Direct Uncertainty Estimates from Angles-Only Initial Orbit Determination

Abstract

Initial orbit determination methods yield only a point solution, with no information about the quality of or confidence in the solution. However, probabilistic information may be inferred directly from the initial orbit determination process, given measurement uncertainty characteristics. A state uncertainty estimate is derived directly from Gauss’s angles-only initial orbit determination method using a novel technique based on sigma points. This method is tested across a range of simulated orbit types and observation geometries. Comparisons with a standard least-squares-based approach are made, and the direct uncertainty estimates are shown to be more realistic than the least-squares estimates. The state and uncertainty estimates from this method are also shown to be suitable to initialize an unscented Kalman filter for processing further measurements.