Space poses some massive dangers for humans, from black holes to the heat death of the universe. But as humanity considers long-haul space travel, there are other, smaller potential hazards that some researchers say may deserve more attention: microbes from Earth.
Astronauts face numerous known health problems in space, including a loss in bone density, muscle atrophy, and psychological issues. And on Earth, researchers are increasingly discovering how the various bacteria and other microorganisms that live inside and outside of people — the human microbiome — affects physical and mental health.
Space, of course, is an entirely different environment from Earth, with high radiation levels and microgravity. Although the science is far from certain, these vast differences may cause unexpected changes in the microbiome of astronauts. In turn, this could result in a range of health problems, which may be more pronounced on long-haul stints in space, like traveling to another planet.
Still, the implications of a disrupted microbiome are poorly understood, even on Earth, said David Pearce, a bioscience researcher at Northumbria University and author of a 2022 paper exploring how a trip to Mars might affect microbes in the gut — which makes the range of related illnesses and diseases in space difficult to predict. And direct research is limited because only around 600 people have ever been to space. Those who have taken the trip don’t typically stay long, as the average length of a trip to the International Space Station is about six months. And some researchers aren’t yet convinced there’s enough evidence suggesting the human microbiome will change much in space at all.
All the same, many researchers, including Pearce, are trying to figure out whether or not astronauts will enter a state in which their microbiome changes in adverse ways, called dysbiosis. “Because they’re going to be away for a long time, will that dysbiosis become a significant problem,” he said, “or lead to them having health impacts that impair their ability to function?”
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