1. German Aerospace CenterInstitute of Planetary Research Berlin Germany
2. Chair of Geodesy and Geoinformation ScienceTechnische Universität Berlin Berlin Germany
3. Moscow State University for Geodesy and Cartography Moscow Russia
4. Department of PhysicsUniversity of California Santa Barbara California USA
5. Deceased 14 May 2015
6. Department of Earth, Planetary, and Space SciencesUniversity of California Los Angeles California USA
7. Department of Physics and AstronomyUniversity of California Los Angeles California USA
8. Southwest Research Institute Boulder Colorado USA
9. NASA Goddard Space Flight Center Greenbelt Maryland USA
10. Department of Earth, Atmospheric and Planetary SciencesMassachusetts Institute of Technology Cambridge Massachusetts USA
11. Lamont‐Doherty Earth ObservatoryColumbia University Palisades New York USA
12. Department of Terrestrial MagnetismCarnegie Institution of Washington Washington District of Columbia USA