ATMOSPHERIC ENTRY OF LARGE METEOROIDS - IMPLICATION TO TITAN

The preparation for the Cassini-Huygens mission gives an opportunity t o revise the problem of an atmospheric entry and breakup of cratering meteoroids. The numerical modeling of the meteoroid's flight through t he atmosphere is presented in comparison with more simple models. The simulation takes into account the brittle/ductile properties of the me teoroid material: the Grady-Kipp-Melosh model of tensile failure is ac companied with a simple model of the shear failure. The main differenc e with previously published models consists in the treating of the pos t-failure deformation of the damaged material as a flow of a cohesionl ess media with a dry friction. Numerical results are used to make a pa rameterization of a simple Grigorian-like model, which finally is appl ied to predict the atmospheric shielding effect on Titan. For a modern atmosphere of Titan and mostly ice projectiles the observable deficie ncy of impact craters due to atmospheric shielding would be in the ran ge of 6-8 km, where the number of craters would be two times smaller t han for the airless Titan. (C) 1997 Elsevier Science Ltd.