A team of scientists at the University of California, San Diego reached a surprising conclusion.
Typically, space explorers live on the station for about six months. However, NASA astronauts Suniti Williams and Barry Wilmore had to stay on the ISS for more than nine months.
During such long missions, astronauts often experience immune system dysfunction, skin rashes, and inflammatory diseases. Scientists have not yet determined the exact causes of these effects of spaceflight.
However, the authors of the new study found that these issues may be related to the “excessive sterility” of the ISS.
There are about a trillion species of microbes on Earth. Some of them cause disease in humans, while others support our health. Beneficial bacteria strengthen the immune system, protect against infections, help the intestines digest food, and regulate the body’s inflammatory responses.
However, the diversity of microbes on the ISS is significantly lower than on our home planet, and most of the species that inhabit it were brought there by astronauts. According to researchers, the lack of beneficial bacteria on the space station may suppress astronauts’ immune systems, making them more vulnerable to rashes, herpes, fungal infections, shingles, and other conditions.
What else have scientists learned?
With the help of astronauts, scientists collected samples from 803 different surfaces of the ISS to thoroughly study the station’s microbes.
After the samples were delivered to Earth, scientists identified which microbial communities accompany astronauts on missions. The team also created three-dimensional maps showing where specific species reside on the ISS. It turned out that the primary source of microbes on the space station was human skin. The researchers also found chemical residues from cleaning and disinfecting agents on nearly every surface.
However, the composition of microbial communities and chemical residues varied in each module of the space station, reflecting the rooms’ different functions. For example, food-preparation and eating areas contained more food-associated microbes, the Daily Mail reported.
Overall, researchers found that the station’s microbiome significantly lags behind most terrestrial environments in diversity. Samples from the ISS resembled those taken from isolated places on Earth, such as hospitals, closed environments, and urban homes.
The team also found evidence that the high levels of chemicals used to clean the ISS suppress the diversity of its microbiome. This is leading to certain health issues for astronauts living on the station.
“Sterile environments are actually not the safest,” noted Professor Rob Knight, co-author of the study. “The influence of beneficial microbes in the environment is important for maintaining health – it’s no surprise, as we humans have evolved alongside these microbes for millions of years,” he added.
Researchers concluded that increasing microbial diversity aboard the space station could reduce some health risks associated with space travel. This does not mean abandoning hygiene. The team says it’s time to consider what ‘beneficial companions’ could be sent into space to help astronauts protect themselves from ailments. “This needs to be figured out on Earth before embarking on expensive space experiments,” Professor Knight said.
