Differential Ablation of Organic Coatings From Micrometeoroids Simulated in the Laboratory

DeLuca, Michael; Sternovsky, Z.; Armes, Steven P.; Fielding, Lee A.; Horányi, M.; Janches, Diego; Kupihár, Zoltán; Munsat, T.; Plane, J. M. C.

doi:10.1029/2021je007168

Cited by 6 publications

(3 citation statements)

References 53 publications

(113 reference statements)

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“…Presumably, phenanthrene undergoes a similar side reaction, which leads to a change in its morphology. Fortunately, no such problems were encountered when using (NH 4 ) 2 S 2 O 8 , which has been previously used to prepare polypyrrole-coated pyrrhotite and polypyrrole-coated olivine microparticles. , This oxidant leads to a much faster rate of pyrrole polymerization than FeCl 3 but a slightly lower conductivity. , Thus, it can be assumed that (i) all of the pyrrole monomer is converted into polypyrrole and (ii) all of the polypyrrole is deposited onto the phenanthrene microparticles (i.e., there is no secondary nucleation) . These assumptions have been validated when coating 20 μm diameter polystyrene latex particles with a polypyrrole coating of comparable mean thickness (20 nm) …”

Section: Resultsmentioning

confidence: 99%

“…Fortunately, no such problems were encountered when using (NH 4 ) 2 S 2 O 8 , which has been previously used to prepare polypyrrole-coated pyrrhotite and polypyrrole-coated olivine microparticles. 47 , 48 This oxidant leads to a much faster rate of pyrrole polymerization than FeCl 3 but a slightly lower conductivity. 49 , 50 Thus, it can be assumed that (i) all of the pyrrole monomer is converted into polypyrrole and (ii) all of the polypyrrole is deposited onto the phenanthrene microparticles (i.e., there is no secondary nucleation).…”

Section: Resultsmentioning

confidence: 99%

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Synthesis of Autofluorescent Phenanthrene Microparticles via Emulsification: A Useful Synthetic Mimic for Polycyclic Aromatic Hydrocarbon-Based Cosmic Dust

Chan,

Wills,

Tandy

et al. 2023

ACS Appl. Mater. Interfaces

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Phenanthrene is the simplest example of a polycyclic aromatic hydrocarbon (PAH). Herein, we exploit its relatively low melting point (101 °C) to prepare microparticles from molten phenanthrene droplets by conducting high-shear homogenization in a 3:1 water/ethylene glycol mixture at 105 °C using poly(N-vinylpyrrolidone) as a non-ionic polymeric emulsifier. Scanning electron microscopy studies confirm that this protocol produces polydisperse phenanthrene microparticles with a spherical morphology: laser diffraction studies indicate a volume-average diameter of 25 ± 21 μm. Such projectiles are fired into an aluminum foil target at 1.87 km s–1 using a two-stage light gas gun. Interestingly, the autofluorescence exhibited by phenanthrene aids analysis of the resulting impact craters. More specifically, it enables assessment of the spatial distribution of any surviving phenanthrene in the vicinity of each crater. Furthermore, these phenanthrene microparticles can be coated with an ultrathin overlayer of polypyrrole, which reduces their autofluorescence. In principle, such core–shell microparticles should be useful for assessing the extent of thermal ablation that is likely to occur when they are fired into aerogel targets. Accordingly, polypyrrole-coated microparticles were fired into an aerogel target at 2.07 km s–1. Intact microparticles were identified at the end of carrot tracks and their relatively weak autofluorescence suggests that thermal ablation during aerogel capture did not completely remove the polypyrrole overlayer. Thus, these new core–shell microparticles appear to be useful model projectiles for assessing the extent of thermal processing that can occur in such experiments, which have implications for the capture of intact PAH-based dust grains originating from cometary tails or from plumes emanating from icy satellites (e.g., Enceladus) in future space missions.

