1. Astrobiology Research Center, Stanford, California, United States of America
2. National Center for Scientific Research, Biogéo-sciences, University of Bourgogne, France
3. Scripps Center for Astrophysics and Space Sciences; Dept. Aerospace Engineering, University of California, San Diego, United States of America
4. Harvard-Smithsonian Center for Astrophysics (Emeritus), Cambridge, MA, United States of America