THE GLOBAL GEOSPACE SCIENCE PROGRAM AND ITS INVESTIGATIONS

The detailed study of the solar-terrestrial energy chain will be great ly enhanced with the launch and simultaneous operation of several spac ecraft during the current decade. These programs are being coordinates in the United States under the umbrella of the International Solar Te rrestrial Physics Program (ISTP) and include fundamental contributions from Japan (GEOTAIL Program) and Europe (SOHO and CLUSTER Programs). The principal United States contribution to this effort is the Global Geospace Science Program (GGS) described in this overview paper. Two s pacecraft, WIND and POLAR, carrying an advanced complement of field, p article and imaging instruments, will conduct investigations of severa l key regions of 'geospace'. This paper provides a general overview of the science objectives of the missions, the spacecraft orbits and the ground elements that have been developed to process and analyze the i nstrument observations.