While SpaceX and Blue Origin engineers work against the clock to prepare their respective spacecraft for the first moon landing since 1972, scores of scientists are addressing the myriad technological challenges future space explorers will face on long-duration missions to the moon and beyond.

One team of scientists has just demonstrated a water-free approach to cleaning laundry in space. The researchers demonstrated a cold-plasma technology that could sanitize astronaut clothing and habitats on future lunar and Martian bases without water.

Keeping clean in space

On the International Space Station (ISS), crews use dry vacuuming devices and chemical surface wipes to clean their clothes. Neither is particularly effective.

This means the ISS crew also have to resort to another method: They wear garments for extended periods, finally discarding them when they are too dirty. This practice is unsustainable for long-duration missions to the Moon or Mars, where resupply missions will be limited.

Water is also a precious resource in space, making traditional washing impractical. The team behind the new water-free solution was led by Gabe Xu of the University of Alabama in Huntsville, in collaboration with NASA microbiologist Chelsi Cassilly. They developed a compact device that generates a pencil-thin jet of cold plasma to kill bacteria on fabrics.

They presented their proof-of-concept device at the Astrobiology Science Conference last month. The device uses high-voltage electricity to ionize a mixture of helium, air, and water vapor. When aimed at fabrics, the plasma generates reactive oxygen species such as ozone. These penetrate fabric fibers and destroy microbes through oxidative stress.

Unlike hot plasma or arc welding, this cold plasma operates at room temperature and poses no risk to fabrics or human skin.

In laboratory tests, the team trained their plasma jet on samples of Staphylococcus caprae, a skin bacterium previously detected on the ISS. They found that their device reduced bacterial spore colonies on cotton samples from approximately 250,000 per milliliter to about 60,000 per milliliter.

Ultimately, the technique killed the bacteria more effectively than existing methods used on the ISS. According to the researchers, their method might not remove noticeable stains, but it will kill the bacteria that could make astronauts sick.

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.”

Enabling healthy habitats for future space explorers

The current prototype cleans only a small area at a time, roughly the width of a pencil.

The researchers aim to develop scaled-up versions, including a plasma chamber resembling a washing machine and a combined plasma jet-vacuum system for surfaces. These tools could also be used to sterilize spacesuits, tools, and soft furnishings in habitats.

As NASA looks to extend humanity’s footprint into space, microbial control will be critical for crew health and survivability. Small populations living in compact habitats will be especially vulnerable to bacteria and illness. While vacuuming removes dust, it fails to eliminate biological contaminants effectively, making the new system particularly valuable.

Though it shows great promise, further testing is needed to confirm efficacy against a broader range of microbes, as well as its long-term impact on fabric durability.

If successful, plasma-based sanitation could help support a permanent human presence beyond Earth. It would help to minimize resource consumption and contamination risks while enabling astronauts to explore the unknown.