Dust Measurements Around the Moon and Across the Solar System

Bernardoni, Edwin A.

Graduate Thesis Or Dissertation

Dust Measurements Around the Moon and Across the Solar System Public Deposited

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Citations

Citeable URL: https://scholar.colorado.edu/concern/graduate_thesis_or_dissertations/nv9354151

Abstract

Dust grains are a key source of impact bombardment which is a critical component of space weathering, a ubiquitous process occurring on all airless bodies in the solar system governing how the surfaces of airless bodies are physically and chemically altered over time. Additionally, these dust grains interact with a broad range of celestial bodies within our solar system resulting in changes to their size distribution and trajectories. Thus characterizing the dynamics and distribution of dust provides key insight into the evolution of our solar system and airless bodies in particular. When impacting solid surfaces, secondary dust ejecta can be produced. These ejecta, following ballistic trajectories, form an exosphere observable to in situ instruments such as the Lunar Dust Experiment (LDEX) aboard the Lunar Dust and Environment Explorer (LADEE) spacecraft. The primary dust grains can also be observed directly through in situ instruments such as the Venetia Burney Student Dust Counter (SDC) aboard the New Horizons spacecraft which to date has produced measurements up to 50 AU.In this thesis, we will constrain the meteoroid environment at 1 AU using a forward modeling approach fitted to LDEX data. First, we expand a prior 2D plume simulation to 3D with additional considerations to derive impact ejecta cone angles relevant for the altitudes observed by LDEX. From these results, we construct a global lunar ejecta model fitted to LDEX observations to produce the product of impactor mass flux and mass yields for each of the primary sporadic background sources: helion, anti-helion, and apex. The potential for additional sources such as beta-meteoroids is also explored. From this we consider the integrated current signal measurements from LDEX presumably produced from smaller ejecta dust grains. The potential for energetic neutral atoms (ENAs) produced from backscattered solar wind is discussed along with the apparent lack of small ejecta on the lunar night-side. Additionally, we implement a simply trajectory tracing model of the solar wind to determine if there exists significant electrostatic lofting enhancement from twilight craters. From this, we find no evidence for such an enhancement. Finally, updated meteoroid flux and densities are reported for several grain size cutoffs using recent SDC measurements under updated methodology.

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