Microscopic Stowaways on the ISS

When the first human crew of the ISS blasted into space on Oct. 31, 2000, a community of microbes was already waiting to receive them in orbit. The station's complement of microbes arrived in space attached to ISS hardware and on the bodies of earlier assembly crews.

November 26, 2000 -- Long before the first humans boarded the International Space Station (ISS), something else was living there.

Something unseen, but potentially dangerous. Something with an uncanny ability to survive and reproduce in even the most hostile environments. Something capable of attacking the Station's crew and even the Space Station itself.

Of course we're not talking about some man-eating alien from a science fiction movie. These lurking, mischievous life forms aboard the Space Station are simply microbes: viruses, bacteria and fungi.

"Microbes were the first inhabitants of the Space Station," said Monsi Roman, chief microbiologist for the Environmental Control and Life Support Systems (ECLSS) project at NASA's Marshall Space Flight Center.

The Space Station's microorganisms are hitchhikers; they were carried there on ISS hardware and by the assembly crews themselves. "When the Station went up, microbes went with it," says Roman. "Microbes will be the last ones in the Station, too."

Microbes are a fact of life anywhere that humans go. The majority are harmless, and several types are actually beneficial to humans. Nevertheless, certain microbes can pose a health threat to the Station's crew and even attack the materials and hardware of the Station itself. Scientists and engineers at NASA must find ways to keep such microorganisms on the Space Station under control.

In this third article in a series about the practical challenges of living in space, Science@NASA takes a look at how microscopic inhabitants of the Space Station will be kept in check.