Science and Exploration

Widespread Hydrogenation of the Moons South Polar Cold Traps

By Keith Cowing
Status Report
March 7, 2023
Filed under , ,
Widespread Hydrogenation of the Moons South Polar Cold Traps
CSETN south polar maps after 10.5 years of observations, with the UL(non-PSR) subtracted, >82° S. a) upper-left: CSETNs collimated WEH wt% map b) upper-right: CSETNs statistical uncertainty map, units = counts sec-1 , (lower bounds) Eqn. 8. Circle and cross pattern indicate low statistical uncertainty at high coverage density attributed to LRO orbital operations and declining inclination since 2011. c) lower-left: CSETN UnCollimated WEH wt% (non-PSR) map d) lower-right: LOLA topography map grey with PSR outlines, olive. A, B, C, D profiles are through the most strongly hydrogenated locations at Cabeus-1, Haworth, Shoemaker and Faustini PSR’s, respectively. — astro-ph.EP

The study shows widespread evidence that the Moons permanently shadowed regions (PSR) are enhanced in hydrogen, likely in the form of water ice, as compared to non-permanently shadowed region locations (non-PSRs), to 79deg S. Results are consistent with the original findings of Watson et al, 1961.

We use a novel method to aggregate the hydrogen response from all PSR, greater than 2 km wide pixels. Poleward of 79deg S, the PSR have a consistent hydrogen spatial response, which is enhanced in PSR (where the PSRs area density is highest) and diminishes with distance from any PSR (where the PSR area density is lowest).

A correlation between the PSRs diameters and their observed hydrogen, is induced by the instrumental blurring of relatively hydrogenated PSR areas. An anomalously enhanced hydrogen concentration observed at Cabeus-1 PSR suggests a second hydrogen budget process at that location.

Linear correlations, derived from the PSRs hydrogen observations, from two independent latitude bands, closely predict the hydrogen observation at Shoemaker, the largest area PSR, 1) 75deg to 83deg S, 2) 83deg to 90deg S. Results are consistent with ongoing processes that introduce volatiles to the surface including outgassing, solar wind production with regolith silicates, and mixing from small-scale meteor impacts and diurnal temperature variation.

Results are derived from the Collimated Sensor for EpiThermal Neutrons (CSETN), which part of the Lunar Exploration Neutron Detector (LEND), onboard the Lunar Reconnaissance Orbiter (LRO).

Timothy P. McClanahan, J.J. Su, Richard D. Starr, Ann M. Parsons, Gordon Chin, Timothy.A. Livengood, David Hamara, Karl Harshman

Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Cite as: arXiv:2303.03911 [astro-ph.EP] (or arXiv:2303.03911v1 [astro-ph.EP] for this version)
Submission history
From: Timothy McClanahan
[v1] Tue, 7 Mar 2023 14:14:00 UTC (1,425 KB)

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