Migration calculations for water in the exosphere of the Moon: Dusk-dawn asymmetry, heterogeneous trapping, and D/H fractionation

作者：Schorghofer Norbert^*

来源：Geophysical Research Letters, 2014, 41(14): 4888-4893.

DOI：10.1002/2014GL060820

Water ice is trapped in permanently shadowed craters near the lunar poles, where it is thought to have arrived from an exogenic or endogenic source via ballistic hops. We use a model of the migration of water molecules in the lunar exosphere to investigate three problems: (1) A strong continuous source would lead to an enhanced concentration of H2O at the morning terminator but not at the evening terminator. Hence, spectral features observed at both terminators do not suggest that there is diurnal migration of volatiles. (2) Cold trapping after a comet impact leads to an unequal partitioning between the two hemispheres depending on the latitude of the impact but to nearly equal partitioning with respect to longitude. (3) The D/H fractionation as the water molecules migrate toward the poles is small. Hence, the isotopic composition of ice deposits in the cold traps can be related to that of the source.

• 出版日期2014-7-28