Imma Perfetto
Cosmos science journalist
Astronauts aboard the International Space Station (ISS) face a multitude of health risks which arise from space travel, from decreased muscle mass and bone density to damaged eyesight.
They also commonly experience persistent skin rashes, allergies, and immune dysfunction. A new study suggests that these issues could be caused by the excessively sterile environment of the spacecraft and making it “dirtier” could help improve astronaut health.
“Future built environments, including space stations, could benefit from intentionally fostering diverse microbial communities that better mimic the natural microbial exposures experienced on Earth, rather than relying on highly sanitised spaces,” says Rodolfo Salido of the University of California, San Diego in the US, co-first author of the paper.
Salido and his colleagues identified the chemicals and bacterial species present on more than 800 surfaces inside the ISS from swabs taken by astronauts. They used this data to illustrate how the chemicals and bacteria interact in 3-dimensional maps of the ISS.
Chemicals from cleaning products and disinfectants were present throughout the ISS and the main source of the microbes present was human skin. Importantly, the composition of these chemical signatures and microbial communities varied between modules, or rooms, depending on their functions.
Dining and food preparation areas contained more food-associated microbes, for example. Whereas the bathroom contained more urine- and faecal-associated microbes. The science modules simply resembled nearby habitation areas.
“We noticed that the abundance of disinfectant on the surface of the International Space Station is highly correlated with the microbiome diversity at different locations,” says co-first author Nina Zhao of UC San Diego.
The team found that the ISS’ microbial communities were similar to industrialised, isolated environments on Earth, such as hospitals, closed habitats, and homes in urbanised areas.
Free-living microbes associated with soil and water on Earth were not found aboard the ISS.
The authors of the study, which is published in the journal Cell, say that the findings suggest “the ISS environment may be suboptimal for supporting human immune function.”
“If we really want life to thrive outside Earth, we can’t just take a small branch of the tree of life and launch it into space and hope that it will work out,” says Salido.
“We need to start thinking about what other beneficial companions we should be sending with these astronauts to help them develop ecosystems that will be sustainable and beneficial for all.”
The biologists suggest that using alternative strategies, such as probiotic-based sanitation, could also be explored to mitigate the antimicrobial resistance that might result from chemical disinfection on the ISS.
Ultimately, the research will help guide long-term efforts to maintain human health in space for longer durations.
