Wherever humans go microbes will surely follow,
and the Space Station is no exception. In this article we take a
look at Microbes on the Space Station and how they will be kept
by Patrick L.Barry
Long before the first humans boarded
the International Space Station (ISS), something else was living
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 Centre.
The Space Station's micro-organisms
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
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 micro-organisms on the Space Station
Living in a microbial world
Microbes are everywhere.
"Just stand and breathe, and you're
releasing microbes," Roman said. "You can wash and scrub and use
antiseptic soap, and you'll still have microbes on your skin. You
have them everywhere: in your clothes, on your skin, in your hair,
in your body -- everywhere you could think of."
Many people may find the thought of
microbes living on and in their bodies disturbing, but living with
an entourage of stowaway microbes is natural.
"Generally speaking, microbes are invisible,
and so people just don't think of them as much as you do some other
things," said Dr. Duane Pierson, director of microbiology at NASA's
Johnson Space Centre.
Image Credit: The Centre for Microscopy
and Microanalysis, The University of Queensland, Australia.
A 5000x scanning
electron microscope image of E. Coli bacteria. It is a normal
resident of human intestines and provides vitamin K and some
of the B vitamins.
"People need to be reminded that we
live in a microbial world," Pierson said. "They were here before
us and they'll probably be here afterwards. We co-exist with them
In fact, bacteria in people's intestines
help to digest food, providing some otherwise unattainable nutrients,
such as vitamin K. A person's resident microbes also actually protect
them from infection by competing with dangerous microbes looking
for a place to grow.
While it is natural for a person to
live with a host of resident microbes, seven people -- each with
their own set of microbes -- living in a small, air-tight can for
months or years is certainly not.
"When the crew goes up to the station,
they'll each have their own microbial flora, and when they return
back, for the most part they've exchanged that flora with each other,"
Roman said. Most of these exchanged microbes are fought off by the
crew's immune systems and their own resident microbes, Pierson noted,
but the potential for infection is there.
The first step in protecting the health
of the crew is testing each crewmate for infection before launch.
Only healthy crew members are allowed to fly into space, and they're
quarantined before launch to prevent them from contracting harmful
germs at the last moment.
Once on the Space Station, the air,
water and surfaces with which the crew members interact must be
in a wide variety of sizes and forms. Tiny, one-celled yeasts
(inset) are important for baking breads and fermenting wines,
beers and vinegars. Many medicines are produced with the help
of fungi, most notably, the antibiotic, Penicillin. Mushrooms
are fungi we buy at the supermarket.
The air in the Space Station will be
kept in constant motion, and all the air on the Station will pass
through filters -- called High Efficiency Particle Air (HEPA) filters
-- on its way to the temperature and humidity control systems.
"The filters were originally designed
to remove particulates," Pierson said. "They're very good at removing
small particles," such as microbes.
Microbes can ride in the air on particles
of dust or in tiny clumps of bacteria or fungi. On Earth, there
might be a couple hundred or thousand microbes in each cubic metre
Water will be disinfected by a machine
called a "catalytic oxidator," which heats the water to as much
as 265 degrees F. The organic molecules in microbes are oxidised
by this process, which kills nearly all of them. Just to be sure,
the water is then treated with iodine.
After this disinfection, the water
should have less than 100 microbes in 100 millilitres of water.
"The water is extremely clean if you
compare it to the water that you drink at home," Roman said. "The
water on the Station is many, many times cleaner."
For the health of the crew as well
as the Station's hardware, microbes must also be kept from growing
on surfaces and in nooks and crannies.
"The biggest threat to the Station
from the microbes is degradation of the materials," Roman said.
"They'll eat pretty much anything."
"As they grow on surfaces, (fungi)
produce an acid which will eventually corrode the material," Roman
continued. "They start using most materials as a source of food.
Have you seen bathroom tile that's been overgrown by mold? Over
time, you will notice that the mold has kind of eaten the tile and
exemplified by the now-famous problems with mold and other fungi
aboard the Russian space station Mir, microbes can not only survive
in the metallic world of a space station, they can thrive.
Considering the inhospitable environments
in which microbes live on Earth, this should come as no surprise.
"They can live in the driest deserts
on Earth; they live in Antarctica and also in these deep sea vents
and in that boiling water out at Yellowstone. They are very adaptable,
and they can grow just about anywhere as long as they have their
basic requirements met," Pierson said.
space station Mir experienced problems with fungi growing
on and sometimes damaging the station's equipment and structural
Growth of microbes on the Station's
hardware will be controlled in several ways.
First, all materials used in the Space
Station are tested for resistance to fungi, such as mold. A paint
with a fungus-killing chemical is also used.
Controlling the humidity of the air
in the Station is also an effective way of discouraging microbe
"If you reduce the humidity to 65 to
70 percent -- which is what the Space Station is doing -- it's harder
for microbes like fungus to grow," Roman said. "They like higher
And finally, the Space Station crew
will keep surfaces clean the old-fashioned way: they'll clean them.
Housekeeping duties will include regularly
wiping down surfaces with a cloth containing an antiseptic solution.
All of these measures to minimize microbes
in the air and water and on surfaces should allow the Station and
its crew to conduct their mission in good health.
"We have a healthy crew going up there,
their food (contains very few microbes), and their water is very
clean," Roman said. "So the chance of them getting sick from an
infection is very low."