title: Detection of pigments of halophilic endoliths from gypsum: Raman portable instrument and European Space Agency's prototype analysis.
abstract: A prototype instrument, under development at the University of Leicester, for the future European Space Agency (ESA) ExoMars mission, was used for the analysis of microbial pigments within a stratified gypsum crust from a hypersaline saltern evaporation pond at Eilat (Israel). Additionally, the same samples were analysed using a miniaturized Raman spectrometer, featuring the same 532 nm excitation. The differences in the position of the specific bands, attributed to carotenoid pigments from different coloured layers, were minor when analysed by the ESA prototype instrument; therefore, making it difficult to distinguish among the different pigments. The portable Delta Nu Advantage instrument allowed for the discrimination of microbial carotenoids from the orange/green and purple layers. The purpose of this study was to complement previous laboratory results with new data and experience with portable or handheld Raman systems, even with a dedicated prototype Raman system for the exploration of Mars. The latter is equipped with an excitation wavelength falling within the carotenoid polyene resonance region. The ESA prototype Raman instrument detected the carotenoid pigments (biomarkers) with ease, although further detailed distinctions among them were not achieved.
authors.affiliation: Institute of Geochemistry, Mineralogy, and Mineral Resources, Charles University in Prague, Prague, Czech Republic culka@natur.cuni.cz.
authors.forename: Adam
authors.initials: A
authors.lastname: Culka
authors.affiliation: Institute of Geochemistry, Mineralogy, and Mineral Resources, Charles University in Prague, Prague, Czech Republic.
authors.forename: Kateřina
authors.initials: K
authors.lastname: Osterrothová
authors.affiliation: Department of Physics and Astronomy, University of Leicester, Leicester, UK.
authors.forename: Ian
authors.initials: I
authors.lastname: Hutchinson
authors.affiliation: Department of Physics and Astronomy, University of Leicester, Leicester, UK.
authors.forename: Richard
authors.initials: R
authors.lastname: Ingley
authors.affiliation: Department of Physics and Astronomy, University of Leicester, Leicester, UK.
authors.forename: Melissa
authors.initials: M
authors.lastname: McHugh
authors.affiliation: Department of Plant and Environmental Sciences, The Alexander Silverman Institute of Life Sciences, The Edmond J. Safra Campus, Givat Ram, Jerusalem, Israel.
authors.forename: Aharon
authors.initials: A
authors.lastname: Oren
authors.affiliation: Division of Chemical and Forensic Sciences, University of Bradford, Bradford BD7 1DP, UK.
authors.forename: Howell G M
authors.initials: HG
authors.lastname: Edwards
authors.affiliation: Institute of Geochemistry, Mineralogy, and Mineral Resources, Charles University in Prague, Prague, Czech Republic.
authors.forename: Jan
authors.initials: J
authors.lastname: Jehlička
keywords: Mars; Raman; gypsum; halophiles; pigments; prototype