NASA solicits lunar radioisotope power

NASA has announced it is seeking proposals for five technological areas, including radioisotope power systems (RPSs), to support exploration missions with a near-term focus on a base at the south lunar pole.

The solicitation specifically seeks to support the research and development of higher-efficiency power conversion systems, such as radioisotope Stirling generators (RSGs), which it said "can reduce the amount of required fuel by a factor of three to four compared to current RPS technologies while also enabling the potential use of alternative fuels."

According to the statement of objectives, NASA is looking to design, fabricate, and test an electrically heated RSG prototype for lunar applications.

The effort is described as "fundamentally a research and development initiative aimed at refining system designs and demonstrating innovative approaches where full system definitions are still evolving."

The other technological areas included in the solicitation are for solar arrays, oxygen extraction, advanced manufacturing in space, and nanomaterials.

System specs: NASA is looking for an RSG that includes a Stirling power convertor, electronic controller, thermal management system, heat source, and potentially dynamic balancer.

The design must be capable of providing survival heat and power for landers and rovers to endure harsh environments, such as permanently shadowed regions. Specifically, NASA is seeking systems that can provide 50 We-150 We DC power output in a vacuum environment.

The solicitation seeks designs with an integrated system performance achieving at least 20 percent system efficiency, a specific power of at least 1 W/kg, and a minimum design life of five years.

Any fuel type that meets the design life will be considered acceptable, and heat source designs that utilize americium-241 fuel with potential extensibility to other radioisotopes will be considered in-scope.

NASA is looking for projects that start at a technology readiness level (TRL)-3 or -4 and that can be progressed to TRL-5 or -6.

The project will be executed in two phases: system concept design and technology planning followed by detailed design, procurement, assembly, integration, testing, and final delivery.

While the overall solicitation is focused on technology for a moon base, NASA is seeking proposals that have considered extension to future applications, including survival in the Mars environment, power output of up to 300 We, design life up to 10 years, and use of alternative radioisotopes, though this project restricts these extensions to analytical demonstrations.

NASA context: In March, NASA announced it was pivoting away from the Gateway Program, which aimed to establish a space station in lunar orbit, and toward the goal of putting a base on the moon's surface. The mission's focus is on operations in the south pole region where the long nights make solar power less effective, making nuclear an important power option for a lunar base.

At the same time, the administration also announced a new project-Space Reactor-1 Freedom-a nuclear electric propulsion rocket that NASA plans to send to Mars in 2028.

He said it: "NASA is accelerating the development of key technologies and closing critical gaps needed for long-term human exploration at the noon," said Greg Stover, director of NASA's Advanced Research and Technology Division. "Partnering with industry will strengthen the U.S. industrial base as we mature the capabilities and infrastructure needed for a sustainable lunar presence."