Europe/United States space activities : proceedings of a conference held March 27-29, 1985, at the NASA Goddard Space Flight Center, Greenbelt, Maryland 20771 : with a supplement covering material available from "Space Propulsion for the 1990s," the 31st National AAS Conference held October 22-24, 1984, at Palo Alto, California / c23rd Goddard Memorial Symposium, 19th European Space Symposium ; edited by Peter M. Bainum, Friedrich von Bun.