Earth microbes could contaminate Mars

Common bacteria found on spacecraft may be able to survive the harsh environs of Mars long enough to inadvertently contaminate Mars with terrestrial life.

To preserve the Martian environment, the bioloads on spacecraft are subject to sterilization.

Despite this, however, 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 for a week by inducing desiccation, hypobaria, low temperatures, and UV irradiation.

They found that Escherichia coli, a potential spacecraft contaminant, could survive – though probably not grow – on the surface of Mars if it were shielded from UV irradiation, for example 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.”

The research is published in Applied and Environmental Microbiology.