Constraining the Ratio of Micrometeoroids From Short‐ and Long‐Period Comets at 1 AU From LADEE Observations of the Lunar Dust Cloud

Janches, Diego; Sarantos, M.; Horányi, M.; Nesvorný, David; Szalay, J. R.; Pokorný, Petr

doi:10.1002/2017gl076065

Cited by 27 publications

(52 citation statements)

References 29 publications

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“…Additionally, we assumed the sources were symmetrically distributed in Solar‐Selenocentric‐Ecliptic coordinates and static in time. However, the impactor distribution is not perfectly symmetric and there are synodic and annual variations, as previously observed by LDEX (Szalay & Horányi, ) and recently modeled (Janches et al, ). Additionally, we assume that the various sources all have similar mass distributions, however, modest changes in the expected M + maps may be expected for relaxing this assumption.…”

Section: Discussionsupporting

confidence: 48%

“…All results derived in this work utilized a model for impact ejecta generation, summing six separate sources represented by

\cos^{3} φ

functions. Corrections to the model using a dynamical interplanetary dust particle impactor model (e.g., Janches et al, ; Nesvorny, Janches, et al, ; Nesvorny, Vokrouhlický, et al, ; Pokorný et al, , ) could potentially improve ejecta estimates. For example, the toroidal source is more of a ring‐like flux structure (e.g., Pokorný et al, ) than a collimated beam at 60° latitude as assumed here.…”

Section: Discussionmentioning

confidence: 99%

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Impact Ejecta and Gardening in the Lunar Polar Regions

et al. 2019

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The Moon is continually bombarded by interplanetary meteoroids. While many of the meteoroid sources are near the ecliptic plane, a significant population of high‐inclination meteoroids exists at 1 au that bombards the lunar polar regions. Building on previous measurements of the response of the lunar impact ejecta cloud to known meteoroid sources, we develop an ejecta model for the entire lunar surface by incorporating the high‐inclination sources. We find that the polar regions of the Moon experience similar quantities of impact ejecta production as the equator. Due to the enhanced impactor fluxes near the equator and at high latitudes on the dawn side, lunar regolith is preferentially distributed to the mid to high‐latitude regions over long timescales, providing a pathway to mix regolith from different regions. We find impact ejecta yields at the Moon to be significantly lower than the Galilean moons, suggesting meteoroids deliver more energy to the local regolith and can be an important driver in the evolution of volatiles near the lunar surface. Additionally, we find that a polar orbiting spacecraft equipped with a dust analyzer can measure appreciable quantities of lunar ejecta near the poles to constrain the water content in the polar regions.

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Section: Discussionsupporting

confidence: 48%

“…All results derived in this work utilized a model for impact ejecta generation, summing six separate sources represented by

\cos^{3} φ

Section: Discussionmentioning

confidence: 99%

Impact Ejecta and Gardening in the Lunar Polar Regions

et al. 2019

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“…The dynamical model of meteoroids used in this manuscript consists of four different meteoroid populations originating from MBAs, JFCs, Halley‐type comets (HTCs), and Oort‐Cloud Comets (OCCs), and is the same as the one used in Pokorný et al () and (Janches et al, ). Since these models have been described extensively in previous works, the reader can follow the references provided in Table for details.…”

Section: Methodsmentioning

confidence: 99%

“… Note . For more detailed information refer to references in the table or Janches et al () and Pokorný et al ().…”

Section: Methodsmentioning

confidence: 99%

“…In this model we account for the gravitational focusing effect on the collisional cross‐section area σ , an effect omitted in Janches et al (). Following Öpik () we define

σ = π {false(r_{1} + r_{2} false)}^{2} ([], 1 + \frac{V_{esc}^{2}}{V_{rel}^{2} + ϵ^{2}}),

where r 1 and r 2 are projectile's and target's average radii, V esc is the escape velocity of the more massive object (i.e., the target), V rel is the relative velocity of the two objects, and ϵ is a softening parameter.…”

Section: Methodsmentioning

confidence: 99%

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Meteoroids at the Moon: Orbital Properties, Surface Vaporization, and Impact Ejecta Production

et al. 2019

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We use a dynamical model to characterize the monthly and yearly variations of the lunar meteoroid environment for meteoroids originating from short and long‐period comets and the main‐belt asteroids. Our results show that if we assume the meteoroid mass flux of 43.3 tons per day at Earth, inferred from previous works, the mass flux of meteoroids impacting the Moon is 30 times smaller, approximately 1.4 tons per day, and shows variations of the order of 10% over a year. The mass flux difference is due to the combined effect of the smaller cross‐section of the Moon (factor of 13.46) and Earth's larger gravitational focusing (factor of 2–2.5). The lunar surface is vaporized by these impactors at an average impact vaporization flux of 11.6 × 10−16 g·cm−2·s−1, providing a significant source for the rarefied lunar exosphere. Our model predicts acceptable vaporization rates and reproduces the local time dependence of observations of the dust ejecta cloud, measured by the Lunar Dust Experiment on board NASA's Lunar Atmosphere and Dust Environment (LADEE) satellite. However, the predicted density of the lunar ejecta cloud is four orders of magnitude larger than reported values by LADEE. This discrepancy might be attributed to a much lower yield from meteoroid impacts on fluffy lunar regolith and/or a lower detection efficiency of the LADEE dust detector. We suggest an upper limit of 30 cm per million years for the soil gardening rate from small meteoroids.

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Review of research on lunar dust dynamics

Yang

Feng

et al. 2022

Astrophys Space Sci

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Constraining the Ratio of Micrometeoroids From Short‐ and Long‐Period Comets at 1 AU From LADEE Observations of the Lunar Dust Cloud

Cited by 27 publications

References 29 publications

Impact Ejecta and Gardening in the Lunar Polar Regions

Impact Ejecta and Gardening in the Lunar Polar Regions

Meteoroids at the Moon: Orbital Properties, Surface Vaporization, and Impact Ejecta Production

Review of research on lunar dust dynamics

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