McCaig Heather C, Stockton Amanda, Crilly Candice, Chung Shirley, Kanik Isik, Lin Ying, Zhong Fang
1 Jet Propulsion Laboratory, California Institute of Technology , Pasadena, California.
2 Georgia Institute of Technology , Atlanta, Georgia .
Astrobiology. 2016 Sep;16(9):703-14. doi: 10.1089/ast.2015.1443.
The analysis of the organic compounds present in the martian regolith is essential for understanding the history and habitability of Mars, as well as studying the signs of possible extant or extinct life. To date, pyrolysis, the only technique that has been used to extract organic compounds from the martian regolith, has not enabled the detection of unaltered native martian organics. The elevated temperatures required for pyrolysis extraction can cause native martian organics to react with perchlorate salts in the regolith and possibly result in the chlorohydrocarbons that have been detected by in situ instruments. Supercritical carbon dioxide (SCCO2) extraction is an alternative to pyrolysis that may be capable of delivering unaltered native organic species to an in situ detector. In this study, we report the SCCO2 extraction of unaltered coronene, a representative polycyclic aromatic hydrocarbon (PAH), from martian regolith simulants, in the presence of 3 parts per thousand (ppth) sodium perchlorate. PAHs are a class of nonpolar molecules of astrobiological interest and are delivered to the martian surface by meteoritic infall. We also determined that the extraction efficiency of coronene was unaffected by the presence of perchlorate on the regolith simulant, and that no sodium perchlorate was extracted by SCCO2. This indicates that SCCO2 extraction can provide de-salted samples that could be directly delivered to a variety of in situ detectors. SCCO2 was also used to extract trace native fluorescent organic compounds from the martian regolith simulant JSC Mars-1, providing further evidence that SCCO2 extraction may provide an alternative to pyrolysis to enable the delivery of unaltered native organic compounds to an in situ detector on a future Mars rover.
Biomarkers-Carbon dioxide-In situ measurement-Mars-Search for Mars' organics. Astrobiology 16, 703-714.
分析火星风化层中存在的有机化合物对于了解火星的历史和宜居性以及研究可能现存或已灭绝生命的迹象至关重要。迄今为止，热解是唯一用于从火星风化层中提取有机化合物的技术，但尚未能够检测到未改变的原生火星有机物。热解提取所需的高温会使原生火星有机物与风化层中的高氯酸盐发生反应，并可能导致原位仪器检测到的氯代烃。超临界二氧化碳（SCCO2）提取是热解的一种替代方法，可能能够将未改变的原生有机物种输送到原位探测器。在本研究中，我们报告了在每千分之三（ppth）高氯酸钠存在的情况下，从火星风化层模拟物中SCCO2提取未改变的蔻，一种代表性的多环芳烃（PAH）。PAHs是一类具有天体生物学意义的非极性分子，通过陨石坠落输送到火星表面。我们还确定，蔻的提取效率不受风化层模拟物上高氯酸盐存在的影响，并且SCCO2没有提取出高氯酸钠。这表明SCCO2提取可以提供脱盐样品，这些样品可以直接输送到各种原位探测器。SCCO2还用于从火星风化层模拟物JSC Mars-1中提取痕量原生荧光有机化合物，进一步证明SCCO2提取可能为热解提供一种替代方法，以便在未来的火星探测器上能够将未改变的原生有机化合物输送到原位探测器。
生物标志物 - 二氧化碳 - 原位测量 - 火星 - 寻找火星有机物。天体生物学16，703 - 714。
