Astronauts often suffer from immune dysfunction, skin rashes, and other inflammatory conditions in space. A new study published on February 27 in the journal Cell suggests that the overly sterile environment of spacecraft could be the culprit.
Researchers found that the International Space Station (ISS) has a much lower diversity of microbes than human-built Earth environments. The few microbes on the ISS are mainly brought by humans, indicating that introducing more natural microbes could improve astronaut health.
“Future space stations could benefit from fostering diverse microbial communities that mimic Earth’s natural microbial exposures, rather than relying on highly sanitized spaces,” said Rodolfo Salido of UC San Diego.
Astronauts swabbed 803 surfaces on the ISS, and researchers identified the bacterial species and chemicals present. They created three-dimensional maps showing where each was found and how they interacted. The main source of microbes was human skin, and cleaning products and disinfectants were seen everywhere. Different ISS rooms had distinct microbial communities based on their use.
Researchers discovered that the ISS microbial communities were less diverse than those on Earth. They resembled samples from hospitals and isolated environments and lacked free-living environmental microbes typically found in soil and water.
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The study suggests that intentionally incorporating these microbes into the ISS could boost astronaut health without compromising hygiene. The researchers compare this to the known benefits of gardening on the immune system.
The researchers aim to refine their analyses to detect potentially harmful microbes and human health signals from environmental metabolites. These methods could also improve people’s health in similarly sterile environments on Earth.
“If we want life to thrive outside Earth, we need to think about what beneficial companions to send with astronauts to develop sustainable ecosystems,” said Salido.
Journal Reference:
- Rodolfo Salido, Haoqi Nina Zhao et al. The International Space Station has a unique and extreme microbial and chemical environment driven by use patterns. Cell. DOI: 10.1016/j.cell.2025.01.039
