NASA builds
its spacecraft in some of the tidiest rooms on Earth, but a few microbial
stowaways always manage to survive and sneak a ride into space.
That could
be because the space agency's super-sterile "clean rooms" nonetheless
support a greater variety of microbes than previously thought, researchers have
now found. And, there more of them than expected. NASA is cataloging
the potential hitchhikers as a result, so they can be easily sorted from
potential extraterrestrial life that might one day be detected somewhere in the
solar system.
"These
findings will advance the search for life on Mars and other worlds," said study
co-author Kasthuri Venkateswaran, a microbiologist at NASA's Jet Propulsion
Laboratory in Pasadena, Calif.
Venkateswaran
and his group's findings are detailed in a recent issue of the journal FEMS
Microbiology Ecology.
Some
like it clean
Most
bacteria prefer plenty of food and fresh air, but some love
"extreme" environments and thrive on just the paint and leftover
cleaning solvents found in some NASA clean rooms. Some of the rooms, in which
the air is continuously filtered, harbor fewer than 10 particles per cubic foot
(0.03 cubic meter)--that's about 100,000 fewer dust particles than an equal
cube of outdoor air.
Catharine Conley,
an astrobiologist and planetary protection officer at NASA headquarters in Washington, D.C., said a lack of competition may cause the super-clean bugs' surprising
diversity.
"The
techniques used to identify microbes almost always miss the less common
ones," Conley told SPACE.com.
Normal microbe sampling is like choosing
animals from a room filled with 1,000 dogs and only 3 cats, she said, and
"if you pull 10 animals out of that crowd, they're all probably going to
be dogs."
When most
of the common bacteria (dogs) are gone, however, the remaining extreme bacteria
(cats) thrive on the lack of competition and show up more readily in samples.
Planetary
protection
To map the
diversity of clean room microbes, biologists got on their hands and knees and
swabbed large areas of NASA clean rooms across the nation.
Instead of
trying to grow the unseen microbes, which is practically impossible to do, the
scientists looked to a key genetic marker found in all bacteria called 16S
ribosomal RNA.
Like the
method that genomics researcher Craig Venter has used to assess the diversity
of bacteria in the world's oceans, Venkateswaran and his colleagues multiplied
the genetic markers and decoded the sequences. The result? About 193 unique
sequences--indicating 193 different bacterial "species"--were
discovered, at least 13 of which were not known to science before.
Conley said
the study will be crucial to sorting out the hitchhikers from the real thing
during future searches for microbial life on other worlds.
"It's
very useful information. We
need to know what microbes a spacecraft is taking with it out into the solar
system," she said. Conley added that NASA is now cataloging every possible
organism it can find in clean rooms, as such a list of critters will help
prevent a spacecraft from incorrectly confirming extraterrestrial life in the
event that it detects some of its stowaways.
Conley said
keeping NASA's facilities even cleaner is a growing priority to prevent "forward
contamination" of other worlds during future missions.
"We
want to do whatever we can to make sure we don't introduce life to places like
Europa or Mars," Conley said.
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