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OCR for page 12
5. LST DATA HANDLING The conference considered the magnitude of the LST data now as presently estimated. While not large compared with that of current earth resources projects, it is large enough to require careful consideration of data handling and distribution procedures. The conference was not able to consider in detail the ways in which the various LST instruments will generate data; such a consideration must be based on a detailed study of various typical missions. These conclusions are based, therefore, on quite elementary estimates of the data-generation rate. Oat> Generotion In its first Oight the LST will be able to generate data from five instruments, and there will be additional positional and housekeeping data. Of the five instruments, the data rate from the SEC Vidicon (if it is selected for use) of the Focal Plane Camera (FPC) will dominate and therefore is the only neces- sary consideration here. The FPC pictures will be made up of 2000 X 2000 pixels, the intensity of each being dlgjtlzed asa 12-bit number and read out twice to minimize errors. In each earth day some 20 pictures of lo" bits each will be transmitted, gjving a total of 2 X 109 bits per day. Data Transmission No great dlfncullies should be encountered in returning data from the LST. Data rates of a few mepblts per second will be easily handled by the proposed Tracking Data Relay Satellite System (ToRss) or by the existing STADAN net. Data Storage on the Ground II seems probable that users wiD wish to store all their raw data for many months; therefore, considerable data.storage capacity on the ground will be necessary. One day's worth of SEC Vidicon data would require something 12
OCR for page 12
like I 0,000 ft of 9-track 1600 BPI tape. Undoubtedly, hJaber-