[1] Australian Natl Univ, Res Sch Informat Sci & Engn, Canberra, ACT 0200, Australia
[2] Univ Texas, Ctr Space Res, Austin, TX 78712 USA
[3] MIT Lincoln Lab, Sensor Technol & Syst Applicat Grp, Lexington, MA 02420 USA
[4] Univ Genoa, Dept Biophys & Elect Engn, I-16145 Genoa, Italy
[5] NASA, Goddard Space Flight Ctr, Appl Informat Sci Branch, Greenbelt, MD 20771 USA