1. National Space Institute; Technical University of Denmark; Lyngby Denmark
2. NASA Jet Propulsion Laboratory; Pasadena California USA
3. Department of Geodesy and Geomatics Engineering; University of New Brunswick; Fredericton New Brunswick Canada
4. Astronomy Department; Caltech; Pasadena California USA
5. Department of Electrical and Computer Engineering; University of Illinois at Urbana-Champaign; Champaign Illinois USA