SPACE MICROBES

There are creatures that were living on the Space Station before the first astronauts went inside. Astronauts found a few living on the Moon. Scientists believe they could even live on Mars. These creatures are capable of living almost anywhere—and they're living inside you right now!

It's not something out of a science fiction movie. It's bacteria and other microbes, such as viruses and fungi. The tiny microorganisms hitchhiked on the International Space Station (ISS) components when they were launched, as well as on other spacecraft. Microbes go everywhere that humans do; in fact, many of them live inside and on our bodies. Most microbes are harmless, and many are actually beneficial. However, some microbes can be harmful to people's health, or could even pose a threat to the hardware and materials of the Space Station.
While microbes are just another part of everyday life here on Earth, they can be a much bigger problem on the Space Station. The threat posed by these microbes may be even greater for astronauts in orbit than for most people here on Earth, since aspects of spaceflight are known to weaken the human immune system, which could make astronauts more vulnerable to infection. In addition, experiments performed on previous spaceflightshave shown that bacteria may grow faster in microgravity than they do on Earth. Another reason microbes are a bigger problem in space is that the people on the Space Station are living in a small, contained environment of metal and plastic for extended periods of time, exposing each other to their own bacteria in the process.

Bacteria have proved to be very resilient in living in harsh conditions in spaceflight. When Apollo 12 astronauts landed on the Moon in 1970, they found something living there—bacteria from Earth. The Streptococcus mitis bacteria were found on the Surveyor 3 probe that had been sent to the Moon 3 years earlier. While unprotected exposure to space would kill a human being very quickly, the bacteria had survived launch, space vacuum, 3 years of radiation exposure, deep-freeze at an average temperature of only 20 degrees Kelvin above absolute zero, and having no nutrients, water, or energy source. Researchers at the University of Arkansas have found that bacteria commonly found in cows' stomachs can survive in an environment like the one found on Mars.

One technique NASA uses for trying to reduce microbe-related problems is by testing astronauts for infection before they begin their spaceflight, and by trying to cut down on exposure to germs before their mission to make sure they don't catch anything prior to launch. On the Space Station, equipment is used to help purify the air and water to keep them free of contamination. Things like a special paint and maintaining low humidity also help fight microbe growth on the Space Station, but despite these high-tech solutions, astronauts still have to keep microbes off surfaces the way people on Earth do—good, old-fashioned cleaning. ISS crew members regularly wipe surfaces on the Station with cloths containing a disinfectant.

However, astronauts don't always try to get rid of the bacteria on their spacecraft, because not all of them are unwanted guests. A Space Shuttle mission scheduled for early 2003, for example, includes an experiment involving Pseudomonas bacteria, a common soil and water bacteria, which actually has been a stowaway in the water supply of previous Shuttle flights. The experiment will study the effect of microgravity on the bacteria.

M.MANJU PARKAVI

I M.Sc., INDUSTRIAL MICROBIOLOGY