ROALD Z. SAGDEEV is Distinguished Professor of Physics and director of the East-West Center for Space Sciences at the University of Maryland. As director of the Space Research Institute, the eminent physicist led the joint U.S.-Soviet Apollo-Soyuz mission and the international missions to Halley's Comet. In addition to his scientific career, Dr. Sagdeev played a major political role during the first five years of perestroika, serving as an advisor to Mikhail Gorbachev at the Geneva, Washington, and Moscow summits.