地球发电机历史期间近侧月壤中发生的地球大气离子注入
Terrestrial atmospheric ion implantation occurred in the nearside lunar regolith during the history of Earth's dynamo
AI总结：
本研究通过三维磁流体力学数值模拟，结合现代与太古代地球大气条件，发现月球仅在地球磁尾内时会有效接收地球大气离子，且月壤非太阳贡献源于地球发电机长期作用，为地球古大气研究提供新线索。
摘要：
月球表岩屑中的轻挥发性元素被认为是太阳风与地球大气的混合物，后者在地球无地磁场时来源。然而，当前和原始地球发电机对地球离子传输的影响程度仍不明确，而始太古代外逸层的神秘成分和位置约束不足进一步加剧了这种不确定性。本文使用三维磁流体力学数值模拟，结合现代磁化大气和太古代无磁化大气，研究地球固有磁场如何影响这种传输，旨在约束月球同位素特征何时以及如何记录地球古大气。研究发现，仅当月球位于地球磁尾内时，大气传输才有效。月球土壤中的非太阳贡献最好通过地球发电机长期历史期间的注入来解释，而非早期地球任何假设的无磁化短时期。这进一步表明，跨越数十亿年的地球大气历史可能保存在埋藏的月壤中。结果表明，阿波罗样本的元素丰度对地球外逸层高度非常敏感，在离子注入时，该高度从未低于190公里。
英文摘要：
Light volatile elements in lunar regolith are thought to be a mixture of the solar wind and Earth's atmosphere, the latter sourced in the absence of geomagnetic field. However, the extent to which both the current and primitive geodynamo influence the transport of terrestrial ions still remains unclear, and this uncertainty is further complicated by the enigmatic composition and poorly constrained location of the Eoarchean exosphere. Here we use 3-D MHD numerical simulations with present-day magnetized and Archean unmagnetized atmospheres to investigate how Earth's intrinsic magnetic field affects this transfer, aiming to constrain how and when the lunar isotopic signature provides a record of Earth's paleoatmosphere. We find that atmospheric transfer is efficient only when the Moon is within Earth's magnetotail. The non-solar contribution to the lunar soil is best explained by implantation during the long history of the geodynamo, rather than any short, putatively unmagnetized epoch of early Earth. This further suggests the history of the terrestrial atmosphere, spanning billions of years, could be preserved in buried lunar soils. Our results indicate that the elemental abundances of Apollo samples are very sensitive to Earth's exobase altitude, which, at the time of ion implantation, was never smaller than 190 km.
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