Laboratory investigation of the effect of surface roughness on photoemission from surfaces in space

Dove, Adrienne; Horányi, M.; Robertson, Scott; Wang, Xu

doi:10.1016/j.pss.2017.10.014

Cited by 12 publications

(6 citation statements)

References 28 publications

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“…These types of boulders are present throughout the Moon, in particular in the highlands, and thus cannot explain the observation of a highly localized occurrence. Another scenario considers the possibility that a peculiar composition and roughness lead to differences in photoelectron yield and local electric field (e.g., Dove et al., 2018; Feuerbacher et al., 1972; Xu et al., 2020) and thus variation in the dust charging and lofting. These variations could be particularly important at topographic reliefs (e.g., boulders) due to the formation of illuminated and shadowed regions (e.g., Berg, 1978; Farrell et al., 2007; Lee, 1996; Piquette & Horanyi, 2017; Poppe et al., 2012).…”

Section: Discussionmentioning

confidence: 99%

Discovery of a Dust Sorting Process on Boulders Near the Reiner Gamma Swirl on the Moon

Rüsch,

Hess,

Wöhler

et al. 2024

JGR Planets

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In a database of lunar fractured boulders (Rüsch & Bickel, 2023, https://doi.org/10.3847/psj/acd1ef), we found boulders with reflectance features dissimilar to previously known morphologies. We performed a photo‐geologic investigation and determined that the features correspond to a dust mantling on top of boulders with a unique photometric behavior. We next performed a photometric model inversion on the dust mantling using Bayesian inference sampling. Modeling indicates that the dust photometric anomaly is most likely due to a reduced opposition effect, whereas the single scattering albedo is not significantly different from that of the nearby background regolith. This implies a different structure of the dust mantling relative to the normal regolith. We identified and discussed several potential processes to explain the development of such soil. None of these mechanisms can entirely explain the multitude of observational constraints unless evoking anomalous boulder properties. Further study of these boulders can shed light on the workings of a natural dust sorting process potentially involving dust dynamics, a magnetic field, and electrostatic dust transport. The presence of these boulders appears to be limited to the Reiner K crater near the Reiner Gamma magnetic and photometric anomaly. This close spatial relationship further highlights that poorly understood processes occur in this specific region of the Moon.

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Section: Discussionmentioning

confidence: 99%

Discovery of a Dust Sorting Process on Boulders Near the Reiner Gamma Swirl on the Moon

Rüsch,

Hess,

Wöhler

et al. 2024

JGR Planets

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“…Computer simulations [Zimmerman et al, 2016] have since also demonstrated charging enhancement due to strong grain-scale electric fields in the regolith. Since then, additional laboratory experiments have produced results in support of the Patched Charge Model [Schwan et al, 2017;Hood et al, 2018;Dove et al, 2018;Orger et al, 2019].…”

Section: Current Understandingmentioning

confidence: 99%

Electrostatic Dust Transport Effects on Shaping the Surface Properties of the Moon and Airless Bodies across the Solar System

Wang

Blewett

Kramer

et al. 2021

Bulletin of the AAS

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Electrostatic dust charging and subsequent transport on the lunar surface due to direct exposure to the solar wind plasma and solar radiation is a more than five-decade-old problem. Dust activity has been suggested as an explanation for several lunar surface observations from the beginning in the Apollo era. Beyond the Moon, related observations indicate that this electrostatic process may be a universal phenomenon on airless bodies across the solar system. Recent studies have made important breakthroughs in understanding the fundamentals of dust charging, mobilization and lofting mechanisms, offering strong support for its occurrence on the surfaces of airless bodies. This white paper reviews historical and recent observational evidence, reports recent findings, examines knowledge gaps and outstanding science questions, and provides recommendations for future studies. Special attention is given to in situ measurements over the next decade in order to ultimately solve the outstanding questions and, more importantly, understand the primary implications for the evolution of the surfaces of the Moon and other airless bodies across the solar system. Furthermore, potential risks posed by electrostatic dust transport to future surface exploration of these bodies, especially any long-term human presence on the lunar surface, needs to be well characterized in order to define and implement appropriate risk mitigation strategies and methods through proper systems design and testing.

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“…As opposed to emission from an ideal flat surface, some of the ejected electrons from the lunar surface will be reabsorbed because of the porous lunar regolith. A laboratory experiment by Dove et al (2018) showed that photoemission currents from a powder surface are reduced by 60%-80% compared to that from a flat solid surface, implying 0.2 ≲ α ≲ 0.4. However, since little knowledge has been obtained for α of the lunar regolith, we treat α as a free parameter and we assume that it is energy independent for simplicity.…”

Section: Model Inputsmentioning

confidence: 99%

Modeling Photoelectron and Auger Electron Emission From the Sunlit Lunar Surface: A Comparison With ARTEMIS Observations

Kato,

Harada,

et al. 2023

JGR Space Physics

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Due to the lack of a dense atmosphere, the Moon directly interacts with ambient plasmas and solar radiation, leading to lunar surface charging. Solar X‐rays drive the emission of photoelectrons and Auger electrons from the lunar surface to space. The Auger electrons have characteristic energies intrinsic to the photo‐emitting atoms and were recently identified at the Moon by Acceleration, Reconnection, Turbulence, and Electrodynamics of the Moon’s Interaction with the Sun (ARTEMIS) observations. In this study, we developed a numerical model of the energy spectrum of lunar photoelectrons and Auger electrons, thereby comparing the predicted and observed energy spectra. By adjusting a scaling factor, the model well reproduces the ARTEMIS observations obtained in the solar wind, where the energy spectra are minimally affected by surface charging. Meanwhile, the energy spectra obtained in the geomagnetic tail can be significantly altered by lunar surface potentials. We show that it is difficult to determine a unique combination of the scaling factor and the lunar surface potential with the ARTEMIS energy resolution because of a strong parameter degeneracy. Nevertheless, for a fixed scaling factor, a strong correlation is identified between the lunar surface potentials inferred from the shifts of the energy spectra and those from the upward photoelectron beam energies, providing a proof of concept for the use of the photo‐emitted electrons as a new remote sensing tool of the lunar surface potential. We advocate for future observations of lunar electrons with a high energy resolution.This article is protected by copyright. All rights reserved.

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Laboratory investigation of the effect of surface roughness on photoemission from surfaces in space

Cited by 12 publications

References 28 publications

Discovery of a Dust Sorting Process on Boulders Near the Reiner Gamma Swirl on the Moon

Discovery of a Dust Sorting Process on Boulders Near the Reiner Gamma Swirl on the Moon

Electrostatic Dust Transport Effects on Shaping the Surface Properties of the Moon and Airless Bodies across the Solar System

Modeling Photoelectron and Auger Electron Emission From the Sunlit Lunar Surface: A Comparison With ARTEMIS Observations

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