Exobiology and Evolutionary Biology

Signatures of Life in Ice (SLIce): A multidisciplinary investigation of organic signatures and habitat of life in surface glacial ice (2)

PI: Jennifer Eigenbrode

Ice is a cryogenic vault for preserving organics. Cold temperatures (<0° C) retard against hydrolysis and oxidation, which degrade biomolecules and other organics, allowing life to persist in the presence of impurities. As an extraterrestrial Mars analog to water-ice environments, such as the polar regions of Mars, glacial ice may not only be a harbor for extant life, but may also be a repository for aeolian materials containing organic matter from extinct life and meteorites.
The problem is that we know very little about the biological and organic inventory contained within modern glacial ice. Moreover, studies of viability, bioactivity, and habitat of microorganisms in glacial ice are still in their rudimentary stages and have largely focused on deep, sediment-rich subglacial ice of Greenland and Antarctica. Thus, we have little guidance for the distinction and interpretation of biosignatures related to ice life in glaciers.
We propose a multidisciplinary, comprehensive investigation of biosignatures in organic materials in near-surface (0-2 m depth) glacial ice and the associated habitat. Biosignatures are objects, substances and/or patterns that originate from biological agents. Mixtures of biosignatures, such as extinct verses extant or autochthonous (native) verses allochthonous (foreign; e.g. aeolian debris and aerosols), can be hard to resolve. However, life adapts and modifies its habitat. Thus, habitat and biological qualities tend to reflect environment-life interactions, which may be detectable. The proposed study will test the (1) influence of allochthonous organics and viable ice-dwelling life on organic matter composition preserved in ice and (2) if biogeochemical and microscopic observations differentiate these sources. We will constrain organic matter sources by comparing molecular biosignatures (in intact polar lipid, amino acid, fatty acid, and other hydrocarbon compositions) with associated cellular material, ATP bioactivity, and 16sRNA phylogenetic diversity of viable ice life and environmental conditions (i.e., ice geochemistry and the hydrocarbon composition, mineralogy, and geochemical mapping of particulates). The SLIce study will focus on the habitat primarily associated with particulates glacial ice from three locations in Svalbard, Norway. Analyses will involve a combination of in situ and laboratory analyses on ship and at PI and Co-I institutions. SLIce results will provide a scientific comparison to help ground interpretations of in situ Martian observations, such as those of NASA’s 2008 Phoenix and contribute to instrument selection for future NASA missions to icy bodies.
On cost and scientific basis, SLIce research is feasible only because it heavily leverages off of existing research initiatives and infrastructure; yet, it requires a separately funded and organized research directive to ensue.