2002-2003 Colloquium Series

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NAU Liberal Arts (Bldg 18, Rm 135), Friday, 1 November 2002, 4:00 PM
(Refreshments at 3:45pm)

Hydrocode Simulations of the Fragmentation and Ejection of Lunar and Martian Meteorites

James N. Head , Raytheon.

Abstract

The physics of hypervelocity impacts has been explored theoretically and experimentally for several decades. An important tool in such studies is the hydrodynamic computer code (hydrocode). A hydrocode uses the hydrodynamic equations, and equation of state, and the constitutive relationships to simulate material response under the imposed pressure and energy density conditions. Highly evolved descendants of the early hydrocodes now incorporate fragmentation models. This permits analysis of fragmentation and ejection in impact events too large to study in the laboratory. The sizes, shock states, and ejection velocity of fragments generated in the near-surface spall zone during small (~50-500 MT) hypervelocity (10-20 km/s) impact events have been computed. the results have been evaluated in the light of the available data from geochemical analyses, celestial mechanics, and geomorphology to establish a quantitatively consistent explanation for the origin of the Martian clan meteorites. An extension of the work has produced a preliminary explanation of the origin of the lunar meteorites.

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