1. Southwest Research Institute; San Antonio Texas USA
2. Astronomy Department; University of Virginia; Charlottesville Virginia USA
3. Lunar and Planetary Laboratory; University of Arizona; Tucson Arizona USA
4. Department of Physics and Astronomy; University of Kansas; Lawrence Kansas USA
5. Space Sciences Laboratory; University of California; Berkeley California USA
6. NASA Goddard Space Flight Center; Greenbelt Maryland USA
7. Service d'Aéronomie du CNRS/IPSL; Paris France
8. Civil Engineering; Indian Institute of Technology; Kanpur India
9. Center for Space Research; Massachusetts Institute of Technology; Cambridge Massachusetts USA