1. Dipartimento di Ingegneria Meccanica e Aerospaziale, Sapienza Università di Roma, via Eudossiana 18, 00184 Rome, Italy.
2. California Institute of Technology, 150-21 Pasadena, CA 91125, USA.
3. Department of Earth and Planetary Sciences, University of California Santa Cruz, 1156 High Street, Santa Cruz, CA 95064, USA.
4. Jet Propulsion Laboratory, California Institute of Technology, 4800 Oak Grove Drive, Pasadena, CA 91109, USA.
5. Department of Astronomy, Cornell University, Ithaca, NY 14850, USA.
6. Dipartimento di Ingegneria Industriale, Università di Bologna, I-47121 Forlì, Italy.