1. Space Science and Engineering Division Southwest Research Institute San Antonio TX USA
2. Department of Physics and Astronomy University of Texas at San Antonio San Antonio TX USA
3. School of Physics & Astronomy University of Leicester Leicester UK
4. Department of Physics University of Oxford Oxford UK
5. Laboratoire de Physique Atmosphérique et Planétaire STAR Institute Université de Liège Liège Belgium
6. Jet Propulsion Laboratory Pasadena CA USA