NSSDCA ID: 1968-069A-01
Mission Name: ESSA 7The ESSA 7 Advanced Vidicon Camera System (AVCS) was a combination camera, tape recorder, and transmitter that could record and store a series of remote daytime cloudcover pictures for subsequent playback to a ground data acquisition facility. The cameras and tape recorder system were essentially the same as those on Nimbus 1 and 2. The ESSA AVCS system consisted of two redundant wide-angle cameras with 2.54-cm-diameter vidicons. The cameras were mounted 180 deg apart on the side of the spacecraft, with the optical axes perpendicular to the spin axis. The camera optic system employed a 108-deg lens with a focal length of 6.0 mm. Each camera was independently triggered into action only when it came in view of the earth. A video frame consisted of 0.25 sec of blanked video followed by 6.25 sec of vidicon scan (833 lines) and a final 0.25-sec period of blanked video. Concurrent with shutter actuation, a 16-increment gray scale was included at the edge of each picture frame as a contrast check. A four-track tape recorder could store up to 36 pictures. The data could be read out between picture taking cycles without losing a picture or interrupting a sequence. Six or 12 AVCS pictures per orbit could be programmed. At nominal attitude and altitude (approximately 1450 km), a picture covered a 3100- by 3100-km square with a horizontal resolution of about 3 km at nadir. There was a 50 percent overlap along the track between successive pictures to ensure complete coverage. One camera failed soon after launch. However, approximately 80,000 usable pictures were obtained from the remaining camera before its tape recorder failed on July 19, 1969. Data from this experiment are available from the National Climatic Center, Asheville, NC. For an index of available data, see the 'Catalog of Meteorological Satellite Data - ESSA 7 Television Cloud Photography,' for sale from the U.S. superintendent of documents. Identical experiments were flown on ESSA 3, 5 and 9.
Questions and comments about this experiment can be directed to: Coordinated Request and User Support Office
Name | Role | Original Affiliation | |
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Principal Investigator | NOAA National Environmental Satellite, Data and Information Service |