1. The Johns Hopkins University Applied Physics Laboratory; Laurel Maryland USA
2. School of Earth and Space Exploration; Arizona State University; Tempe Arizona USA
3. Department of Geological Sciences; Brown University; Providence Rhode Island USA
4. Center for Earth and Planetary Studies, National Air and Space Museum; Smithsonian Institution; Washington D.C. USA
5. Department of Terrestrial Magnetism; Carnegie Institution of Washington; Washington D.C. USA
6. Lamont-Doherty Earth Observatory; Columbia University; Palisades New York USA
7. Southwest Research Institute; Boulder Colorado USA