NASA solicits lunar radioisotope power

To tackle this, NASA launched the NextSTEP-3 Broad Agency Announcement Appendix A: Lunar Enabling Infrastructure Accelerator solicitation, as reported by the agency’s news release. The program targets five distinct technological capability gaps required to establish a continuous operational base in the lunar South Pole region.

Radioisotope Stirling Generators and Lunar Power Solutions

Among the core power technologies requested in the solicitation are radioisotope Stirling generators (RSGs). The solicitation specifically seeks to support the research and development of higher-efficiency power conversion systems, such as 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.

NASA is looking for an RSG that includes a Stirling power convertor, electronic controller, thermal management system, heat source, and potentially dynamic balancer. The agency specifies that these systems 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. Furthermore, the designs must achieve an integrated system performance of 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.

Broad Agency Solicitation and Five Technology Focus Areas

The broader solicitation intends to cultivate U.S.-led capabilities while maintaining full and open competition among private industry, academic institutions, and not‑for‑profit entities, as well as international partners participating through U.S.-led teams. The NextSTEP-3 solicitation aims to mature and demonstrate capabilities in five areas:

• Vertical solar array technology that can provide consistent power generation, management, distribution, and energy storage.
• In-situ resource utilization oxygen from regolith production to extract usable oxygen molecularly bonded to rock and dust covering the Moon’s surface.
• Radioisotope Stirling generator, a type of nuclear energy technology that uses heat from fissile materials to produce electric power for operating spacecraft systems in the darkest, dustiest, and most remote places.
• In-space advanced manufacturing to reduce reliance on resupply missions from Earth and to optimize mission flexibility and resilience on the Moon.
• Innovative nanomaterials production to advance the commercial availability and quality of nanomaterials that can be used in lunar exploration.

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. NASA may apply insights gained from the resulting contracts of this solicitation, such as technical data and demonstration results, to shape future acquisition strategies. 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 Mars environments, 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.

Strategic Pivot Toward a Sustainable Lunar Base

This solicitation aligns with a wider strategic pivot within the agency. 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. Stover added, Partnering with industry will strengthen the U.S. industrial base as we mature the capabilities and infrastructure needed for a sustainable lunar presence.