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Analysis of water ice and ice/dust mixtures using laser-induced breakdown spectroscopy (LIBS).
In 1992, LIBS was proposed as a new method for stand-off detection of geological samples for use on landers and rovers to Mars. Recently, there has been increased interest in the technique for this and other space applications and studies have determined some of the characteristics and capabilities of the method under the conditions that these measurements will have to be made. In addition to rocks and soils, there is interest in using LIBS to analyze ices and dusts entrained in ice . This is especially true for missions to the Mars polar regions . Of particular interest is determining the nature of polar layered deposits, the geochemistry of polar surface materials, detection of water ice and the distribution of ice, and the presence of possible organics in these materials (via C/N ratios
Capabilities of LIBS for analysis of geological samples at stand-off distances in a Mars atmosphere
The use of LIBS for stand-off elemental analysis of geological and other samples in a simulated Mars atmosphere is being evaluated. Analytical capabilities, matrix effects, and other factors effecting analysis are being determined. Through funding from NASA's Mars Instrument Development Program (MIDP), we have been evaluating the use of LIBS for future use on landers and rovers to Mars. Of particular interest is the use of LIBS for stand-off measurements of geological samples up to 20 meters from the instrument. Very preliminary work on such remote LIBS measurements based on large laboratory type equipment was carried out about a decade ago. Recent work has characterized the capabilities using more compact instrumentation and some measurements have been conducted with LIBS on a NASA rover testbed
Trace element geochemistry as a tool for interpreting microbialites
Microbialites are critical for documenting early life on earth and-possibly elsewhere in the solar system. However, criteria for microbialite identification are controversial. Trace element geochemistry provides two types of information that aid interpretation of putative microbialites. Firstly, because most microbialites-consist of hydrogenous precipitates, trace elements can be used to investigate the fluids in which the structures formed, thus aiding identification of environments of formation. For example, rare earth elements preserved in microbialites have proven very useful in discriminating depositional environments. Secondly, microbes utilize and concentrate a wide range of elements, including many metals. Preservation of such elemental enrichments may provide a valuable biosignature. Although research in this field is relatively young, high precision, in situ measurement of metals in microbialites using techniques such as laser ablation-inductively coupled plasma-mass spectrometry, now with spatial mapping, have identified consistent enrichments in biologically important metals in microbialites. Hence, trace element studies are finding increasing utility in studying microbialites, and so long as diagenesis and the degree to which specific precipitates represent microenvironments are taken into account, trace element inventories may provide important information about depositional settings and, potentially, metabolic processes within biofilms