| Title | Biosignature detection at an Arctic analog to Europa |
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| Author | Gleeson, D F; Pappalardo, R T; Anderson, M S; Grasby, S E ; Mielke, R E; Wright, K E; Templeton, A S |
| Source | Astrobiology vol. 12, no. 2, 2012 p. 135-150, https://doi.org/10.1089/ast.2010.0579 |
| Image |  |
| Year | 2012 |
| Alt Series | Earth Sciences Sector, Contribution Series 20110214 |
| Publisher | Mary Ann Liebert Inc |
| Document | serial |
| Lang. | English |
| Media | paper; on-line; digital |
| File format | pdf |
| Province | Nunavut |
| NTS | 340B/16NW; 340C/01SW |
| Area | Ellesmere Island; Borup Fiord; Europa |
| Lat/Long WENS | -82.0000 -81.0000 81.0833 80.9167 |
| Subjects | surficial geology/geomorphology; extraterrestrial geology; biota; ice; glaciers; sulphur; microorganisms; electron microscopy; analytical methods |
| Illustrations | photographs |
| Program | GEM:
Geo-mapping for Energy and Minerals Sverdrup Sedimentary Basin |
| Released | 2012 02 01 |
| Abstract | The compelling evidence for an ocean beneath the ice shell of Europa makes it a high priority for astrobiological investigations. Future missions to the icy surface of this moon will query the plausibly
sulfur-rich materials for potential indications of the presence of life carried to the surface by mobile ice or partial melt. However, the potential for generation and preservation of biosignatures under cold, sulfur-rich conditions has not
previously been investigated, as there have not been suitable environments on Earth to study. Here, we describe the characterization of a range of biosignatures within potentially analogous sulfur deposits from the surface of an Arctic glacier at
Borup Fiord Pass to evaluate whether evidence for microbial activities is produced and preserved within these deposits. Optical and electron microscopy revealed microorganisms and extracellular materials. Elemental sulfur (S0), the dominant
mineralogy within field samples, is present as rhombic and needle-shaped mineral grains and spherical mineral aggregates, commonly observed in association with extracellular polymeric substances. Orthorhombic a-sulfur represents the stable form of
S0, whereas the monoclinic (needle-shaped) c-sulfur form rosickyite is metastable and has previously been associated with sulfide-oxidizing microbial communities. Scanning transmission electron microscopy showed mineral deposition on cellular and
extracellular materials in the form of submicron-sized, needle-shaped crystals. X-ray diffraction measurements supply supporting evidence for the presence of a minor component of rosickyite. Infrared spectroscopy revealed parts-per-million level
organics in the Borup sulfur deposits and organic functional groups diagnostic of biomolecules such as proteins and fatty acids. Organic components are below the detection limit for Raman spectra, which were dominated by sulfur peaks. These combined
investigations indicate that sulfur mineral deposits may contain identifiable biosignatures that can be stabilized and preserved under low-temperature conditions. Borup Fiord Pass represents a useful testing ground for instruments and techniques
relevant to future astrobiological exploration at Europa. |
| GEOSCAN ID | 289285 |
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