Exogenic origin for the volatiles sampled by the Lunar CRater Observation and Sensing Satellite impact

Mandt, K.; Mousis, O.; Hurley, D. M.; Bouquet, Alexis; Retherford, Kurt D.; Magaña, L. O.; Luspay‐Kuti, A.

doi:10.1038/s41467-022-28289-6

Cited by 18 publications

(16 citation statements)

References 35 publications

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“…However, here we show that not all of the ice deposits may represent pure ice, potentially changing the timing of the cometary impact. In fact, cometary impacts have been shown to be the likely source of lunar water at the near surface (Mandt et al 2022) and so the state of the Mercurian deposits may help shed light on the timing of the impact. Additionally, we found that the observed gradational pattern in SC radar backscatter occurs in both large and small craters.…”

Section: Discussionmentioning

confidence: 99%

Arecibo S-band Radar Characterization of Local-scale Heterogeneities within Mercury’s North Polar Deposits

et al. 2022

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Ground-based planetary radar observations first revealed deposits of potentially nearly pure water ice in some permanently shadowed regions (PSRs) on Mercury’s poles. Later, the MESSENGER spacecraft confirmed the icy nature of the deposits, as well as their location within PSRs. Considering the geologic context provided by MESSENGER, we further characterized the north polar deposits by pairing spacecraft data with new Arecibo S-band radar observations. Here we show that some ice deposits within PSRs have a gradational pattern in their radar properties that is likely associated with differences in ice purity. Radar-bright features with a circular polarization ratio μ c > 1 can be characterized by water ice with ≳3% impurities by volume while those with μ c < 1 by ≳20% impurities. Furthermore, areas in PSRs with μ c < 1 typically surround locations of stronger radar backscatter with μ c > 1. Therefore, deposits of nearly pure water ice are likely surrounded by lower-purity material, such as water-ice-rich regolith, which could be the result of impact gardening or the crater’s thermal environment. However, such deposits are not always colocated within large polar craters where ice should be the most stable, even at the surface. In fact, we found that there is no significant difference between the radar backscattering properties of deposits thought to have surficial ice and those with buried ice. Our results also help improve the identification of icy reservoirs elsewhere, such as the Moon. Indeed, we found that μ c is not an adequate diagnostic, but rather the radar backscatter in each circular polarization independently provides information to identify water-ice deposits.

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Section: Discussionmentioning

confidence: 99%

Arecibo S-band Radar Characterization of Local-scale Heterogeneities within Mercury’s North Polar Deposits

et al. 2022

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“…Indeed, the existence of water produced by impacts from meteoroids in known streams was discovered by LADEE, though it can be interpreted as preexisting lunar water liberated by the impacts rather than exogenic delivery (Benna et al 2019). Analysis of the LCROSS plume indicates a cometary origin for the volatiles in the permanently shadowed region of Cabeus (Mandt et al 2022), where we also detect water with SOFIA. Further SOFIA observations covering a wider range of latitudes are being analyzed and will address latitude variations as well as localized emission in the 6 μm feature.…”

Section: Discussion Of the Potential Relation To The Source Of The Lu...mentioning

confidence: 62%

The Distribution of Molecular Water in the Lunar South Polar Region Based upon 6 μm Spectroscopic Imaging

et al. 2023

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The amount and distribution of water on the lunar surface are related to the input and production of water by solar wind and meteoroid bombardment, balanced by photodestruction and mobility across the surface. Using the Stratospheric Observatory for Infrared Astronomy (SOFIA), we imaged the 6.1 μm feature that uniquely traces molecular water, covering 1/4 of the lunar nearside surface south of −60° latitude with 5 km resolution on 2022 February 17 UTC. The water feature strength varies significantly across the region, being drier at +28° longitude to more wet (170 ppm) at −7° longitude, and also decreasing toward the pole. Significant local enhancements are found, associated with south-facing, high-altitude topographic features. This includes relatively high H2O concentrations in a “wet ridge” just north of the Curtius crater; the south-facing, northern, inner rims of the most prominent craters; the south face of the central peak of the Moretus crater; and permanently shadowed polar regions.

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“…Second, volcanic activity‐driven water is supplied equally during the Imbrian. This contribution, however, is currently under debate (Aleinov et al., 2019; Mandt et al., 2022). Third, the water supply made by asteroids and comets is proportional to their impact fluxes and so determined by applying the Neukum chronology model (Neukum et al., 2001).…”

Section: Water Redistribution At Lunar South Polementioning

confidence: 99%

Survival of Ancient Lunar Water Affected by Topographic Degradation of Old, Large Complex Craters

Talkington

Hirabayashi

Montalvo

et al. 2022

Geophysical Research Letters

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Various remote sensing observations have shown the existence of water and related species around the lunar poles (Lucey et al., 2021, and references therein). Potential water sources include meteoroid and comet impacts (Ong et al., 2010), solar wind implantation (Hurley et al., 2017), and volcanic outgassing (Head et al., 2020;Needham & Kring, 2017). Water delivery to the lunar surface was likely more active during and before the Imbrian era (≳3.2 Ga) than at present because of a higher rate of asteroid and comet impacts, and enhanced volcanic outgassing. However, competing processes may have redistributed water over time. A key issue is whether the observed surface water indicates recent or ancient deposition. The present study seeks possible interpretations of the existence of ancient water (≳3.2 Ga) in the subsurface areas on lunar south polar complex craters by considering the net effect on water redistribution due to topographic diffusion (

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Exogenic origin for the volatiles sampled by the Lunar CRater Observation and Sensing Satellite impact

Cited by 18 publications

References 35 publications

Arecibo S-band Radar Characterization of Local-scale Heterogeneities within Mercury’s North Polar Deposits

Arecibo S-band Radar Characterization of Local-scale Heterogeneities within Mercury’s North Polar Deposits

The Distribution of Molecular Water in the Lunar South Polar Region Based upon 6 μm Spectroscopic Imaging

Survival of Ancient Lunar Water Affected by Topographic Degradation of Old, Large Complex Craters

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