A study by the Russian Academy of Sciences has indicated that ISS currently has a population of 76 microorganisms, some of them hazardous. The International Space Station is an enclosed environment, meaning that microorganisms that make their way aboard tend to stay aboard. This can have consequences for crew health, already weakened by the microgravity environment, and care is taken to limit introduction of new species. However, it turns out that these organisms can also endanger the station itself.
“The biggest threat to the Station from the microbes is degradation of the materials,” says Monsi Roman, chief microbiologist for the Environmental Control and Life Support Systems (ECLSS) project at NASA’s Marshall Space Flight Center, “They’ll eat pretty much anything.” Microbes travel onboard the station on equipment and with crew members, increasing overtime as more components and people bring them along for the ride.
This phenomenon was first demonstrated on the Russian Mir station which suffered corroded glass, metallic casings, and insulation, all eaten away by aggressive microorganisms. By the time Mir was decommissioned in 2001 at 15 years old it had 140 species of microorganism. The ISS is expected to have a lifetime of at least 20 years. The Zarya capsule may be most at risk, since it was the first module to be launched to space in 1998.
The ISS crew is taking action against the intruders by wiping down station surfaces with antiseptic solution. It remains to be seen whether such measures are effective. Scientists believe that some space-mutated microbes can become highly resilient, even surviving outside the station for several years.