Pattern of Impact-induced Ejecta from Granular Targets with Large Inclusions

Kadono, Toshihiko; Suetsugu, Ryo; Arakawa, Dai; Kasagi, Yoshiki; Nagayama, Syuichi; Suzuki, Ayako; Hasegawa, Susumu

doi:10.3847/2041-8213/ab303f

Cited by 12 publications

(27 citation statements)

References 11 publications

(12 reference statements)

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“…When the particles in the ejecta curtain are spatially concentrated, the intensity contrast should be high. To evaluate the intensity contrast, we analyzed the images using the same procedure by Kadono et al (2019). We investigated the intensity I within the area of N 0 = 100 × 100 pixels around the center of the ejecta curtain, and the area was fixed at the same position in the ejecta curtain in each image.…”

Section: Resultsmentioning

confidence: 99%

“…1d in Kadono et al (2020b). Kadono et al (2015), Kadono et al (2019), Kadono et al (2020a)] have experimentally investigated the pattern in ejecta curtains in laboratories, using targets of single-size particles (glass beads, 50, 100, and 300 μm, and silica sand, 70 μm) and particles with bimodal size distributions (glass beads, 100 μm + 1 mm, 100 μm + 4 mm). The pattern in the ejecta curtains was significantly different: a mesh-like pattern appeared for targets of single-sized particles, whereas a complex filament pattern extending the entire curtain was observed for targets of particles with a bimodal size distribution.…”

Section: Introductionmentioning

confidence: 99%

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Pattern in ejecta curtain generated by the impact into granular targets of various sized particles and application to the ejecta curtain observed in the Hayabusa2 impact experiment

Kadono

Suzuki

Suetsugu

et al. 2022

Earth Planets Space

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We conducted impact experiments using targets composed of particles with size distributions and projectiles with a size larger than or comparable with the maximum size of particles in targets. The pattern and particle concentration in the ejecta curtain were investigated. The results show three types of ejecta curtain features: (i) filament pattern extending throughout the entire curtain and high concentration, (ii) filament pattern and low concentration, and (iii) mesh-like pattern with a structure on smaller scales than the entire curtain and low concentration. When the target consists of particles using a bimodal size distribution with size differences of more than one order of magnitude, the filament pattern appears, exhibiting case (i). If the target consists of particles with various sizes with size differences of more than one order of magnitude, the filament pattern appears, but the concentration decreases, appearing the features of case (ii). Case (iii) occurs when the target consists of particles with a single size or when the mass of particles with a certain size is dominant. Thus, the size distribution of the particles in the targets determines the pattern and particle concentration in the ejecta curtain. Based on these results, we confirm that the pattern in the ejecta curtain caused by the impact of the Small Carry-on Impactor (SCI) in the Hayabusa2 mission showing case (i) is consistent with the evaluated sizes and masses of grains and boulders in the ejecta curtain. Graphical Abstract

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Pattern in ejecta curtain generated by the impact into granular targets of various sized particles and application to the ejecta curtain observed in the Hayabusa2 impact experiment

Kadono

Suzuki

Suetsugu

et al. 2022

Earth Planets Space

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“…As a result, the patterns may be different. In fact, the recent experiments with the target consisting of two kinds of particles in size (0.1 mm and 1 or 4 mm) mixed at almost the same weight % show that large inclusions disturb excavation flow as obstacles and cause different flow patterns such as drags and spurts, but these patterns are temporary and not periodic (Kadono et al 2019). On the other hand, when the amount of small particles is relatively large, the pattern would become similar to the one observed in our experiments.…”

Section: Dependence Of θC On Impact Conditionsmentioning

confidence: 99%

Crater-ray formation through mutual collisions of hypervelocity-impact induced ejecta particles

Kadono

Suzuki

Matsumura

et al. 2020

Icarus

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We investigate the patterns observed in ejecta curtain induced by hypervelocity impact (2−6 km/s) with a variety of the size and shape of target particles. We characterize the patterns by an angle, defined as the ratio of the characteristic length of the pattern obtained by Fourier transformation to the distance from the impact point. This angle is found to be almost the same as that obtained by the reanalysis of the patterns in the previous study at lower impact velocities (Kadono et al., 2015, Icarus 250, 215-221), which are consistent with lunar crater-ray systems. Assuming that the pattern is formed by mutual collision of particles with fluctuation velocity in excavation flow, we evaluate an angle at which the pattern growth stops and show that this angle is the same in the order of magnitude as the ratio of the fluctuation velocity and the radial velocity. This relation is confirmed in the results of experiments and numerical simulations. Finally, we discuss the dependence of the patterns on impact conditions. The experiments show no dependence of the angle on impact velocity. This indicates that the ratio between the fluctuation and radial velocity components in excavation flow does not depend on impact velocity. Moreover, the independences on particle size and particle shape suggest that the angle characterizing the structure of the patterns does not depend on cohesive force. Since cohesive forces should be related with elastic properties of particles, the structure does not depend on elastic properties, though inelastic collisions are important for the persistence and contrast of the patterns.

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“…Another strong assumption in our model is that all ejecta particles are of equal size. Kadono et al (2019) reported that a target made of different-sized granules produces ejecta curtains with filament patterns. Extending our analytic model to polydisperse granular targets will be the subject of future work.…”

Section: Validity and Limitations Of The Modelmentioning

confidence: 99%

Modeling Early Clustering of Impact-induced Ejecta Particles Based on Laboratory and Numerical Experiments

Kanon

Okuzumi²,

Kurosawa³

et al. 2021

Planet. Sci. J.

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A projectile impact onto a granular target produces an ejecta curtain with heterogeneous material distribution. Understanding how the heterogeneous pattern forms is potentially important for understanding how crater rays form. Previous studies predicted that the pattern formation is induced by inelastic collisions of ejecta particles in early stages of crater formation and terminated by the ejecta’s expanding motion. In this study, we test this prediction based on a hypervelocity impact experiment together with N-body simulations where the trajectories of inelastically colliding granular particles are calculated. Our laboratory experiment suggests that pattern formation is already completed on a timescale comparable to the geometrical expansion of the ejecta curtain, which is ∼10 μs in our experiment. Our simulations confirm the previous prediction that the heterogeneous pattern grows through initial inelastic collisions of particle clusters and subsequent geometric expansion with no further cluster collisions. Furthermore, to better understand the two-stage evolution of the mesh pattern, we construct a simple analytical model that assumes perfect coalescence of particle clusters upon collision. The model shows that the pattern formation is completed on the timescale of the system’s expansion independently of the initial conditions. The model also reproduces the final size of the clusters observed in our simulations as a function of the initial conditions. It is known that particles in the target are ejected at lower speeds with increased distance to the impact point. The difference in the ejection speed of the particles may result in the evolution of the mesh pattern into rays.

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Pattern of Impact-induced Ejecta from Granular Targets with Large Inclusions

Cited by 12 publications

References 11 publications

Pattern in ejecta curtain generated by the impact into granular targets of various sized particles and application to the ejecta curtain observed in the Hayabusa2 impact experiment

Pattern in ejecta curtain generated by the impact into granular targets of various sized particles and application to the ejecta curtain observed in the Hayabusa2 impact experiment

Crater-ray formation through mutual collisions of hypervelocity-impact induced ejecta particles

Modeling Early Clustering of Impact-induced Ejecta Particles Based on Laboratory and Numerical Experiments

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