Laakso, Harri (NASA Goddard Space Flight Center Greenbelt, MD, United States)
Pedersen, Arne (European Space Agency. European Space Research and Technology Center ESTEC, Noordwijk, Netherlands)
Craven, John D. (Alaska Univ. Fairbanks, AK., United States)
Frank, L. A. (Iowa Univ. Iowa City, IA., United States)