The Ampte charge Composition Explorer and the 4-7 September 1984 geomagnetic storm

The Charge Composition Explorer (CCE) was launched as part of the tri-lateral Active Magnetospheric Particle Tracer Explorers (AMPTE) mission, to which the United States, the Federal Republic of Germany, and the United Kingdom each contributed a satellite (Krimigis et al., 1982). The three satellites were launched as a stack by a Delta launch vehicle on 16 August 1984. To carry out the main AMPTE objective of gas releases in the solar wind and distant magnetosphere, the West German Ion Release Module (IRM) and the United Kingdom Subsatellite (UKS) were placed in the same highly elliptical orbit with an apogee of 18.7 R_E. To observe the entry into and transport through the magnetosphere, the CCE was placed in a near-equatorial orbit having a perigee of 1108 km, an apogee of 8.8 R_E, a 4.8° inclination and a 15.7 hour period. This orbit and the CCE payload provide an excellent opportunity for observing the geomagnetically trapped particle population in general and the earth’s ring current in particular. The following papers report on the geomagnetic storm of 4-7 September 1984 and present the initial findings of the CCE investigators on the earth’s ring current. In this paper we discuss the ring current problem, describe the CCE satellite and payload, and present a global view of the 4 September 1984 geomagnetic storm.