Space geodesy has evolved in the last twenty years into one of the most exciting disciplines in the earth sciences. This development is due to a large extent to the versatility of applications provided by the radio interferometric technique called Global Positioning System or GPS. Appropriately, Symposium 102: Global Positioning System: An Overview was held at the 125th Anniversary Meeting of the International Association of Geodesy in August, 1989. A broad review of GPS geodesy, achievements to date and the prospects for future study and application was presented. Papers included in...