The ISS is too clean––and it’s making astronauts sick

With the exception of Pig-Pen from Peanuts, it’s hard to imagine any passenger complaining that their travel accommodations are “too clean.” But astronauts onboard the International Space Station should be doing just that, according to a new study.

What’s going on? For decades, crews onboard the ISS have been plagued by persistent rashes, unusual allergies, and a variety of infections like fungi, cold sores, and shingles.

These effects don’t end immediately upon their leaving, either. For up to a month after returning to Earth, astronauts have reduced immune systems and can get seriously ill from common bugs.

Scientists finally believe they know why: The space station doesn’t have enough germs.

• While there are some bacteria present on the ISS that arrived with their human hosts, researchers found the array of free-living microbes present on Earth is lacking.
• This kind of imbalance among microbes is linked to chronic inflammatory diseases that carry similar symptoms to those seen in ISS astronauts, scientists said.

Big picture: The lack of healthy germs represents an annoyance for current astronauts, who only spend a few months on the ISS at a time. But it could represent a much larger issue for longer term space life, like living at Moon bases or traveling to Mars.

The study’s authors say their findings can help identify which kinds of health-boosting bacteria should be added to future space habitats.