International coordination of solar terrestrial science

A broad, international, cooperative effort is under way to study and develop quantitative understanding of the fundamental electrodynamic processes in the solar-terrestrial environment. Japan, Europe, Russia, the United States, and other countries are providing spacecraft to be placed in key regions with the aim of utilizing coordinated, multipoint spaceflight measurements, ground-based observations, and theory to study the global energy budget of geospace. The U.S. contribution began in the late 1970's as the OPEN program (Origin of Plasmas in Earth's Neighborhood) and was reconstituted in the 1980's as the Global Geospace Science (GGS) program. The international effort, known in the U. S. as the International Solar Terrestrial Physics program (ISTP), began with the launch of the Japanese GEOTAIL in 1992, and will continue with the U. S. spacecraft WIND and POLAR in 1994–1995, and the European four-spacecraft Cluster fleet and its Solar and Heliospheric Observatory (SOHO) in 1995. Russia will launch its Interball set of four spacecraft in 1995. The Inter-Agency Consultative Group (IACG) is promoting the coordination of the spacecraft observations by means of scientific campaigns aimed at addressing scientific questions that can only be answered by observations from the multiple spacecraft. The Solar Terrestrial Energy Program (STEP) is coordinating the involvement of the broad scientific community and especially the correlative ground observations.