Astronauts are falling sick on board the International Space Station because it is too clean for human health, scientists fear.
Wary of falling ill in orbit, contaminating the Solar System or bringing mysterious alien microbes back to Earth, space voyagers keep their craft in sanitised hospital-like conditions. But living without the healthy bacteria found in nature may be causing them skin rashes and other health problems, according to a study.
Just as gardening can be good for the gut, scientists say spacefarers could afford to get a bit dirtier. "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," said biologist Rob Knight of the University of California in San Diego, which produced the study.
The International Space Station is due for retirement in 2030, with several commercial designs now in development. SpaceX founder Elon Musk has suggested ending its orbit several years early to focus on space flight to Mars. The scientists said their findings could "guide long-term efforts" to keep people healthy during longer voyages in space.
Using more than 800 swabs from the ISS they made a 3D map of the station that found chemicals and cleaning products right across its 110-metre wingspan, but a lack of the natural microbes that would normally be found in soil and water. The samples were similar to those from isolated environments on Earth, such as hospitals, and homes in urban areas away from nature.
Astronauts living on board the space station have often reported rashes, unusual allergies and immune failures, which researchers believe could be linked to the lack of natural microbes. There is also concern about germs mutating on board the ISS and developing resistance to medicines.
Mimicking Earth
The space station could benefit from "fostering diverse microbial communities that better mimic the natural microbial exposures experienced on Earth, rather than relying on highly sanitised spaces", said Rodolfo Salido, a co-author of the study.
"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," he said. "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 study, The International Space Station Has a Unique and Extreme Microbial and Chemical Environment Driven by Use Patterns, is published in the journal Cell on Thursday.
