Siljeström Sandra, Li Xiang, Brinckerhoff William, van Amerom Friso, Cady Sherry L
RISE Research Institutes of Sweden, Department of Chemistry, Biomaterials and Textiles, Stockholm, Sweden.
Center for Research and Exploration in Space Science & Technology, University of Maryland Baltimore County, Baltimore, Maryland, USA.
Astrobiology. 2021 Dec;21(12):1515-1525. doi: 10.1089/ast.2020.2368. Epub 2021 Mar 16.
The Mars Organic Molecule Analyzer (MOMA) is a key scientific instrument on the ExoMars Rover mission. MOMA is designed to detect and characterize organic compounds, over a wide range of volatility and molecular weight, in samples obtained from up to 2 m below the martian surface. Thorough analog sample studies are required to best prepare to interpret MOMA data collected on Mars. We present here the MOMA characterization of Mars analog samples, microbial streamer communities composed primarily of oxygenic and anoxygenic phototrophs, collected from an alkaline silica-depositing hot spring in Yellowstone National Park, Wyoming, USA. Samples of partly mineralized microbial streamers and their total lipid extract (TLE) were measured on a MOMA Engineering Test Unit (ETU) instrument by using its laser desorption/ionization mass spectrometry (LDI-MS) mode. MOMA LDI-MS detected a variety of lipids and pigments such as chlorophyll monogalactosyldiacylglycerol, digalactosyldiacylglycerol, diacylglycerols, and β-carotene in the TLE sample. Only chlorophyll was detected in the untreated streamer samples when using mass isolation, which was likely due to the higher background signal of this sample and the relative high ionization potential of the chlorophyll compared with other compounds in unextracted samples. The results add to the LDI-MS sample characterization database and demonstrate the benefit of using mass isolation on the MOMA instrument to reveal the presence of complex organics and potential biomarkers preserved in a natural sample. This will also provide guidance to analysis of surface samples during Mars operations.
火星有机分子分析仪（MOMA）是ExoMars火星车任务中的关键科学仪器。MOMA旨在检测和表征从火星表面以下2米深处获取的样本中挥发性和分子量范围广泛的有机化合物。需要进行全面的模拟样本研究，以便为解释在火星上收集的MOMA数据做好最佳准备。我们在此展示了对火星模拟样本的MOMA表征，这些样本是从美国怀俄明州黄石国家公园的一个碱性硅沉积温泉中采集的，主要由产氧和不产氧的光合微生物组成的微生物丝状群落。使用MOMA工程测试单元（ETU）仪器的激光解吸/电离质谱（LDI-MS）模式，对部分矿化的微生物丝状样本及其总脂质提取物（TLE）进行了测量。MOMA LDI-MS在TLE样本中检测到了多种脂质和色素，如叶绿素、单半乳糖二酰基甘油、二半乳糖二酰基甘油、二酰基甘油和β-胡萝卜素。在使用质量隔离时，未处理的丝状样本中仅检测到了叶绿素，这可能是由于该样本的背景信号较高，以及与未提取样本中的其他化合物相比，叶绿素的电离电位相对较高。这些结果丰富了LDI-MS样本表征数据库，并证明了在MOMA仪器上使用质量隔离来揭示天然样本中保存的复杂有机物和潜在生物标志物的存在的益处。这也将为火星任务期间的表面样本分析提供指导。
