Bulk hydrogen abundances in the lunar highlands: Measurements from orbital neutron data

Lawrence, D. J.; Peplowski, P. N.; Plescia, J. B.; Greenhagen, B. T.; Maurice, S.; Prettyman, T. H.

doi:10.1016/j.icarus.2015.01.005

Cited by 24 publications

(25 citation statements)

References 38 publications

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“…However, additional trends might also be expected. For example, on the Moon a correlation is seen between epithermal measured hydrogen abundance and other measures of maturity including crater density and optical maturity, which is explained as the result of solar wind proton implantation over time (Lawrence, Patrick, et al, ). In addition, one might expect correlations between hydrogen and other elements if the regolith type affects hydrogen implantation or stability.…”

Section: Comparison Of Hydrogen Abundance and Other Datamentioning

confidence: 99%

“…On the Moon, nonpolar hydrogen has been observed by the Lunar Prospector's Neutron Spectrometer (Lawrence, Patrick, et al, ). Correlation between the neutron‐derived map and several measures of maturity (e.g., optical maturity; Lucey et al, ), Christiansen Feature position, and 750‐nm albedo led to the conclusion that hydrogen abundance was also a measure of lunar regolith maturity.…”

Section: Introductionmentioning

confidence: 99%

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MESSENGER Gamma Ray Spectrometer and Epithermal Neutron Hydrogen Data Reveal Compositional Differences Between Mercury's Hot and Cold Poles

et al. 2019

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The presence of hydrogen, most likely in the form of water ice, is well established in Mercury's permanently shaded polar craters. But lower concentrations that may exist away from the poles have not previously been well constrained. In this work we use data from the MErcury Surface, Space ENvironment, GEochemistry, and Ranging (MESSENGER) Gamma‐Ray and Neutron Spectrometer to produce the first map of the absolute hydrogen abundance in Mercury's northern hemisphere. We find a mean abundance of ppm and a latitudinal trend that agrees with earlier results showing enhanced hydrogen contained within Mercury's radar bright craters. Additionally, we observe a middle‐ and low‐latitude variation in hydrogen abundance that is correlated most strongly with temperature 20 cm beneath Mercury's surface.

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Section: Comparison Of Hydrogen Abundance and Other Datamentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

MESSENGER Gamma Ray Spectrometer and Epithermal Neutron Hydrogen Data Reveal Compositional Differences Between Mercury's Hot and Cold Poles

et al. 2019

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“…Eros' measured hydrogen concentration is significantly larger than that found in the lunar highlands, as inferred from the analyses of Apollo 16 samples (~10-110 ppm; Haskin and Warren 1991) and orbital neutron spectroscopy (~20-160 ppm; Lawrence et al 2014). These hydrogen concentrations are generally attributed to the gradual accumulation of hydrogen via solar-wind implantation over age of the highlands (~4.6 Gyr), a process that should operate similarly on near-Earth asteroids given their similar solar-wind environments.…”

Section: Hydrogen Abundancementioning

confidence: 85%

Hydrogen and major element concentrations on 433 Eros: Evidence for an L‐ orLL‐chondrite‐like surface composition

Peplowski

Bazell

Evans

et al. 2015

Meteorit & Planetary Scien

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A reanalysis of NEAR X‐ray/gamma‐ray spectrometer (XGRS) data provides robust evidence that the elemental composition of the near‐Earth asteroid 433 Eros is consistent with the L and LL ordinary chondrites. These results facilitated the use of the gamma‐ray measurements to produce the first in situ measurement of hydrogen concentrations on an asteroid. The measured value, 1100−700+1600 ppm, is consistent with hydrogen concentrations measured in L and LL chondrite meteorite falls. Gamma‐ray derived abundances of hydrogen and potassium show no evidence for depletion of volatiles relative to ordinary chondrites, suggesting that the sulfur depletion observed in X‐ray data is a surficial effect, consistent with a space‐weathering origin. The newfound agreement between the X‐ray, gamma‐ray, and spectral data suggests that the NEAR landing site, a ponded regolith deposit, has an elemental composition that is indistinguishable from the mean surface. This observation argues against a pond formation process that segregates metals from silicates, and instead suggests that the differences observed in reflectance spectra between the ponds and bulk Eros are due to grain size differences resulting from granular sorting of ponded material.

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“…; Lawrence et al. ). In the initial study of HEGRs, Peplowski and Lawrence () mentioned that HEGR systematic variations with hydrogen had not been studied.…”

Section: Planetary High‐energy Gamma Rays: Backgroundmentioning

confidence: 98%

Compositional variability on the surface of 1 Ceres revealed through GRaND measurements of high‐energy gamma rays

Lawrence

Peplowski

Beck

et al. 2018

Meteorit & Planetary Scien

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High-energy gamma rays (HEGRs) from Ceres's surface were measured using Dawn's Gamma Ray and Neutron Detector (GRaND). Models of cosmic-ray-initiated gamma ray production predict that the HEGR flux will inversely vary with single-layer hydrogen concentrations for Ceres-like compositions. The measured data confirm this prediction. The hydrogen-induced variations in HEGR rates were decoupled from the measurements by detrending the HEGR data with Ceres single-layer hydrogen concentrations determined by GRaND neutron measurements. Models indicate that hydrogen-detrended HEGR counting rates correlate with water-free average atomic mass, which is denoted as *. HEGR variations across Ceres's surface are consistent with * variations of AE0.5 atomic mass units. Chemical variations in the CM and CI chondrites, our closest analogs to Ceres's surface, suggest that * variations on Ceres are primarily driven by variations in the concentration of Fe, although other elements such as Mg and S could contribute. Dawn observations have shown that Ceres's interior structure and surface composition have been modified by some combination of physical (i.e., ice-rock fractionation) and/or chemical (i.e., alteration) processes that has led to variations in bulk surface chemistry. Locations of the highest inferred * values, and thus possibly the highest Fe and least altered materials, tend to be younger, less cratered surfaces that are broadly associated with the impact ejecta of Ceres's largest craters. 1805

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Bulk hydrogen abundances in the lunar highlands: Measurements from orbital neutron data

Cited by 24 publications

References 38 publications

MESSENGER Gamma Ray Spectrometer and Epithermal Neutron Hydrogen Data Reveal Compositional Differences Between Mercury's Hot and Cold Poles

MESSENGER Gamma Ray Spectrometer and Epithermal Neutron Hydrogen Data Reveal Compositional Differences Between Mercury's Hot and Cold Poles

Hydrogen and major element concentrations on 433 Eros: Evidence for an L‐ orLL‐chondrite‐like surface composition

Compositional variability on the surface of 1 Ceres revealed through GRaND measurements of high‐energy gamma rays

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