posted 09-09-2002 12:47 PM            

Space Station Crews Are Not Alone In Space

The International Space Station (ISS) wasn't empty when the first
crew arrived in 2000. A welcome party was waiting to greet them.
Russia's Mir Space Station wasn't lifeless when it made that fiery
plunge into the Pacific Ocean in 2001. Mir was teeming with life
after the last crew abandoned ship.

Ignore the official crew counts on the next space shuttle flight.
Hitchhikers ride each shuttle into orbit. Microbes have been the
first, last, and most numerous inhabitants of manned space vehicles
since Yuri Gagarin blazed that new frontier in 1961.

Viruses, bacteria and fungi get into space vehicles during assembly
on Earth as workers breathe, cough, and touch surfaces. Crews bring
more. Microbes not only survive in space, they thrive. NASA
experiments in 1968 on Biosatellite II first showed that microbes
grow better in space than on Earth.

Mir became a showcase for the nasty situation. With cramped living
quarters and a hapless climate control system, Mir's air was so damp
that moisture condensed on the walls.

Human beings on Earth constantly shed dead skin, hair and tiny
particles of mucus in coughs and sneezes. In space, the flurry
becomes a blizzard.

American astronaut Norm Thaagard, who spent four months on Mir,
noticed that callused skin on his feet flaked off because there was
no pressure when he stood. In the damp air, Mir's microbes thrived
on the cast-offs.

Mir went 15 years without a thorough cleaning. American astronauts
complained bitterly about the filth and stench. Michael Foale, who
spent 134 days on Mir in 1997, described interior cabin walls slick
with a film of mildew.

The microgravity conditions, and higher radiation levels, fostered
mutations or changes in the microbes' genetic material. New forms of
the microbes appeared - slightly different from those people
encounter on Earth.

In 2001, Tulane University researchers confirmed that the
environment in Earth-orbit makes some bacteria mutate and become more
virulent, or dangerous in causing infections.

Russian cosmonauts often complained about coughs, skin boils and
other infections after returning to Earth. Nobody knows whether they
were caused by bacteria that evolved on Mir, or unsanitary conditions
on Earth.

By the late 1990s Mir's littlest cosmonauts and astronauts were
literally eating parts of up the station. One Russian scientist
described "a green mat" of fungus and bacteria growing on cables and
electronic components. The fungus produced acid wastes that damaged
electrical equipment and even etched and fogged a window, clouding
cosmonauts' view of space.

The counterparts of these "germs from space" now are growing inside
Mir's successor, the $60-billion ISS. NASA, which built ISS with
partners from a dozen other countries, learned lessons from Mir's
problems.

ISS has an upgraded climate control system, for instance, that
filters out many microbes and keeps the humidity low. Drinking water
is super-purified - a good thing since the source includes recycled
astronaut urine and breath.

Astronauts swab down surfaces with germicidal wipes, and take other
precautions to discourage their microscopic crewmates.

NASA also is monitoring the space station for signs that microbes
are mutating into new strains that could pose a health danger to
astronauts. Long space flights weaken the human immune system, making
astronauts more vulnerable to infections.

Could astronauts bring alien germs back to Earth, triggering a plague
from outer space? Stifle those smirks. Who knows?

The risk may be bigger later in the 21st century. Astronauts may be
returning from three-year missions to Mars, and lunar colonists may
be heading back to Hometown USA for a vacation. ISS and its crews,
big and little, are the laboratory and volunteers in a real-life
experiment that may help provide the answer.