Ricochets on asteroids: Experimental study of low velocity grazing impacts into granular media

Wright, Esteban; Quillen, Alice C.; South, Juliana; Nelson, Randal C.; Sánchez, Paul; Siu, John; Askari, Hesam; Nakajima, M.; Schwartz, S. R.

doi:10.1016/j.icarus.2020.113963

Cited by 17 publications

(19 citation statements)

References 41 publications

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“…In addition to investigation a depth-dependent theoretical model in the future (e.g., Goldman & Umbanhowar 2008;Brzinski et al 2013;Clark & Behringer 2013;Bester & Behringer 2017), interesting future work will be to consider how this theoretical model applies to oblique impacts and for collisions involving rebounds. For example, Wright et al (2020) perform experiments of low velocity oblique impacts of spherical projectiles into a fine sand (under terrestrial gravity). They find that a single force law does not fit both the penetration and rebound phases of the trajectories.…”

Section: Methodsmentioning

confidence: 99%

Low-velocity impacts into granular material: application to small-body landing

Murdoch

Drilleau

Sunday

et al. 2021

Monthly Notices of the Royal Astronomical Society

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With the flourishing number of small body missions that involve surface interactions, understanding the mechanics of spacecraft - surface interactions is crucial for improving our knowledge about the landing phases of space missions, for preparing spacecraft operations, and for interpreting the results of measurements made during the surface interactions. Given their regolith-covered surfaces, the process of landing on a small body can be considered as an impact at low-velocity onto a granular material in reduced-gravity. In order to study the influence of the surface material, projectile shape, and gravity on the collision dynamics we used two experimental configurations (one for terrestrial gravity experiments and one for reduced-gravity experiments) to perform low-velocity collisions into different types of granular materials: quartz sand, and two different sizes of glass beads (1.5 and 5 mm diameter). Both a spherical and a cubic projectile (with varying impact orientation) were used. The experimental data support a drag model for the impact dynamics composed of both a hydrodynamic drag force and quasi-static resistance force. The hydrodynamic and quasi-static contributions are related to the material frictional properties, the projectile geometry, and the gravity. The transition from a quasi-static to a hydrodynamical regime is shown to occur at lower impact velocities in reduced-gravity trials than in terrestrial gravity trials, indicating that regolith has a more fluid-like behaviour in low-gravity. The reduced quasi-static regime of a granular material under low-gravity conditions leads to a reduction in the strength, resulting in a decreased resistance to penetration and larger penetration depths.

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Section: Methodsmentioning

confidence: 99%

Low-velocity impacts into granular material: application to small-body landing

Murdoch

Drilleau

Sunday

et al. 2021

Monthly Notices of the Royal Astronomical Society

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“…Though the sensitivity to penetration depth is fairly weak, it may play an important role for the largest boulders on asteroids, preventing them from effectively sinking below the surface if ejected at speeds below the escape speed. This framework may explain the observation of boulders perching on the surface of Itokawa (Miyamoto et al 2007;Wright et al 2020) and the Hayabusa's spacecraft bouncing interaction with the surface (Yano et al 2006). On Bennu, there appear to be boulders both perched and lying underneath the local surface (Walsh et al 2019;Daly et al 2020;Jawin et al 2020).…”

Section: Low-energy Events On Asteroidsmentioning

confidence: 90%

“…Because the approach speed of a spacecraft undergoing a controlled descent to the surface of a low-gravity asteroid is similar to that asteroid's escape speed, the impact dynamics of crater ejecta should be similar to that of spacecraft and landers. In particular, lowspeed impact dynamics have been used to estimate the burial depth of boulders on the surfaces of asteroids (Nakamura et al 2013, Wright et al 2020. The global values of the four geotechnical properties mentioned in Sec.…”

Section: Low-energy Events On Asteroidsmentioning

confidence: 99%

Modified granular impact force laws for the OSIRIS-REx touchdown on the surface of asteroid (101955) Bennu

Ballouz

Walsh

Sánchez

et al. 2021

Preprint

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The OSIRIS-REx mission collected a sample from the surface of the asteroid (101955) Bennu in 2020 October. Here, we study the impact of the OSIRIS-REx Touch-and-Go Sampling Acquisition Mechanism (TAGSAM) interacting with the surface of an asteroid in the framework of granular physics. Traditional approaches to estimating the penetration depth of a projectile into a granular medium include force laws and scaling relationships formulated from laboratory experiments in terrestrial-gravity conditions. However, it is unclear that these formulations extend to the OSIRIS-REx scenario of a 1300-kg spacecraft interacting with regolith in a microgravity environment. We studied the TAGSAM interaction with Bennu through numerical simulations using two collisional codes, PKDGRAV and GDC-I. We validated their accuracy by reproducing the results of laboratory impact experiments in terrestrial gravity. We then performed TAGSAM penetration simulations varying the following geotechnical properties of the regolith: packing fraction (P), bulk density, inter-particle cohesion (σ c ), and angle of friction (φ). We find that the outcome of a spacecraft-regolith impact has a non-linear dependence on packing fraction. Closely packed regolith (P 0.6) can effectively resist the penetration of TAGSAM if φ 28 • and/or σ c 50 Pa. For loosely packed regolith (P ࣠ 0.5), the penetration depth is governed by a drag force that scales with impact velocity to the 4/3 power, consistent with energy conservation. We discuss the importance of low-speed impact studies for predicting and interpreting spacecraft-surface interactions. We show that these low-energy events also provide a framework for interpreting the burial depths of large boulders in asteroidal regolith.

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“…Section 3.2 studies eighteen simulations; nine at an impact angle of 30°ranging from 2 m/s to 10 m/s and nine at 60°over the same velocity range. To present this work on the same plane as Wright et al (2020), we also report the dimensionless Froude number of each impact, calculated in terms of projectile velocity , radius , and gravitational acceleration by the expression ∕ √ .…”

Section: Simulation Methods and Setupmentioning

confidence: 99%

“…projectile ricocheted off the media or not (Wright et al, 2020(Wright et al, , 2021. This body of work provides valuable information about the surface and overall impactor behavior in low velocity impact conditions, but the dynamics of sub-surface grains and how these correspond to the impact dynamics are rarely studied.…”

Section: Introductionmentioning

confidence: 99%

Sub-surface granular dynamics in the context of oblique, low-velocity impacts into angular granular media

Miklavčič,

Askari,

Sánchez

et al. 2022

Preprint

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Finite element methods support modeling of impacts into discrete triangular grains • Simulations reproduce experimental ricochet, roll-out, and full-stop behaviors of projectile • Visualization of local grain packing reveals breadth of granular disturbance from impact • Strain distributions reveal zones of perturbed media around the crater • Higher velocity impacts spur increasingly lateral granular dissipative mechanisms

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Ricochets on asteroids: Experimental study of low velocity grazing impacts into granular media

Cited by 17 publications

References 41 publications

Low-velocity impacts into granular material: application to small-body landing

Low-velocity impacts into granular material: application to small-body landing

Modified granular impact force laws for the OSIRIS-REx touchdown on the surface of asteroid (101955) Bennu

Sub-surface granular dynamics in the context of oblique, low-velocity impacts into angular granular media

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