Dr. Dale Andersen

December 18, 2006

“Exobiological Investigations of Perennial Springs in the Canadian High Arctic”

NAG 5–12395

Perennial springs located at Axel Heiberg Island in the Canadian High Arctic provide useful analogs to liquid water habitats that may have existed on Mars. The springs occur in a region with a mean annual air temperature of –17°C, and thick, continuous permafrost breaching depths of 400–600 meters. Spring flow rates and discharge temperatures are constant throughout the year. Filamental bacteria, biofilms, and mineral precipitates occur in association with the emergent, anoxic brine flowing from the springs. This low-temperature setting provides an example of hydrothermal systems operating in the presence of thick permafrost—as would be expected to have been present on Mars during an earlier, more habitable period. This research examines the microbial communities found in association with the springs located at Axel Heiberg. The composition and distribution of the microbiota along environmental gradients particularly with respect to changes in redox, pH, temperature, light and dissolved gases will be characterized. This characterization will involve the application of both culturing and culture-independent approaches. This will allow us to determine the abundance of microorganisms, their phylogenetic identity and their possible physiological function within the spring system and the run-off areas. The travertine and other precipitates will be examined microscopically for microfossils which may have been preserved within the mineral matrix. Data obtained from this work will lead to a better understanding of the adaptive strategies used by microbial life found in extreme polar environments. On Mars, protected subsurface niches associated with hydrothermal activity in conditions of thick, continuous permafrost could have continued to support life even after surface conditions became inhospitable. The research at Axel Heiberg springs will provide information relevant to the search for evidence of life on Mars. Insight gained from the study of terrestrial polar spring environments will help guide the site selection of targets of exobiological interest and will aid with the interpretation of data returned from missions to those sites.