THE RADIATION BELTS

The Earth's radiation belts, formed by energetic electrons and ions (p rincipally protons) trapped in the Earth's quasi-dipolar field, are re viewed. The magnitudes of particle energies and fluxes encountered mak e this a very severe environment in which to conduct space missions. T he effects of radiation belt particles are briefly described. Particle motions and particle trapping are introduced, along with geomagnetic coordinates, which are used to map the radiation belts. The morphologi es of the proton and electron belts are described, including the south Atlantic anomaly and east-west asymmetries at low altitudes, and the highly dynamic electron environment at high altitudes. Empirical model s of the radiation belts are described and problems with their functio nality are outlined. Finally, future developments in radiation-belt st udies, including those resulting from analysis of CRRES satellite data are discussed.