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Semiannual Oscillation of the Lunar Exosphere: Implications for Water and Polar Ice
Author(s) -
Hodges R. Richard
Publication year - 2018
Publication title -
geophysical research letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.007
H-Index - 273
eISSN - 1944-8007
pISSN - 0094-8276
DOI - 10.1029/2018gl077745
Subject(s) - exosphere , astrobiology , atmosphere (unit) , water vapor , thermosphere , atmospheric sciences , polar , oscillation (cell signaling) , latitude , environmental science , geology , geophysics , physics , ionosphere , chemistry , meteorology , astronomy , ion , biochemistry , geodesy , quantum mechanics
A time‐dependent simulation of the argon‐40 exosphere of the Moon shows that the semiannual oscillation of argon detected by the neutral mass spectrometer on the Lunar Atmosphere and Dust Environment Explorer spacecraft is consistent with adsorptive respiration in seasonal cold traps near the lunar poles. The magnitude of the oscillation requires that high‐energy adsorption sites on soil grain surfaces at polar latitudes be as free of water contamination as soils at low latitudes. This requirement is met by the combination of two generally ignored water removal mechanisms: solar wind bombardment of exposed adsorption sites and the serpentinization reaction of water with olivine. The significance of these processes is supported by the lack of evidence of water in Lunar Atmosphere and Dust Environment Explorer data, which, in turn, establishes an upper bound for exospheric transport of water to polar traps at less than 10 14 molecules/Ga.