DARPA Backs Ground Test of Autonomous Nuclear Reactor Controller With SpaceNukes Award

Space Nuclear Power Corporation, known as SpaceNukes, has been awarded an Other Transaction Agreement by the Defense Advanced Research Projects Agency (DARPA), the company announced on October 21, 2026. The agreement falls under DARPA's Fast Capacitance, or Fat Cat, program, which aims to advance autonomous reactor operation for national security missions.

The Fat Cat program is managed by Dr. Tabitha Dodson in DARPA's Defense Sciences Office. The contract funds the development and ground testing of advanced reactor control technologies intended to extend the demonstrated capability of American nuclear power.

Under the agreement, SpaceNukes and Los Alamos National Laboratory will design, build and carry out a follow-on nuclear ground test of a Kilopower reactor. The new test will feature active control rod operation, a step beyond the passively controlled design demonstrated in the 2018 Kilopower Reactor Using Stirling Technology (KRUSTY) test.

The company said the award builds on that earlier work. In 2018, key members of the SpaceNukes team, then employed by Los Alamos National Laboratory and NASA, performed the foundational KRUSTY work, which SpaceNukes describes as the only full-power ground test of a new American space reactor in five decades.

The program is organized in phases, with design, procurement and integration gates leading to the ground demonstration. SpaceNukes expects it to yield both nuclear-tested hardware and the engineering basis for autonomous, actively controlled reactor operation. Integration work will take place at the company's workshop in Medina, Ohio, under Chief Engineer Marc Gibson.

According to the company, the work positions American industry to supply reliable nuclear power for a wider range of mission profiles, including those that demand dynamic power management and rapid response under varying operational conditions.

"This award recognizes the maturity and continuity of the team that designed, built, and tested KRUSTY in 2018," said Patrick McClure, SpaceNukes' chief operating officer. He added that the company is proud to work alongside Dodson and Los Alamos National Laboratory to deliver "the next demonstrated step in American nuclear power."

Andy Phelps, the company's chief executive, said: "There is no substitute for demonstrated technology when American national security objectives are at stake." He said the award lets the company advance work begun in the KRUSTY program and bring another tested capability forward for the nation.

SpaceNukes says it was founded on the belief that nuclear power is essential to the future on Earth and in space, and its stated goal is to enable the deployment of fission reactors in space. David Poston, the chief technology officer, and McClure carried out the KRUSTY work at Los Alamos National Laboratory, while Gibson led the program at NASA Glenn Research Center. Omar Mireles, formerly of NASA Marshall Space Flight Center, is also part of the team. The company holds a license from Los Alamos National Laboratory for the Kilopower technology, with headquarters and a 3D-printing workshop in Los Alamos, New Mexico, and a workshop with thermal and vacuum capabilities in Medina, Ohio.