Constraints on the dust size distribution of 46P/wirtanen from in-situ and ground-based observations

Abstract The ESA Rosetta mission is planned to orbit around the nucleus of comet 46P/Wirtanen for years during the comet approach to its perihelion. All the probe operations will heavily depend on the dust environment of the comet, which will determine the possibility of close approaches to the nucleus, the pollution to the experiments, the good sampling of collecting dust experiments, the orbit perturbations due to the dust flux on the solar panels, and so on. A sufficiently realistic model of the dust environment requires detailed information on the nucleus surface and topography, which determines the 3D gas flux dragging the dust towards the spacecraft. Therefore, complex models of the nucleus surface and of the gas expansion are required to properly predict the environment characteristics inside which the probe will operate. These models depend on many parameters, whose most probable ranges can be determined by past in-situ measurements and available and/or future ground-based observations. We review present information about crucial parameters describing cometary dust environments, and in particular the available constraints on poorly known dust parameters, such as the dust size distribution, bulk density and loss rates provided by in-situ and ground-based observations. In particular, the most probable power index of the dust size distribution ranges between −4 and −3.