Earth bacteria may contaminate Martian environments

Scientists are expressing fears that some bacteria common to spacecrafts may even survive on Mars and contaminate the Red Planet's environment. 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.The scientists said: "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."Thus, a diversity of microbial species should be studied to characterize their potential for long term survival on Mars."The study has appeared in the April 2010 issue of the journal Applied and Environmental Microbiology.