Impact and intrusion experiments on the deceleration of low-velocity impactors by small-body regolith

Nakamura, Akiko; Setoh, M.; Wada, Koji; Yamashita, Yasuyuki; Sangen, Kazuyoshi

doi:10.1016/j.icarus.2012.11.038

Cited by 20 publications

(23 citation statements)

References 27 publications

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“…Some were more interested in very low speed impacts (less than 4 m s −1 ), and among them different parts were emphasized, but always in the context of Earth's gravity, such as the restraining force (Katsuragi & Durian 2007;Katsuragi & Blum 2017) or the crater's shape and size (Uehara et al 2003;Walsh et al 2003;de Vet & de Bruyn 2007;Nordstrom et al 2013). Others conducted experiments with much faster projectiles, closer to the speed used for the Hayabusa2 sampling mechanism: for example Yamamoto et al (2005) looked at the velocity distribution of ejecta, Yamamoto et al (2009) at the transient crater growth, and Nakamura et al (2013) at the penetration depth of the impactor. Experiments have even been possible under low-gravity or microgravity, through the use of an Atwood machine (Murdoch et al 2017) or parabolic flights (Nakamura et al 2013;Brisset et al 2018).…”

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confidence: 99%

“…Others conducted experiments with much faster projectiles, closer to the speed used for the Hayabusa2 sampling mechanism: for example Yamamoto et al (2005) looked at the velocity distribution of ejecta, Yamamoto et al (2009) at the transient crater growth, and Nakamura et al (2013) at the penetration depth of the impactor. Experiments have even been possible under low-gravity or microgravity, through the use of an Atwood machine (Murdoch et al 2017) or parabolic flights (Nakamura et al 2013;Brisset et al 2018).…”

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confidence: 99%

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Numerical modelling of medium-speed impacts on a granular surface in a low-gravity environment application to Hayabusa2 sampling mechanism

Thuillet

Michel

Tachibana

et al. 2019

Monthly Notices of the Royal Astronomical Society

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Even if craters are very common on Solar System body surfaces, crater formation in granular media such as the ones covering most of visited asteroids still needs to be better understood, above all in low-gravity environments. JAXA’s sample return mission Hayabusa2, currently visiting asteroid (162173) Ryugu, is a perfect opportunity for studying medium-speed impacts into granular matter, since its sampling mechanism partly consists of a 300 m s−1 impact. In this paper, we look at medium-speed impacts, from 50 to 300 m s−1, into a granular material bed, to better understand crater formation and ejecta characteristics. We then consider the sampler horn of Hayabusa2 sampling mechanism and monitor the distribution of particles inside the horn. We find that the cratering process is much longer under low gravity, and that the crater formation mechanism does not seem to depend on the impact speed, in the considered range. The Z-model seems to rightly represent our velocity field for a steady excavation state. From the impact, less than $10{{\ \rm per\ cent}}$ is transmitted into the target, and grains are ejected mostly with angles between 48° and 54°. Concerning the sampling mechanism, we find that for most of the simulations, the science goal of 100 mg is fulfilled, and that a second impact increases the number of ejecta but not necessarily the number of collected particles.

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confidence: 99%

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confidence: 99%

Numerical modelling of medium-speed impacts on a granular surface in a low-gravity environment application to Hayabusa2 sampling mechanism

Thuillet

Michel

Tachibana

et al. 2019

Monthly Notices of the Royal Astronomical Society

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“…This result is consistent with the observation result that the boulders were exposed inside the dimple. A similar result of penetration depth was estimated from impact and intrusion experiments in which the resistance force of the granular material was investigated (Nakamura et al, ). To estimate the secondary crater diameter on Itokawa, we used the crater size scaling law for the sand target (Housen & Holsapple, ) shown in Figures b and 4c.…”

Section: Application To Dimples On Itokawamentioning

confidence: 54%

Experimental Study on Gravitational and Atmospheric Effects on Crater Size Formed by Low‐Velocity Impacts Into Granular Media

2019

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Collisions are ubiquitous phenomena on the surface of solar system objects. When secondary craters form on the surface of small bodies, such as asteroids and comets, the impactors have very low velocities of several meters per second or less. These secondary collisions can affect the surface topography of small bodies. Therefore, it is important to investigate low‐velocity impacts on a target simulating regolith to understand the effects of secondary collisions on the surface of small bodies. We conducted impact experiments into granular materials with a velocity range of 1 to 4.6 m/s, under a gravity range of 0.20 to 1 G, to investigate the effects of gravity on crater diameter. The gravitational dependence obtained under the reduced ambient pressure almost agreed with those obtained for high‐velocity impacts in previous studies. Gravitational dependences obtained under the standard atmospheric condition roughly agreed with the dependence obtained under the reduced pressure condition when a term of nondimensional atmospheric pressure was added to the scaling relationship. It was found that the crater‐size scaling law obtained for high‐velocity impacts could be applied to low‐velocity impacts of several meters per second under the reduced ambient pressure when the density ratio of the projectile to the target was close to unity. Finally, we applied the experimental results to estimate the diameters of secondary craters on asteroid 25143 Itokawa and compared the diameters with the dimple topography on Itokawa. The results support the hypothesis that dimples are formed by low‐velocity impacts of meter‐sized boulders.

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“…In the present experimental study, a body was shot into a particle-laden space as seen in [3]. For convenience of observation and simplicity of analysis, we experimentally simulated the two-dimensional on-plane impact and penetration of a projectile in a sheet of particles.…”

Section: Introductionmentioning

confidence: 99%

Visualization of High-Speed Impact of Projectile in Granular Sheet with Destructive Collision of Particles

Masaki¹,

Suzuki²,

Watanabe³

2018

JFCMV

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The impact and penetration of a projectile in a particle-laden space, which are expected to have frequently occurred during the formation of the solar system and will occur in the case of an impact probe for future planetary exploration, were experimentally simulated by using the ballistic range. A two-dimensional sheet made from small glass beads or emery powder was formed by the free-falling device through a long slit in the test chamber evacuated down to about 35 Pa. A polycarbonate projectile of a hemisphere-cylinder or sphere shape with the mass and diameter about 4 g and 25 mm, respectively, was launched at the velocity up to 430 m/s, and the phenomena were observed by the high-speed camera at 20,000 fps. From a series of images, the bow-shock-wave-like laterally facing U-shaped pattern over the projectile and the absence of particles in the trail behind it were clearly seen. At the impact of the particles on the projectile surface, fine grains were formed due to the destructive collision and injected outward from the projectile. The images obtained by different lighting methods including the laser light sheet were compared. The effects of the particle diameter, its material and the impact velocity were also investigated.

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Impact and intrusion experiments on the deceleration of low-velocity impactors by small-body regolith

Cited by 20 publications

References 27 publications

Numerical modelling of medium-speed impacts on a granular surface in a low-gravity environment application to Hayabusa2 sampling mechanism

Numerical modelling of medium-speed impacts on a granular surface in a low-gravity environment application to Hayabusa2 sampling mechanism

Experimental Study on Gravitational and Atmospheric Effects on Crater Size Formed by Low‐Velocity Impacts Into Granular Media

Visualization of High-Speed Impact of Projectile in Granular Sheet with Destructive Collision of Particles

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