several government agencies and academic institutions, at different temporal and spatial scales. NASA's Earth Observing System Data and Information System was built to provide a means for scientists to integrate disparate data types collected by NASA and to study earth processes in a more comprehensive manner than was possible before.

EOSDIS includes many players—the EOSDIS Core System (ECS) contractor, the science and instrument teams, the DAACs, and the Earth Science Data and Information System (ESDIS) Project—each with well-defined roles. As originally conceived, these roles were as follows:

  • the ECS contractor designs the EOSDIS Core System to capture, process, and distribute data from the EOS instruments and provides the necessary hardware and software to the DAACs;

  • the science and instrument teams develop algorithms for creating data products;

  • the seven DAACs process and disseminate remote sensing and in situ data and data products (land, atmosphere, ocean), and provide services to a wide variety of users (primarily scientists and NASA's partner agencies); and

  • NASA's ESDIS Project sets the program requirements and provides funding and system-wide coordination.

Technical problems leading to delays in the ECS, however, have led NASA to rethink these roles. NASA's current plans are to make EOSDIS a more distributed system by having the science and instrument teams, rather than the DAACs, do much of the data processing. In addition, some of the DAACs will be permitted to develop and use their own systems, rather than the ECS, for managing data. Indeed, DAAC-unique information systems are already being used to process and distribute data from the first EOS-related mission, the Tropical Rainfall Measuring Mission (TRMM), which was launched in November 1997. By involving a broader array of constituencies in EOSDIS, and employing diverse approaches to providing data services, NASA is taking another step toward creating an EOSDIS federation.

In the new EOSDIS model, the role of the DAACs may be strengthened or diminished, depending on how much flexibility and authority NASA management is prepared to give and how much initiative the DAACs are prepared to take. However, serving the needs of their users will remain their most important task. Based on the site visit reports of the seven DAAC review panels and a user survey, the Committee on Geophysical and Environmental Data (CGED) concludes that most of the DAACs are serving their scientific user community well. (Indeed, the Physical Oceanography [PO.DAAC] and the National Snow and Ice Data Center [NSIDC] DAACs are model in this regard, although neither has to face the immediate challenge of handling the enormous data streams of the AM-

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