Geochemical analysis of layered outcrops using laser-induced breakdown spectroscopy (LIBS) - Implications for Mars exploration
Abstract
The chemistry and the stratigraphy of sedimentary, evaporative, and other types of deposits are indicators of their depositional environment and climate, and the evolution of these over time. Over the past eight years, the Mars Exploration Rovers (MER) have investigated several outcrops at Meridiani Planum and Gusev Crater. Compared to the MER, the capabilities of Curiosity to investigate outcrops and other deposits are enhanced because the rover incorporates a stand-off laser-induced breakdown spectroscopy (LIBS) instrument within the ChemCam suite. ChemCam's LIBS instrument has the capability to obtain chemical information from a large variety of targets at various distances, up to 7 m, including targets at a distance within stratigraphic layers non-accessible to other payload elements. In this work we demonstrate that semi-quantitative chemical stratigraphy can be very rapidly obtained by performing LIBS measurements on visually distinct layers within an outcrop at a terrestrial Mars analogue: the Atacama Desert, Chile. Such semi-quantitative chemical stratigraphy provides very valuable information on the distribution of elements within the analyzed layers, which can be used for tactical mission planning purposes. We performed laboratory laser-induced breakdown spectroscopy (LIBS) and laser Raman spectroscopy measurement on field samples from a layered outcrop from the Atacama Desert, Chile. This layered outcrop is a good terrestrial morphological analogue for similar formations that will likely be investigated by the Mars Science Laboratory on Gale crater. Our results demonstrate that LIBS can generate semi-quantitative chemical profiles in less than 1 min using automated data processing tools, and therefore the LIBS instrument can become an invaluable tactical tool on MSL for rapid geochemical survey of layered outcrops. The derived chemical profile at the terrestrial analogue is consistent with the range of minerals identified by Raman spectroscopy. In the framework of planetary exploration, LIBS can be used during MSL daily tactical operations for rapid geochemical survey of layered outcrops. Morphologically analogous sub-meter layered outcrops exist in Gale crater, and will be potential scientific targets during the MSL mission due to their high relevance to the mission's objectives. On the other hand, a combined Raman/LIBS investigation may provide a rapid mineralogical/chemical evaluation of the target that can be very useful for selecting samples to be eventually collected for sample return purposes or sample sites to be drilled in the search for astrobiology-related species.
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2012
- Bibcode:
- 2012AGUFM.P11E1879S
- Keywords:
-
- 5470 PLANETARY SCIENCES: SOLID SURFACE PLANETS / Surface materials and properties;
- 6225 PLANETARY SCIENCES: SOLAR SYSTEM OBJECTS / Mars