NASA Testing Advances Space Nuclear Propulsion Capabilities
Reactor Cold-Flow Test Campaign Completed
Nuclear propulsion and power technologies could unlock new frontiers in missions to the Moon, Mars, and beyond. NASA has reached an important milestone advancing nuclear propulsion that could benefit future deep space missions by completing a cold-flow test campaign of the first flight reactor engineering development unit since the 1960s.
“Nuclear propulsion has multiple benefits including speed and endurance that could enable complex deep space missions.”
Greg Stover, NASA
Teams at the agency’s Marshall Space Flight Center in Huntsville, Alabama, conducted more than 100 tests on the engineering development unit over several months in 2025. The 44-inch by 72-inch unit, built by BWX Technologies of Richmond, Virginia, is a full-scale, non-nuclear, flight-like development test article the size of a 100-gallon drum that simulates propellant flow throughout the reactor across a range of operational conditions.
“Nuclear propulsion has multiple benefits including speed and endurance that could enable complex deep space missions,” said Greg Stover, acting associate administrator of NASA’s Space Technology Mission Directorate at NASA Headquarters in Washington. “By shortening travel times and expanding mission capabilities, this technology will lay the foundation to explore farther into our solar system than ever before. Information from the cold-flow test series is instrumental in understanding the operational characteristics and fluid flow performance of nuclear reactors.”
The cold-flow tests at NASA Marshall are the culmination of a multi-year activity for the agency and its industry partners. Key test objectives included simulating operational fluid-dynamic responses, gathering critical information for design of the flight instrumentation and control system, providing crucial validation of analytical tools, and serving as a pathfinder for manufacturing, assembly, and integration of near-term flight-capable nuclear propulsion systems.
Other benefits to space travel include increasing the science payload capacity and higher power for instrumentation and communication.
Test engineers were able to demonstrate that the reactor design is not susceptible to destructive flow-induced oscillations, vibrations or pressure waves that occur when a moving fluid interacts with a structure in a way that makes the system shake.
“We’re doing more than proving a new technology,” said Jason Turpin, manager of the Space Nuclear Propulsion Office at NASA Marshall. “This test series generated some of the most detailed flow responses for a flight-like space reactor design in more than 50 years and is a key steppingstone toward developing a flight-capable system. Each milestone brings us closer to expanding what’s possible for the future of human spaceflight, exploration, and science.”
The Space Nuclear Propulsion Office is part of NASA’s Technology Demonstration Missions Program within the agency’s Space Technology Mission Directorate.
Impressive milestone. The cold-flow validation is crucial because proving a reactor can handle fluid dynamics without destructive oscillations is what stopped previous attempts in the 60s. The pathfinding value for manufaturing and assembly is probably more important than the flow data itself since building flight-rated nuclear hardware hasnt been done at this scale in decades. Travel time reduction for Mars missions becomes way more realistic once propulsion can deliever higher specific impulse.