Comets pre and post Halley

Abstract

The recent intensive study of Comet Halley based on in situ measurements, observations carried out with rockets and satellites and supplemented with coordinated earth based observations has not only confirmed pre-Halley results, but also has given new insight into the nature of the nucleus, dust, gas, and the interaction of cometary plasma with the solar wind. These observations also have raised many new questions and problems. Several of these aspects are discussed. For a better understanding of these problems, the planned future missions to comets are also discussed.