1. Division of Geological and Planetary Sciences; California Institute of Technology; Pasadena CA USA
2. NASA Goddard Space Flight Center; Greenbelt MD USA
3. Department of Physical Sciences; Open University; Milton Keynes UK
4. NASA Johnson Space Center; Houston TX USA
5. School of Earth Sciences; University of Queensland; Brisbane Queensland Australia
6. Instituto de Ciencias Nucleares; Universidad Nacional Autónoma de México, Ciudad Universitaria; México City Mexico