Earth
microbes may contaminate the search for life on
Mars
Tuesday, April 27, 2010
Bacteria common to spacecraft may be able to survive the harsh
environs of Mars long enough to inadvertently contaminate Mars with
terrestrial life according to research published in the April 2010
issue of the journal Applied and Environmental
Microbiology.
The search for life on Mars remains a stated goal of NASA's Mars
Exploration Program and Astrobiology Institutes. To preserve the
pristine environments, the bioloads on spacecraft headed to Mars
are subject to sterilization designed to prevent the contamination
of the Martian surface.
Despite sterilization efforts made to reduce the bioload on
spacecraft, recent studies have shown that diverse microbial
communities remain at the time of launch. The sterile nature of
spacecraft assembly facilities ensures that only the most resilient
species survive, including acinetobacter, bacillus, escherichia,
staphylococcus and streptococcus.
Researchers from the University of Central Florida replicated
Mars-like conditions by inducing desiccation, hypobaria, low
temperatures, and UV irradiation. During the week-long study they
found that Escherichia coli, a potential spacecraft contaminant,
may likely survive but not grow on the surface of Mars if it were
shielded from UV irradiation by thin layers of dust or UV-protected
niches in spacecraft.
"If long-term microbial survival is possible on Mars, then past and
future explorations of Mars may provide the microbial inoculum for
seeding Mars with terrestrial life," say the researchers. "Thus, a
diversity of microbial species should be studied to characterize
their potential for long term survival on Mars."
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American Society for Microbiology
Thanks to American Society for Microbiology for this
article.