Magnetospheric structure.

Magnetospheric research over the period from 1969 to 1971 is surveyed by describing significant results obtained from studies of the bow shock, magnetosheath, magnetopause, polar cusp, convection-driving electric fields, and the composition of trapped particles with charge greater than one. Particle and field observations are related to general questions of particle origin and destination as well as the mechanism by which the entire system remains in equilibrium.