“The solar cells used in space now are amazing, reaching efficiencies of 30% to even 40%, but that efficiency comes with a price,” said Felix Lang, senior author at the University of Potsdam, Germany, in research published in the Device journal. His statement summarizes a fundamental challenge in space travel: the weighty and expensive cost of lifting stuff from Earth. Then Lang and his team propose a groundbreaking answer using the Moon’s native surface dust to create solar cells.
Lunar regolith, the loose rock debris that coats the Moon, has fascinated scientists for decades with its applications. From being used to make bricks for lunar residences to serving as a source of oxygen and as a means to extract titanium, this material is a stepping stone to a sustainable presence on the Moon. Lang’s group has taken it a step further by demonstrating how lunar regolith can be melted into “moonglass” a key ingredient in solar cells that might power next-generation Moon bases.
To test their concept, the researchers employed a synthetic model of Moon dust since actual lunar samples are rare and very valuable. They heated up the simulant to create moonglass, then added perovskite, a crystalline material and one that is known for its ability to convert sunlight into electricity. Perovskite solar cells are already established as being light and cheap, but combining them with moonglass brings an entire new dimension. For every gram of material that was put into space, the new solar panels produced as much as 100 times more energy than traditional ones.
This technology would cut spacecraft launch weight by 99.4% and transportation costs by 99%, according to Lang’s team. The stakes are staggering: fewer missions to transport Earth-bound material, less payload weight, and more energy production on the Moon. “If you cut the weight by 99%, you don’t need ultra-efficient 30% solar cells, you just make more of them on the Moon,” Lang said in an interview with Space.com.
Resistance to radiation is another area where solar cells constructed of moonglass excel. Ordinary glass that is used in solar panels manufactured on Earth tans with time when exposed to cosmic radiation and reduces in efficiency at solar absorption. Moonglass, being naturally brown in color as a result of lunar regolith impurities, stabilizes the material and tans no further. This distinctive property makes moonglass more resistant to the harsh conditions of space, as confirmed by radiation tests conducted by Lang’s crew.
The process of producing moonglass is surprisingly straightforward. Focused sunlight is sufficient to produce the high heat required to melt lunar regolith, rendering costly purification systems redundant. Lang’s colleague even tried this technique on the roof of his university, observing signs of regolith melting with focused sunlight. Such simplicity can pave the way for mass production on the Moon, where bent mirrors can concentrate sunlight to produce moonglass for solar panels.
But there are still obstacles to be overcome. The Moon’s lower gravity may affect the manner in which moonglass crystallizes, and the vacuum conditions may degrade known perovskite processing solvents. The extreme temperature fluctuations between day and night on the Moon can also degrade the stability of solar cells. To counteract such uncertainties, Lang’s team suggests a small-scale mission to install their solar cells under real lunar conditions.
The potential rewards are vast. Successful demonstration would open the door to the creation of lunar production facilities churning out moonglass-based solar cells, powering Moon bases and enabling extended settlements. The same technology would potentially be transferable to other space systems, like satellites, which would benefit from the lower energy to launch payloads from the Moon compared to Earth.
Lang’s team is already looking at how to make their solar cells more efficient. By screening out impurities in the regolith using magnets, they hope to produce clearer moonglass which allows more sunlight to pass through. Their current prototypes have an efficiency of about 10%, but computer programs predict they could achieve up to 23% or even as high as the 26% of conventional perovskite solar cells.
Looking to the future of the Moon, Lang is considering whether the same techniques could be used on Martian regolith. This forward-thinking approach indicates the broader implications of their research for space exploration in the long term. As Lang said in an interview with New Scientist, “We are already thinking, ‘Can we make this work with Mars regolith?”
The dream of robots gathering lunar regolith, melting it into moonglass, and constructing solar cells to power Moon cities is now out of science fiction. Such advancements make the prospect of sustainable moon settlements and more within reach. As Lang accurately summed in Interesting Engineering, “Now, we can turn [Moon dust] into solar cells too, possibly providing the energy a future Moon city will need.”
