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Past studies have focused on moderate-temperature microbes that pose a more common risk of contaminating spacecraft parts and hitching a ride into space. NASA has long worried that contamination by Earth microbes could upset ongoing efforts to find Martian or other extraterrestrial life.

Schuerger and his colleagues chose to test Psychrobacter cryohalolentis, an extremophile that thrives under extremely dry conditions and at temperatures as low as minus 10 degrees C. That choice allowed them to push scientific understanding of what may or may not survive on the Martian surface.

"If we can find any of extremophilic terrestrial species that are capable of growth and replication under Martian conditions, it puts the search for life on Mars a bit closer to success," Schuerger explained.

Testing under Martian surface conditions meant turning to the Mars Simulation Chamber (MSC) at the Kennedy Space Center, where researchers simulated everything from dust free skies to global dust storm conditions. The study grew out of the undergraduate work of David Smith from Princeton University, who has since gone on to conduct his Ph.D. research at the University of Washington.

The team also tested how well a salt mineral matrix similar to parts of the Martian surface could protect against UV, and how well the extremophiles dealt with very dry conditions.