An energy balance simulation tool for TOMS-EP

A computer analysis tool has been developed to perform energy balance simulations of a spacecraft power subsystem. The purpose of the program is to predict the battery state-of-charge (SOC) as a function of time for different scenarios for the first few orbits of the Total Ozone Mapping Spectrometer-Earth Probe (TOMS-EP) satellite. The satellite proceeds from boot-up while tumbling, through deployment and attitude stabilization via a combination of ground commanded and autonomous events during this period. The model calculates the battery state-of-charge profile, based on initial input conditions and variable load profiles (power use versus time). This model has the capability to reflect changes in the power generated by the solar array, which varies as the simulation progresses. Using this process, which includes an ability to define the events that trigger changes in the loads or solar array output power, many different operational scenarios can be modeled. This tool has been used to evaluate responses to various failure modes and contingencies for the first few orbits of the TOMS EP mission