The Thermophysical Properties of Lunar Cold Spots: Extensive Regolith Modification Around Young Impact Craters

Powell, Tyler M.; Greenhagen, B. T.; Taylor, S. E.; Williams, J.-P.; Hayne, P. O.; Paige, D. A.

doi:10.1130/abs/2019am-336794

Cited by 2 publications

(2 citation statements)

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“…Finally, we would like to mention the discovery of a cold spot at the Apollo 16 landing site by Powell, Williams, et al. (2023), close to where the sample of the highland thermal conductivity measurement was taken from. Cold spots show reduced nighttime temperatures and can be explained by a decompaction of the upper regolith layer.…”

Section: Resultsmentioning

confidence: 97%

A Microphysical Thermal Model for the Lunar Regolith: Investigating the Latitudinal Dependence of Regolith Properties

Bürger,

Hayne,

Gundlach

et al. 2024

JGR Planets

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The microphysical structure of the lunar regolith provides information on the geologic history of the Moon. We used remote sensing measurements of thermal emission and a thermophysical model to determine the microphysical properties of the lunar regolith. We expand upon previous investigations by developing a microphysical thermal model, which more directly simulates regolith properties, such as grain size and volume filling factor. The modeled temperatures are matched with surface temperatures measured by the Diviner Lunar Radiometer Experiment on board the Lunar Reconnaissance Orbiter. The maria and highlands are investigated separately and characterized in the model by a difference in albedo and grain density. We find similar regolith temperatures for both terrains, which can be well described by similar volume filling factor profiles and mean grain sizes obtained from returned Apollo samples. We also investigate a significantly lower thermal conductivity for highlands, which formally also gives a very good solution, but in a parameter range that is well outside the Apollo data. We then study the latitudinal dependence of regolith properties up to ±80° latitude. When assuming constant regolith properties, we find that a variation of the solar incidence‐dependent albedo can reduce the initially observed latitudinal gradient between model and Diviner measurements significantly. A better match between measurements and model can be achieved by a variation in intrinsic regolith properties with a decrease in bulk density with increasing latitude. We find that a variation in grain size alone cannot explain the Diviner measurements at higher latitudes.

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Section: Resultsmentioning

confidence: 97%

A Microphysical Thermal Model for the Lunar Regolith: Investigating the Latitudinal Dependence of Regolith Properties

Bürger,

Hayne,

Gundlach

et al. 2024

JGR Planets

Self Cite

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“…Because cold spots quickly degrade, any crater that still exhibits these features is part of the youngest and most recent impact population on the Moon (Williams et al 2018). In fact, the larger (>40 m) members of the population of new craters observed by LROC were observed to form cold spots, indicating that this is a ubiquitous feature of fresh impact craters (Powell et al 2021).…”

Section: Data Setsmentioning

confidence: 98%

Depth-to-diameter Ratios of Fresh Craters on the Moon and Implications for Surface Age Estimates

Hoover,

Robbins,

Hynek

et al. 2024

Planet. Sci. J.

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The depth-to-diameter (d/D) ratios of small lunar craters (D < 400 m) can be used to determine important properties of the upper regolith, specifically material strength or thickness. The d/D is also an important component of topographic diffusion models that describe how different erosive processes influence and change the topography of a surface over time, and these models have been applied to estimate surface ages. These models must make assumptions regarding rates of erosion and the initial d/D of a crater. Previous works investigating d/D of small craters, which use various methodologies to calculate depth, typically assume that a fresh appearing crater is a young crater. Work presented here provides d/D measurements of known—rather than assumed—young, meter-scale craters to provide better constraints on small crater depths and to help further our understanding of lunar surface ages and upper regolith properties. Given the interest in impact crater modification at small, human scales on the Moon and the wide range of assumptions built into topographic diffusion models and their predictions, understanding whether the results for initial d/D from past work hold up under different analyses is critical. We observed no distinct trends in d/D for small, young craters and report a wide range of d/D from 0.08 to 0.215, in contrast with past work that derived different averages based on crater size. The variation in d/D may correspond to heterogeneous regolith properties or be a result of a data source artifact.

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The Thermophysical Properties of Lunar Cold Spots: Extensive Regolith Modification Around Young Impact Craters

Cited by 2 publications

References 0 publications

A Microphysical Thermal Model for the Lunar Regolith: Investigating the Latitudinal Dependence of Regolith Properties

A Microphysical Thermal Model for the Lunar Regolith: Investigating the Latitudinal Dependence of Regolith Properties

Depth-to-diameter Ratios of Fresh Craters on the Moon and Implications for Surface Age Estimates

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