Physical Properties of Cometary Dust. The Case of Churyumov-Gerasimenko

Abstract

Observations of the linear polarization of light scattered by cometary dust (spatial variations, phase and wavelength dependences) provide unique clues to the physical properties of the dust particles. The polarization of 67P/Churyumov-Gerasimenko has, up to now, only been observed at its 1982/1983 return. Data suggest that the coma is rather dust poor, in agreement with the absence of any silicate feature in the infrared spectra. However, outbursts may modify for a while the properties of the dust coma. Laboratory experiments on aggregates of grains representative of cometary particles should take place on board the ISS before the Rosetta rendezvous. Their results, together with complementary remote observations, should provide a better understanding of the morphology, size distribution and porosity properties of the dust particles to be encountered by the spacecraft within the coma.KeywordsComets67P/Churyumov-Gerasimenkodustlight scatteringpolarizationlaboratory measurements