In situ analysis of Mars soil and rocks samples with the SAM experiment: laboratory measurements supporting treatment and interpretation of the detection of organics

Abstract : The Sample Analysis at Mars (SAM) experiment onboard the Curiosity rover detected numerous organic compounds when analyzing the solid samples collected on the way to Mount Sharp. But MTBSTFA, the chemical reactant for the chemical treatment of the refractory molecules present in the solid samples and present in cups of SAM, was shown to be unfortunately present in the Sample Manipulation System (SMS). During the sample analysis, this chemical species reacts with the organic and inorganic molecules present in the samples. This reaction leads to the production and subsequent detection of numerous MTBSTFA derivatives which makes the treatment and the interpretation of the SAM data complex. Moreover, for the first time on Mars, the wet chemistry method was used on a Cumberland sample to help the GC separation and the MS identification of non volatile compounds. To ensure the identification of the organic molecules and try to discriminate organics generated internally to SAM from those present in the samples analyzed, it is mandatory to perform laboratory experimental calibrations under martian operating conditions.