| Summary: | International audience The Curiosity rover is currently analyzing the stratigraphic layers of Mount Sharp, searching for clues of Mars' habitability. The Sample Analysis at Mars (SAM) instrument suite aboard Curiosity—a pyrolyzer coupled to a gas chromatograph-mass spectrometer (pyro-GCMS)—is dedicated to searching for organic molecules. In addition to volatilizing compounds by heating solid samples, SAM also carries two reagents for wet chemistry experiments to extract and detect polar/refractory molecules. One of the reagents, N-methyl-N-(tert-butyldimethylsilyl)-trifluoroacetamide (MTBSTFA), reacts with organics of astrobiological interest while preserving their chemical structure from degradation. Laboratory experiments on Martian analogs is conducted to highlight the best preservation environments and minerals to target for MTBSTFA analyses. Results are also used to evaluate derivatization efficiency and understand the precursors and origins of organics detected by SAM, including as part of the first full wet chemistry experiment on Mars with MTBSTFA. This run was recently performed on the Ogunquit Beach (OG) dune sample, producing MTBSTFA by-products and derivative species yet to be identified. The analog suite includes carbonate ooids, a shale, an Antarctic paleolake deposit, iron oxides, and a mixture of iron oxides and clays from acid saline lake sediments. Thus far, SAM-like pyrolysis and derivatization GCMS experiments have been performed on the samples. SAM-like pyrolysis of the Antarctic paleolake indicated the presence of 200 organics confirming that this sample is a promising organic check material. SAM-like derivatization primarily revealing carboxylic acids from 3 to 18 carbon atoms, showed the best organic preservation in the oldest, most neutral pH lake samples as well as the Shale. The shale also contained the most variety and greatest abundance of organics. Results suggest that clays and mixtures of iron oxides/clays are most conducive to the preservation of organics. They also give ...
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