Early in 1984, NASA asked the Space Science Board to undertake a study to determine the principal scientific issues that the discipline of space science would face during the period from about 1995 to 2015. This request was made partly because NASA expected the Space Station to become available at the beginning of this period, and partly because the missions needed to implement research strategies previously developed by the various committees of the board should have been launched or their development under way by that time. A two-year study was called for. To carry out the study the board...

The past quarter century of space science has been extraordinarily productive. The United States has held the lead in space science during most of these years, exploring new worlds, discovering new phenomena in space, and providing new ways to observe and predict changes in the global environment. The national space science program has amply fulfilled the objective of the National Aeronautics and Space Act of 1958 to extend "human knowledge of the Earth and of phenomena in the atmosphere and in space." Moreover, it has contributed substantially to other objectives set forth in the act,...