Power on the Moon. What Will it Take to Survive the Lunar Night?

With the help of international and commercial partners, NASA is sending astronauts back to the Moon for the first time in over fifty years. In addition to sending crewed missions to the lunar surface, the long-term objective of the Artemis Program is to create the necessary infrastructure for a program of “sustained lunar exploration and development.” But unlike the Apollo missions that sent astronauts to the equatorial region of the Moon, the Artemis Program will send astronauts to the Moon’s South Pole-Aitken Basin, culminating in the creation of a habitat (the Artemis Basecamp).

This region contains many permanently-shadowed craters and experiences a night cycle that lasts fourteen days (a “Lunar Night“). Since solar energy will be limited in these conditions, the Artemis astronauts, spacecraft, rovers, and other surface elements will require additional power sources that can operate in cratered regions and during the long lunar nights. Looking for potential solutions, the Ohio Aerospace Institute (OAI) and the NASA Glenn Research Center recently hosted two space nuclear technologies workshops designed to foster solutions for long-duration missions away from Earth.

NASA’s Glenn is the home of NASA’s power systems research, where engineers and technicians work to develop advanced power generation, energy conversion, and storage methods – with applications ranging from solar, thermal, and batteries to radioisotopes, fission, and regenerative fuel cells. The Clevand-based OAI is a non-profit research group dedicated to fostering partnerships between government and industry to further aerospace research. The OAI has a long history of collaborating and contracting with NASA and the DoD.

These workshops were the latest step in NASA and the DOE’s collaborative development of nuclear technologies for crewed space exploration programs. In terms of propulsion, these efforts have aimed to advance proposals for nuclear-thermal and nuclear-electric propulsion systems (NTP/NEP). In the former case, a nuclear reactor is used to heat propellants like liquid hydrogen (LH₂); in the latter, the reactor generates electricity for a magnetic engine that ionizes an inert gas like xenon (aka. Ion Propulsion).

In 2021, NASA and the DoE selected three reactor design proposals for a nuclear thermal system that could send cargo and crews to Mars and science missions to the outer Solar System. The contracts, valued at around $5 million apiece, were awarded through the DOE’s Idaho National Laboratory (INL). In June 2022, they followed up by selecting three design concept proposals for a Fission Surface Power (FSB) system that would expand on NASA’s Kilopower project and could be sent to the Moon as a technology demonstration for the Artemis Program.

The nuclear technologies workshops saw over 100 engineers, managers, and experts in power systems from across government, industry, and academia come together to discuss topics ranging from Fission Surface Power to space nuclear propulsion systems. The event featured speakers and panelists from NASA, the U.S. Department of Energy (DoE), the Department of Defense (DoD), and the commercial sector to share knowledge, results, and lessons learned from past efforts to develop nuclear technology. Todd Tofil, NASA’s Fission Surface Power project manager, explained in a NASA press release:

“Reliable energy is essential for exploration of the Moon and Mars, and nuclear technology can provide robust, reliable power in any environment or location regardless of available sunlight. As we move forward with projects like Fission Surface Power and nuclear propulsion, it makes sense to look at work that’s been done in the past at NASA and other agencies to see what we can learn.”

The first workshop (in November) included discussions on mission requirements that call for nuclear power, such as long-duration missions beyond Earth where solar power isn’t always an option. This includes the Moon’s southern polar region but also on Mars, where the increased distance and periodic dust storms can also limit solar energy. The workshop also included discussions about test hardware from previous programs that could be relevant to today’s projects. Things concluded with a tour of the seven Glenn facilities engaged in nuclear research. Said Lee Mason, associate chief of Glenn’s Power Division:

“The workshop provided an excellent opportunity to discuss technology advancements and provide the new industry teams an opportunity to learn from the past and build on the foundation that’s been established. Strong industry-government collaboration and knowledge sharing will help us be successful with Artemis and missions beyond.”

The second workshop took place in early December and saw over 500 people from 28 countries meeting (in-person and virtually) to discuss how to address the extreme challenges of operating in the Lunar Night. During the three-day workshop, attendees learned about relevant developments in the field from power and thermal technology experts from NASA and other organizations. These included those funded by NASA’s Space Technology Mission Directorate (STMD) and Exploration System Development Mission Directorate (ESDMD).

Status updates were also provided by several commercial entities that are partnered with NASA through the Commercial Lunar Payload Services (CLPS) initiative, which will begin delivering experiments and technology demonstrations to the lunar surface in early 2023. Most of these missions rely on solar panels or batteries and will face power and thermal challenges as they land in the South-Pole Aitken Basin. Since these systems need to remain in operation longer than a Lunar Day (also 14 days), CLPS providers will also benefit from advanced power systems.

As Tibor Kremic, chief of the Space Science Project Office at NASA Glenn, summarized:

“The Moon is rife with extreme conditions, especially during the lunar night, that we must prepare for. We do that by bringing together leading experts from NASA, commercial partners, academia, and other government entities to share insights, review technical capabilities, and discuss the challenges and solutions ahead. The workshop was a learning experience for all of us, helping better prepare our CLPS providers and increase our understanding of the various technical capabilities and constraints as we continue to prepare for ever more ambitious payload deliveries to some of the toughest places in the solar system.” 

These workshops also build on NASA’s Lunar Surface Innovation Initiative, which is dedicated to fostering partnerships that will lead to technologies needed to live and explore on the surface of the Moon. The Initiative is particularly focused on technologies that allow for in-situ resource utilization (ISRU), power generation, mitigating lunar dust, excavating and constructing on the Moon’s surface, exploring the lunar environment, and other methods that will ensure a sustainable human presence on the Moon for decades to come.

Another long-term objective of the Artemis Program is to establish the infrastructure and expertise that will allow for crewed missions to Mars in the early 2030s. This presents even greater challenges, ranging from logistics and transportation (transit times of up to nine months) to power systems for surface operations. Here too, nuclear propulsion (which could reduce transit times to 100 days) and nuclear reactors that can power surface habitats and vehicles for long-duration missions are in high demand.

This is yet another example of how this age of renewed space exploration (Space Age 2.0) is spurring the development of technologies that have been dreamt of for decades!

Further Reading: NASA