Space nuclear power and propulsion programs in the United States face near-term operational challenges and longer-term risks, despite growing political and financial momentum around them. During the Space Nuclear Industry Symposium on August 13, government officials and industry representatives presented progress on projects including NASA’s Space Reactor 1 Freedom project, which aims to launch a nuclear electric propulsion system by the end of 2028, and the Lunar Reactor 1 program to develop a nuclear power system for use on the Moon.
Aaron Miles, strategic capabilities coordinator at the White House Office of Science and Technology Policy, said these programs lie at the intersection of growing interest in the space and nuclear energy sectors, describing the current phase as an opportunity whose effects could extend across an entire generation. But this interest does not eliminate constraints that could affect the United States’ ability to turn its plans into a sustainable production system.
HALEU Fuel Could Become a Bottleneck
One of the most prominent challenges concerns high-assay low-enriched uranium fuel, known as HALEU, which is likely to be used in space reactors. Miles noted that the United States currently has no production line for ceramic HALEU fuel, while demand for the fuel itself is growing among terrestrial nuclear reactor programs, including small modular reactors.
The U.S. Department of Energy is currently the only domestic supplier of HALEU. On July 23, the department announced that it had allocated an unspecified quantity to NASA for use in the SR-1 mission. It also allocated fuel to Radiant, a reactor company, following similar allocations to other reactor companies during the previous year.
Jeremy Kenny, director of NASA’s Office of Advanced Nuclear Energy Technologies, said that the availability of HALEU and its supply chain represent a positive challenge resulting from expanding activity, but could become an obstacle when setting priorities and ensuring the required quantities. Other risks raised include reactor-component supply chains, the limited number of workers who combine nuclear and space expertise, and the small number of available ground test sites.
Parallel Programs Compete for the Same Resources
NASA’s programs do not operate in a vacuum. At the same time, other commercial and government entities are developing small nuclear reactors, which could increase competition for fuel, components, and expertise. One example is the U.S. Army’s Janus program, which aims to develop microreactors to supply bases with power.
Jeff Waksman, the Army’s first deputy assistant secretary for installations, energy, and environment, said the Army would soon announce the names of five companies it had selected to proceed with developing microreactors under the program, along with the bases that will host the reactors and the overall budget. Although Janus does not focus on space applications, Waksman described it as a spearhead for advanced nuclear energy applications, noting the Army’s cooperation with NASA because of the technical overlap and the limited expertise available.
In practical terms, this means that the success of space nuclear programs may depend in part on the ability of terrestrial and space programs to coordinate their needs rather than compete directly for fuel, personnel, and facilities. Miles and Waksman emphasized the need for public- and private-sector cooperation to build a permanent space nuclear industrial capability.
The More Distant Problem: What Happens After 2029?
The concerns are not limited to hardware readiness. Bhavya Lal, a former NASA official in the areas of technology, policy, and strategy, warned that current support for the programs may be tied more to individuals and political positions than to stable institutional frameworks. She raised a direct question about whether a space nuclear program would still exist three years from now, specifically when a new U.S. administration takes office in January 2029.
Lal believes that the SR-1 mission does not have a sufficiently clear customer. It carries a technology-demonstration payload, including a group of Mars helicopters called SkyFall, but that payload could launch on another mission. The LR-1 lunar reactor program also does not directly depend on SR-1. According to her argument, missions SR-2, SR-3, and SR-4 are the ones that actually require SR-1 to continue, but they do not yet exist.
This situation carries a practical risk: even if SR-1 launches on schedule in December 2028, a subsequent administration could cancel the following missions. These concerns are based on a historical precedent; the United States launched its first space nuclear reactor, SNAP-10A, in the 1960s, and subsequent missions were then canceled.
What Is Needed to Stabilize the Program?
Lal proposed that NASA begin work on the SR-2 mission before SR-1 launches and develop contingency plans in case the mission experiences delays. She also called for involving Congress in ownership of the program by securing multiyear funding allocations, rather than merely briefing it on project developments.
These proposals show that the challenge is not simply launching a single reactor, but creating a connected chain of funding, manufacturing, testing, and follow-on missions. Without this continuity, the United States may succeed in carrying out a single technology demonstration, but it will not necessarily build a scalable and sustainable space nuclear capability.