Stability of polar frosts in spherical bowl-shaped craters on the Moon, Mercury, and Mars

Ingersoll, Andrew P.; Svítek, T.; Murray, Bruce C.

doi:10.1016/0019-1035(92)90016-z

Cited by 140 publications

(137 citation statements)

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“…At or near the lunar poles, theoretical studies suggest that temperatures in the permanently shadowed regions of craters would be low enough to retain water ice across the lifetime of the Moon (Hodges, 1980). Larger, flat-shaped complex craters with more vertical crater walls would also generate lower internal temperatures than simple, bowl-shaped craters due to differences in the internal radiometry generated by the crater structure (Hodges, 1980;Paige et al, 1992;Ingersoll et al, 1992;Butler et al, 1993). Hence, the equatorward (cooler, sometimes shadowed) walls of the large, complex craters located near the poles could retain water vapor, liquid or ice over longer time scales.…”

Section: Phyllosilicatesmentioning

confidence: 99%

A newly-identified spectral reflectance signature near the lunar South pole and the South Pole-Aitken Basin

et al. 2008

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Signal analysis of Galileo images of the Moon suggests the presence of an absorption band centered near 0.7 μm in the reflectance spectra of areas located adjacent to the equatorward walls of lunar craters at latitudes ranging from −58 to −78• , and areas contained in the South Pole-Aitken Basin. We propose three potential explanations: an Fe 2+ →Fe 3+ charge transfer transition in oxidized iron in clinopyroxenes (high-Ca bearing pyroxenes) or phyllosilicates (Fe-and Mg-bearing sheet silicates containing adsorbed H 2 O and interlayer OH − ), or an effect of titanium in ilmenite (a common lunar opaque material). No identification of the mineralogy is conclusive. The presence and nature of the absorption feature could be confirmed using AMICA images of the lunar far side from the Japanese mission Hayabusa, spectroscopic results from the Japanese mission Selene scheduled for launch in 2007, or the Moon Mineralology Mapper on the Indian mission Chandrayaan-1. Key words: Moon, lunar surface composition, spectral reflectance, lunar mineralogy, lunar remote sensing. Motivation and Background for Search for Lunar PhyllosilicatesSpectral observations of reflected sunlight from the surface of a planetary regolith serve as a remote sensing probe of surface mineralogical composition and particle state. Variations from the solar spectrum in the spectrum of a planetary regolith, apparent in the form of broad absorption features, reflect the presence of electronic charge transfers and vibrations between ions governed by structural spacing within crystals of a specific mineralogy (c.f., Burns, 1993). By identifying and analyzing these spectral variations, the underlying mineralogy of the planetary regolith can be determined. The identification of different minerals provides clues to the processes that formed or altered these solar system bodies. On the Moon, regolith particles of diameters ≤25 μm dominate the remotely-sensed spectral properties of the surface over the visible/near-infrared wavelength region (Pieters et al., 1993a).Water ice has long been postulated to exist in permanently shaded areas at the lunar poles (c.f., Watson et al., 1961;Arnold, 1979). Recent observations provide conflicting evidence for the presence and form of lunar polar water ice. Clementine bistatic radar detected a weak sig- * Present address: MMT Observatory, P.O. Box 210065, University of Arizona, Tucson, Arizona 85721. nal at the lunar South pole attributed to water ice (Nozette et al., 1996), while Lunar Prospector has recently detected large amounts of H at both poles (Feldman et al., 2000(Feldman et al., , 2001. Conversely, ground-based radar searches show no bright signal suggesting water ice at either pole (Stacy et al., 1997), andCampbell et al. (2006) find no evidence of thick deposits of ice at the South pole. Reanalysis of the Clementine radar data by Simpson and Tyler (1999) suggest that the radar reflection results were caused by underlying variations in terrain. Galileo near-infrared spectra detected no sign of the prominent 3.0-μm...

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Section: Phyllosilicatesmentioning

confidence: 99%

A newly-identified spectral reflectance signature near the lunar South pole and the South Pole-Aitken Basin

et al. 2008

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“…This is a fascinating possibility both because such deposits would serve as a natural resource for future human lunar activity and because the plausible sources of lunar water (e.g., comets and asteroids) are of inherent interest. In fact, modeling the temperatures of shadowed craters near the poles [Ingersoll et al, 1992;Salvail and Fanale, 1994; Vasavada, 1998] shows temperatures low enough to cold trap materials substantially more volatile than water ice. Studies of the transport and retention of water ice and other volatiles also support the possibility of water ice being present at the pole [Butler, 1997; Morgan and Shemansky, 1991 ].…”

