Spacecraft potential calculations: A model

A simple model for calculating the potential on a spacecraft by balancing the currents to and from the spacecraft surface is developed. The model, calibrated using ATS-5 plasma data during periods when the satellite was in the earth's shadow, is used to predict potentials on a shadowed, electrically isolated surface at geosynchronous orbit as a function of local time. Potentials are also predicted as the spacecraft moves into and out of the earth's shadow. The results indicate accuracies of + or - 800 V over a range of 10,000 V. (Author)