1. Laboratoire de Physique et Chimie de l'Environnement et de l'Espace, CNRS; Orléans France
2. Jet Propulsion Laboratory; California Institute of Technology; Pasadena California USA
3. Space and Atmospheric Science Department; Arecibo Observatory/SRI International; Arecibo Puerto Rico
4. Instituto Nacional de Pesquisas Espaciais; São José dos Campos Brazil