Critical issues in space plasma physics

It has been shown that solar, magnetospheric, and ionospheric plasmas exhibit remarkable global coherence and collective behavior. On the small scale, it has been possible in space research to perform experiments in what has been characterized as a “laboratory without walls.” Wave–particle interactions, particle acceleration, and transport phenomena have been studied in revealing detail. There remain many outstanding issues in space plasma research such as the location, timing, and detailed mechanisms of magnetic reconnection; the processes of rapid particle acceleration to relativistic energies; the physics of thin current sheets; and the nature of a host of plasma instabilities in ionospheric, magnetospheric, and solar contexts. In this paper we provide a guide to special jargon and concepts employed in space plasma research. An assessment is made of the present state of observational and theoretical investigations in critical areas and possible future directions in space plasma research are considered.