Orbit determination using line-of-sight and range measurements between multiple spacecraft

It has been previously demonstrated that the orbit of two or more spacecraft can be determined using only measurements of the inertial-frame position vector between the spacecraft over time. Constellations of satellites employing optical data crosslinks could obtain these position vector measurements as a byproduct of the optical communications system. An Unscented Kalman Filter and Unscented Rauch-Tung-Striehel Smoother are implemented to estimate the orbit of satellites in several two-satellite formations as well as a five-satellite formation with a high-fidelity orbit model. For cases where objects are in different planes, position estimation errors of under 100 meters are demonstrated.