NASA has completed the initial phase of its Fission Surface Power Project, which sought to develop concept designs for a small, electricity-generating nuclear fission reactor that could be used during a future demonstration on the Moon and to inform future designs for Mars.
NASA awarded three $5m contracts in 2022, tasking each commercial partner with developing an initial design that included the reactor; its power conversion, heat rejection, and power management and distribution systems; estimated costs; and a development schedule that could pave the way for powering a sustained human presence on the lunar surface for at least 10 years.
“A demonstration of a nuclear power source on the Moon is required to show that it is a safe, clean, reliable option,” said Trudy Kortes, programme director at Technology Demonstration Missions within NASA’s Space Technology Mission Directorate. While solar power systems have limitations on the Moon, a nuclear reactor could be placed in permanently shadowed areas (where there may be water ice) or generate power continuously during lunar nights, which are 14-and-a-half Earth days long.
NASA designed the requirements for this initial reactor to be open and flexible to maintain the commercial partners’ ability to bring creative approaches for technical review. “There was a healthy variety of approaches; they were all very unique from each other,” said Lindsay Kaldon, Fission Surface Power project manager at NASA’s Glenn Research Centre in Cleveland. “We didn’t give them a lot of requirements on purpose because we wanted them to think outside the box.”
NASA specified that the reactor should stay under six tonnes and be able to produce 40 kilowatts (kW) of electrical power, ensuring enough for demonstration purposes and additional power for running lunar habitats, rovers, backup grids, or science experiments. NASA also set a goal that the reactor should be capable of operating for a decade without human intervention. Safety, especially concerning radiation dose and shielding, was another key driver for the design.
Beyond these set requirements, the partnerships envisioned how the reactor would be remotely powered on and controlled. They identified potential faults and considered different types of fuels and configurations. Having terrestrial nuclear companies paired with companies with expertise in space made for a wide range of ideas.
NASA plans to extend the three Phase 1 contracts to gather more information before Phase 2, when industry will be solicited to design the final reactor to demonstrate on the Moon. This additional knowledge will help the agency set the Phase 2 requirements, Kaldon said.
After Phase 2, the target date for delivering a reactor to the launch pad is in the early 2030s. On the Moon, the reactor will complete a one-year demonstration followed by nine operational years. If all goes well, the reactor design may be updated for potential use on Mars.
Image: Artist's impression of a nuclear plant on the moon (courtesy of NASA)
