Honda has teamed up with Astrobotic to meet one of the most difficult engineering challenges in lunar exploration yet: keeping systems on the surface alive and working through two weeks of darkness—called a “lunar night.” Their strategy revolves around a regenerative fuel cell system that stores solar energy as hydrogen during the day and converts it to electricity at night, combined with vertical solar arrays engineered for the Moon’s harsh conditions.
Why Reliable Power During the Two-Week Lunar Night Matters
The Moon spins on its axis so slowly that any one site on the surface spends about 14 Earth days in the light before plunging back into darkness for another two weeks or so. In sunlit areas, temperatures drop to a chilly -173°C after sunset, falling much further inside permanently shadowed craters near the south pole. Peterson says solar-powered assets fall silent without sunlight unless they’ve got huge batteries, or indefinite-life radioisotope heat sources.
NASA’s plans for the lunar surface focus on the south pole, where high ridges receive near-constant—though not continuous—sunlight and water ice is suspected to exist in shadowed regions nearby. That mix requires sturdy energy storage to last through the dark between sunrises, along with heaters to control temperature and instruments that won’t work—much less communicate with Earth—while their solar panels are standing idle.
Inside Honda’s Regenerative Fuel Cell Loop
Honda’s day-to-night system brings power generation together with demand. In the daytime, electricity from solar panels on the surface of foreign worlds conducts electrolysis to separate water into hydrogen and oxygen. At nighttime, a fuel cell combines those gases to make electricity and water—essentially turning sunlight into a way to store the chemical energy of gas when it’s needed.
Now, on Earth, state-of-the-art electrolyzers can be 70% efficient and fuel cells commonly convert 50–60% of the chemical energy back to electricity.
Despite lunar thermal losses and balance-of-plant issues, a round-trip efficiency in the 30–40% range is achievable for initial systems. What the RFC loses in efficiency compared with batteries, it could make up for in the ability to scale, long-duration storage, and resistance to extreme cold—which the Moon has a lot of.
Decades of experience in developing fuel cell stacks and high-pressure hydrogen systems for automotive programs informed Honda’s use of those technologies. The company has also investigated space-based, closed-loop water-electrolysis energy cycles in collaboration with Japanese aerospace interests, an element well aligned with the hopes of JAXA and the rest of the Artemis partnership to support long-term mission operations beyond low Earth orbit.
Pairing With Astrobotic’s Vertical Solar Arrays
That’s not what the Sun does above the rugged terrain of the Moon’s south pole, however; there, the Sun skims low along the horizon, with topography casting long shadows.
Astrobotic’s Vertical Solar Array Technology (VSAT) is designed to track and collect sunlight through a full range of motion—something that would be impossible for port or starboard solar panels on other lunar landers.
The baseline VSAT aims for up to 10 kilowatts, with an XL variant in development targeting about five times that output. This array supports the RFC through water electrolysis, and thanks to low-mass, high-efficiency, configured Si panels, it is capable of this operation only during sunlight hours.
As an example, a typical 10 kW VSAT that nets, say, several kilowatts of production over the long lunar day could amass over a megawatt-hour of chemical energy stored as hydrogen and oxygen. Used wisely, such inventory keeps thermal systems working, communications ongoing, science payloads warm, and even movement-capable assets alive through the long night. Scaling to multiple arrays compounds the effect, which means micro-grid style services can be provided to clusters of instruments or habitats.
This vision is in alignment with Astrobotic’s LunaGrid concept, a proposed surface power and distribution network that could also sell power as a service (PaaS) to government and commercial users. The capability to store energy on demand makes the difference between “survival” and actual continuous operations, especially in missions that cannot afford weeks-long energy loss.
Engineering Obstacles They Need to Overcome
The hardest issues in the RFC chain are hydrogen storage and thermal management. High-pressure tanks are more straightforward systems compared to cryogenic storage but carry mass and volume penalties. Cryogenic solutions, meanwhile, generate unwanted boil-off and also need to be very precisely thermally managed. The dusty, abrasive regolith drives the complexity of everything from deployable array mechanisms to radiator performance.
Astrobotic and Honda intend to perform illumination studies at their candidate south pole locations in order to inform array siting and forecast power duty cycles, examining how much energy might need to be banked on worst-case shadowing. These analyses are important—recent mission concepts from NASA’s Space Technology Mission Directorate have demonstrated that small variations in the profile of the local horizon can change the available sunlight by perhaps tens of percent around a single crater rim.
Software integration is equally critical. Power needs to be scheduled wisely among electrolysis, battery buffers, communication windows, and heaters. “Fault” is the name of the game: a ‘safe-mode’ approach that leaves enough stored energy in the tank to ride out unexpected eclipses or dust defilements will be a non-negotiable for service-level assurances.
What Continuous Lunar Surface Power Can Unlock Next
Having power through the night is a force multiplier. Prospecting for volatiles, in turn, demands thermal management and stable power for practiced drills and spectrometers. Rovers also need to be heated overnight so their batteries and electronics don’t freeze. Communications relays can also keep connections up and running for international missions operated through the Artemis Accords. Morell and his colleagues believe that, longer-term, RFC-sponsored microgrids could supplement fission surface power systems being examined by U.S. agencies at the 40 kW scale in order to provide redundancy and load sharing.
Modular power also decreases mission risk, and it saves money. Instead of custom energy storage in every lander, customers could connect to a local power utility assembled once and used as needed. That model—familiar to terrestrial microgrids—is also applicable to logistics-constrained lunar operations.
What to Watch Next as Honda and Astrobotic Progress
Key achievements include site-dependent illumination maps, a hardware-in-the-loop demonstration of the RFC with VSAT control integration, and an obvious mass–power–volume trade against alternatives such as large battery banks or radioisotope systems. The involvement, for validation, of an organization such as NASA, JAXA, or a national lab will add credibility, and environmental testing—cycling hardware through vacuum, extreme cold, and exposure to dust—will boost confidence.
If Honda and Astrobotic can demonstrate a repeatable RFC–VSAT stack, with reliable performance during the lunar day–night cycle, they won’t simply be turning on the lights—they’ll be laying the groundwork for a power market on the Moon.
That’s the sort of underpinning infrastructure every other lunar ambition out there quietly relies on.
