NASA Solicits Proposals for Advanced Lunar Radioisotope Power Systems

NASA has officially opened a solicitation for research and development proposals targeting five critical technological areas, with a primary focus on high-efficiency radioisotope power systems (RPSs) designed for lunar surface operations. The agency is specifically seeking to advance the development of radioisotope Stirling generators (RSGs) to support long-term human exploration at the lunar south pole. This initiative aims to address the unique power challenges of the region, where extended periods of darkness significantly limit the effectiveness of traditional solar energy arrays.

The solicitation represents a strategic shift in NASA's infrastructure planning, moving away from orbital station concepts toward the establishment of a sustainable base on the lunar surface. By prioritizing the development of compact, reliable nuclear power sources, the agency intends to provide consistent survival heat and electrical power for landers and rovers operating in harsh, permanently shadowed environments. This effort is part of a broader push to mature the industrial capabilities required for a permanent human presence on the moon.

At the heart of the new solicitation is the requirement for higher-efficiency power conversion systems. NASA has identified radioisotope Stirling generators as a key technology capable of reducing fuel requirements by a factor of three to four compared to existing radioisotope thermoelectric generators. The agency is looking for designs that can deliver between 50 We and 150 We of DC power in a vacuum environment, while achieving at least 20 percent system efficiency and a specific power of at least 1 W/kg.

These systems must include a Stirling power convertor, an electronic controller, a thermal management system, and a robust heat source. The design life for these units is set at a minimum of five years, though the agency is encouraging proposals that consider potential extensions for future applications. NASA is targeting projects that currently sit at a technology readiness level of 3 or 4, with the goal of advancing them to TRL-5 or TRL-6 through a structured two-phase development process.

The decision to solicit these technologies follows NASA's pivot toward surface-based lunar exploration. The south pole region has become the focal point for these efforts due to its unique environmental conditions and potential for in-situ resource utilization. Because solar power is intermittent or unavailable during the long lunar nights, nuclear power is viewed as an essential component for maintaining critical infrastructure and life-support systems.

Beyond the immediate lunar requirements, the solicitation encourages developers to consider the broader utility of their designs. NASA is interested in analytical demonstrations that show how these systems could be adapted for future Mars missions, including potential power outputs of up to 300 We and design lives extending to 10 years. While the current project restricts these advanced capabilities to conceptual planning, they highlight the agency's long-term vision for standardized, high-reliability power systems across multiple planetary environments.

NASA is emphasizing the role of private industry in closing the critical gaps necessary for deep-space exploration. By partnering with commercial entities, the agency aims to bolster the U.S. industrial base and accelerate the maturation of essential technologies. This collaborative approach is intended to ensure that the infrastructure required for sustainable lunar operations is developed with the necessary speed and technical rigor.

"NASA is accelerating the development of key technologies and closing critical gaps needed for long-term human exploration at the moon," 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."

In addition to radioisotope power systems, the solicitation covers four other technological domains essential for lunar surface operations. These include the development of advanced solar arrays, oxygen extraction systems, in-space manufacturing tools, and the production of advanced nanomaterials. This multi-faceted approach reflects the complexity of building a self-sustaining base, where power generation is only one of several interdependent systems that must function reliably in an extreme environment.

These initiatives are running in parallel with other major agency projects, such as the Space Reactor-1 Freedom program, which is developing nuclear electric propulsion for a planned 2028 Mars mission. By simultaneously investing in surface power and propulsion technologies, NASA is attempting to create a comprehensive suite of nuclear-enabled capabilities that will support both lunar and deep-space exploration objectives over the coming decade.

The development of these technologies will follow a rigorous two-phase execution plan. The first phase focuses on system concept design and technology planning, ensuring that the proposed approaches are technically sound and aligned with NASA's mission requirements. The second phase will involve detailed design, procurement, assembly, integration, and testing, culminating in the final delivery of an electrically heated prototype for evaluation.

While the agency is open to various fuel types that meet the design life requirements, it has explicitly noted that heat source designs utilizing americium-241 are considered in-scope. This flexibility allows for potential extensibility to other radioisotopes as the technology matures. The agency's commitment to this development cycle underscores its intent to move beyond theoretical research and toward the deployment of flight-ready hardware for upcoming lunar missions.