Initial Relative Orbit Determination for Close-in Proximity Operations

The study investigates initial relative orbit determination (IROD) problem for close-in proximity operations using a camera offset from the chaser center of mass and three or more line-of-sight (LOS) observations to either the center of mass of an object or to known object features. The solution takes the form of simple algebraic equations and requires the inversion of one matrix of dimension 3N - 6, where N is the number of observations. During v-bar station-keeping, the accuracy of the algorithm is dependent on the ratio of the camera offset to the chaser?target separation distance, the time interval between observations, and standard deviation of the measurement errors. The measurement time interval is also a key parameter in this problem. When the measurement errors are not zero, the observations must be separated by less than 100's of seconds (for Low Earth Orbit) to achieve useful solutions. For all cases examined, the solution accuracy depends on the magnitude of the camera offset or the magnitude of a known target feature offset from the center of mass.