Distal ejecta from lunar impacts: Extensive regions of rocky deposits

Cahill, Joshua; Carter, Lynn M.; Neish, C. D.; Patterson, G. W.; Williams, J. P.; Paige, D. A.

doi:10.1016/j.icarus.2016.05.013

Cited by 42 publications

(49 citation statements)

References 26 publications

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“…In particular, we used derived rock abundance and regolith temperatures, which are described in detail by Bandfield et al (2017Bandfield et al ( , 2011. Their approach uses the spectral information from Diviner and modeled rock temperatures to discriminate between warm rocks and cooler regolith in the nighttime data.…”

Section: Data Setmentioning

confidence: 99%

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Global Regolith Thermophysical Properties of the Moon From the Diviner Lunar Radiometer Experiment

et al. 2017

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We used infrared data from the Lunar Reconnaissance Orbiter (LRO) Diviner Lunar Radiometer Experiment to globally map thermophysical properties of the Moon's regolith fines layer. Thermal conductivity varies from 7.4 × 10−4 W m−1 K−1 at the surface to 3.4 × 10−3 W m−1 K−1 at depths of ~1 m, given density values of 1,100 kg m−3 at the surface to 1,800 kg m−3 at 1 m depth. On average, the scale height of these profiles is ~7 cm, corresponding to a thermal inertia of 55 ± 2 J m−2 K−1 s−1/2 at 273 K, relevant to the diurnally active near‐surface layer, ~4–7 cm. The temperature dependence of thermal conductivity and heat capacity leads to an ~2 times diurnal variation in thermal inertia at the equator. On global scales, the regolith fines are remarkably uniform, implying rapid homogenization by impact gardening of this layer on timescales <1 Gyr. Regional‐ and local‐scale variations show prominent impact features <1 Gyr old, including higher thermal inertia (> 100 J m−2 K−1 s−1/2) in the interiors and ejecta of Copernican‐aged impact craters and lower thermal inertia (< 50 J m−2 K−1 s−1/2) within the lunar cold spots identified by Bandfield et al. (2014). Observed trends in ejecta thermal inertia provide a potential tool for age dating craters of previously unknown age, complementary to the approach suggested by Ghent et al. (2014). Several anomalous regions are identified in the global 128 pixels per degree maps presented here, including a high‐thermal inertia deposit near the antipode of Tycho crater.

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Section: Data Setmentioning

confidence: 99%

“…For the present study, we used rock abundance and regolith temperatures derived from available gridded Diviner data, using the same data set as in Bandfield et al (2017). As described earlier, the regolith temperatures used to derive H-parameter are the result of the same initial fitting procedure used for rock abundance.…”

Section: Comparison To Rock Abundancementioning

confidence: 99%

Global Regolith Thermophysical Properties of the Moon From the Diviner Lunar Radiometer Experiment

et al. 2017

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“…On the Moon, an area of ponded deposits and rocky material within the otherwise nominal lunar highlands terrain may be the result of a concentration of material at the antipode of the 86 km diameter Tycho crater (Artemieva ; Jögi and Paige ; Bandfield et al. ; Robinson et al. ).…”

Section: Crater Formation Heterogeneitymentioning

confidence: 99%

Dating very young planetary surfaces from crater statistics: A review of issues and challenges

Williams

Bogert

Pathare

et al. 2017

Meteorit & Planetary Scien

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Abstract-Determining the ages of young planetary surfaces relies on using populations of small, often sub-km diameter impact craters due to the higher frequency at which they form. Smaller craters however can be less reliable for estimating ages as their sizefrequency distribution is more susceptible to alteration with debate as to whether they should be used at all. With the current plethora of meter-scale resolution images acquired of the lunar and Martian surfaces, small craters have been widely used to derive model ages to establish the temporal relation of recent geologic events. In this review paper, we discuss the many factors that make smaller craters particularly challenging to use and should be taken into consideration when crater counts are confined to small crater diameters. Establishing confidence in a model age ultimately requires an understanding of the geologic context of the surface being dated as reliability can vary considerably and limitations of the dating technique should be considered in applying ages to any geologic interpretation.

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“…From a remote sensing standpoint, Pieters et al () have shown that the smallest size fraction (<25 μm) is spectrally dominant, at least in the visible to near‐infrared range, and early studies by Logan et al () suggest similar small particle size (<74 μm) in the MIR for the Moon. Bandfield et al () demonstrated that little of the upper few centimeters of regolith across the lunar surface is rocky; however, young fresh craters tend to have regolith particle size heterogeneity detectable by Diviner (Bandfield et al, , ), and future hyperspectral or surface missions could benefit from a spectral library of varying particle size as exist for studies of the Earth and Mars.…”

Section: Introductionmentioning

confidence: 99%

Particle Size Effects on Mid‐Infrared Spectra of Lunar Analog Minerals in a Simulated Lunar Environment

Shirley

Glotch

2019

JGR Planets

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Mid‐infrared spectroscopic analysis of the Moon and other airless bodies requires a full accounting of spectral variation due to the unique thermal environment in airless body regoliths and the substantial differences between spectra acquired under airless body conditions and those measured in an ambient environment on Earth. Because there exists a thermal gradient within the upper hundreds of microns of lunar regolith, the data acquired by the Diviner Lunar Radiometer Experiment are not isothermal with wavelength. While this complication has been previously identified, its effect on other known variables that contribute to spectral variation, such as particle size and porosity, have yet to be well characterized in the laboratory. Here we examine the effect of particle size on mid‐infrared spectra of silicates common to the Moon measured within a simulated lunar environment chamber. Under simulated lunar conditions, decreasing particle size is shown to enhance the spectral contrast of the Reststrahlen bands and transparency features, as well as shift the location of the Christiansen feature to longer wavelengths. This study shows that these variations are detectable at Diviner spectral resolution and emphasizes the need for simulated environment laboratory data sets, as well as hyperspectral mid‐infrared instruments on future missions to airless bodies.

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Distal ejecta from lunar impacts: Extensive regions of rocky deposits

Cited by 42 publications

References 26 publications

Global Regolith Thermophysical Properties of the Moon From the Diviner Lunar Radiometer Experiment

Global Regolith Thermophysical Properties of the Moon From the Diviner Lunar Radiometer Experiment

Dating very young planetary surfaces from crater statistics: A review of issues and challenges

Particle Size Effects on Mid‐Infrared Spectra of Lunar Analog Minerals in a Simulated Lunar Environment

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