April 2024
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9 Reads
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April 2024
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9 Reads
February 2024
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24 Reads
The lunar surface evolves over time due to space weathering, and the visible–near‐infrared spectra of more mature (i.e., heavily weathered) soils are lower in reflectance and steeper in spectral slope (i.e., darker and redder) than their immature counterparts. These spectral changes have traditionally been attributed to the space‐weathered rims of soil grains (and particularly nanophase iron therein). However, understudied thus far is the spectral role of agglutinates—the agglomerates of mineral and lithic fragments, nanophase iron, and glass that are formed by micrometeoroid impacts and are ubiquitous in mature lunar soils. We separated agglutinates and non‐agglutinates from six lunar soils of varying maturity and composition, primarily from the 125–250 μm size fraction, and measured their visible–near‐infrared reflectance spectra. For each soil, the agglutinate spectra are darker, redder, and have weaker absorption bands than the corresponding non‐agglutinate and unsorted soil spectra. Moreover, greater soil maturity corresponds to darker agglutinate spectra with weaker absorption bands. These findings suggest that agglutinates (rather than solely the space‐weathered rims) play an important role in both the darkening and reddening of mature soils—at least for the size fractions examined here. Comparisons with analog soils suggest that high nanophase iron abundance in agglutinates is likely responsible for their low reflectance and spectrally red slope. Additional studies of agglutinates are needed both to more comprehensively characterize their spectral properties (across size fractions and in mixing with non‐agglutinates) and to assess the relative roles of agglutinates and rims in weathering‐associated spectral changes.
February 2024
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9 Reads
The lunar surface evolves over time due to space weathering, and the visible–near-infrared spectra of more mature (i.e., heavily weathered) soils are lower in reflectance and steeper in spectral slope (i.e., darker and redder) than their immature counterparts. These spectral changes have traditionally been attributed to the space-weathered rims of soil grains (and particularly nanophase iron therein). However, understudied thus far is the spectral role of agglutinates—the agglomerates of mineral and lithic fragments, nanophase iron, and glass that are formed by micrometeoroid impacts and are ubiquitous in mature lunar soils. We separated agglutinates and non-agglutinates from six lunar soils of varying maturity and composition, primarily from the 125–250 μm size fraction, and measured their visible–near-infrared reflectance spectra. For each soil, agglutinate spectra are darker, are redder, and have weaker absorption bands than the corresponding non-agglutinate and unsorted soil spectra. Moreover, greater soil maturity corresponds to darker agglutinate spectra with weaker absorption bands. These findings suggest that agglutinates (rather than solely the space-weathered rims) play an important role in both the darkening and reddening of mature soils—at least for the size fractions examined here. Comparisons with analog soils suggest that high nanophase iron abundance in agglutinates is likely responsible for their low reflectance and spectrally red slope. Additional studies of agglutinates are needed, both to more comprehensively characterize their spectral properties (across size fractions and in mixing with non-agglutinates) and to assess the relative roles of agglutinates and rims in weathering-associated spectral changes.
December 2023
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103 Reads
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7 Citations
Reviews in Mineralogy and Geochemistry
December 2023
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19 Reads
Reviews in Mineralogy and Geochemistry
November 2023
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18 Reads
The lunar surface evolves over time due to space weathering, and the visible–near-infrared spectra of more mature (i.e., heavily weathered) soils are lower in reflectance and steeper in spectral slope (i.e., darker and redder) than their immature counterparts. These spectral changes have traditionally been attributed to the space-weathered rims of soil grains (and particularly nanophase iron therein). However, understudied thus far is the spectral role of agglutinates—the agglomerates of mineral and lithic fragments, nanophase iron, and glass that are formed by micrometeoroid impacts and are ubiquitous in mature lunar soils. We have separated agglutinates and non-agglutinates from six lunar soils of varying maturity and composition, primarily from the 125–250 μm size fraction, and have measured their visible–near-infrared reflectance spectra. For each soil, agglutinate spectra are darker, are redder, and have weaker absorption bands than the corresponding non-agglutinate and unsorted soil spectra. Moreover, greater soil maturity corresponds to darker agglutinate spectra with weaker absorption bands. These findings suggest that agglutinates (rather than solely the space-weathered rims) play an important role in both the darkening and reddening of mature soils—at least for the size fractions examined here. Comparisons with analog soils suggest that high nanophase iron abundance in agglutinates is likely responsible for their low reflectance and spectrally red slope. Additional studies of agglutinates are needed, both to more comprehensively characterize their spectral properties (across size fractions and in mixing with non-agglutinates) and to assess the relative roles of agglutinates and rims in weathering-associated spectral changes.
