Specification of the natural plasma environment at geosynchronous orbit

This work has made extensive use of data taken by instruments funded by NASA contracts NAS 5-10364 (ATS-5) and NAS 5-21055 (ATS-6). Much use has been made of software also developed under the same contracts. The present contract was negotiated as a result of the realization that the UCSD plasma instruments onboard the ATS spacecraft could be used to specify an environmental model which would be of use to the Air Force in developing design specifications for spacecraft to prevent faulty operation due to environmentally induced electrostatic charging. In addition, reorganization and study of the existing data would also be of use in developing models which could be of use in predicting times when hazards to spacecraft from charging might be great. Within the next year, SCATHA will make the first observations from a vehicle specifically designed to study charging at geosynchronous orbit. We expect that refinements to the data presented here will result from that program, and that new models will result.