The dust environment of comet 67P/Churyumov-Gerasimenko

The new target of the ESA Rosetta Mission is comet 67P/Churyumov-Gerasimenko, which passed its last perihelion on 18 August 2002 and was well observed from fall 2002 to spring 2003. Its most prominent feature was a thin dust tail, which is best fitted by the Neck-Line model. Fits of the whole tail provide the dust environment of 67P during a year around perihelion; it shows a strong asymmetry between pre and post perihelion times. The dust mass loss rate appears constant since 2 AU before perihelion at about 200 kg s-1, a factor 100 higher than 46P/Wirtanen, the previous Rosetta target. Neck-Line photometry during 2002 and 2003 suggests that such a dust environment has remained similar since 3.6 AU before perihelion, i.e. the distance at which Rosetta science operations will start and the lander will be delivered to the surface. Based also on observations collected at the National Galileo Telescope and the 2 m telescope of the Thüringer Landessternwarte Tautenburg.