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Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

Synthesis of Autofluorescent Phenanthrene Microparticles via Emulsification: A Useful Synthetic Mimic for Polycyclic Aromatic Hydrocarbon-Based Cosmic Dust

Chan,

Wills,

Tandy

et al. 2023

ACS Appl. Mater. Interfaces

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“…This can create variation in radar cross‐section during head echo detection, and such variation at the Arecibo radar facility was demonstrated to match the results of an ablation model (L. Dyrud & Janches, 2008; Janches et al., 2009). The effect has been observed in the laboratory for submicron‐scale particles (DeLuca et al., 2022). The process of differential ablation may cause the meteoroid to fragment during atmospheric entry.…”

Section: Introductionmentioning

confidence: 82%

Meteor Head Echo Analyses From Concurrent Radar Observations at AMISR Resolute Bay, Jicamarca, and Millstone Hill

2022

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Researchers frequently use high-power large aperture (HPLA) incoherent scatter radar (ISR) instruments around the world to gather data about meteoroids entering Earth's atmosphere. HPLA radar instruments measure between hundreds and thousands of head echoes per hour, depending on factors including frequency, power, geographic location and beam direction, in addition to the observed meteor population, that influence head echo detectability. High detection rates enable the use of statistical methods for head echo populations. The observed head echoes often originate from particles that are tens of microns in diameter; larger than the particles that can be observed in situ via impact detectors (Baggaley et al., 2007), but smaller than those observed via optical methods (Brown et al., 2017;Campbell-Brown & Close, 2007). Furthermore, signal processing techniques can be leveraged to obtain extremely accurate measurements of meteor motion during atmospheric entry from radar data.As a meteoroid ablates in Earth's atmosphere, a plasma forms at altitudes from 80 to 130 km due to sputtering and thermal ablation upon high-velocity collisions between the meteoroid and atmospheric molecules (Guttormsen et al., 2020;Popova et al., 2001). The high-density plasma cap that surrounds the meteoroid reflects radio waves, producing the head echo radar signature. Head echoes are observable at any HPLA radar. As the plasma expands and undergoes collisions with the surrounding atmosphere, a Farley-Buneman gradient-drift instability may develop in the meteor trail and create a non-specular radar return (Oppenheim & Dimant, 2015;Oppenheim et al., 2000). Most trails occur at equatorial radars due to field-aligned-irregularity (FAI) scattering when the incident wave is perpendicular to the background magnetic field (L. P. Dyrud et al., 2005), although non-FAI scattering has also been observed at higher latitudes (Chau et al., 2014;Kozlovsky et al., 2020).As the meteoroid heats and ablates, differential ablation may occur where certain constituents thermalize before others. This can create variation in radar cross-section during head echo detection, and such variation at the Arecibo radar facility was demonstrated to match the results of an ablation model (L. Dyrud & Janches, 2008;Janches et al., 2009). The effect has been observed in the laboratory for submicron-scale particles (DeLuca et al., 2022). The process of differential ablation may cause the meteoroid to fragment during atmospheric entry. Fragmentation has been observed optically (Vida et al., 2021), and on radar instruments via polarization of the

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Radar analysis algorithm for determining meteor head echo parameter probability distributions

Kastinen

Kero

2022

Monthly Notices of the Royal Astronomical Society

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We present an automated radar data analysis algorithm developed to calculate probability distributions of meteor- and meteoroid parameters for head echoes detected with the Middle and Upper atmosphere (MU) radar in Shigaraki, Japan. The algorithm utilizes direct Monte Carlo simulations of uncertainties, with Bayesian Markov-chain Monte Carlo estimation of meteor model parameters and N-body propagation of distributions to perform orbit determination. The implementation has been validated using raw data simulations and a comparison with previous analysis methods. The concepts are applicable on a wide range of possible head echo measurements with other radar systems. The generated probability distributions provide quantitative reliability, which enables improved statistical studies and investigating the origins of detected meteoroids. The methodology section is highly detailed in order for the methods to be reproducible and provide a solid reference foundation for future studies. One such study is presented in a companion paper called ‘High-altitude meteors detected by the interferometric MU radar’.

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Differential Ablation of Organic Coatings From Micrometeoroids Simulated in the Laboratory

Cited by 6 publications

References 53 publications

Synthesis of Autofluorescent Phenanthrene Microparticles via Emulsification: A Useful Synthetic Mimic for Polycyclic Aromatic Hydrocarbon-Based Cosmic Dust

Synthesis of Autofluorescent Phenanthrene Microparticles via Emulsification: A Useful Synthetic Mimic for Polycyclic Aromatic Hydrocarbon-Based Cosmic Dust

Meteor Head Echo Analyses From Concurrent Radar Observations at AMISR Resolute Bay, Jicamarca, and Millstone Hill

Radar analysis algorithm for determining meteor head echo parameter probability distributions

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