Astronauts Keep Getting Sick on the ISS, but Not for a Reason You'd Expect

The International Space Station (ISS) is one of the cleanest places humans have ever lived. But new research suggests that might be part of the problem. Astronauts aboard the ISS are dealing with rashes, strange allergies, and even fungal and bacterial infections — and the cause might actually be the lack of germs.

Too Sterile to Be Healthy?

On Earth, we're constantly exposed to a wide range of microbes from soil, water, plants, and animals. These microbes play an important role in keeping our immune systems balanced. In space, astronauts are isolated in a tightly controlled and highly sanitized environment. That means most of the helpful microbes we're used to don't exist there.

According to The Wall Street Journal, Rob Knight, director of the Center for Microbiome Innovation at the University of California, San Diego said, "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," as reported by Fox Business.

Knight, along with NASA^® and other researchers, recently mapped the microbes living on the ISS. What they found was surprising: The station is even more sterile than normal living spaces on Earth, and the few bacteria that do exist there are mostly from human bodies. Almost none came from soil, plants, or water like we'd see back home.

What the Study Found

The results, published in the journal Cell, came from more than 800 samples taken across the space station. Scientists swabbed lockers, drawers, and structures to test what kinds of microbes lived there.

The study stated, "By placing the ISS in the context of thousands of samples from various built and natural environments, we revealed a striking loss of microbial diversity," as reported by PEOPLE. The ISS ranked at the most extreme end — much closer to sterile labs than places like rainforests or homes on Earth.

The study concluded that this extreme cleanliness might be contributing to astronauts' skin problems and other health issues. "Our data suggest that it has too few kinds of microbes overall and too many of the specific kinds that can be associated with poor health in humans," Knight said, according to the Australian Broadcasting Corporation.

Life Without Showers

Living on the ISS also comes with physical limitations. Astronaut Kathleen Rubins, who co-authored the study and helped collect the samples, explained that life in space lacks basic hygiene comforts.

In an email to The Wall Street Journal, Rubins said, "We don't have showers on the ISS and can only use a small amount of water to wash," according to Fox Business. "We wear our clothes for two weeks straight because we don't have a way to do laundry in space."

This lack of cleanliness, combined with an overly sterile environment, may be throwing astronauts' immune systems out of balance.

A New Way Forward

As NASA and other agencies plan for future space missions, finding a better balance of microbes could be key to keeping astronauts healthy.

"We probably need to bring a little more of the outdoors inside," Rubins said. "But we have to do that safely so we don't have fungal overgrowth or anything pathogenic," as reported by PEOPLE.

Future spacecraft may need to include more natural microbial exposure, possibly by adding safe soil bacteria or other healthy microbes into the environment. Because when it comes to life in space, being too clean might not be so healthy after all.

References: The space station is too clean, and it’s making astronauts sick | The Space Station Is Too Clean and It's Making Astronauts Sick, Study Says | International Space Station could be too sterile, making astronauts sick: study