Summary: GAO discussed the National Aeronautics and Space Administration's (NASA) strategy for developing the Earth Observing System Data and Information System (EOSDIS). GAO noted that: (1) NASA is developing EOSDIS to perform extensive data processing, archiving, and distribution functions to serve the needs of scientists performing integrated, interdisciplinary studies of Earth; (2) the intended scope of EOSDIS far exceeds that of any previous civilian data management system; (3) the NASA EOSDIS development strategy does not adequately identify and mitigate the significant technological risks inherent to a project of this size, scope, and technical complexity; (4) the NASA near-term EOSDIS prototype projects do not address critical areas where technical feasibility is in question and are not substantial enough to allow users to assess key EOSDIS functions; and (5) NASA did not specifically address certain key technologies in its development strategy, including new data-base search techniques and data storage and retrieval methods, even though it has identified them as critical to EOSDIS long-term success. GAO believes that without specific plans to address identified technological weaknesses, NASA is taking an unnecessarily high risk that EOSDIS may be unable to provide the global change research community with fast, efficient access to earth science data.