The detection and identification of biosignatures on planetary bodies such as Mars in situ is extremely challenging. Current knowledge from space exploration missions suggests that a suite of complementary instruments is required in situ for a successful identification of past or present life. For future exploration missions, new and innovative instrumentation capable of high spatial resolution chemical (elemental and isotope) analysis of solids with improved measurement capabilities is of considerable interest because a multitude of potential signatures of extinct or extant life have dimensions on the micrometer scale. The aim of this study is to extend the current measurement capabilities of a miniature laser ablation ionization mass spectrometer (LIMS) designed for space exploration missions to detect signatures of microbial life. In total, 14 martian mudstone analogue samples were investigated regarding their elemental composition. Half the samples were artificially inoculated with a low number density of microbes, and half were used as abiotic controls. The samples were treated in a number of ways. Some were cultured anaerobically and some aerobically; some abiotic samples were incubated with water, and some remained dry. Some of the samples were exposed to a large dose of γ radiation, and some were left un-irradiated. While no significant elemental differences were observed between the applied sample treatments, the instrument showed the capability to detect biogenic element signatures of the inoculated microbes by monitoring biologically relevant elements, such as hydrogen, carbon, sulfur, iron, and so on. When an enrichment in carbon was measured in the samples but no simultaneous increase in other biologically relevant elements was detected, it suggests, for example, a carbon-containing inclusion; when the enrichment was in carbon and in bio-relevant elements, it suggests the presences of microbes. This study presents first results on the detection of biogenic element patterns of microbial life using a miniature LIMS system designed for space exploration missions.

中文翻译：

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使用高空间分辨率激光烧蚀电离质谱法检测火星泥岩类似物中微生物的元素特征

原位检测和识别行星体（如火星）上的生物特征极具挑战性。目前来自太空探索任务的知识表明，现场需要一套补充仪器成功识别过去或现在的生活。对于未来的探索任务，能够对固体进行高空间分辨率化学（元素和同位素）分析并提高测量能力的新型创新仪器具有相当大的兴趣，因为许多已灭绝或现存生命的潜在特征具有微米级的尺寸。本研究的目的是扩展微型激光烧蚀电离质谱仪 (LIMS) 的当前测量能力，该质谱仪专为太空探索任务而设计，以检测微生物生命的特征。总共研究了 14 个火星泥岩类似物样品的元素组成。一半样品人工接种低数量密度的微生物，一半用作非生物对照。以多种方式处理样品。有些是厌氧培养的，有些是有氧培养的；一些非生物样品用水培养，一些保持干燥。一些样品暴露在大剂量的γ辐射下，而另一些则没有受到辐射。虽然在应用的样品处理之间没有观察到显着的元素差异，但该仪器显示了通过监测生物相关元素（如氢、碳、硫、铁等）来检测接种微生物的生物元素特征的能力。当在样品中测量到碳的富集但没有检测到其他生物相关元素同时增加时，它表明，例如，含有碳的内含物；当富集是碳和生物相关元素时，它表明微生物的存在。本研究展示了使用专为太空探索任务设计的微型 LIMS 系统检测微生物生命的生物元素模式的初步结果。