Freja is a joint Swedish and German satellite, launched on October 6, 1992 and orbiting at 600--1750 km, covering the lower part of the auroral acceleration region. It has been designed to provide high-resolution measurements (both temporal and spatial) of auroral plasma characteristics. The high telemetry rate, together with the 15 Mbyte distributed on-board memories allow Freja to resolve meso and micro-scale phenomena in the 100 m range for particles and 1--10 m range for electric and magnetic fields. The UV imager resolves auroral structures of 1 km size at a time resolution of...

Freja is a joint Swedish and German satellite, launched on October 6, 1992 and orbiting at 600--1750 km, covering the lower part of the auroral acceleration region. It has been designed to provide high-resolution measurements (both temporal and spatial) of auroral plasma characteristics. The high telemetry rate, together with the 15 Mbyte distributed on-board memories allow Freja to resolve meso and micro-scale phenomena in the 100 m range for particles and 1--10 m range for electric and magnetic fields. The UV imager resolves auroral structures of 1 km size at a time resolution of...