The International Space Station (ISS) could do with being a bit dirtier, new research has suggested.
A sparkling clean space station may sound perfect for the astronauts who have to spend six-month stints there, but the spotless conditions could be playing havoc with their health.
It’s long been known that astronauts often experience immunity issues, skin rashes, and other inflammatory conditions while aboard the orbital outpost, and new research suggests it could be due to its excessively sterile conditions.
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Published this week in the scientific journal Cell, the study showed that the ISS contains a much lower diversity of microbes compared to human-built environments on Earth, with most of the species brought to the ISS by visiting astronauts.
The researchers believe that astronauts’ health could be improved by bringing more Earth microbes to the facility.
“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 sanitized spaces,” said Rodolfo Salido of the University of California, San Diego, co-first author of the paper.
The research was carried out with the assistance of ISS astronauts, who swabbed 803 different surfaces on the station. The samples were then examined in laboratories back on Earth, enabling scientists to accurately identify the bacterial species and chemicals present on the ISS.
Human skin was found to be the main source of microbes throughout the station, while chemicals from cleaning products and disinfectants were also ubiquitous.
Notably, different microbial communities and chemical signatures were found in different station modules, and as you might expect, the different types depended largely on the how the module was used. For example, dining areas contained more food-associated microbes, whereas the bathrooms had more urine- and fecal-associated microbes and metabolites.
But the researchers found that the space station lacked free-living microbes that are usually found in soil and water, and that adding these microbes to the ISS had the potential to improve astronaut health without adversely affecting hygiene.
“There’s a big difference between exposure to healthy soil from gardening versus stewing in our own filth, which is kind of what happens if we’re in a strictly enclosed environment with no ongoing input of those healthy sources of microbes from the outside,” said Professor Rob Knight, a microbiologist at the University of California, San Diego, and a senior author on the paper.
Salido added: “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. 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 findings could also have implications for people living and working in similarly sterile environments on Earth, the researchers said.
The ISS is kept spick and span in a number of ways, including regular vacuuming sessions that in microgravity conditions look like a lot of fun.