1. Intercosmos Council, 117901 Moscow, U.S.S.R.
2. Space Research Institute, 117810 Moscow, U.S.S.R.
3. Institute of Radio Techniques and Electronics, Academy of Sciences, 103907 Moscow, U.S.S.R.
4. Centre National d'Etudes Spatiales, 75039 Paris Cedex 01, France.
5. Service d'Aeronomie du Centre National de la Recherche Scientifique, 91370 Verrieres le Buisson, France.
6. NASA Ames Research Center, Moffett Field, CA 94035.
7. Jet Propulsion Laboratory, California Institute of Technology, Pasadena 91109.
8. Division of Geological and Planetary Sciences, California Institute of Technology, Pasadena 91125.