440 research outputs found
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Mars simulated exposure and the characteristic Raman biosignatures of amino acids and halophilic microbes
Though Raman bands of α-amino acids (AA) are well documented, often only the strongest intensity bands are quoted as identifiers (e.g. Jenkins et al., 2005; De Gelder et al., 2007; Zhu et al., 2011). Unknown regolith mixtures on Mars-sampling missions could obscure these bands. Here the case is made for determining, via a statistical method, sets of characteristic bands to be used as identifiers, independent of band intensity or number of bands (Rolfe et al., 2016). AA have upwards of 25 potentially identifying bands and this method defines sets of 10–19 bands per AA. Examination of AA-doped Mars-like basalt resulted in a maximum of eight bands being identified, as some characteristic bands were obscured by mineral bands, including the strongest intensity band in some cases. This proved the need for characteristic bands to be defined, enabling successful identification of AA. The ESA ExoMars Rover mission will crush and then pass the sample to the Raman Laser Spectrometer. We crushed a Mars-like basalt to a similar grain size expected to be created by the rover. Our samples were doped with 1 % (by weight) AA samples, resulting in no detection of AA, because of loss of original spatial context and spaces between the grains. We recommend that Raman spectroscopy on future missions should be conducted before the sample is crushed. Halite-entombed halophilic microbes, known to survive being entombed, were exposed to Mars-like surface (including temperature, pressure, atmospheric composition and UV) and freeze-thaw cycle (plus pressure and atmospheric composition) conditions. This test on the survival of the microbes showed that survival rates quickly deteriorated in surface conditions, but freeze-thaw cycle samples had well preserved Raman biosignatures, indicating that similar signatures could be detectable on Mars if similar life persists in evaporitic material or brines today
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Surface Profiling of Natural Dust Devils
We present results from the first high-resolution near-surface profiles conducted on dust devil wind fields. These results are integrated with extensive geologic mapping to understand the factors that influence vortex generation and erosive efficacy
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Trace gas transport in the subsurface of Mars
The ExoMars Trace Gas Orbiter (TGO) will have the capability of detecting and characterizing a broad suite of trace gases in the atmosphere of Mars. Interpreting the results of this mission will require an understanding of how these trace gases are transported from their sources, which may be deep underground, to the atmosphere. Here we present results of modeling designed to measure the timescales of release from putative subsurface methane sources. These transport timescales are far longer than mixing times in the atmosphere and could be up to 10 million years
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A close encounter with a terrestrial dust devil
We report on an extremely well characterised encounter with a terrestrial dust devil, and its comparison with martian dust devils
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The Beagle 2 environmental sensors: intended measurements and scientific goals
The Beagle 2 lander, due for arrival on Mars in December 2003, carries an Environmental Sensors Suite to monitor the local meteorology and carry out simple dust and oxidant measurements. The suite is described, and the scientific goals are discussed
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Detecting biomarkers on Mars using Raman spectroscopy
Raman spectroscopy is a powerful technique for the characterisation of organic molecules as it provides a unique ‘fingerprint’ spectrum. Incident monochromatic light on a sample is shifted in wavelength giving rise to the Raman spectrum, with peaks that are attributable to the specific
vibrational bonds within the molecule. Raman spectroscopy is useful for analysing not only geological samples but also biological molecules, and has been recommended for use as a detection method (among others) for biomarkers on missions to planetary bodies [1]. The ExoMars Rover mission is due to launch in 2018 with a Raman spectrometer as part of its scientific payload [2].
Amino acids, the ‘building-blocks’ of proteins, have been identified as a high priority biomarker in the search for evidence of life on planetary bodies [3]. Raman spectroscopy is often a qualitative method, but if signatures of biomarkers are detected by Raman spectroscopy, it is critical that correct identification of such biomarkers can be undertaken. To aid in molecule identification, we take a statistical approach to determine the position of characteristic peaks of several amino acids. We present evidence for statistically significant changes in the peak positions when using different excitation wavelengths. Furthermore, we present evidence that martian conditions have an effect on the Raman spectra of amino acids, which could have implications when performing in situ measurements on Mars.
1. Jehlicka, J., H.G.M. Edwards, and P. VÃtek, Assessment of Raman spectroscopy as a tool for
the non-destructive identification of organic minerals and biomolecules for Mars studies.
Planetary and Space Science, 2009. 57(5-6): p. 606-613.
2. Edwards, H.G.M., I. Hutchinson, and R. Ingley, The ExoMars Raman spectrometer and the
identification of biogeological spectroscopic signatures using a flight-like prototype.
Analytical and Bioanalytical Chemistry, 2012. 404(6-7): p. 1723-1731.
3. Parnell, J., et al., Searching for Life on Mars: Selection of Molecular Targets for ESA's Aurora
ExoMars Mission. Astrobiology, 2007. 7(4): p. 578-604
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Raman spectroscopy of biologically relevant amino acids under martian condtions
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Raman spectroscopy of amino acids and other biomarkers on Mars
In the search for life elsewhere in the Solar System, our nearest planetary neighbour, Mars, offers great potential for finding past or present life. Whether life is extant or not, signs of biological activity can be inferred through the detection of specific biomarkers, such as amino acids.
Raman spectroscopy is an extremely effective method of detecting biomarkers. It is non-destructive and is used to identify different molecular species through observations of the Raman shift created by the bonds within the molecule.
Amino acids that are part of a biological system could provide potential evidence of life on Mars. It is thought that amino acids could survive in the sub-surface of Mars, making them a high-priority biomarker candidate. Terrestrial life utilises homochiral amino acids, and if detected on Mars it would provide an important piece of evidence for the case for life on Mars.
In this work, a number of biologically essential amino acids that are utilised in terrestrial organisms will be studied using Raman spectroscopy. We aim to characterise the Raman signature for these molecules in detail in order to aid interpretation of results from future Mars landers, and presented here are initial results from the preliminary investigations.
Further work will extend to other high-priority biomarkers that may be found at the surface/sub-surface of Mars
Implementation of the QUBE Force Field in SOMD for High-Throughput Alchemical Free-Energy Calculations
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