Great achievements by NASA and other space agencies have shown us what opportunities lie in the opening of the space frontier. A broad and vigorous science program in NASA is vital to full U.S. exploitation of these new opportunities. Today, science in NASA Centers is characterized by its breadth, relevance, and excellence. The NASA in-house science program and its links to university programs constitute a vitally important national resource. Maintaining excellence as a foundation for the future is a fundamental responsibility of NASA, one that requires constant attention and effort. This report by the NASA Center Science Assessment Team documents the current state of science within NASA and recommends actions to maintain a healthy program. NASA scientists have always played key roles in planning, guiding, and conducting national programs in space science. The review of Center science programs is intended to ensure that both NASA and the nation can depend on their continuing contribution in these roles. Unspecified Center...