INTERBALL is the solar-terrestrial programme aimed to study various plasma processes in the Earth magnetosphere by the system of spacecraft consisting of two pairs (satellite-subsatellite) above the polar aurora and in the magnetospheric tail respectively. The INTERBALL was a part of of the Programme coordinated by the Inter-Agency Consultative Group (IACG) for Space Science consisting of representatives of the European Space Agency (ESA), the National Aeronautics and Space Administration (NASA), Russian Space Agency (RKA) and Japan Institute of Space and Aeronautics Sciences (ISAS). According to this Programme a system of ten core spacecraft of the above agencies was to be spatially distributed between the L1 and L2 Sun-Earth libration points to study solar-terrestrial relationship.