Subglacial Ecosystem Hints at Extraterrestrial Life

Artist's interpretation of a subglacial lake on Europa. Credit: Britney Schmidt/Dead Pixel VFX/Univ. of Texas at Austin.

A new paper published in the Nature journal has concluded that there is indeed a microbial ecosystem underneath the Antarctic ice sheet, providing evidence that ends decades of speculation about whether life can exist in such extreme habitats. The ecosystem is ancient and diverse, holding in the region of 4,000 distinct species of microorganisms.

A microbe examined as part of the study. Credit: Trista Vick-Majors.

Lead researcher Brent Christner told the Telegraph: "This does nothing but strengthen the case for life on other icy bodies in solar system and beyond. The first time we went to Antarctica and the first place we selected to drill a hole we found life. So it’s not much of a stretch that in similar conditions, like on the icy moon of Jupiter, Europa, life could exist there."

Video: Microbial Life Discovered Beneath Antarctic Ice Sheet. Credit: National Science Foundation

The research made use of a NASA designed and funded submarine in conjunction with the international Whillans Ice Stream Subglacial Access Research Drilling (WISSARD) project. The submarine was used to access Lake Whillans, on the West Antarctica's Ross Ice Shelf. The NASA JPL website describes the site as a "20-square-mile (50-square-kilometer) lake... totally devoid of sunlight (with) a temperature of 31 degrees Fahrenheit (minus 0.5 degrees Celsius). It is part of a vast Antarctic subglacial aquatic system that covers an area about the size of the continental United States."

The paper characterizes the ecosystem found beneath the ice layer covering Lake Whillans as "chemosynthetically driven... inhabited by a diverse assemblage of bacteria and archaea".

However, astrobiologist Chris McKay of NASA's Ames Research Center was critical of the suggestion that this finding has off-wold implications. Commenting on the paper, but not connected to it, McKay told Space.com: "First, it is clear that the water sampled is from a system that is flowing through ice and out to the ocean.

"Second, and related to this, the results are not indicative of an ecosystem that is growing in a dark, nutrient-limited system. They are consistent with debris from the overlying ice — known to contain micro-organisms — flowing through and out to the ocean. Interesting in its own right, but not a model for an isolated ice-covered ecosystem."

The research is part of a trend in astrobiology towards investigating habitats that most closely resemble ice worlds such as Enceladus and Europa. By studying terrestrial analogues of these conjectured subglacial environments, the likelihood of their habitability may be weighed. There is growing confidence that extraterrestrial life exists in such environments; so much so that NASA is currently investing in a Europa orbiting mission, while ESA are developing in a program called JUICE which aims to launch a mission to Jupiter and its moons Ganymede, Callisto and Europa in 2022, with a projected arrival in 2030.