–DARPA effort with Lockheed Martin and BWX Technologies, aimed to demonstrate an NTP engine in LEO by 2027. Key specifications included:

1. Reactor power output: ~300 MW_th.
2. Propellant: Cryogenic liquid hydrogen at ~20 K in an insulated tank.
3. Chamber temperature: Up to 2,760 °C (5,000 °F) to achieve ~900 s Isp.
4. Thrust: 25–50 kN, double the efficiency of LH₂/LOX chemical engines.
5. Fuel: High-assay low-enriched uranium (<20% U-235).

NTP offers high thrust-to-weight ratios and elevated Isp, combining the rapid burn of chemical rockets with the efficiency of electric systems—critical for crewed Mars missions.

Technical foundations of nuclear propulsion

Nuclear Thermal Propulsion (NTP) uses a nuclear reactor to heat hydrogen propellant. Advantages:

• High thrust (10⁴–10⁵ N) suitable for crewed transits.
• Specific impulse of 800–1,000 s, roughly twice that of LH₂/LOX.
• Reduced propellant mass—up to 40% mass savings on a Mars cargo mission.

Nuclear Electric Propulsion (NEP) employs a reactor to generate electricity for ion/plasma thrusters:

• Isp 3,000–10,000 s, ideal for deep-space cargo.
• Low thrust (~0.1–1 N), requiring long-duration burns.
• Power densities >50 kW/kg target for compact reactors.

“To achieve in-space NTP testing, you must resolve ground-test radiological scrubbing and high-temperature materials,”
—Greg Meholic, Aerospace Corporation

Testing infrastructure and regulatory hurdles

The 21st-century regulatory environment demands advanced containment and scrubbers to remove radioactive particulates from exhaust. Building a ground-test facility with full radiological protection could require multi-billion-dollar investment and 5–7 years of construction—far beyond NASA’s current budget.

By contrast, chemical engine test stands cost tens of millions and can be operational in under two years. This disparity underpins the administration’s argument that near-term missions can rely on conventional propulsion while private industry tackles long-lead nuclear R&D.

Policy and funding landscape post-2025

Congress has historically boosted nuclear propulsion funding above White House proposals:

• FY 2024 enacted: $117 million for nuclear propulsion vs. Biden’s $91 million request.
• Senate appropriators in March 2025 recommended $130 million for STMD, including NTP & NEP.
• House hearing (May 2025) saw bipartisan support for continued DARPA–NASA collaboration on DRACO.

The FY 2026 appropriations process will reconcile these differences. NASA Administrator nominee Jared Isaacman—withdrawn in June 2025—had pledged to champion nuclear propulsion, highlighting its lack of commercial appeal and regulatory challenges as reasons for NASA leadership to pursue it.

Expert perspectives on mission architectures

“Chemical-only architectures demand pre-positioned propellant on Mars and multiple Earth refuelings—an operational Rube Goldberg machine,” said Kurt Polzin, chief engineer for NASA’s nuclear projects. “NTP simplifies logistics: carry fuel for round-trip in one integrated system.”

Elon Musk’s SpaceX counters with Starship and in-situ resource utilization (ISRU) on Mars, aiming to produce ~1 Mt of CH₄/LOX propellant via Sabatier and water electrolysis plants. However, setting up and operating these factories poses high risks and complexity.

Future prospects and commercial opportunities

Despite DRACO’s cancellation, NASA’s Fission Surface Power program—funded in the President’s request—continues reactor development for lunar/Martian bases, with Lockheed Martin and BWXT as prime contractors. Compact reactors generating ~40 kW_e are slated for Artemis Vk landers.

Commercial interest in small modular reactors (SMRs) is rising, yet investors remain cautious given 10–20 year ROI horizons. Dark Fission’s CEO Fred Kennedy notes that “space-nuclear is hard-squared,” urging sustained government commitment to de-risk early-stage technology.

Conclusions: Balancing near-term needs and long-term vision

The Trump FY 2026 budget reflects a strategic pivot toward private-sector-led lunar and Martian landers, deprioritizing government-led propulsion R&D. While conventional propulsion suffices for Artemis III and initial Mars cargo runs, broad consensus holds that nuclear rockets are indispensable for sustainable human exploration of the outer Solar System.

As Congress drafts its appropriation bills, stakeholders—from aerospace contractors to National Academies researchers—will lobby to preserve at least partial funding for NTP and NEP, ensuring that the U.S. retains leadership in the next generation of space propulsion.