火星大气中强烈的水同位素异常：探测当前和古代储层。

Strong water isotopic anomalies in the martian atmosphere: probing current and ancient reservoirs.

机构信息

NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA. Catholic University of America, Washington, DC 20064, USA.

NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA.

出版信息

Science. 2015 Apr 10;348(6231):218-21. doi: 10.1126/science.aaa3630. Epub 2015 Mar 5.

DOI:10.1126/science.aaa3630

PMID:25745065

Abstract

We measured maps of atmospheric water (H2O) and its deuterated form (HDO) across the martian globe, showing strong isotopic anomalies and a significant high deuterium/hydrogen (D/H) enrichment indicative of great water loss. The maps sample the evolution of sublimation from the north polar cap, revealing that the released water has a representative D/H value enriched by a factor of about 7 relative to Earth's ocean [Vienna standard mean ocean water (VSMOW)]. Certain basins and orographic depressions show even higher enrichment, whereas high-altitude regions show much lower values (1 to 3 VSMOW). Our atmospheric maps indicate that water ice in the polar reservoirs is enriched in deuterium to at least 8 VSMOW, which would mean that early Mars (4.5 billion years ago) had a global equivalent water layer at least 137 meters deep.

摘要

我们测量了火星全球大气水（H2O）及其氘代形式（HDO）的分布图，显示出强烈的同位素异常和显著的高氘/氢（D/H）富集，表明大量的水损失。这些地图样本反映了从北极冰帽升华的演化过程，揭示了释放的水具有代表性的 D/H 值，相对于地球海洋（维也纳标准平均海水（VSMOW））富集了约 7 倍。某些盆地和地形洼地显示出更高的富集，而高海拔地区则显示出低得多的值（1 至 3 VSMOW）。我们的大气地图表明，极地储层中的水冰至少富集了 8 VSMOW 的氘，这意味着早期火星（45 亿年前）曾经有一个全球等效水层，至少有 137 米深。