The Atacama desert lies on the western edge of South America, covering much of northern Chile and parts of Argentina. It is the closest one can get to Mars while remaining grounded on Earth. High atop the Socompa volcano on the Eastern edge of the Atacama desert, the atmosphere is thin, the ultraviolet radiation is intense, and the climate is dry. Nevertheless, the improbable has been found: life. Near the rim of the 19,850-foot-high Socompa volcano, researchers from the University of Colorado at Boulder's Alpine Microbial Observatory found a thriving, complex microbial community that appears to be supported by gases emanating from volcanic vents around the rim.

The Atacama desert is the driest place on Earth. Weather stations in the Antofagasta region of Chile average one millimeter of precipitation per year, and a number of weather stations in the Atacama have never recorded rainfall throughout their entire operational life. The extreme climate there is often compared to the surface of Mars. It is believed to be so similar that a Science article, published in 2003, used it in an attempt to re-create the experiments that Viking One and Two performed on the Martian surface. It is also a proving ground for equipment that NASA plans to send to Mars one day. Given the geologic similarities, the discovery of life in such a hostile place suggests that life could exist elsewhere as well.

The microbial communities atop Socompa are "are unique little oases in the vast, barren landscape of the Atacama Desert and are supported by gases from deep within the Earth," according to Steven Schmidt, the corresponding author on the paper. In a paper published in a February edition of Applied and Environmental Microbiology, researchers reported on the results of a combined "biogeochemical and molecular-phylogenetic approach" to examining the system. They extracted genetic material, using novel techniques and cloned via PCR reactions to take a "snapshot" of the genetic diversity atop the mountain.

The generic volcanic soil found in the area turned out to be home to a few varieties of Actinbacteria and Fungi, but little else. The areas around the volcanic fumaroles, on the other hand, were found to be home to photoautotrophic microbial communities and a newly identified species of mite. Some of the basic chemicals needed for life to continue are provided by the volcano itself. As coauthor of the paper, Elizabeth Costello says, "it's as if these bacterial communities are living in tiny, volcanic greenhouses."

A second expedition to the site was carried out last month as well. Even though the site is extremely remote, requiring a two day drive followed by two days of hiking, footprints were found that the researchers worry may have destroyed some of the plant communities found there. With further understanding of the extremophiles that are living on the edge, so to speak, here on Earth, it may enhance our ability to find similar such organisms throughout the solar system.

Relevant to that speculation, a paper has been published in Geology that describes modeling the surface of Olympus Mons, Mars' largest volcano. The results indicate that some of the features of the terrain on this peak are best explained by the presence of clays, which have been spotted elsewhere on Mars. Clays require water, which may be another reason to suspect that Socompa could be a reasonable analog of Martian environments.

Applied and Environmental Microbiology, 2009. DOI: 10.1128/AEM.01469-08