The Challenge of Hygiene in Deep Space
As space agencies look toward long-duration missions to the Moon and Mars, maintaining a clean environment becomes a critical hurdle. Unlike missions on the International Space Station (ISS), where astronauts dispose of dirty clothing by letting it burn up in Earth's atmosphere, future lunar and Martian outposts will require sustainable solutions. Current hygiene practices are insufficient, as microbes have been found to thrive on surfaces and even adapt to microgravity, potentially threatening both crew health and spacecraft infrastructure.
The accumulation of bacteria is particularly concerning for "soft goods"—such as furniture, bedding, and clothing—which are difficult to sanitize without vast amounts of water. Conventional disinfectants used on Earth are largely impractical for space travel due to the risks posed by lingering chemical fumes and aerosolized droplets in enclosed habitats.
Harnessing Plasma for Sterilization
To address this, researchers led by Gabe Xu, a professor at the University of Alabama, in collaboration with NASA planetary protection engineer Chelsi Cassilly, have explored the use of plasma. Plasma, often described as an energized gas similar to controlled lightning, was tested as a water-free disinfectant.
In a recent lab trial, the team treated cotton T-shirt samples contaminated with Staphylococcus caprae—a bacterium commonly found on human skin and aboard the ISS—using a compact, handheld device. The device emitted a focused jet of purple plasma, which effectively neutralized the microbes. According to Xu, the technique outperformed existing ISS sanitation methods, such as dry vacuuming and chemical wipes.
Mechanism and Future Potential
The effectiveness of the plasma jet lies in its ability to generate highly reactive oxygen and nitrogen species. These particles penetrate fabric fibers and destroy bacterial cell membranes through oxidative stress. Importantly, the process appears to be gentle on materials. As Xu noted, «We think that it's probably not any worse than just normal wear and tear» on the fabric fibers.
Because the system requires only electricity and a working gas, it eliminates the need for water-intensive laundry systems. The team is currently expanding their research to test the plasma technology against a wider variety of microbes known to inhabit spacecraft environments. The ultimate goal is to develop a handheld, user-friendly tool that astronauts can incorporate into their regular housekeeping routines during future deep-space missions. Preliminary findings from this research were recently presented at the Astrobiology Science Conference.