1. Space and Atmospheric Physics Group, Blackett Laboratory; Imperial College London; London UK
2. Mullard Space Science Laboratory, Department of Space and Climate Physics; University College London; Dorking UK
3. Center for Planetary Sciences; University College London; London UK
4. Atmospheric Physics Laboratory, Department of Physics and Astronomy; University College London; London UK
5. Institute of Geophysics and Planetary Physics; University of California; Los Angeles California USA
6. Office of Space Research and Technology; Academy of Athens; Athens Greece
7. Space Science and Applications; Los Alamos National Laboratory; Los Alamos New Mexico USA
8. Johns Hopkins University Applied Physics Laboratory; Laurel Maryland USA
9. Max-Planck-Institut für Sonnensystemforschung; Katlenburg-Lindau Germany