1. European Space Research and Technology Centre, Science and Robotic Exploration Directorate, European Space Agency, Noordwijk, Netherlands.
2. Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA, USA.
3. European Space Astronomy Centre, Science and Robotic Exploration Directorate, European Space Agency, Madrid, Spain.
4. INAF–Osservatorio Astronomico, Trieste, Italy.
5. Laboratoire d'Etudes Spatiales et d'Instrumentation en Astrophysique, Observatoire de Paris, France.
6. Max-Planck-Institut für Kernphysik, Heidelberg, Germany.