Section: Introductionmentioning

confidence: 99%

Integration of lunar polar remote‐sensing data sets: Evidence for ice at the lunar south pole

Nozette¹,

Spudis²,

Robinson³

et al. 2001

J. Geophys. Res.

126

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Abstract. In order to investigate the feasibility of ice deposits at the lunar south pole, we have integrated all relevant lunar polar data sets. These include illumination data, Arecibo ground-based monostatic radar data, newly processed Clementine bistatic radar data, and Lunar Prospector neutron spectrometer measurements. The possibility that the lunar poles harbor ice deposits has important implications not only as a natural resource for future human lunar activity but also as a record of inner solar system volatiles (e.g., comets and asteroids) over the past billion years or more. We find that the epithermal neutron flux anomalies, measured by Lunar Prospector, are coincident with permanently shadowed regions at the lunar south pole, particularly those associated with Shackleton crater. Furthermore, these areas also correlate with the • = 0 circular polarization ratio (CPR) enhancements revealed by new processing of Clementine bistatic radar echoes, which in turn are colocated with areas of anomalous high CPR observed by Arecibo Observatory on the lower, Sun-shadowed wall of Shackleton crater. Estimates of the extent of high CPR from Arecibo Observatory and Clementine bistatic radar data independently suggest that •10 km 2 of ice may be present on the inner Earth-facing wall of Shackleton crater. None of the experiments that obtained the data presented here were ideally suited for definitively identifying ice in lunar polar regions. By assessing the relative merits of all available data, we find that it is plausible that ice does occur in cold traps at the lunar south pole and that future missions with instruments specifically designed to investigate these anomalies are worthy. IntroductionThe lunar poles have long been theorized to harbor ice deposits in permanently shadowed regions because these regions can act to cold trap volatile compounds, including water introduced into the lunar environment [Watson et al., 1961]. This is a fascinating possibility both because such deposits would serve as a natural resource for future human lunar activity and because the plausible sources of lunar water (e.g., comets and asteroids) are of inherent interest. In fact, modeling the temperatures of shadowed craters near the poles [Ingersoll et al., 1992;Salvail and Fanale, 1994; Vasavada, 1998] shows temperatures low enough to cold trap materials substantially more volatile than water ice. Studies of the transport and retention of water ice and other volatiles also support the possibility of water ice being present at the pole [Butler, 1997; Morgan and Shemansky, 1991 ]. The latter work suggested that sputtering was rapid enough to destroy slow continuous deposits of water ice, for example, from micrometeorite water, or water produced from reduction of lunar surface materials to produce water from solar wind hydrogen but that thick deposits of ice introduced by comets or large "wet" asteroids might survive by sequestering of ice by regolith overturn.•Naval Research Laboratory, Washington, D.C. No conclusive evidence of w...

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“…The possible source mechanisms for that water include cometary and meteroidal impacts, reduction of FeO by hydrogen derived from the solar wind, and degassing of the interior (1,2). Water molecules liberated on the moon assume ballistic trajectories (1, 2, 4 ) until they are destroyed in flight or trapped in low-temperature regions (5 ). Ice on the lunar surface is subject to destructive processes, including solar photon-induced desorption (2, 6 ), erosion by sputtering (2,6,7 ), and photodissociation by interstellar hydrogen Lyman-␣ radiation (6 ).…”

mentioning

confidence: 99%

Topography of the Lunar Poles from Radar Interferometry: A Survey of Cold Trap Locations

Margot

Campbell

Jurgens

et al. 1999

Science

160

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Detailed topographic maps of the lunar poles have been obtained by Earth-based radar interferometry with the 3.5-centimeter wavelength Goldstone Solar System Radar. The interferometer provided maps 300 kilometers by 1000 kilometers of both polar regions at 150-meter spatial resolution and 50-meter height resolution. Using ray tracing, these digital elevation models were used to locate regions that are in permanent shadow from solar illumination and may harbor ice deposits. Estimates of the total extent of shadowed areas poleward of 87.5 degrees latitude are 1030 and 2550 square kilometers for the north and south poles, respectively.

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Stability of polar frosts in spherical bowl-shaped craters on the Moon, Mercury, and Mars

Cited by 140 publications

References 8 publications

A newly-identified spectral reflectance signature near the lunar South pole and the South Pole-Aitken Basin

A newly-identified spectral reflectance signature near the lunar South pole and the South Pole-Aitken Basin

Integration of lunar polar remote‐sensing data sets: Evidence for ice at the lunar south pole

Topography of the Lunar Poles from Radar Interferometry: A Survey of Cold Trap Locations

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