Hydrothermal spring deposits host unique microbial ecosystems and have the capacity to preserve microbial communities as biosignatures within siliceous sinter layers. This quality makes terrestrial hot springs appealing natural laboratories to study the preservation of both organic and morphologic biosignatures. The discovery of hydrothermal deposits on Mars has called attention to these hot springs as Mars-analog environments, driving forward the study of biosignature preservation in these settings to help prepare future missions targeting the recovery of biosignatures from martian hot-spring deposits. This study quantifies the fatty acid load in three Icelandic hot-spring deposits ranging from modern and inactive to relict. Samples were collected from both the surface and 2–18 cm in depth to approximate the drilling capabilities of current and upcoming Mars rovers. To determine the preservation potential of organics in siliceous sinter deposits, fatty acid analyses were performed with pyrolysis–gas chromatography–mass spectrometry (GC-MS) utilizing thermochemolysis with tetramethylammonium hydroxide (TMAH). This technique is available on both current and upcoming Mars rovers. Results reveal that fatty acids are often degraded in the subsurface relative to surface samples but are preserved and detectable with the TMAH pyrolysis-GC-MS method. Hot-spring mid-to-distal aprons are often the best texturally and geomorphically definable feature in older, degraded terrestrial sinter systems and are therefore most readily detectable on Mars from orbital images. These findings have implications for the detection of organics in martian hydrothermal systems as they suggest that organics might be detectable on Mars in relatively recent hot-spring deposits, but preservation likely deteriorates over geological timescales. Rovers with thermochemolysis pyrolysis-GC-MS instrumentation may be able to detect fatty acids in hot-spring deposits if the organics are relatively young; therefore, martian landing site and sample selection are of paramount importance in the search for organics on Mars.

中文翻译：

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冰岛现代和遗迹温泉矿床中的脂肪酸保存，对火星上的有机物检测有影响

热液泉矿床拥有独特的微生物生态系统，能够将微生物群落作为硅质烧结层内的生物特征进行保存。这种品质使陆地温泉成为研究有机和形态生物特征保存的天然实验室。火星上热液矿床的发现引起了人们对这些温泉作为火星模拟环境的关注，推动了这些环境中生物特征保存的研究，以帮助准备未来的任务，目标是从火星温泉沉积物中恢复生物特征。这项研究量化了三个冰岛温泉矿床中的脂肪酸负荷，范围从现代和不活跃到残存。从地表和 2 至 18 厘米深度收集样品，以估算当前和即将推出的火星探测器的钻探能力。为了确定硅质烧结矿床中有机物的保存潜力，利用四甲基氢氧化铵 (TMAH) 的热化学分解，通过热解-气相色谱-质谱 (GC-MS) 进行脂肪酸分析。该技术适用于当前和即将推出的火星探测器。结果表明，相对于表面样品，脂肪酸通常在次表面降解，但可以用 TMAH 热解-GC-MS 方法保存和检测。在较旧的、退化的陆地烧结系统中，温泉中到远端通常是最好的纹理和地貌可定义特征，因此在火星上最容易从轨道图像中检测到。这些发现对探测火星热液系统中的有机物具有重要意义，因为它们表明在火星上相对较新的温泉沉积物中可以检测到有机物，但随着地质时间尺度的推移，保存可能会恶化。如果有机物相对年轻，配备热化学裂解-GC-MS 仪器的漫游车可能能够检测到温泉沉积物中的脂肪酸；因此，火星着陆点和样本选择对于在火星上寻找有机物至关重要。如果有机物相对年轻，配备热化学裂解-GC-MS 仪器的漫游车可能能够检测到温泉沉积物中的脂肪酸；因此，火星着陆点和样本选择对于在火星上寻找有机物至关重要。如果有机物相对年轻，配备热化学裂解-GC-MS 仪器的漫游车可能能够检测到温泉沉积物中的脂肪酸；因此，火星着陆点和样本选择对于在火星上寻找有机物至关重要。