The Mars Organic Molecule Analyzer (MOMA) onboard the ExoMars 2020 rover (to be landed in March 2021) utilizes pyrolysis gas chromatography-mass spectrometry (GC-MS) with the aim to detect organic molecules in martian (sub-) surface materials. Pyrolysis, however, may thermally destroy and transform organic matter depending on the temperature and nature of the molecules, thus altering the original molecular signatures. In this study, we tested MOMA flight-like pyrolysis GC-MS without the addition of perchlorates on well-characterized natural mineralogical analog samples for Oxia Planum, the designated ExoMars 2020 landing site. Experiments were performed on an iron-rich shale (that is rich in Fe-Mg-smectites) and an opaline chert, with known organic matter compositions, to test pyrolytic effects related to heating in the MOMA oven. Two hydrocarbon standards (n-octadecane and phytane) were also analyzed. The experiments show that during stepwise pyrolysis (300°C, 500°C, and 700°C), (1) low-molecular-weight hydrocarbon biomarkers (such as acyclic isoprenoids and aryl isoprenoids) can be analyzed intact, (2) discrimination between free and complex molecules (macromolecules) is principally possible, (3) secondary pyrolysis products and carryover may affect the 500°C and 700°C runs, and (4) the type of the organic matter (functionalized vs. defunctionalized) governs the pyrolysis outcome rather than the difference in mineralogy. Although pyrosynthesis reactions and carryover clearly have to be considered in data interpretation, our results demonstrate that pyrolysis GC-MS onboard MOMA operated under favorable conditions (e.g., no perchlorates) will be capable of providing important structural information on organic matter found on Mars, particularly when used in conjunction with other techniques on MOMA, including derivatization and thermochemolysis GC-MS and laser desorption/ionization-MS.

中文翻译：

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在ExoMars 2020流动站上的Oxia Planum模拟样品上，通过火星有机分子分析仪进行的类似飞行的热解气相色谱-质谱法测试。

ExoMars 2020流动站（将于2021年3月着陆）上的火星有机分子分析仪（MOMA）利用热解气相色谱-质谱（GC-MS）来检测火星表面（子）表面的有机分子。但是，热解可能会根据分子的温度和性质热破坏并转化有机物，从而改变原始的分子特征。在这项研究中，我们在Oxia Planum（指定为ExoMars 2020着陆点）的特性良好的天然矿物模拟样品上测试了MOMA飞行式热解GC-MS，未添加高氯酸盐。在具有已知有机物成分的富铁页岩（富含铁，镁，蒙脱石）和乳白硅石上进行实验，以测试与在MOMA烤箱中加热相关的热解效果。还分析了两种烃标准品（正十八烷和植烷）。实验表明，在分步热解过程中（300°C，500°C和700°C），（1）可以完整分析低分子量烃类生物标志物（例如无环类异戊二烯和芳基类异戊二烯），（2）鉴别自由和复杂分子（大分子）之间的相互作用是可能的，（3）二级热解产物和残留物可能会影响500°C和700°C的运行，并且（4）有机物的类型（官能化与去官能化）决定着热解的结果，而不是矿物学的差异。尽管在数据解释中显然必须考虑热解反应和残留物，但我们的结果表明，MOMA板上的热解GC-MS在有利的条件下（例如，