Space stations could wage war on hitchhiking bacteria with self-cleaning tech

Astronauts can't avoid viruses even in space, but the European Space Agency is working on chemicals to help clean up the International Space Station.

A whole ecology of tiny hitchhikers lives aboard the International Space Station. It's practically difficult to keep these small, potentially deadly invaders, such as germs and other potentially dangerous microbes, from following humans into space, but the European Space Agency is working on technology that might halt them in their tracks: self-cleaning spacecrafts.

And, as humans strive for long-term space travel, clean space habitats are becoming increasingly important—especially given indications that the ecosystem is already swiftly developing. "Microbes transferred from Earth to the ISS are evolving," explains Malgorzata Holynska, the project's technical officer and an ESA materials and process engineer.
“Strains are evolving that are resistant to common antimicrobial agents.” 

The necessity to combat these strains has increased in recent years. Microbes may someday infect astronauts and the rest of the solar system as they evolve to thrive in the harsh environment of space. While bacteria found on the ISS haven't been shown to be more virulent or resistant to antibiotics, experts can't predict how the billions of species of microbes would operate in space. Microbes that fly to space have the ability to harm the spacecraft's interior as well as its equipment.They achieve this by forming biofilms, which are collections of one or more bacteria that develop on various surfaces, such as your teeth. Metals, polymers, and rubber are all susceptible to biofilms.

Many astronauts have previously reported corroded space technology, including electrical connectors, air conditioners, and portions of space suits, according to Holynska. Colonies of organisms were seen growing around rubber window seals, cable tubing, spacesuits, and communications systems aboard the Russian space station Mir, indicating that such damage was a widespread problem. Scientists now know that these events aren't limited to the retired spacecraft. Researchers discovered in 2019 that mold growing on the walls of the International Space Station may readily survive being exposed to extraordinarily high amounts of radiation.

Self-cleaning surfaces, materials covered with substances that easily remove germs or debris, might be a promising approach to tackle microorganisms. The ESA intends to combine titanium oxide, or titania—a substance often used in self-cleaning glass and antimicrobial surfaces in hospitals—with photoactive coatings, which may alter chemically when exposed to specific wavelengths of light.

Photocatalytic oxidation is the mechanism through which the coating functions. When exposed to UV radiation, titanium oxide oxidizes germs and breaks down water vapor in the air, thereby disintegrating bacterial membranes. This has an extra benefit: the materials aren't selective in terms of killing certain microbial strains, so there's minimal risk of bacterial resistance emerging.

The coating has so far been successfully tested on glass, silicon wafers, aluminum foil, and specially-made paper tissue. However, Holynska's team hopes to improve titania's effectiveness by "doping" the chemical, or modifying its components to extend its antimicrobial activities under normal light.
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