Date of Award


Document Type


Degree Name

Master of Science


Department of Aeronautics and Astronautics

First Advisor

Richard G. Cobb, PhD


This research is designed to demonstrate that a change in satellite propellant can be determined using measured moments of inertia (MOI) from a satellite. Because satellites are currently incapable of being refueled in orbit it is important to have multiple methods to determine the remaining fuel onboard. This research can also support satellite operator selection of control-system gains to improve performance or recover the spacecraft. To meet the research objectives, new mathematical models of the Air Force Institute of Technology's Simulated Satellite (SimSat) were developed. These models were created using dynamic response analysis techniques on the reaction wheel and SimSat systems. The models were than validated against the existing SimSat hardware. Using a least-squares parameter estimation technique, the model and hardware data were compared to determine the resulting change in measured MOI. Then, using a calibrated baseline model, telemetry data was compared to the model to determine the MOI of the unknown system. The research found it is possible to determine the change in satellite fuel from measured MOI. The research also found there are limits to this detection technique based on the accuracy of the mathematical model and the angle of the detection maneuver being performed.

AFIT Designator


DTIC Accession Number