Parnell John, Cullen David, Sims Mark R, Bowden Stephen, Cockell Charles S, Court Richard, Ehrenfreund Pascale, Gaubert Francois, Grant William, Parro Victor, Rohmer Michel, Sephton Mark, Stan-Lotter Helga, Steele Andrew, Toporski Jan, Vago Jorge
Department of Geology and Petroleum Geology, University of Aberdeen, Aberdeen, United Kingdom.
Astrobiology. 2007 Aug;7(4):578-604. doi: 10.1089/ast.2006.0110.
The European Space Agency's ExoMars mission will seek evidence of organic compounds of biological and non-biological origin at the martian surface. One of the instruments in the Pasteur payload may be a Life Marker Chip that utilizes an immunoassay approach to detect specific organic molecules or classes of molecules. Therefore, it is necessary to define and prioritize specific molecular targets for antibody development. Target compounds have been selected to represent meteoritic input, fossil organic matter, extant (living, recently dead) organic matter, and contamination. Once organic molecules are detected on Mars, further information is likely to derive from the detailed distribution of compounds rather than from single molecular identification. This will include concentration gradients beneath the surface and gradients from generic to specific compounds. The choice of biomarkers is informed by terrestrial biology but is wide ranging, and nonterrestrial biology may be evident from unexpected molecular distributions. One of the most important requirements is to sample where irradiation and oxidation are minimized, either by drilling or by using naturally excavated exposures. Analyzing regolith samples will allow for the search of both extant and fossil biomarkers, but sequential extraction would be required to optimize the analysis of each of these in turn.
欧洲航天局的火星外生物学任务将在火星表面寻找生物源和非生物源有机化合物的证据。巴斯德载荷中的仪器之一可能是生命标记芯片，它利用免疫测定方法来检测特定的有机分子或分子类别。因此，有必要为抗体开发确定特定的分子靶点并排出优先级。已选择目标化合物来代表陨石输入物、化石有机质、现存（活着的、刚死亡的）有机质和污染物。一旦在火星上检测到有机分子，更多信息可能来自化合物的详细分布，而非单个分子的鉴定。这将包括地表以下的浓度梯度以及从一般化合物到特定化合物的梯度。生物标志物的选择以地球生物学为依据，但范围广泛，非地球生物学可能从意想不到的分子分布中显现出来。最重要的要求之一是通过钻探或利用自然挖掘出的暴露区域，在辐射和氧化最小化的地方进行采样。分析风化层样本将有助于寻找现存和化石生物标志物，但需要进行顺序提取以依次优化对每一种的分析。
