Arctic Microbes Provide Clues in Search for Extraterrestrial Life
24.05.2012 - Atmosphere & Space, Flora & Fauna, Arctic
Researchers from Indiana State University recently went to the western edge of the Greenland Ice Sheet – one of the most readily accessible ice margin areas on the planet – to study microorganisms and the methane (CH4) they produce in order to gain insight into how life might have evolved on Mars, Jupiter’s moon Europa, or Saturn’s moon Enceladus.
While methane is also produced abiotically – via reactions between water and rock as well as the breakdown of hydrocarbons through geological processes – acetate fermentation accounts for as much as 95% of methane production in cold environments. Methane emanating from methanogenic microbial communities, which produce methane and carbon dioxide as byproducts of the fermentation of acetate (a derivative of vinegar).
It “seems reasonable” to look for similar biological process in the icier parts of our solar system, according to Dr. Jeffrey White, an environmental biochemist at Indiana State University who lead the research. Subterranean water ice glaciers can be found in the Hells Basin region on Mars. Europa and Enceladus are icy worlds thought to contain liquid oceans beneath an icy surface.
The goal of the study is to determine which methods can best determine whether sources of methane in these regions might be biological or not. Analysis of the carbon isotopes in the molecules of methane sampled allows one to determine whether the methane originates from microbes or not. Methane originating from microbial sources contains significantly larger numbers of lighter isotopes of carbon than methane produced abiotically.
The team focused on investigating methane at multiple sites in lakes and wetland areas in a large valley near the edge of the Greenland Ice Sheet. They took measurements at about 2 metres above the soil surface for 1 to 4.5 hours each time. However as measurements of methane were close to levels of methane one would normally expect to find in the atmosphere in that part of Greenland, the team will take their next measurements at greater heights above the surface of the soil so they can more clearly distinguish local sources of methane.
During the upcoming summer, the team plans to use an innovative drill they’ve invented to investigate potential subsurface signs of life. The drill can directly transfer gasses sampled into analytical instruments for analysis. Such instruments could one day be used to take samples beneath the Martian surface.
