THE PLASMA ENVIRONMENT OF COMETS

This review concentrates on US research activities in the area of cometary plasma physics during the four year period from 1987 to 1990. This quadrennium immediately followed the historic "traffic jam" on the dusty roads of Giacobini-Zinner and Halley; during this period there has been a substantial increase of activity in the area of cometary science. During these years the "comet rush" resulted in a better understanding of the major physical and chemical processes controlling cometary environments. The quantitative and qualitative leap of available information paved the road to a new generation of comprehensive models synthesizing our knowledge about the ionosphere, magnetosphere, and solar wind interaction. In spite of these major advances cometary plasma physics is still a rapidly changing - and sometimes controversial - subject, and one can expect significant progress during the next quadrennium.