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"Multi-column gas chromatography analysis of chlorohydrocarbons 1with the SAM experiment onboard NASA’s Mars Curiosity rover" est le titre provisoire de la publication.; International audience; The Sample Analysis at Mars (SAM) instrument is a gas chromatograph-mass spectrometer onboard the NASA Curiosity rover, currently operating on the surface of Mars. Organic compounds are of major importance with regard to questions of habitability and the potential presence of life on Mars, and one of the mission’s main objectives is to analyze the organic content of soil and rock samples. In SAM’s first chromatographic measurements, however, unexpected chlorine-bearing organic molecules were detected. These molecules have different origins but the presence of perchlorates and chlorates detected at the surface of Mars suggests that reactivity between organic molecules and thermal decomposition products from oxychlorines is one of the major sources of the chlorinated organic molecules. Here we perform a comprehensive and systematic study of the separation of volatile chlorohydrocarbons with the chromatographic columns used in the SAM instrument. Despite the constrained operating conditions of the flight instrument, we demonstrate that SAM’s capillary chromatographic columns allow for effective separation and identification of a wide range of chlorine-bearing species. We also show that instrumental limitations prevent the detection of certain molecules, obscuring our ability to make definitive conclusions about the origin of these organic materials.

As part of the development of the European Space Agency Rosetta space mission to investigate a cometary nucleus, the selection of columns dedicated to the gas chromatographic subsystem of the Cometary Sampling and Composition (COSAC) experiment was achieved. Once the space probe launched, these columns will be exposed to the harsh environmental constraints of space missions: vibrations, radiation (by photons or energetic particles), space vacuum, and large temperature range. In order to test the resistance of the flight columns and their stationary phases, the columns were exposed to these rough conditions reproduced in the laboratory. The comparison of the analytical performances of the columns, evaluated prior and after the environmental tests, demonstrated that all the columns withstand space constraints, and that their analytical properties were preserved. Therefore, all the selected capillary columns, even having porous layer or chiral stationary phases, were qualified for space exploration.