The same dirt that clings to astronauts' boots may one day keep their lights on. In a study publishing April 3 in the Cell Press journal Device, researchers created solar cells made out of simulated Moon dust. The cells convert sunlight into energy efficiently, withstand radiation damage, and mitigate the need for transporting heavy materials into space, offering a potential solution to one of space exploration's biggest challenges: reliable energy sources.
"The solar cells used in space now are amazing, reaching efficiencies of 30% to even 40%, but that efficiency comes with a price," says lead researcher Felix Lang of the University of Potsdam, Germany. "They are very expensive and are relatively heavy because they use glass or a thick foil as cover. It's hard to justify lifting all these cells into space."
Instead of hauling solar cells from Earth, Lang's team is looking to materials available on the Moon itself. They aim to replace Earth-made glass with glass crafted from lunar regolith -- the Moon's loose, rocky surface debris. This change alone could cut a spacecraft's launch mass by 99.4%, slash 99% of transport costs, and make long-term lunar settlements more feasible.
To test the idea, the researchers melted a substance designed to simulate Moon dust into moonglass and used it to build a new kind of solar cell. They crafted the cells by pairing moonglass with perovskite -- a class of crystals that are cheaper, easier to make, and very efficient in turning sunlight into electricity. For every gram of material sent to space, the new panels produced up to 100 times more energy than traditional solar panels.
"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," says Lang. "Plus, our cells are more stable against radiation, while the others would degrade over time."
When the team zapped the solar cells with space-grade radiation, the moonglass versions outperformed the Earth-made ones. Standard glass slowly browns in space, blocking sunlight and reducing efficiency. But moonglass has a natural brown tint from impurities in the Moon dust, which stabilizes the glass, prevents it from further darkening, and makes the cells more resistant to radiation.
Making moonglass, the team found, is surprisingly simple. It does not require complex purification and concentrated sunlight alone can provide the extreme temperatures needed to melt lunar regolith into glass. By tweaking the thickness of the moonglass and fine-tuning the solar cell's composition, the team managed to achieve 10% efficiency. With clearer moonglass that lets in more light, they believe they could reach 23%.
Still, the Moon poses challenges that Earth doesn't. Lower gravity could change how moonglass forms. The solvents currently used to process perovskite won't work in the Moon's vacuum. Wild temperature swings could threaten the materials' stability. To find out if their moon dust solar cells are truly viable, the team hopes to launch a small-scale experiment to the Moon to test them out in real lunar conditions.
"From extracting water for fuel to building houses with lunar bricks, scientists have been finding ways to use Moon dust," says Lang. "Now, we can turn it into solar cells too, possibly providing the energy a future Moon city will need."
This research was supported by funding from the Volkswagen Foundation for funding via the Freigeist Q14 Program.