1. Physics and Astronomy Department; Rice University; Houston Texas USA
2. Los Alamos National Laboratory; Los Alamos New Mexico USA
3. Mullard Space Science Laboratory; University College London; Surrey UK
4. Johns Hopkins University; Applied Physics Laboratory; Laurel Maryland USA
5. Blackett Laboratory; Imperial College; London UK
6. Institute of Geophysics; University of California; Los Angeles California USA
7. Space Science and Engineering; Southwest Research Institute; San Antonio Texas USA