Summary: NASA has identified the major overall challenge it faces: to manage a world-class research and development agency for aeronautics and space science and technology in a period of resource constraints. NASA has reduced its program plans substantially during the past several years to better align them with likely budgets. Recent plans to balance the federal budget, however, may require NASA to absorb additional reductions. Overall, GAO sees 11 challenges for NASA management. Three require immediate attention: controlling space station costs, managing budget carryover balances, and streamlining management of test facilities. Eight warrant "watchful waiting," or more routine, periodic oversight: overseeing space shuttle operations, reducing Earth Observing System costs, helping develop new launch system technologies, preserving an adequate workforce while downsizing, developing a fully integrated financial management system, determining environmental liability, overseeing contract management activities, and improving information technology management.