Relativisitc electron dynamics in the Earth's Radiation Belts: 
            SAMPEX and POLAR measurements 

           The Earth's radiation belts were discovered nearly fifty years ago
           by Van Allen. It is now well known that the electron belt comprises 
           of a dynamic outer zone separated by the slot region from a less
           variable inner zone. Earlier questions regarding the source of
           energetic electrons have largely been answered and it is currently 
           believed that these particles are internally energised. However the
           detailed understanding of energization mechanisms remains an open
           question. In the recent years the practical aspects of relativistic 
           or "killer" electrons have become  important due to increased human
           presence and spacecraft in the near-earth geospace.

           We present results from SAMPEX and POLAR observations of electron
           dynamics. Measurements of relativistic electron fluxes by SAMPEX 
           POLAR and geo spacecraft will be used to characterize electron 
           energization, long term variability of electron fluxes, and the 
           Jovian electron source.