New Insights from the Cumberland Analog Investigation: Benzoic Acid as the Preferred Precursor for Chlorobenzene Detected on Mars

International audienceThe Curiosity rover on Mars is composed of ten instruments. On of them, the Sample Analysis at Mars (SAM), discovered the first evidence of organic molecules in a martian mudstone named Cumberland. The major molecule found in Cumberland was chlorobenzene, a compound composed of carbon, hydrogen and chlorine. Although the carbon, hydrogene and chlorine atoms are martian, chlorobenzene was likely made up in SAM, meaning that a precursor of it must exist at Mars' surface. In the laboratory, we recreated Cumberland from the minerals it is composed of, to the best of Curiosity's knowledge. This Cumberland analog sample was doped with a potential precursor of chlorobenzene, benzoic acid, and with magnesium perchlorates, ubiquiteous on Mars and the likely source of chlorine. This sample was then analyzed in SAM testbed, a high-fidelity mockup of SAM in the laboratory, within similar experimental conditions that were performed on Mars at Cumblerland. In this experiment, we observed the formation of chlorobenzene. Thus, the case for benzoic acid as a potential precursor for the chlorobenzene detected in the martian regolith is strengthened

New Insights from the Cumberland Analog Investigation: Benzoic Acid as the Preferred Precursor for Chlorobenzene Detected on Mars

International audienceThe Curiosity rover on Mars is composed of ten instruments. On of them, the Sample Analysis at Mars (SAM), discovered the first evidence of organic molecules in a martian mudstone named Cumberland. The major molecule found in Cumberland was chlorobenzene, a compound composed of carbon, hydrogen and chlorine. Although the carbon, hydrogene and chlorine atoms are martian, chlorobenzene was likely made up in SAM, meaning that a precursor of it must exist at Mars' surface. In the laboratory, we recreated Cumberland from the minerals it is composed of, to the best of Curiosity's knowledge. This Cumberland analog sample was doped with a potential precursor of chlorobenzene, benzoic acid, and with magnesium perchlorates, ubiquiteous on Mars and the likely source of chlorine. This sample was then analyzed in SAM testbed, a high-fidelity mockup of SAM in the laboratory, within similar experimental conditions that were performed on Mars at Cumblerland. In this experiment, we observed the formation of chlorobenzene. Thus, the case for benzoic acid as a potential precursor for the chlorobenzene detected in the martian regolith is strengthened

The Search for Lipids on Mars: Examining the Influence of Mineralogy on the Pyrolysis of Carboxylic Acids

International audienceLipids, such as fatty acids and waxes, are essential for all life on Earth. As early Mars shared many similarities with the early Earth multiple missions have examined ancient martian sediments for the presence of fatty acids and other organic species. No clear detection of lipids has been made so far, instead only small simple molecules have been observed, with the results dominated by species containing chlorine or sulfur. It has become clear that further developing our understanding of how organic and inorganic phases interact, both in situ and within flight instrumentation on Mars, is greatly needed. In this work, we mixed various fatty acid standards with different Mars-relevant minerals and examined them with a range of flight-relevant analytical methods. We also investigated how certain minerals might trap and preserve organics as they crystallize out of solution. The result inform how fatty acids may appear to the heating experiments used by past and present missions and the laser and spectroscopic methods included in upcoming science payloads

Five Years of Analyses of Volatiles, Isotopes and Organics in Gale Crater Materials

International audienceOver the last five years, the Curiosity rover has explored a variety of fluvial, lacustrine and aeolian sedimentary rocks, and soils. The Sample Analysis at Mars (SAM) instrument has analysed 3 soil and 12 rock samples, which exhibit significant chemical and mineralogical diversity in over 200 meters of vertical section. Here we will highlight several key insights enabled by recent measurements of the chemical and isotopic composition of inorganic volatiles and organic compounds detected in Gale Crater materials.Until recently samples have evolved O2 during SAM evolved gas analyses (EGA), attributed to the thermal decomposition of oxychlorine phases. A lack of O2 evolution from recent mudstone samples may indicate a difference in the composition of depositional or diagenetic fluids, and can also have implications for the detection of organic compounds since O2 can combust organics to CO2 in the SAM ovens. Recent mudstone samples have also shown little or no evolution of NO attributable to nitrate salts, possibly also as a result of changes in the chemical composition of fluids [1]. Measurements of the isotopic composition of sulfur, hydrogen, nitrogen, chlorine, and carbon in methane evolved during SAM pyrolysis are providing constraints on the conditions of possible paleoenvironments [e.g., 2, 3]. There is evidence of organic C from both EGA and GCMS measurements of Gale samples [e.g., 4, 5]. Organic sulfur volatiles have been detected in several samples, and the first opportunistic derivatization experiment produced a rich dataset indicating the presence of several organic compounds [6, 7]. A K-Ar age has been obtained from the Mojave mudstone, and the age of secondary materials formed by aqueous alteration is likely <3 Ga [8]. This relatively young formation age suggests fluid interactions after the end of most fluvial activity on the surface of Mars.As these highlights show, SAM measurements of solid samples have made diverse and important contributions to the exploration of Gale’s rock records of martian environmental history and habitability