Elsevier

Icarus

Volume 124, Issue 2, December 1996, Pages 359-371
Icarus

Regular Article
Impact Craters on Asteroids: Does Gravity or Strength Control Their Size?

https://doi.org/10.1006/icar.1996.0214Get rights and content

Abstract

The formation of kilometer-size craters on asteroids is qualitatively different from the formation of meter-size (laboratory- and weapons-scale) craters on Earth. A numerical hydrocode model is used to examine the outcomes of various-size cratering impacts into spheres and half-spaces. A shock wave fractures the target in advance of the crater excavation flow; thus, for impactors larger than 100 m, impacting at typical asteroid impact velocities, target tensile strength is irrelevant to the impact outcome. This result holds whether the target is initially intact or a “rubble pile,” even ignoring the effects of gravity. Because of the shock-induced fracture, crater excavation is controlled by gravity at smaller sizes than would otherwise be predicted. Determining the strength–gravity transition by comparing the physical strength of the material to the force of gravity will not work, because strength is eliminated by the shock wave.

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E-mail: [email protected]

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Current address: Arecibo Observatory, PO Box 995, Arecibo PR 00613 USA.

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