Arne Pedersen: "New Science from the four Cluster Satellites"

 Four Cluster satellites were lost on the test flight of Ariane5 when it exploded after launch in 1996. Four new Cluster satellites were successfully launched in 2000. The Space and Plasma Physics Group at the Department of Physics, UiO, is involved in electric field experimenst on these satellites, and cooperate with several international groups that are active in studies of the Earths magnetosphere. New results, based on data from the four Cluster satellites, orbiting in a variable tetrahedron configuration, will be presented. Electric field measurements in the magnetosphere are still under development, however, they still provide insight into microphysics problems with a time resolution which by far exceeds particle measurements. This is important for coming closer to understand reconnection processes at the magnetopause and in the tail of the magnetosphere.