Available at: https://digitalcommons.calpoly.edu/theses/3280
Date of Award
6-2026
Degree Name
MS in Aerospace Engineering
Department/Program
Aerospace Engineering
College
College of Engineering
Advisor
Kira Abercromby
Advisor Department
Aerospace Engineering
Advisor College
College of Engineering
Abstract
Growing congestion in low Earth orbit is increasing the demand for effective space situational awareness, straining ground station capabilities. Space-based relative orbit determination offers an alternative, using line-of-sight angle measurements from a chaser spacecraft to estimate a target spacecraft's orbit. This research focuses on angles-only initial relative orbit determination (IROD), where no prior target state knowledge is assumed. It investigates how IROD solution accuracy is affected by differential atmospheric drag between the chaser and target spacecraft. A nonlinear batch least squares filter is designed to estimate the target's initial state, which is compared against a truth solution. It was found that incorporating differential drag results in increased solution accuracy, but the level of accuracy depends on the altitude and amount of solar activity. Additionally, a case investigating drag uncertainty determined that the solution is sensitive to density error. It is also found that differential drag effects improve solution accuracy in a close-proximity coplanar configuration, but varying orbital parameters such as inclination and eccentricity introduce additional perturbation effects on the solution. These findings establish the orbital configurations where incorporating differential drag improves IROD solution accuracy.