Raman spectroscopy of the Dukhan sabkha: identification of geological and biogeological molecules in an extreme environment (original) (raw)
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Analytical and Bioanalytical Chemistry, 2006
The Raman spectroscopic biosignatures of halotrophic cyanobacterial extremophiles from sabkha evaporitic saltpans are reported for the first time and ideas about the possible survival strategies in operation have been forthcoming. The biochemicals produced by the cyanobacteria which colonise the interfaces between large plates of clear selenitic gypsum, halite, and dolomitized calcium carbonates in the centre of the salt pans are identifiably different from those which are produced by benthic cyanobacterial mats colonising the surface of the salt pan edges in the intertidal zone. The prediction that similar geological formations would have been present on early Mars and which could now be underlying the highly peroxidised regolith on the surface of the planet has been confirmed by recent satellite observations from Mars orbit and by localised traverses by robotic surface rovers. The successful adoption of miniaturised Raman spectroscopic instrumentation as part of a scientific package for detection of extant life or biomolecular traces of extinct life on proposed future Mars missions will depend critically on interpretation of data from terrestrial Mars analogues such as sabkhas, of which the current study is an example.
The search for signatures of early life on Mars: Raman spectroscopy and the Exomars mission
2011
search for traces of life on Mars in the Aurora space exploration programme has confirmed that Raman spectroscopy will perform a key role for the molecular and elemental analysis of the Martian surface and subsurface on the ExoMars rover vehicle (Figure 1, Table 1). It is undeniable that the most important scientific discovery in a future space mission would be evidence for life on another planet, whether this be extant or extinct; however, this statement itself of life” situations; the recognition of key biomolecular spectral markers in the geological record provides the basis of a database of life detection both terrestrially and extraterrestrially. The advantages of Raman spectroscopy for the detection of biomolecules in geological mineral matrices will be illustrated using terrestrial extremophilic specimens from hot and cold deserts where temperatures, desiccation and exposure to low wavelength, high energy radiation in the ultraviolet region demand response strategies for spec...
The Rio Tinto Mars Analogue site: An extremophilic Raman spectroscopic study
Spectrochimica Acta Part A-molecular and Biomolecular Spectroscopy, 2007
The Rio Tinto site is recognised as a terrestrial Mars analogue because of the presence of jarosite and related sulfates which have recently been identified by the NASA Mars Exploration Rover “Opportunity” in the El Capitan region of Meridiani Planum on Mars. It has long been known that acidophilic microbial action is responsible for the deep blood-red colour of the water in Rio Tinto, where the pH varies from about 1.5 to 3.0 and the water is rich in iron and sulfur. Following recent Raman spectroscopic characterisation of the mineral phases of the Rio Tinto system, we report here a study of the biological components found in several specimens of deposited minerals and near the waterside that were collected during a GeoRaman VI Conference organized field trip in 2006. Key biosignatures were found for carotenoids, scytonemin and mycosporine-like amino acids, which are indicative of the biological colonisation of exposed mineral substrates; information from this study will be useful for targeting Martian sites using a miniaturized Raman instrument where the biosignatures of relict or extant life could remain in the geological record.