May 2023
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11 Reads
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3 Citations
Icarus
December 2022
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29 Reads
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6 Citations
Acta Astronautica
March 2022
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16 Reads
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4 Citations
April 2021
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429 Reads
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8 Citations
The Planetary Science Journal
We present the Inner SOlar System CHRONology (ISOCHRON) concept to return samples of the youngest extensive mare basalt for age-dating and geochemical analysis. The young basalt is exposed at a site southwest of Aristarchus Plateau, for which complete remote-sensing data are available for thorough landing site analysis. Data from these samples would revolutionize the ability to assign exposure ages to rocky planetary surfaces based on the samples returned by Apollo and Luna. Their petrology and geochemistry will enable assessment of the most recent voluminous lunar magmatism. Regolith evolution and mixing models such as ballistic sedimentation would be directly testable to provide crucial ground truth that would enhance the science value of current and future remotely sensed data sets. ISOCHRON’s science goals support NASA’s Artemis program to return to the Moon and its related robotic programs currently in planning. © 2021. The Author(s). Published by the American Astronomical Society.
... It is interesting to note that regions A2-A4 in this study are located in the region of stronger 1 µm band depth, where region A2 is located in number 9 area, A3 in number 6 area and A5 in number 7 area in [7] (his Figure 5), suggesting that the 1 µm band depth of regions A2-A4 is similar to that of the Ocean Procellarum basalt features. The same features were also shown in [36]. We also find strong evidence of later volcanism at the surface (Fig. 13). ...
May 2023
Icarus
... Such areas are extremely cold and act as cold traps for any volatile components, including water [2,3]. Meanwhile, the illumination of topographically high regions at the poles, unlike equatorial regions, can significantly exceed 50 % [4]. The unique lighting conditions, as well as the presence of water ice deposits [5], make the polar regions of the Moon potentially very attractive for future outposts [6][7][8]. ...
December 2022
Acta Astronautica
... There are several aspects of the lunar surface and its environment which must be accurately modeled before these simulations can be relied upon to influence Artemis program decisions. The Digital Lunar Exploration Sites (DLES) project is generating just such a digital representation (model) of the lunar surface [14]. DLES is being developed by the NASA Exploration Systems Simulation (NExSyS) team at the National Aeronautics and Space Administration's (NASA) Johnson Space Center (JSC). ...
March 2022
... Crater size-frequency distribution (CSFD) measurements are widely used to date the planetary surface. The CSFD measurements rely heavily on the lunar crater chronology function (e.g., [123][124][125][126][127]), which is based on the returned lunar samples with known sources. However, due to the lack of young samples (<3 Ga) at the age range of 1-3 Ga, the chronology function maybe not be constrained well [128]. ...
April 2021
The Planetary Science Journal
... The mare units within the Gassendi crater are rich in calcium pyroxene, and band parameters analysis indicates that they vary from a sub-calcic to calcic composition. The CSFD-based age estimation of mare units shows that they were formed 3.59 to 2.99 Ga ago [20,21]. The Posidonius FCC also possesses similar and consistent results in size, morphology, fracture system and igneous intrusion. ...
September 2020
... This is also supported by the geological and gravity (Figure 6d) data, which generally indicate younger surfaces (Tanaka et al., 2005). It is worth noting that dating based on size-frequency distribution curves of boulders has already been employed on the Moon (Basilevsky et al., 2015;Mistick et al., 2022;Watkins et al., 2019) and asteroids (Cheng et al., 2021;Walsh et al., 2019). However, given the complex nature of Mars' environment, it is important to exercise caution. ...
November 2019
... Furthermore, these returned samples also provide critically important "ground truth" for verifying and calibrating remotesensed measurements. These claims have been amply demonstrated by the lunar samples returned by the United States Apollo and Soviet Luna missions, which have basically transformed our understanding of the solar system (e.g., LSPET, 1970;Vinogradov, 1971;Bence et al., 1972;Lawrence and Neal, 2019;Zeigler et al., 2019). Planetary scientists have been endeavoring to collect samples from extraterrestrial bodies, despite the significant costs involved and the availability of many meteorites delivered from outer space to the Earth. ...
October 2019
Elements
... Mons Agnes will allow access to both mound and floor material for a small rover that will return samples to the lander for radiometric dating. The mission profile is similar to those previously proposed for Ina (Stopar et al. 2019;Qiao et al. 2021) that would seek to determine the age and origin of the Ina deposits through in situ analysis. ...
April 2019
Planetary and Space Science
... The figure clearly demonstrates that the influence of the Hubbard correction on the phonon DOS is insignificant within the considered pressure ranges, consistent with the available experimental data. [73][74][75]. Theoretical data at T = 500 K evaluated using the Kubo-Greenwood formula stems from [72]. ...
July 2018
Icarus
... The interactions between the ambient space plasma environment and crustal magnetic fields (Halekas, Saito, Delory, & Farrell, 2011;Halekas, Brain, & Holmström, 2015), as well as electrostatic fields at the lunar surface (Zimmerman, Farrell, Stubbs, Halekas, & Jackson, 2011;Stubbs et al., 2014;Fatemi et al., 2015) are still poorly understood, especially at the lunar poles or lunar swirls (which is also a region of interest for future exploration, Robinson et al., 2018). Such anthropogenic interactions of rovers and scientific equipment may disrupt the ambient, natural lunar environment. ...
Reference:
Moon: Handle With Care
June 2018
Planetary and Space Science