Cislunar, Orbit Determination, Line of sight, Angles-only


This work presents a measurement model designed for multiple observers (space-based and/or ground-based) for cislunar orbit determination and estimation for space domain awareness (SDA). The measurement model is able to rely solely on angles-only measurements by defining the line between the observer and the target object as the intersection of two non-parallel planes. There are two primary applications for the measurement model related to cislunar SDA: (1) It provides a new initial orbit determination (IOD) technique that does not require any knowledge of the dynamical environment, and (2) It is adopted into a sequential estimation scheme to provide continuous orbit tracking. The present measurement model is studied and demonstrated for both Earth orbits and cislunar space applications. While the goal is to operate in cislunar space, evaluating the measurement model in Earth orbits allows for the comparison against established IOD and estimation methods, resulting in a more rigorous analysis of the performance. Within this work, several different aspects of the present measurement model are studied, both analytically and computationally, to understand their effect on the orbit determination and estimation problems. By methodically varying the location of the observers, relative to the target, it is shown that the error produced by the IOD solution to the measurement behaves in a predictable manner. The IOD solution model can then be compared against similar IOD methods for Earth orbit. For orbit estimation, the measurement model is used in a modified extended Kalman filter that incorporates Analytic Continuation, allowing it to propagate the perturbed orbit dynamics to increase estimation accuracy. The measurement model is then incorporated in both an extended Kalman filter and unscented Kalman filter, comparing the resulting accuracy and computational time as the measurement frequency and nonlinearity of the dynamics are varied. For cislunar space, the measurement model is used to perform IOD and tracking of objects in orbits with relevance to future space missions. Finally, the present measurement model is shown to be capable of fusing other measurement methods from heterogeneous sensors to perform accurate orbit estimation. Overall, it is shown that the measurement model produces highly accurate results for IOD and orbit estimation. The results of the IOD solution have the same level of accuracy as other Earth orbit IOD methods and is shown to be able to easily translate to cislunar orbits without any modification, while maintaining that accuracy. For orbit estimation, the measurement model is shown to converge to an accurate estimate quickly and maintain that level of accuracy even in the absence of measurements, which is to be expected due to the vastness of cislunar space. The present approach will have future applications in space-based space surveillance networks for on-orbit cislunar SDA operations.

Completion Date




Committee Chair

Elgohary, Tarek


Doctor of Philosophy (Ph.D.)


College of Engineering and Computer Science


Mechanical and Aerospace Engineering

Degree Program

Aerospace Engineering





Release Date

June 2024

Length of Campus-only Access


Access Status

Doctoral Dissertation (Open Access)

Campus Location

Orlando (Main) Campus