Numerical simulations of impacts involving porous bodies

Jutzi, Martin; Benz, W.; Michel, Patrick

doi:10.1016/j.icarus.2008.06.013

Cited by 129 publications

(93 citation statements)

References 20 publications

(29 reference statements)

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“…This method has been used in the original studies of collisions and reaccumulations by Michel et al (2001) and in later studies. Here, we will not describe the numerical method used to simulate the fragmentation phase as this is not the topic of this paper, and we refer the interested readers to Benz & Asphaug (1994, Wünnemann et al (2006), and Jutzi et al (2008Jutzi et al ( , 2009) for a description of some of the fragmentation models for non-porous or porous materials.…”

Section: Methodsmentioning

confidence: 99%

Collision and gravitational reaccumulation: Possible formation mechanism of the asteroid Itokawa

Michel

Richardson

2013

A&A

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Aims. We investigate the possibility that the observed sea-otter shape of the asteroid Itokawa, associated with the presence of big boulders on its surface, originates from the reaccumulation process that may have formed this asteroid, assuming that it consists of reaccumulated fragments from a catastrophically disrupted parent body. Methods. We computed the gravitational phase of an asteroid disruption, during which fragments can reaccumulate and form aggregates, using a version of the N-body code pkdgrav that includes a model of rigid aggregates. This new model allows the formation of non-idealized rubble piles as a result of reaccumulation that are made up of irregular, competent pieces. Shape and spin information of reaccumulated bodies are thus preserved by allowing fragments to stick on contact (and optionally bounce or cause further fragmentation, depending on user-selectable parameters), instead of merging into growing spheres. Results. We find that the reaccumulation process of an asteroid disruption can produce aggregates whose form is similar to that of Itokawa, and can lead to the deposit of big boulders on the surface, as observed on Itokawa.

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Section: Methodsmentioning

confidence: 99%

Collision and gravitational reaccumulation: Possible formation mechanism of the asteroid Itokawa

Michel

Richardson

2013

A&A

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“…We use a parallel SPH impact code (Benz & Asphaug 1995;Nyffeler 2004;Jutzi et al 2008;Jutzi 2015) which includes self-gravity as well as material strength models. To avoid numerical rotational instabilities, the scheme suggested by Speith (2006) is used.…”

Section: Modeling Approachmentioning

confidence: 99%

“…Crush curve parameters P e and P s (Jutzi et al 2008), density of matrix material ρ s0 , initial bulk density ρ 0 , density of the compacted material ρ compact , initial distention α 0 , bulk modulus A, friction coefficient µ, cohesion Y 0 , average tensile strength Y T . Pressure-porosity relation (high strength) Pressure-porosity relation (medium strength) Pressure-porosity relation (low strength) Dust agglomerates (3D); Guetller et al, 2009 Ice pebbles (quasi 3D); Lorek et al, 2016 Fig.…”

Section: Modeling Approachmentioning

confidence: 99%

“…It is well known that the impacts in highly porous material, given its dissipative properties, can lead to very different results compared to impacts involving solid materials (e.g. Housen & Holsapple 2003;Jutzi et al 2008). Furthermore, complex shapes such as the one of 67P may already be substantially affected by relatively low energy, sub-catastrophic impacts.…”

Section: Introductionmentioning

confidence: 99%

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How primordial is the structure of comet 67P?

Jutzi

Benz

Τόλιου

et al. 2016

A&A

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Context. There is an active debate about whether the properties of comets as observed today are primordial or, alternatively, if they are a result of collisional evolution or other processes. Aims. We investigate the effects of collisions on a comet with a structure like 67P/Churyumov-Gerasimenko (67P). We develop scaling laws for the critical specific impact energies Q reshape required for a significant shape alteration. These are then used in simulations of the combined dynamical and collisional evolution of comets in order to study the survival probability of a primordially formed object with a shape like 67P. Although the focus of this work is on a structure of this kind, the analysis is also performed for more generic bi-lobe shapes, for which we define the critical specific energy Q bil . The simulation outcomes are also analyzed in terms of impact heating and the evolution of the porosity. Methods. The effects of impacts on comet 67P are studied using a state-of-the-art smooth particle hydrodynamics shock physics code. In the 3D simulations, a publicly available shape model of 67P is applied and a range of impact conditions and material properties are investigated. The resulting critical specific impact energy Q reshape (as well as Q bil for generic bi-lobe shapes) defines a minimal projectile size which is used to compute the number of shape-changing collisions in a set of dynamical simulations. These simulations follow the dispersion of the trans-Neptunian disk during the giant planet instability, the formation of a scattered disk, and produce 87 objects that penetrate into the inner solar system with orbits consistent with the observed JFC population. The collisional evolution before the giant planet instability is not considered here. Hence, our study is conservative in its estimation of the number of collisions. Results. We find that in any scenario considered here, comet 67P would have experienced a significant number of shape-changing collisions, if it formed primordially. This is also the case for generic bi-lobe shapes. Our study also shows that impact heating is very localized and that collisionally processed bodies can still have a high porosity. Conclusions. Our study indicates that the observed bi-lobe structure of comet 67P may not be primordial, but might have originated in a rather recent event, possibly within the last 1 Gy. This may be the case for any kilometer-sized two-component cometary nuclei.

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“…We included a model of fragmentation of porous materials (Jutzi et al 2008) in our 3D numerical hydrodynamical code based on the Smooth Particle Hydrodynamics (SPH) technique (Benz 1990;Monaghan 1992), which already contained a model of fragmentation of non-porous materials (Benz & Asphaug 1994). This new model was then tested in the laboratory by comparing with impact experiments on pumice targets (Jutzi et al 2009).…”

Section: Introductionmentioning

confidence: 99%

A large crater as a probe of the internal structure of the E-type asteroid Steins

Jutzi

Michel²,

Benz

2010

A&A

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Context. The detection of a large crater (2 km in diameter) on Steins, a diamond-shape asteroid with a diameter of only about 4.6 km, was a large surprise given the size of the asteroid itself. Steins belongs to the rare class of E-type asteroids, which had not been observed by any spacecraft before the Rosetta mission of the European Space Agency (ESA) in 2008. Aims. We demonstrate that this large crater places constraints on both the internal structure of Steins and its age based on crater counting. Methods. Numerical simulations of impacts were performed to reproduce the large crater, assuming four different initial internal structures of the asteroid: monolithic with or without microporosity, and rubble pile with or without microporosity. Results. To reproduce this crater, Steins must be either a rubble pile, which also contains microporosity, or a monolithic body with or without microporosity. The lack of porosity in meteorite analogues favors a structure without microporosity, which, according to our results, must have been monolothic. Moreover, the asteroid would be transformed into a rubble pile structure as a result of the crater formation, allowing it to be reshaped in its current shape by the YORP spin-up thermal effect. Conclusions. A combination of modeling and observations of surface features can thus serve as a probe of the internal structure of a small body and constrains its age estimate. Since the surface was totally refreshed when the large crater was formed, crater counting on Steins indicates the time that has passed since this impact event occurred.

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Numerical simulations of impacts involving porous bodies

Cited by 129 publications

References 20 publications

Collision and gravitational reaccumulation: Possible formation mechanism of the asteroid Itokawa

Collision and gravitational reaccumulation: Possible formation mechanism of the asteroid Itokawa

How primordial is the structure of comet 67P?

A large crater as a probe of the internal structure of the E-type asteroid Steins

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