Oxygen isotopic ratios in Martian water vapour observed by ACS MIR on board the ExoMars Trace Gas Orbiter
Oxygen isotopic ratios in Martian water vapour observed by ACS MIR on board the ExoMars Trace Gas Orbiter
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DOI：
10.1051/0004-6361/201936234
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发表时间：
2019-09-26
影响因子：
6.5
通讯作者：
Shakun, A.
中科院分区：
文献类型：
--
作者：
Alday, J.;Wilson, C. F.;Shakun, A.
氧同位素比为火星挥发性系统的历史提供了重要的限制，揭示了可能使它们分馏的几个过程的影响，例如大气损失到太空或与表面的相互作用。我们报告了火星大气层的红外测量结果，该测量结果是由ExoMars微量气体轨道器上的大气化学套件（ACS）的中红外通道（MIR）获得的。在透射光谱中观察到的水蒸气的三种主要氧同位素（（H_2O）-O-16、（H_2O）-O-18和（H_2O）-O-17）的吸收线允许首次测量大气水蒸气中O-18/O-16和O-17/O-16比率的垂直分布。观测到的比值比地球上的值更高（相当于维也纳标准平均海水的δ O-18 =千分之200 +/- 80，δ O-17 =千分之230 +/- 110）。这些比率的垂直结构似乎没有显示出态度变化的显着证据。
Oxygen isotope ratios provide important constraints on the history of the Martian volatile system, revealing the impact of several processes that might fractionate them, such as atmospheric loss into space or interaction with the surface. We report infrared measurements of the Martian atmosphere obtained with the mid-infrared channel (MIR) of the Atmospheric Chemistry Suite (ACS), onboard the ExoMars Trace Gas Orbiter. Absorption lines of the three main oxygen isotopologues of water vapour ((H2O)-O-16, (H2O)-O-18, and (H2O)-O-17) observed in the transmission spectra allow, for the first time, the measurement of vertical profiles of the O-18/O-16 and O-17/O-16 ratios in atmospheric water vapour. The observed ratios are enriched with respect to Earth-like values (delta O-18 = 200 +/- 80 parts per thousand and delta O-17 = 230 +/- 110 parts per thousand corresponding to the Vienna Standard Mean Ocean Water). The vertical structure of these ratios does not appear to show significant evidence of attitudinal variations.