THE GIOTTO EXTENDED MISSION TO COMET GRIGG-SKJELLERUP - SUMMARY OF PRELIMINARY-RESULTS

Comets, besides providing us with clues as to the origin of the Solar System, the Earth and probably also star formation in general when we study their structure and chemical composition, serve as 'space laboratories' for the study of magneto-hydrodynamic processes. The latter occur in the hot gases or plasmas containing charged particles or ions along with magnetic fields, such that the clouds of gas are partially or primarily controlled by the magnetic fields. The investigations of the Giotto Extended Mission, or 'GEM' (see ESA Bulletin No. 70, pp. 55-59 for a detailed description of the second encounter mission), have provided excellent new data concerning the interaction of the solar wind with a non-magnetised body in space.