Impact craters on asteroids: Does gravity or strength control their size?

Michael C. Nolan, Erik Asphaug, H. Jay Melosh, Richard Greenberg

Research output: Contribution to journalArticlepeer-review

54 Scopus citations


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.

Original languageEnglish (US)
Pages (from-to)359-371
Number of pages13
Issue number2
StatePublished - Dec 1996
Externally publishedYes

ASJC Scopus subject areas

  • Astronomy and Astrophysics
  • Space and Planetary Science


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