A paradoxical conclusion has been reached by a team of scientists from the University of California, San Diego.
Typically, space explorers spend about six months aboard the International Space Station (ISS). However, NASA astronauts Sunita Williams and Barry Wilmore found themselves stuck on the ISS for over nine months.
During such extended missions, astronauts often experience immune system dysfunction, skin rashes, and inflammatory diseases. Until now, researchers have struggled to pinpoint the exact causes of these side effects of space travel.
However, the authors of a new study have discovered that these issues may be linked to the “over-sterility” of the ISS.
On Earth, there are about a trillion species of microbes. Some can cause diseases in humans, while others actually support our health. Beneficial bacteria strengthen the immune system, protect against infections, aid the gut in digesting food, and regulate the body’s inflammatory responses.
Yet, the diversity of microbes on the ISS is significantly lower than that on our home planet, with most species present having been brought there by astronauts. According to the 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 more.
What Else Did the Scientists Discover?
With the help of astronauts, scientists collected swabs from 803 different surfaces on the ISS to thoroughly investigate the station’s microbial environment.
Once the samples were returned to Earth, researchers identified the microbial communities that accompany astronauts during their space 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. Additionally, the samples revealed chemical residues from cleaning and disinfecting agents, which were found on nearly every surface.
However, the composition of microbial communities and chemical substances varied in each module of the space station, reflecting the different functions of the spaces. For instance, food preparation and dining areas contained more microbes associated with food, as reported by the Daily Mail.
Overall, researchers found that the station’s microbiome significantly lags behind the diversity of most terrestrial environments. The samples obtained from the ISS were similar to those taken from isolated locations on Earth, such as hospitals, closed environments, and homes in urban areas.
The team also found evidence that high levels of the chemicals used to clean the ISS suppress the diversity of its microbiome. This contributes to certain health issues faced by astronauts living on the station.
“A sterile environment is not necessarily the safest,” noted Professor Rob Knight, a co-author of the study. “The influence of beneficial microbes in the environment is crucial for maintaining health—it’s no surprise, as we humans have evolved alongside these microbes for millions of years,” he added.
The researchers concluded that increasing microbial diversity aboard the space station could reduce some health risks associated with space travel. However, this does not mean that hygiene should be neglected. The team believes it’s time to consider what “helpful companions” could be sent into space to assist astronauts in warding off ailments. “This needs to be figured out on Earth before embarking on costly space experiments,” emphasized Professor Knight.