NASA has passed a significant milestone in the development of nuclear thermal propulsion (NTP), a technology poised to revolutionize deep space exploration. The agency recently completed a critical “cold-flow” test campaign—the most comprehensive of its kind in over 50 years—on a full-scale, flight-like reactor prototype.
“This work is a key steppingstone toward a flight-capable system,” said Jason Turpin, manager of the Space Nuclear Propulsion Office at NASA’s Marshall Space Flight Center in Huntsville, Alabama, where the tests were conducted. “Nuclear propulsion has the potential to shorten travel times and expand mission capabilities, laying the foundation to explore farther into our solar system than ever before.”
Unlike traditional chemical rockets, an NTP system uses a fission reactor to superheat a propellant like liquid hydrogen, expelling it at tremendous speeds to generate thrust. This offers profound advantages for crewed missions, including drastically reduced transit times to destinations like Mars, increased mission flexibility, and greater power for science instruments and communications.
The recently tested unit, built by BWX Technologies, is a non-nuclear engineering development article the size of a 100-gallon drum. Over several months in 2025, engineers at Marshall conducted more than 100 tests, simulating how propellant would flow through an actual operating reactor under various conditions.
“By shortening travel times and expanding mission capabilities, this technology will lay the foundation to explore farther into our solar system than ever before,” said Greg Stover, acting associate administrator of NASA’s Space Technology Mission Directorate.
A primary goal was to ensure the reactor’s structural integrity under intense fluid dynamics. The team successfully demonstrated the design is not susceptible to destructive flow-induced vibrations or pressure waves—a crucial safety validation. The campaign also provided invaluable data for designing the flight instrumentation and control systems and served as a pathfinder for manufacturing and assembling future flight systems.
“This test series generated some of the most detailed flow responses for a flight-like space reactor design in decades,” Turpin added. “Each milestone brings us closer to expanding what’s possible for the future of human spaceflight.”
Managed under NASA’s Technology Demonstration Missions program, this progress in nuclear thermal propulsion represents a pivotal step toward unlocking faster, more capable missions to the Moon, Mars, and beyond.
