Artist's conception of a spacecraft powered by nuclear thermal propulsion.

Artist's conception of a spacecraft powered by nuclear thermal propulsion. NASA

America Can Beat China in Space with Safe Nuclear Propulsion

A reactor that heats up and expels non-radioactive gas promises unprecedented mobility in orbit.

Propelled by a “nuclear plasma drive,” the spaceship in 2001: A Space Odyssey fascinated moviegoers as the height of science fiction in 1969, even though nuclear-powered submarines had been quietly patrolling the world’s oceans for more than a decade. Today, nuclear-propelled spacecraft are on the verge of becoming reality — and indeed, will be crucial to the West’s efforts in the 21st-century space race with China.

Far from the controlled nuclear explosions envisioned by the Sputnik-era Project Orion, nuclear thermal propulsion, or NTP, will use a reactor’s thermal energy to heat and eject rocket propellant — specifically, liquid hydrogen — at a higher temperature and at a faster velocity than can be achieved with a chemical rocket. NTP engines promise to be roughly twice as efficient as today’s chemical rockets while also offering a much longer service life. This is thanks to Isaac Newton’s third law of motion — every action has an equal and opposite reaction — because the single-use chemical rockets require both a fuel and an oxidizer that burn at a lower temperature and accelerate heavier exhaust at a lower velocity.  

NTP can’t get a spacecraft to orbit, but’s it’s far more efficient for moving things around in space and for longer periods of time — say, moving satellites between orbits, parking them at Lagrange points, and rendezvousing quickly with suspicious foreign spacecraft. This kind of rapid maneuvering in cis-lunar space — from Earth orbit to the moon’s surface — will become increasingly important in U.S. efforts to protect DoD space missions (missile warning, satellite communications, positioning/navigation/timing, environmental sensing, etc.) and those parts of the economy that rely heavily on space systems (financial, transportation, communications, etc.). By reducing the time and cost of moving heavier payloads, NTP will expand warfighter capabilities and the “art of the possible” from Earth orbit out to the Moon.

As such, NTP will become a crucial tool in America’s starlit struggle with China. As the Director of National Intelligence recently reported, China is “working to match or exceed U.S. capabilities in space to gain the military, economic, and prestige benefits that Washington has accrued from space leadership.” Beijing apparently sees lunar missions — the kind that might benefit from NTP — as part of its campaign: China landed a probe on the Moon’s far side in 2019 and is working on sending a crewed mission there. 

U.S. research and development in NTP has long been subject to fits and starts, but appears to be making solid progress again. DARPA and industry are aiming to put a NTP system in orbit by 2025 under a program called DRACO, for Demonstration Rocket for Agile Cis-lunar Operations. In 2019, Congress appropriated $125 million to help NASA develop its own NTP demonstration.

Critically, modern NTP systems are designed with minimal radioactive components and improved safety features. The reactors are designed to not turn on accidentally, even under catastrophic circumstances. Fissile material is both minimized (less than a typical Mars rover) and designed to be inherently safe by encapsulating small individual quantities with protective layers to reduce the danger of scattering radioactive material in an unsuccessful launch. And they violate no law or treaty. Unlike Project Orion or Kubrick’s original engine concept, NTP does not use nuclear explosions. It is a safe, legal approach to motive power in space. 

There is growing bipartisan support for developing space nuclear power and propulsion — SNPP, for short. The Trump administration produced a flurry of national security documents in its final few months to turn SNPP goals into official policy. The Biden administration has indicated willingness to continue this momentum, at least as far as developing advanced nuclear reactors for terrestrial use. The American Jobs Plan announced in March backs nuclear power as a means to modernize power generation and deliver clean energy. The White House has also highlighted nuclear-power R&D in its hints about the 2022 budget request. 

But more must be done to advance this crucial technology. The Biden White House can, for example, highlight SNPP in its upcoming update to the National Security Strategy. Its Office of Management and the Budget can support SNPP in the near term by directing a formal, multi-year program of record in the upcoming 2023 budget build; it should also declare implementation of Trump’s Executive Order on Promoting Small Modular Reactors for National Defense and Space Exploration as to be a cross-agency priority goal. The Biden administration has wisely chosen to embrace the National Space Council, the ideal forum to carry momentum across administrations. It would be prudent to establish a standing subcommittee to oversee SNPP.

DoD has similar opportunities to prioritize SNPP in its forthcoming defense strategy documents and posture hearings. The Pentagon might also consider addressing such capabilities in a space posture review, which would inform force development, doctrine, and operations, while helping industry and allies learn to be better partners. 

Congress also has a vital role to play. Lawmakers should work to codify the goals of the modular-space-reactors executive order into law; direct a federally funded research and development center to review the recent National Academy of Sciences report on space nuclear propulsion from a national security perspective; conduct a hearing with government and outside experts; and fully support SNPP programs in 2022 appropriation acts, including boosting R&D funding, as endorsed in a recent report from the American Nuclear Society. 

While Kubrick’s depiction of space travel has not arrived, the U.S. space enterprise is steadily marching forward. The United States is twenty years past due, but with continued bipartisan leadership, the fundamental technologies will be in place to realize this vision and continue American dominance in space. And it can’t happen soon enough. 

Gregory Pejic served as Deputy Assistant Secretary of Defense for Space Policy from 2020 to 2021. Earlier, he helped the Deputy Secretary of Defense establish the U.S. Space Command and U.S. Space Force.