NASA and DARPA will partner on future phases of the DRACO program to demonstrate a space nuclear thermal propulsion system. Credit: DARPA
By Jeff Foust,
Published by Space News, 16 July 2025
WASHINGTON — A new study recommends that the United States pursue rapid development of a space nuclear power system to keep pace with geopolitical rivals, but is less clear about which agency should take the lead.
The study, “Weighing the Future: Strategic Options for U.S. Space Nuclear Leadership,” offered three options to support in-space demonstrations of nuclear power systems by 2030, learning from past efforts that have failed.
“Everything since 1965, when we launched our first reactor, has fizzled despite billions invested,” said Bhavya Lal, former NASA associate administrator for technology, policy and strategy, during a presentation about the report at a Washington Space Business Roundtable luncheon July 15. “We remain in R&D purgatory, producing papers, not kilowatts.”
The study, co-authored by Lal and former Aerojet Rocketdyne executive Roger Myers and funded by the Idaho National Laboratory, concluded a lack of “mission pull” caused past efforts to falter. Lal described a vicious cycle where that lack of real missions for nuclear systems prevented sustained technology development and, in turn, flight demonstrations and building up of trust in nuclear technologies that create demand for their use in missions.
Lal argued that several factors could break that cycle, emphasizing one of them, geopolitical competition. She cited reports that China and Russia will work together on a megawatt-class nuclear reactor for their International Lunar Research Station. Such a reactor, she said, could allow China to control access to the south polar region of the moon by invoking exclusion zones for safety under the Outer Space Treaty: “In space as on the Earth, first movers make the law.”
The report calls for rapid development of nuclear reactors, although not starting with megawatt-class systems. “We found that if we need to make progress in space nuclear, we need to begin with a small, manageable system on a timeline that keeps stakeholder interest,” she said.
The report offered two approaches for building space nuclear power systems. One scenario, called “Go Big or Go Home,” would develop a government-owned and -operated reactor producing 100 to 500 kilowatts of power, potentially as part of a nuclear electric propulsion system. The reactor would cost about $3 billion to develop, with ground tests in 2028 and a flight demonstration in 2030.
A second scenario, dubbed “Chessmaster’s Gambit,” would support two parallel public private partnerships for reactors in the range of 10 to 100 kilowatts. One, led by NASA, would be used for surface power, while the other, led by the Defense Department, would be for in-space power. The scenario would have the same schedule as the first with an estimated cost of $1 billion per agency.
A third scenario, which could be done in parallel with the other two, would support commercial development of radioisotope power systems using isotopes other than plutonium-238, such as americium-241 or strontium-90, for flight demonstrations in 2028. Such systems would produce less than one kilowatt of power, but she argued could build up flight experience and address regulatory issues in advance of larger reactors.
“It buys time, credibility and momentum, no matter what, and it provides a fallback if larger efforts slip,” she said.
The focus on all the scenarios is primarily on producing power, not nuclear propulsion, a break with recent efforts like the canceled NASA-DARPA Demonstration Rocket for Agile Cislunar Operations (DRACO) project, which sought to demonstrate nuclear thermal propulsion, and NASA efforts for both nuclear thermal and nuclear electric propulsion that the agency’s fiscal year 2026 budget proposal does not fund.
There are several reasons for focusing on power, Lal said, including a lack of demand for nuclear propulsion in contrast to growing interest in nuclear power, as well as a less technical complexity for a system that only needs to generate power.
“Prioritizing power before propulsion is not about abandoning propulsion,” she concluded. “It’s about sequencing smartly: power is needed now, has real customers and builds the foundation for everything else.”
Who leads, and how
A panel of industry officials at the event said they generally agreed with the report’s conclusions, including the recommendation to swiftly move ahead with development of space nuclear power systems.
“It’s been 60 years since we flew SNAP-10,” the first U.S. space nuclear reactor, said Joe Cassady, director of civil space programs at L3Harris. “We can do this before 2028, 2030 to be sure. We just have to make the commitment to go so it.”
“We need to fly something as soon as possible,” said Alex Gilbert, vice president of regulation at Zeno Power, which is developing commercial radioisotope power systems. He said such systems can “stress test” regulatory and policy issues ahead of larger fission reactors.
“If we want to go fast, we can do it in less than two years,” said Robert O’Brien, director of the Center for Space Nuclear Research, leveraging the designs developed back in the 1960s for SNAP-10. “Everything we have on the table today can support a launch approval process. It has flown.”
What was less clear was who should lead development of space nuclear power systems. Some panelists suggested that a separate agency be created rather than assigning it to NASA, DARPA or another organization.
“I think you should do a new one, because all the existing ones have issues,” said Gilbert, suggesting it be patterned after the Manhattan Project that led development of the atomic bomb in World War II. “You need to really have something where everything is institutionally aligned solely with that mission and not diverting funds to other types of vested interests.”
Cassady agreed, saying such an effort needed a leader like Gen. Leslie Groves, who commanded the Manhattan Project, or Adm. Hyman Rickover, who led the U.S. Navy’s development of naval reactors. “You need somebody Rickover-like to direct that national imperative to make it happen.”
O’Brien recommended that NASA create an office of nuclear power and propulsion to oversee work in those topics, modeled on the U.S. Navy’s Office of Naval Reactors. That can allow collaboration with other agencies with necessary expertise, he noted, while focusing on space applications.
Lal said that option two of the report assigned one reactor project to NASA and another to a DOD agency. “It almost doesn’t matter whether it’s AFRL or MDA or DARPA or SDA, if the mission pull is there, whichever entity it is will take it seriously,” she said.
See: Original Article
