1. Max Planck Institute for Solar System Research Göttingen Germany
2. Rheinisches Institut fuer Umweltforschung, Abteilung Planetforschung Cologne Germany
3. Space Sciences Laboratory University of California Berkeley CA USA
4. Department of Physics and Astronomy University of Iowa Iowa City IA USA
5. NASA Goddard Space Flight Center Greenbelt MD USA
6. Laboratory for Atmospheric and Space Physics University of Colorado Boulder Boulder CO USA
7. Institute of Space Research Moscow Russia