1. Research and Scientific Support Department of ESA; ESTEC; Noordwijk The Netherlands
2. Laboratoire de Chimie Physique; Centre Universitaire Paris Sud; Orsay France
3. Laboratoire de Planétologie de Grenoble; France
4. V. Cermak Laboratory; Prague Czech Republic
5. Laboratoire LURE; Centre Universitaire Paris Sud; Orsay France
6. Centre d'Etudes Spatiales des Rayonnements; Toulouse France
7. Lunar and Planetary Laboratory; Tucson USA
8. Institute of Physics and Astronomy; Aarhus University; Aarhus Denmark