Comet 46P/Wirtanen: The dust distribution out of 20 nucleus radii

Detailed information of the dust environment around comet nuclei is fundamental to properly plan future space missions to short period comets. All these missions will be strongly influenced by the encountered dust environment which will determine the mission safety, the pollution of the orbiter and lander experiments, the good sampling of collecting; dust experiments. Although first order isotropic models can offer estimates of the averaged dust fluxes and fluences on the spacecraft, only realistic 3D models can provide reliable estimates of the variations of these dust quantities due to the strong anisotropies of the inner comae. Within the Dust Environmental Working Group established by ESA to support the Rosetta mission to comet 46P/Wirtanen: detailed 3D models of the expected dust flux are being performed starting from the outputs of 3D hydrodynamical codes able to link the surface properties of the comet nucleus to the dusty gas environment close to the nucleus surface. These 3D dust flux outputs are used as input for 3D numerical codes which compute the dust trajectories influenced by the solar radiation pressure acting on each sample dust grain. We review the results obtained so far for selected nucleus shapes and for several possible probe orbits covering a wide range of nucleocentric distances. (C) 1999 COSPAR. Published by Elsevier Science Ltd.