Time-of-day–dependent global distribution of lunar surficial water/hydroxyl

Wöhler, Christian; Grumpe, A.; Berezhnoy, A. A.; Шевченко, В. В.

doi:10.1126/sciadv.1701286

Cited by 63 publications

(96 citation statements)

References 42 publications

(121 reference statements)

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“…When applying a similar correction to the M 3 spectra, Wöhler et al () also found that there was significant concentration of hydroxyls at all latitudes. Contrary to Bandfield et al, they reported the presence of diurnal effects noting a larger day‐night variation at high latitudes compared to low latitudes.…”

Section: Discussionmentioning

confidence: 91%

Solar Wind Implantation Into the Lunar Regolith: Monte Carlo Simulations of H Retention in a Surface With Defects and the H₂ Exosphere

et al. 2019

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The solar wind implants protons into the top 20–30 nm of lunar regolith grains, and the implanted hydrogen will diffuse out of the regolith but also interact with oxygen in the regolith oxides. We apply a statistical approach to estimate the diffusion of hydrogen in the regolith hindered by forming temporary bonds with regolith oxygen atoms. A Monte Carlo simulation was used to track the temporal evolution of bound OH surface content and the H2 exosphere. The model results are consistent with the interpretation of the Chandrayaan‐1 M3 observations of infrared absorption spectra by surface hydroxyls as discussed in Li and Milliken (2017, https://doi.org/10.1126/sciadv.1701471). The model reproduced the latitudinal concentration of OH by using a Gaussian energy distribution of f(U0 = 0.5 eV, UW = 0.078–0.1 eV) to characterize the activation energy barrier to the diffusion of hydrogen in space weathered regolith. In addition, the model results of the exospheric content of H2 are consistent with observations by the Lyman Alpha Mapping Project on the Lunar Reconnaissance Orbiter. Therefore, we provide support for hydroxyl formation by chemically trapped solar wind protons.

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Section: Discussionmentioning

confidence: 91%

Solar Wind Implantation Into the Lunar Regolith: Monte Carlo Simulations of H Retention in a Surface With Defects and the H₂ Exosphere

et al. 2019

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“…At Reiner Gamma, the field strength is comparable to Gerasimovich, yet Reiner Gamma shows a weaker difference in water supression. We attribute this weaker difference due to the slightly lower latitude of Reiner Gamma (7°N vs 22°S), where warmer temperatures will reduce the background water (Benna et al, ; Farrell et al, ; Hendrix et al, ; Jones et al, ; Li & Milliken, ; Tucker et al, ; Wöhler, Grumpe, Berezhnoy, & Shevchenko, ).…”

Section: Discussionmentioning

confidence: 95%

“…Another concern is that the absorption strength of water bands near 3 μm exhibit a dependence on temperatures used for removing the thermal effects of M 3 data (Bandfield et al, ; Li & Milliken, ; McCord et al, ; Wöhler, Grumpe, Berezhnoy, & Shevchenko, ). False water absorptions may be present if the thermal effect of M 3 data is overestimated (Li & Milliken, ).…”

Section: Discussionmentioning

confidence: 99%

“…Lunar surface water was then discovered with infrared data from spacecraft measurements (Clark, ; Pieters et al, ; Sunshine et al, ) and later on was confirmed with ground‐based telescope observations (Honniball et al, ); this water is stable in sunlight at middle to high latitudes (e.g., Clark, ; Honniball et al, ; Pieters et al, ; Sunshine et al, ). A major formation mechanism of this type of lunar surface water is attributed to solar wind implantation (Bandfield et al, ; Clark, ; Hendrix et al, ; Jones et al, ; Li & Milliken, ; McCord et al, ; Pieters et al, ; Sunshine et al, ; Tucker et al, ; Wöhler, Grumpe, Berezhnoy, & Shevchenko, ). Water was also directly observed in the Lunar Crater Observation and Sensing Satellite ejecta plumes at Cabeus crater (Colaprete et al, ; Gladstone et al, ; Hayne et al, ; Schultz et al, ).…”

