HEOS-2 (Highly Eccentric Orbit Satellite-2) was the second satellite in the HEOS series launched by the European Space Research Organisation (ESRO), which later became part of the European Space Agency (ESA). The mission was designed to continue and expand upon the scientific objectives of HEOS-1, focusing on the Earth's magnetosphere, interplanetary space, and the solar wind. HEOS-2 transmitted valuable scientific data until August 1974, when the mission concluded. The satellite is now inactive and remains in a highly eccentric orbit around the Earth.