1. School of Physics and AstronomyQueen Mary University of London London UK
2. Space and Atmospheric Physics Group, Blackett LaboratoryImperial College London London UK
3. Electrical and Computer Engineering DepartmentVirginia Polytechnic Institute and State University Blacksburg Virginia USA
4. Department of Mechanical Engineering and Center for Space PhysicsBoston University Boston Massachusetts USA
5. Department of Earth, Planetary and Space SciencesUniversity of California Los Angeles California USA