Optical navigation for nanosatellite star trackers

Abstract

This thesis looks at the effectiveness of using nanosatellite class star trackers to perform optical navigation. Although star trackers used for these missions lack the accuracy and sensitivity of sensors employed on larger spacecraft, they offer great resolution relative to its compact size. Two Extended Kalman Filter-based navigation filters illustrate the applications of this class of sensor. The first filter looks at horizon-based techniques using observations of Mars and its moons to assist the navigation filter in a hyperbolic approach. Results show low position (< 300 m) and velocity (< 0:15 m/s) errors as spacecraft reaches periapse. The filter formulation serves as a basis for a design case study exploring different possible sensor configurations for this mission type. The second filter looks at landmark-based techniques using absolute and relative landmarks as observations. Measurement frequency appears as a key parameter in this study, simulation results show position errors in the order of tens of kilometers, or better even if absolute landmarks are only available every 30 minutes. The accuracy of the results are validated through series of Monte Carlo simulation.