Review of recent results on the plasmasphere by the CLUSTER and IMAGE missions

Plasmaspheric exploration got a major boost since 2000, when the CLUSTER and IMAGE spacecraft were launched. ESA's four CLUSTER satellites continue to orbit Earth in a coordinated constellation until today, visiting the plasmasphere on each perigee pass and returning correlated multi-spacecraft measurements. NASA's IMAGE spacecraft ceased operations after almost 6 years of discovery by pioneering global imaging and radio sounding techniques. These missions offered a new and different view of the plasmasphere. We review recent results on the plasmasphere provided with the help of those two missions. A book entitled "The Earth's Plasmasphere: A Cluster and Image Perspective" is being published by Springer. The first chapter reviews old and new techniques for exploring the plasmasphere. The second one concerns plasmaspheric structures at different scales. The magnetic and electric fields are described in the third part and plasmaspheric waves in the fourth one. The final two chapters present physics-based and empirical models of the plasmasphere.