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N°32 I quarterly I january 2014 Live from the Labs | Spotlight 7 w site, a few hundred meters away from the landing area. “Although it is in the opposite direction from Mount Sharp, the rover’s main destination, the first images showed geological structures that encouraged us to make a short detour,” explains Maurice. The scientists were definitely not disappointed. “We discovered rocks whose shape revealed that they had been rolled along in water, evidence that Curiosity was in the bed of a river or stream,” says Michel Cabane, from LATMOS.2 This is not the first time that scientists confirm the presence of water on ancient Mars. Yet as Cabane points out, “at Glenelg, we have evidence that water flowed for quite some time with significant speed, strength, and decimeter-scale depth, if not more. It is incompatible with a flow caused merely by a shortlived instability.” Promisi ng Analyses “Curiosity then examined its first unusual specimen, namely a volcanic rock similar to the ones erupted by Tenerife volcanoes,” reports Cabane. Although this did not provide any information about Mars’s past habitability, it did show that the rover’s various instruments could operate together and complement one another. A sandbank gave the scientists an opportunity to test the rover’s mechanical shovel. It was able to collect samples before delivering them to the instruments designed to carry out in situ analyses. “These were the first soil analyses carried out by SAM, just to test the device’s capacity,” Cabane explains. Developed partly by CNES, LATMOS, and LISA,3 SAM is a miniaturized laboratory. The different chemicals present in a rock matrix, especially the carbon compounds associated with life, are first separated out in a set of ovens before being sent to three instruments that determine their chemical and isotopic composition. One of SAM’s projects, co-headed by Cabane, is to investigate the presence of organic molecules— a signature of life—in the Martian atmosphere, soil, and rocks. Further analysis showed that the sand in the dune is chemically similar to that already studied in other spots by the rovers Spirit and Opportunity and is thus representative of the planet as a whole. In addition, tests revealed that the fine grains richest in iron and magnesium exhibit hydration associated with a noncrystalline mineral phase, and that this water has the same isotopic composition as that found in the Martian atmosphere. As Pierre-Yves Meslin, also at IRAP, explains, “this level of hydration is consistent with that of the global Martian surface as measured by satellites. It is therefore likely that the global hydration of Mars could be due to the hydration of this non-crystalline phase contained in the sand. Moreover, the isotopic similarity with the water vapor in the atmosphere suggests that Mars built up these reserves of water in a recent phase of its development rather than through interaction with liquid water in the distant past.” This is a crucial finding given that the origin of these reserves is one of the keys to understanding the evolution of the Martian climate. Converging Evidence The real highlight, however, came a year ago. Curiosity was exploring a site known as Yellowknife Bay, made up of what appeared to be sedimentary rocks crisscrossed by veins filled with white crystals. “We immediately thought that these might be salts left by water after evaporation,” Cabane recalls. The CheMin, ChemCam, and APXS instruments then went into action, followed by SAM and 05 At FIMOC (French Instrument Mars Operation Center) in Toulouse, the data sent by the ChemCam instrument is analyzed in real time. 05 © S. GIRARD/CNES 01 Curiosity’s ChemCam instrument analyzes rocks and soil. 02 Images of the Martian ground before (left) and after (right) the laser beams are fired. 03 The scoop that Curiosity uses to collect samples of small aeolian deposits (04). © NASA/JPL-Cal tech/MSSS © NASA 02 03 04 © NASA/JPL-Caltech/LANL/CNES/IRAP/IAS/CNRS


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