Scale Effects in Strength-Dominated Collisions of Rocky Asteroids

Housen, K. R.; Holsapple, K. A.

doi:10.1006/icar.1999.6206

Cited by 165 publications

(136 citation statements)

References 27 publications

(32 reference statements)

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“…We consider here a value for C similar to the one measured by Housen & Holsapple (1999) for Georgia Keystone granite specimens, that is C = 2.25 × 10 8 dynes/cm 2 . The size-dependent strength accounts for the fact that larger bodies are weaker than smaller ones, because in nature they have a greater likelihood of having large cracks inside (e.g., Housen & Holsapple 1999). Thus, the strength of our aggregates does not only account for the self-gravity resulting from the different particle masses composing them, but also for some cohesion.…”

Section: Application: Itokawa-like Fragmentsmentioning

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: Application: Itokawa-like Fragmentsmentioning

confidence: 99%

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

Michel

Richardson

2013

A&A

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“…scale of the impact event, larger targets are effectively weaker than smaller ones (e.g., Housen and Holsapple 1999). Indeed, Housen and Holsapple (1999) have shown that for collision tests where the kinetic energy per unit target mass and impact velocity were kept constant, the target damage became increasingly severe as the size scale increased-a result of effective weakening of the target at larger size scales.…”

Section: Influence Of An Overlying Water Layermentioning

confidence: 99%

“…Indeed, Housen and Holsapple (1999) have shown that for collision tests where the kinetic energy per unit target mass and impact velocity were kept constant, the target damage became increasingly severe as the size scale increased-a result of effective weakening of the target at larger size scales. We can therefore postulate that our lab specimens are actually stronger than their large-scale counterparts.…”

Section: Influence Of An Overlying Water Layermentioning

confidence: 99%

Laboratory impacts into dry and wet sandstone with and without an overlying water layer: Implications for scaling laws and projectile survivability

Baldwin

Milner

Burchell

et al. 2007

Meteorit & Planetary Scien

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Abstract-Scaling laws describing crater dimensions are defined in terms of projectile velocity and mass, densities of the materials involved, strength of the target, and the local gravity. Here, the additional importance of target porosity and saturation, and an overlying water layer, are considered through 15 laboratory impacts of 1 mm diameter stainless steel projectiles at 5 km s −1 into a) an initially uncharacterized sandstone (porosity ~17%) and b) Coconino Sandstone (porosity ~23%). The higher-porosity dry sandstone allows a crater to form with a larger diameter but smaller depth than in the lower-porosity dry sandstone. Furthermore, for both porosities, a greater volume of material is excavated from a wet target than a dry target (by 27-30%). Comparison of our results with Pi-scaling (dimensionless ratios of key parameters characterizing cratering data over a range of scales) suggests that porosity is important for scaling laws given that the new data lie significantly beneath the current fit for ice and rock targets on a π v versus π 3 plot (π v gives cratering efficiency and π 3 the influence of target strength). An overlying water layer results in a reduction of crater dimensions, with larger craters produced in the saturated targets compared to unsaturated targets. A water depth of approximately 12 times the projectile diameter is required before craters are no longer observed in the targets. Previous experimental studies have shown that this ratio varies between 10 and 20 (Gault and Sonett 1982). In our experiments ~25% of the original projectile mass survives the impact.

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“…The actual relation between k and D is related to the distribution of cracks throughout the body. Housen & Holsapple (1999) showed, that for a wide range of samples, k = κr −1/2 , where r = D/2. To estimate the value of κ, one would have to apply static pressure to a sample of asteroid material.…”

Section: Summary Of the Resultsmentioning

confidence: 99%

“…The Carancas meteorite, considered to be a monolithic body with few cracks, is an exception here as it survived atmospheric entry without fragmentation. For comparison we also quote the results obtained by Housen & Holsapple (1999) for granite specimens.…”

Section: Summary Of the Resultsmentioning

confidence: 99%

Photometric survey of the very small near-Earth asteroids with the SALT telescope

Kwiatkowski¹,

Polińska²,

Loaring

et al. 2010

A&A

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Aims. Very small asteroids (VSAs) are thought to be the building blocks of larger asteroids and, as such, are interesting to study. Many of these monolithic or deeply fractured objects display rapid rotations with periods as short as several minutes. Observations of such asteroids can reveal their spin limits, which can be related to the tensile strength of their interiors. The evolution of the spins of these objects is primarily shaped by the YORP effect, the theory of which needs comparison with observations. Methods. With the 10 m SALT telescope, we observed VSAs belonging to near-Earth asteroids. The obtained lightcurves were used to derive synodical periods of rotation, amplitudes, and elongations of these bodies. Results. Results for 14 rapidly rotating asteroids were reported in the first paper in this series. Here we show lightcurves of 2 fast rotators, 9 objects with periods ≥1 h, and a possible non-principal axis rotator. We also list negative detections that most probably indicate asteroids with long periods and/or low amplitudes. Combining our results with the data from the literature, we obtain a set of 79 near-Earth VSAs with a median period of 0.25 h (15 min). By adjusting the spin limits predicted by theory to those observations, we find tentative evidence that the tensile strengths of VSAs, after scaling them to the same size, are of the same order as the minimum tensile strengths of stony meteoroids that undergo fragmentation under the atmospheric load.

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Scale Effects in Strength-Dominated Collisions of Rocky Asteroids

Cited by 165 publications

References 27 publications

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

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

Laboratory impacts into dry and wet sandstone with and without an overlying water layer: Implications for scaling laws and projectile survivability

Photometric survey of the very small near-Earth asteroids with the SALT telescope

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