Enhanced hydrogen at the lunar poles: New insights from the detection of epithermal and fast neutron signatures

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Abstract

[1] The Lunar Prospector (LP) and Lunar Reconnaissance Orbiter (LRO) orbital neutron spectroscopy data sets represent a unique comprehensive multimission lunar resource. A rigorous statistical approach has been used to (re)analyze neutron data from both missions to provide new details regarding the relationships between the individual detector data sets, as well as a new evaluation of enhanced hydrogen deposits at the lunar poles. Using the multimission epithermal neutron data set, we find water ice distributed broadly across the poles, but showing evidence for a dependence on topographical features. A footprint averaged water equivalent hydrogen (WEH) abundance of 106 ± 11 ppm at each pole, with maxima of 131 and 112 ppm at the north and south poles, respectively, is derived from the epithermal neutron data. We also report the first definitive detection of a fast neutron signature consistent with an enhanced hydrogen hypothesis. These data suggest a highly localized distribution, consistent with Shackleton Crater, corresponding to a footprint averaged WEH abundance of 194 ± 11. If confined to this crater, this abundance yields a localized deposit of ∼0.7% WEH. Details of the analysis approach are presented along with spatial distribution maps showing the intriguing enhanced hydrogen deposits at the lunar poles.

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