Ten Years of Geotail and its Current Status: A Brief Summary

Abstract

Abstract Since its launch in 1992, GEOTAIL has extensively surveyed the magnetotail with a full set of plasma and field instruments over a wide range of distances from 9 Re to 220 Re away from the Earth by means of a sophisticated orbit strategy. In the first two years, the orbit was optimized to explore the distant tail, and thereafter was changed to study substorm processes in the near-Earth tail region. The near-tail orbit has also facilitated exploration of the dayside outer magnetosphere, the magnetopause, the magnetosheath, and the bow shock, as well as the upstream solar wind. GEOTAIL observations have revealed a number of new phenomena in these regions, and as of the end of 2003, about 600 papers have been published in refereed journals. Recent GEOTAIL studies have significantly advanced our understanding of the structure and formation of thin current sheets in the mid-tail plasma sheet during substorms, and have elucidated new kinetic aspects of magnetic reconnection. GEOTAIL has operated far beyond the designed mission life of three and half years. Most of the onboard instruments are still functioning well, and it is expected that GEOTAIL will continue to generate scientifically useful data.