CIS-LUNAR ORBIT DETERMINATION SENSITIVITY ANALYSIS WITH REFERENCE TO OBSERVATIONAL GEOMETRY

The sensitivity of the initial condition [epoch state] orbit determination program with respect to ranging geometry is studied in this paper. Using the nonlinear least squares orbit determination program with representative dynamics and sensor models, the effects of operational considerations, such as the drop of regular ranging, information are studied. A representation of the linearized error covariance of the epoch state as a function of observation epoch is presented to provide a visual inspection of the relative measures of accuracy of the state. Applications of this analysis are applied to an orbit estimation problem, whereby the orbit of an artificial satellite around the Moon is estimated using range and range rate observations from sites located on the Earth. Information-gain measures are presented to reveal optimal observation epochs and the influence of observational geometry. Comparisons are made between information-gain profiles determined from true measurement data and measurement data generated from a priori estimates.