Section: Introductionmentioning

confidence: 99%

“…Resolving the origins of surface water requires an improved understanding of what variables are controlling its abundance at different locations. Presently, surface water is found to increase in abundance at high latitudes (Clark, ; Hendrix et al, ; Honniball et al, ; Li & Milliken, ; McCord et al, ; Pieters et al, ; Sunshine et al, ; Wöhler, Grumpe, Berezhnoy, & Shevchenko, ). Solar wind flux, UV photon flux, and temperature all decrease with increasing latitudes.…”

Section: Introductionmentioning

confidence: 99%

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Surface Water at Lunar Magnetic Anomalies

Garrick‐Bethell

2019

Geophysical Research Letters

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The presence of water on the lunar surface has been confirmed by multiple Earth-based and orbital observations. However, the origins of this water and the factors that control its stability at different latitudes are still debated. Magnetic anomalies on the Moon systematically reduce solar wind flux while locally keeping other confounding variables constant, which provides a natural laboratory for understanding the contribution of solar wind to lunar surface water. We find that water mapped with Moon Mineralogy Mapper data exhibit strong suppressions at magnetic anomalies, indicating that reduced solar wind flux prevents the formation of water. Our results support the hypothesis that the solar wind contributes significantly to the presence of the lunar surface water. Future missions and studies focusing on how magnetic fields affect water production can provide essential clues about how surface water is formed on the Moon and other airless bodies. Plain Language SummaryThe presence of water and/or hydroxyl molecules on the Moon has been confirmed by multiple observations. However, the origins of the lunar surface water are still unknown. The water may arise from three possible origins: solar wind, impacts, and the lunar interior. Lunar magnetic anomalies provide a natural laboratory to assess which of the three sources may dominate. Strong magnetic fields can significantly reduce the energy and flux of solar wind particles reaching the surface while keeping other conditions unchanged, such as temperature and UV photon flux. In this study, we examined water maps derived from orbital data at magnetic anomalies across the lunar surface. We confirmed that the water content at anomalies is much lower than the surrounding regions, providing direct evidence that solar wind contributes substantially to the lunar surface water production. Future missions and studies may help quantify how magnetic fields affect the formation rate of water by solar wind implantation. These results may be important for understanding solar wind water formation on other airless bodies. Key Points:• The spatial correlation between 3-μm water absorption features from Moon Mineralogy Mapper (M 3 ) data and lunar lithospheric magnetic fields is assessed • Magnetic anomalies exhibit strong water suppressions that are not artifacts of thermal corrections • Strong suppression of water features at magnetic anomalies suggests that lunar surface water mostly originates from solar wind implantation Supporting Information:• Supporting Information S1

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Telescopic Observations of Lunar Hydration: Variations and Abundance

Honniball

Lucey

Ferrari-Wong

et al. 2020

Preprint

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Time-of-day–dependent global distribution of lunar surficial water/hydroxyl

Abstract: Variations in H2O/OH absorption band strength with time of lunar day exhibit strong dependence on latitude and terrain type.

Cited by 63 publications

References 42 publications

Solar Wind Implantation Into the Lunar Regolith: Monte Carlo Simulations of H Retention in a Surface With Defects and the H₂ Exosphere

Solar Wind Implantation Into the Lunar Regolith: Monte Carlo Simulations of H Retention in a Surface With Defects and the H₂ Exosphere

Surface Water at Lunar Magnetic Anomalies

Telescopic Observations of Lunar Hydration: Variations and Abundance

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Time-of-day–dependent global distribution of lunar surficial water/hydroxyl

Abstract: Variations in H2O/OH absorption band strength with time of lunar day exhibit strong dependence on latitude and terrain type.

Cited by 63 publications

References 42 publications

Solar Wind Implantation Into the Lunar Regolith: Monte Carlo Simulations of H Retention in a Surface With Defects and the H2 Exosphere

Solar Wind Implantation Into the Lunar Regolith: Monte Carlo Simulations of H Retention in a Surface With Defects and the H2 Exosphere

Surface Water at Lunar Magnetic Anomalies

Telescopic Observations of Lunar Hydration: Variations and Abundance

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Product

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Solar Wind Implantation Into the Lunar Regolith: Monte Carlo Simulations of H Retention in a Surface With Defects and the H₂ Exosphere

Solar Wind Implantation Into the Lunar Regolith: Monte Carlo Simulations of H Retention in a Surface With Defects and the H₂ Exosphere