Spacecraft Orbital Power Evaluation (SCOPE)

A Fortran program for analysing the energy balance in a satellite power system during Transfer Orbit and other mission phases is presented. Piece-wise integration is employed for computation of average battery current as the spacecraft spins, instead of calculus, to give full visibility of modelling techniques and provide data for plotting composite current and voltage waveforms. The program models a general power subsystem circuit which it solves for current, voltage and battery depth of discharge at increments of theta (spacecraft attitude) and time. Most aspects of the simulation method are discussed, including flexibility, limitations and interpretation of results. Ways of defining battery capacity are also explained to clarify the battery model.