Nuclear thermal propulsion ship
An illustration of a spacecraft for deep space missions powered by nuclear thermal propulsion. Congress has added funding to NASA appropriations bills to support development of the technology. Credit: NASA/Marshall

WASHINGTON — NASA has selected three teams of companies to perform concept studies of nuclear thermal propulsion (NTP) reactors while making plans to fund similar studies for nuclear surface power systems.

Jim Reuter, NASA associate administrator for space technology, announced the awards in a presentation at the American Astronautical Society’s Glenn Memorial Symposium July 13. Each contract is worth approximately $5 million and will last one year.

One contract will go to BWX Technologies, working with Lockheed Martin. A second contract will go to General Atomics Electromagnetic Systems, working with X-energy and Aerojet Rocketdyne. The third will go to Ultra Safe Nuclear Technologies, working with its parent company, Ultra Safe Nuclear Corporation, as well as Blue Origin, General Electric Hitachi Nuclear Energy, General Electric Research, Framatome and Materion.

All three studies are focused on developing a design for a reactor that would be part of a future NTP system. That reactor would heat up a propellant such as liquid hydrogen, generating thrust at far higher efficiencies than conventional propulsion systems and enabling shorter transit times for missions to Mars.

Under the study contracts, each team will mature their reactor designs to “30% fidelity” of the final design, demonstrating that it is feasible and estimating the cost and schedule to build a prototype reactor. They will also develop fundamental operating and performance requirements for the overall NTP engine and its subsystems.

NASA is working with the Department of Energy’s Idaho National Laboratory on the contracts, and that lab will conduct design reviews of each team’s reactor concepts at the end of the study period.

The potential benefits of reduced travel time for Mars missions have elevated interest in both NTP and nuclear electric propulsion (NEP) after an extended period of little work on those technologies. A study in February by a National Academies committee recommended NASA accelerate its work on those technologies so they can be available for human missions to Mars by the late 2030s.

Reuter, speaking at a Space Transportation Association webinar in June, said that study’s conclusions didn’t surprise the agency. “You need a lot of technology development on both of them,” he said of both NTP and NEP. “That has caused us to step back a little bit and see how can put together a total road map that can address both technologies as we go forward.”

NASA is not the only agency pursuing NTP technologies. DARPA’s Demonstration Rocket for Agile Cislunar Operations (DRACO) program is supporting initial studies of NTP systems that would be used for rapid maneuvering in cislunar space. In April, DARPA awarded General Atomics a $22 million contract for reactor design work, while Blue Origin and Lockheed Martin won contracts to develop spacecraft contracts using NTP systems for the DRACO program.

Reuter said at the Glenn Symposium that NASA is cooperating with DARPA on their respective NTP programs. “We’re very well integrated,” he said. “Our intent is to work even more closely as we go forward, and we see lots of ways that we can jointly go forward.”

Congress has pushed NASA to develop NTP systems by setting side funding in appropriations bills for technology development, even when NASA has not requested it. That includes a fiscal year 2022 appropriations bill a House subcommittee advanced July 12, which provides $110 million for NTP work.

That funding has sometimes put work on nuclear propulsion in conflict with NASA’s interest in surface fission power systems, which the agency anticipates needing before NTP in order to support Artemis missions on the surface of the moon. A reactor can provide power during the extended lunar night, when solar power is unavailable.

Reuter said that, with the NTP study contracts awarded, the agency will move ahead with similar work on nuclear surface power. “A forthcoming request for proposals will ask similar things from industry: preliminary designs of a 10-kilowatt-class system for fission surface power that we could demonstrate on the lunar surface,” he said. He did not give a more specific schedule for that call for proposals.

Jeff Foust writes about space policy, commercial space, and related topics for SpaceNews. He earned a Ph.D. in planetary sciences from the Massachusetts Institute of Technology and a bachelor’s degree with honors in geophysics and planetary science...