VITAL PROBLEMS OF VENUS GEOLOGY - OUTLOOK FOR THEIR RESOLUTION BY MAGELLAN AND POST-MAGELLAN MISSIONS

Five problems are considered to be vital for progress in Venus geology: (1) General style of endogenetic activity of Venus: (2) Relative stratigraphy and absolute age dating of terrains and formations; (3) Major geochemical types of crust material on Venus; (4) Character and intensity of exogenetic process; and (5) Structure of Venus' interiors and its seismicity. It is evident that the first two problems will receive decisive advances from MAGELLAN data. Problems 3 and 4 will progress but it is evident too that significant progress in these areas demands new post-Magellan mission(s). Problem five requires mostly new mission(s). No post-Magellan missions to Venus are in the plans of space-dealing countries and agencies, and this gives the impression that there is no need for them. But this is not true and this paper is an invitation to discuss not only goals and tests for Magellan study but the prospective plans of post-Magellan studies of Venus too.