A series of evolutionary changes have taken place since the early beginnings of the Landsat (Earth Resources Technology Satellite) program. Since the first satellite launch on July 23, 1972, many tens of thousands of multispectral views of the Earth have been taken and processed at the NASA/Goddard Space Flight Center (GSFC) data processing facility located at Greenbelt, Maryland. This satellite and the subsequent Landsats 2 and 3 have supplied a continuous flow of data to a widely diverse number of users for the past 6.5 years.
For the first 6 years of operation, all multispectral images were processed as photographic imagery with only a very small percentage processed digitally in the form of computer compatible tapes (CCT's). Photographic imagery was chosen originally to accommodate the use of existing experience in using photointerpretation techniques to extract information.
For the last 6 months, the GSFC Image Processing Facility has been experimenting in the production of Landsat MSS data in digitally processed form. These data consist of fully radiometrically and geometrically corrected scenes on high-density digital tapes. This change to a digitally processed product was made to accommodate the rapid emergence of a more sophisticated user and his reliance on automated digital data correlation and extraction techniques. Although the recent work in digital domain processing of MSS data at GSFC is still in its infancy, much has already been learned that can be applied to the new Landsat-D system.
For the Landsat-D mission, NASA is developing a separate and dedicated facility at GSFC to support ground data processing. This separate development will provide for autonomous development and integration of the new system while permitting ongoing Landsat operations to continue without conflict in time or concepts. The system developed will use digital processing techniques and communications satellites to minimize the loss of information between the sensor output and the ultimate user. This is to be accomplished by providing timely delivery of master data products to a public domain facility located at Sioux Falls, South Dakota.
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