Microsatellite Control System for Exceptional Positional Accuracy

Princeton Satellite Systems proposes an ultra-precise attitude and orbit determination system to provide exceptional ground location accuracy for Earth imaging. Improving the location accuracy from 60 m to less than 10 m requires minimization of all sources of errors in the pointing knowledge, pointing accuracy, and orbit knowledge. The attitude determination system uses nonlinear attitude filters, optical gyros and star cameras with PSS-developed star centroiding algorithms. These algorithms will dramatically reduce centroiding errors and produce unprecedented attitude knowledge accuracy. The attitude filters can incorporate nontraditional measurements from various attitude-dependent sources onboard the spacecraft, such as the communication system, for improved robustness and accuracy. The optical gyros enable a high bandwidth control system which can acquire multiple targets in one pass. The GPS-based orbit determination is enhanced with two-way ranging from the communication system to reduce the navigation error. The pointing system uses PSS ultra-low-jitter reaction wheels for high pointing accuracy and to reduce image smear. The technology in this system, which was developed by and is unique to Princeton Satellite Systems, will provide ground location accuracy of better than 10 m in a nanosatellite-class package.