A two-satellite mission by NASA in collaboration with the Los Alamos National Laboratory and others to study neutral atoms and charged particles, the geomagnetic field, geomagnetic storms and substorms, auroras, the 11-year solar cycle, and the effects of space weather on human life on Earth and in space. The satellites were launched on 28 June 2006, from California, into highly elliptical orbits of perigee about 1100 km and apogee about 46 000 km (= 7.2 Earth radii), most of the period spent near apogee.