Initial Development and Verification of a Precise Orbit Determination Filter for the APEX CubeSat Mission

Current research for the Advanced Propulsion Experiment (APEX) at Missouri University of Science and Technology is focused on precise orbit and parameter determination to verify the performance of the Multi-Mode Ionic Monopropellant thruster payload. A batch filter to process dual-frequency GPS pseudoranges using the International GNSS Service precise position, clock, and phase center data products was developed. The filter estimates the dynamic states of the vehicle in conjunction with the coefficients of drag and solar radiation pressure, a constant average thrust magnitude, and the time biases of the GNSS receiver clock at each measurement epoch. Furthermore, it considers uncertainty in the vehicle attitude and mass measurement. The framework is extended to support examination of other parameters of interest. The statistical consistency of the filter is verified using a Monte Carlo analysis. The filter dynamics and measurement models are verified using AGI’s Systems Tool Kit and initial results of verification using NASA ICESat mission data are presented.