First placed into operation in 1998, the space station is Earth’s base for missions and experiments outside of the atmosphere. For more than two decades, it has hosted more than 277 astronauts and sizable amounts of cargo from multiple countries. Because it plays such a large role as a docking station and laboratory, you might expect it to be sterile— or at least clean. In reality, it is anything but.

A Robust Population Of Bacteria And Fungi

Surprisingly, the International Space Station hosts its fair share of bacteria and fungus. While at first, this sounds pretty gross, it actually makes sense considering the number of visitors and items from Earth that come there. In order to better understand this population, scientists have recently set out to analyze and catalog microorganisms present on the Space Station’s surfaces. The results were published in the journal Microbiome.

To prepare for the study, astronauts took sterile swab samples at eight carefully chosen locations on the Space Station. They did three times in a 14-month period. Locations included the station’s toilet, viewing window, exercise station, sleeping area, dining table, and storage platform.

In the report, which became the first comprehensive listing of Space Station bacteria, researchers show that most of the germs present were connected to humans. Identified organisms included Staphylococcus, Pantoea, Staphylococcus aureus, Enterobacter, and Bacillus. Some of these are generally associated with people and some found only in specific areas such as nasal passages and the GI tract. There were some challenges to identifying the cultures and a specific protocol needed to be developed because of the space station’s unique environment.

Health Impacts Of Bacteria In Space

While these may sound disgusting, in reality, the types of bacteria are similar to what is commonly present in offices, homes, and other places on Earth. What is different, however, is the ways that these bugs behave in a hermetically sealed, zero-gravity environment with higher than normal exposures to radiation, altered ventilation systems, altered air pressure, and more restricted medical access.

On Earth, these bugs can cause allergies, colds, the flu, and intensely infectious, life-threatening diseases. At the same time, there are colonies of beneficial bacteria present in all human environments that counter the effects of damaging bugs. What happens to these bacteria in space depends on a number of factors. For example, how sick an individual astronaut may become in space depends on the health of the astronaut and on how their immunity against bad organisms changes once they leave Earth. Their health may also be impacted by how both good and bad organisms survive and change in microgravity. Future research efforts are aimed at predicting bacterial behaviors.

Can Bacteria Affect The Space Station’s Structure?

The researchers also found that the bacteria showed the capacity to cluster together in sheets as a biofilm. While this also happens on Earth, there is some concern that the films could play a role in damaging the structure of the Space Station. Researchers expressed concern about corrosion, mechanical blockages, and reduced heat transfer efficiency. They noticed this could particularly happen with the organisms Methylobacterium, Sphingomonas, Bacillus, Penicillium, and Aspergillus. Experts are using this knowledge to develop protocols to ensure the colonies of bugs don’t cause a problem.

Information Helps Increase Space Station Safety

Scientists expect to continue to monitor how the Space Station’s bacteria populations change over time and how astronauts show susceptibility or resistance to germ exposure. This work will help prepare them to keep astronauts healthy and space travel vehicles and other equipment in top shape. as they travel beyond the Earth’s atmosphere and even into deepest space.