Categories: Space Station

The One Place on the Space Station Astronauts Aren’t Supposed to Clean

While most of us are now more fastidious about keeping our homes and workplaces clean, on board the International Space Station, cleanliness is imperative. Of high importance is anti-bacterial measures, since bacteria tends to build up in the constantly-recycled air inside the ISS. Every Saturday in space is “cleaning day” where surfaces are wiped down, and the astronauts vacuum and collect trash.

But there’s one spot on board the station where cleaning is a no-no. But don’t worry, its all for science!

The MatISS experiment, or the Microbial Aerosol Tethering on Innovative Surfaces in the International Space Station tests out five advanced materials and how well they can prevent illness-causing microorganisms from settling and growing in microgravity. MatISS also has provided insight into how biofilms attach to surfaces in microgravity conditions.

The experiment is sponsored by the French space agency CNES and was conceived of in 2016. Three iterations of the experiment have been used on the ISS.

The first was MatISS-1, and it had four sample holders set up in for six months in three different locations in the European Columbus laboratory module. This provided some baseline data points for researchers, as when they were returned to Earth, researchers characterized the deposits on each surface and used the control material to establish a reference for the level and type of contamination.

MatISS-2 had four identical sample holders containing three different types of materials, installed in a single location in Columbus. This study aimed to better understand how contamination spreads over time across the hydrophobic (water-repellant) and control surfaces. The upgraded Matiss-2.5 was set up to study how contamination spreads — this time spatially — across the hydrophobic surfaces using patterned samples. This experiment ran for a year and recently the samples were returned to Earth and are now undergoing analysis.

A close-up view of the MatISS experiment. Credit: ESA

The samples are made of a diverse mix of advanced materials, such as self-assembly monolayers, green polymers, ceramic polymers and water-repellent hybrid silica. The smart materials should stop bacteria from sticking and growing over large areas, and effectively making them easier to clean and more hygienic. The experiment hopes to figure out which materials work the best.

ESA says that “understanding the effectiveness and potential use of these materials will be essential to the design of future spacecraft, especially those carrying humans father out in space.”

Long-duration human space missions will certainly need to limit biocontamination of astronaut habitats. 

NASA astronaut Jack Fisher is seen here using a wet wipe on the surfaces of the European Cupola module of the International Space Station. Credit: ESA

Read more about the MatISS experiment here.

Nancy Atkinson

Nancy has been with Universe Today since 2004, and has published over 6,000 articles on space exploration, astronomy, science and technology. She is the author of two books: "Eight Years to the Moon: the History of the Apollo Missions," (2019) which shares the stories of 60 engineers and scientists who worked behind the scenes to make landing on the Moon possible; and "Incredible Stories from Space: A Behind-the-Scenes Look at the Missions Changing Our View of the Cosmos" (2016) tells the stories of those who work on NASA's robotic missions to explore the Solar System and beyond. Follow Nancy on Twitter at and and Instagram at and

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