Plasma Jets Offer Water-Free Laundry for Future Moon and Mars Habitats

University of Alabama in Huntsville researchers, with NASA, built a handheld device that emits a pencil-thin cold-plasma jet to sanitize fabrics without water. The cellphone-sized prototype was applied to cotton swatches inoculated with *Staphylococcus caprae*, a skin bacterium found on the ISS. The plasma generates reactive oxygen and nitrogen species that penetrate fibers and rupture bacterial membranes via oxidative stress.

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ISS crews rely on dry vacuuming and chemical wipes, which leave microbial colonies on surfaces that appear clean. Water scarcity makes conventional washing impractical, and resupply for lunar or Martian outposts will be infrequent, making garment reuse unsustainable for permanent habitats.

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The experiment was led by Professor Gabe Xu of the University of Alabama in Huntsville, with NASA planetary protection engineer Chelsi Cassilly; results were presented at the Astrobiology Science Conference in Madison.

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Exposure times from 30 seconds to five minutes reduced *S. caprae* colonies from roughly 250,000 CFU mL?¹ to about 60,000 CFU mL?¹. Visual inspection showed no noticeable fabric damage, indicating wear comparable to normal use.

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Xu noted the method targets health-critical contamination rather than stains and warned that many Earth-based disinfectants pose inhalation hazards in sealed habitats. Cassilly stressed the need to address microbes that thrive in human environments and spacecraft. NASA officials consider microbial control essential for crew health and equipment longevity, viewing plasma treatment as a promising complement to existing protocols.

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The prototype treats only a narrow area, limiting garment throughput. Researchers must test more microbial species and evaluate long-term fabric effects. Scaling to a chamber-style washer or integrating with vacuum cleaning remains an engineering hurdle.

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• “We think that it's probably not any worse than just normal wear and tear," he told Live Science.” — Gabe Xu, professor, University of Alabama in Huntsville

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• “In an interview with LiveScience, Xu explained that “there are microbes that are UV resistant, but as far as we can tell from our experiments, there is nothing that is oxidative-stress resistant – if you eat poison, it kills you.” — Gabe Xu, professor, University of Alabama in Huntsville

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The team plans to scale the device into a chamber-style system and combine plasma jets with vacuum cleaning. Further testing will cover more bacterial species and assess fabric durability. Successful integration could cut water use, reduce waste, and support sustainable habitats on the Moon and Mars.

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