Current and future trends in ionospheric research

In the early days of upper atmosphere research, radio signals were the most useful diagnositic for studying ionospheric processes. During the space era, it has become possible to measure directly solar radiations that are screened from reaching the surface of the Earth, to measure the structure and composition of the upper atmosphere directly with in situ sensors, to conduct plasma experiments in space, to carry out remote sensing of the atmosphere from space, and to measure directly transionospheric radio propagation properties of the ionosphere. This recent dominance of space research methods in ionospheric research is becoming less marked as satellite opportunities diminish and greater emphasis is placed on studies of the ionosphere using new types of ground-based instrumentation. Looking to the 1980s, the principal space flight opportunities will be associated with Spacelab, and new initiatives in ionospheric research will depend on a combined approach using all available methods for studying the dynamics and structure of the ionosphere. Future possibilities are outlined, with particular reference to new radio experiments on the ionosphere. (auth)