Testing the capabilities of the Mars Organic Molecule Analyser (MOMA) chromatographic columns for the separation of organic compounds on Mars

International audienceMars is our planetary neighbor and is now known to host trace levels of organic matter at its surface. However, little is known of the organic molecular composition or the survival potential for organic biosignatures, such as the enantiomeric excess of amino acids or the carbon chain patterns of lipid hydrocarbons, as a function of depth below the martian surface. The Mars Organic Molecule Analyser (MOMA) is an instrument onboard the Rosalind Franklin rover that is scheduled to be launched to Mars in the summer of 2020 as part of the ExoMars mission. This experiment includes a gas chromatograph instrument dedicated to the in situ analysis of organic molecules and their enantiomers present in martian samples collected by the rover at the surface down to 2 m depth. In order to evaluate the performance of the integrated chromatographic system which was selected for the flight model, experiments were carried out with a laboratory setup that reproduced the flight configuration and mimicked the in situ operating conditions. We show that the column instrument package can separate and detect a wide range of organic and inorganic volatile compounds, from noble gases to hydrocarbon chains with up to 29 carbon atoms (C29). We study the enantiomeric resolution of selected chiral chemical standards and compare our laboratory results to: i. tests performed with the same instrumental setup but using a natural sample spiked with amino acids in order to evaluate the influence of a mineral phase on the analysis, and ii. tests run on a MOMA engineering test unit (ETU) which is representative of the flight model. In each case, tests on the more complex sample and the more flight-like instrument allows a comparison with laboratory results, in order to confirm that laboratory data are reliable for supporting peak identification within flight data. The obtained results demonstrate the ability of the gas chromatographic subsystem to identify a wide range of organic and inorganic volatile compounds, including biomolecular signatures, within the constrained space operating conditions of MOMA. The results form a retention time and mass spectral database for MOMA which will be critical for analysis of the eventual flight data