Is the International Space Station clean? A research article published in the journal Microbiome shows that a variety of bacterial pathogens live there alongside the astronauts.
The pathogens are mostly innocuous on Earth, and haven’t been the cause of anything like a contagious space flu. However, they could cause infections, resulting in possible inflammations or skin irritation. The purpose of the study was not necessarily to conclude whether the microbes were harmful. Because it was based on genetic analysis, such conclusions were impossible. Instead, the purpose of the study was to help NASA establish a set of house rules for ISS cleanliness, ideally improving their management of astronaut health in the future.
“By using both traditional and state-of-the-art molecular analysis techniques we can build a clearer picture of the International Space Station’s microbial community, helping to spot bacterial agents that may damage equipment or threaten astronaut health, and identify areas in need of more stringent cleaning,” said Kasthuri Venkateswaran, the lead author of the study.
Scientists from NASA’s Jet Propulsion Laboratory used DNA sequencing to identify microorganisms collected from dust samples on the ISS. They collected the microorganisms from air filters and vacuum bags, and compared them to environmentally controlled NASA cleanrooms built on Earth. The cleanrooms circulate fresh air and on average are used by 50 people per day, but are not inhabited continuously. They have several layers of rooms that prevent air from circulating inside, although they are not air tight. For comparison, the ISS recycles air and is home to a continuous crew of six people.
The researchers found that there was a larger proportion of Actinobacteria in the ISS than in the cleanrooms. Actinobacteria is a type of bacteria associated with human skin. Along with it were also found two groups of opportunistic pathogens that could cause infections, but the research did not focus on these or address their virulence in closed environments.
The larger proportion of microorganisms could be due to the difficulty of following stringent cleaning regimes on the ISS as opposed to on Earth.
The same cutting-edge DNA sequencing technology used to study the microorganisms in this case can also be used to study how those organisms are impacted by microgravity, which will be useful when astronauts start taking longer-duration missions such as to Mars.