Laboratory Investigation of Rate of Electrostatic Dust Lofting Over Time on Airless Planetary Bodies

Hood, N.; Carroll, A.; Mike, R.; Wang, X.; Schwan, J.; Hsu, Hsiang-Wen; Horányi, M.

doi:10.1029/2018gl080527

Cited by 31 publications

(19 citation statements)

References 31 publications

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“…One of prominent surface processes on airless bodies is electrostatic dust mobilization and transport, which has been related to a number of observations (Wang et al, , and references therein) and has been confirmed using laboratory experiments (Hood et al, ; Schwan et al, ; Wang et al, ) and computer simulations (Zimmerman et al, ). One of these space observations is the so‐called dust ponds, which are flat and smooth deposits of fine dust particles in the craters observed on both asteroid Eros (Robinson et al, ) and comet 67P (Thomas et al, ).…”

Section: Introductionmentioning

confidence: 72%

Plasma Sheath Formation at Craters on Airless Bodies

2019

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The surfaces of airless planetary bodies directly interact with the solar wind plasma and ultraviolet radiation, resulting in surface charging and formation of a sheath above the surface. These interactions are further complicated by the presence of craters with characteristic sizes spanning over orders of magnitude from centimeters to kilometers. Here we present laboratory results to show that the plasma sheath formed in a crater varies significantly, depending on the radius of the crater compared to the Debye length of ambient plasma. When the Debye length is much smaller than the radius of the crater, the plasma expands into the crater and forms a sheath along the crater wall and floor. When the Debye length is comparable to or larger than the radius of the crater, the potential in the crater becomes more homogenous with a largely reduced electric field. A double layer is formed between the crater and ambient plasma. It is likely that the electrons slowed down by the sheath cannot be efficiently reflected back to the plasma due to the reduced electric field and pile up within the crater, causing an increased electron density that crosses over the density of the ions.

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Section: Introductionmentioning

confidence: 72%

Plasma Sheath Formation at Craters on Airless Bodies

2019

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“…The exact physical reasons for the absence of high concentrations of lunar dust particles over the sharp sunlight/shadow boundaries in CE‐3 landing site are not yet fully understood; however, the weak dust activity in the geologically young CE‐3 landing region (Yan et al, 2019) and the lack of strong electric field forces on the lunar surface for lunar dust particles to overcome gravity and cohesion (Popel et al, 2018; Szalay & Horányi, 2015; Wang et al, 2016) are the two most likely causes. However, it cannot be entirely ruled out that high concentrations of lunar dust particles may still exist in the lower lunar space environment at altitudes below ~2.05 m because recent laboratory experiments showed that the inner walls of microcavities between dust particles can collect very large negative charge under electron beam or UV radiation conditions (Hood et al, 2018; Schwan et al, 2017; Wang et al, 2016), and the negatively charged dust particles can be electrostatically lofted by the repulsion from the adjacent like‐charged particles to reach an equivalent height of ~0.11 m on the lunar surface, comparable to the height of the lunar horizon glow observed by Surveyors. Unfortunately, the SCP cannot detect dust particles at this height range.…”

Section: Resultsmentioning

confidence: 99%

In Situ Investigations of Dust Above the Lunar Terminator at the Chang'E‐3 Landing Site in the Mare Imbrium

Wang

Zhang

Wang

et al. 2020

Geophysical Research Letters

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It was suspected that the horizon glow observed over the lunar terminator was caused by electrostatically levitated dust particles, but do high concentrations of dust particles really exist over the lunar terminator? This is an important question that cannot be answered even today. In fact, no in situ investigations about the lunar dust have been conducted on lunar surface since Apollo. Here we first report in situ investigations of lunar dust at Chang'E‐3 (CE‐3) landing site using solar cell probe (SCP). The results show that, different from Apollo's observation, the short‐circuit current of SCP did not decrease sharply during the first several lunations except the first lunation, indicating the recently developed minimalist qualitative model of sunrise‐driven dust transport might not be applicable at the geologically young CE‐3 landing site. In addition, within detector's detection limit, no abrupt changes in dust concentration were observed above the sharp sunlight/shadow boundaries on lunar surface.

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“…If small particles are residing on the rocks by cohesion force, a supercharging effect near the terminator or the shadow on asteroids may free the particle from the AR with initial kinetic energy and achieve the condition H r a . From Wang et al (2016) (Figure 4 of them) and Hood et al (2018), particles of radius r a = 5−22 µm (2r a = 10−44 µm) could achieve an initial speed of up to v z,0 ∼ 0.6 m/s due to the supercharging effect at r h = 1 au. This is the aftermath of Coulomb interaction, and therefore the particle size range and initial speed are independent of asteroid size (D) or r h .…”

Section: Electrostatic Dust Lofting and Levitationmentioning

confidence: 96%

“…The electrostatic lofting mechanism, which is the mechanism that launches the particles from the AR, has recently been studied extensively both theoretically (Zimmerman et al 2016 experimentally (Wang et al 2016;Hood et al 2018). If small particles are residing on the rocks by cohesion force, a supercharging effect near the terminator or the shadow on asteroids may free the particle from the AR with initial kinetic energy and achieve the condition H r a .…”

Section: Electrostatic Dust Lofting and Levitationmentioning

confidence: 99%

Thermal radiation pressure as a possible mechanism for losing small particles on asteroids

Bach,

Ishiguro

2021

Preprint

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Context. Recent observations of dust ejections from active asteroids, including (3200) Phaethon, have drawn considerable interest from planetary astronomers studying the generation and removal of small dust particles on asteroids. Aims. In this work, we aim to investigate the importance of thermal radiation pressure from asteroid regolith (AR) acting on small dust particles over the surface of the AR. In particular, we aim to understand the role of thermal radiation in the near-Sun environment. Methods. We describe the acceleration of particles over the AR within the radiation fields (direct solar, reflected (scattered) solar, and thermal radiation) in addition to the asteroid's rotation and gravitational field. Mie theory is used because the particles of interest have sizes comparable to thermal wavelengths (∼ 1−100 µm), and thus the geometric approximation is not applicable. A new set of formalisms is developed for the purpose. Results. We find that the acceleration of particles with spherical radius 1 µm to ∼ 10 µm is dominated by the thermal radiation from the AR when the asteroid is in the near-Sun environment (heliocentric distance r h 0.8 au). Under thermal radiation dominance, the net acceleration is towards space, that is, outwards from the AR. This outward acceleration is the strongest for particles of ∼ 1 µm in radius, regardless of other parameters. A preliminary trajectory integration using the Phaethon-like model shows that such particles escape from the gravitational field within about 10 minutes. Our results are consistent with the previous observational studies on Phaethon in that the ejected dust particles have a spherical radius of ∼ 1 µm.

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Laboratory Investigation of Rate of Electrostatic Dust Lofting Over Time on Airless Planetary Bodies

Cited by 31 publications

References 31 publications

Plasma Sheath Formation at Craters on Airless Bodies

Plasma Sheath Formation at Craters on Airless Bodies

In Situ Investigations of Dust Above the Lunar Terminator at the Chang'E‐3 Landing Site in the Mare Imbrium

Thermal radiation pressure as a possible mechanism for losing small particles on asteroids

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