McLaughlin, Craig A.Hiatt, Andrew Timothy2009-05-082009-05-082009-01-012009http://dissertations.umi.com/ku:10289https://hdl.handle.net/1808/4553Current atmospheric models are incapable of properly modeling all of the density variations in the Earth’s upper atmosphere. Precision orbit ephemerides (POE) are utilized in an orbit determination process to generate improved atmospheric density estimates. Based on their correlation to accelerometer density, the POE density estimates were demonstrated to be an improvement over existing atmospheric models and somewhat better than the improved density estimates from the High Accuracy Satellite Drag Model regardless of solar and geomagnetic activity levels. The POE density estimates were obtained with the desired accuracy for a ±10% variation in the ballistic coefficient used to initialize the process. Fit span length showed little influence on the POE density estimate accuracy. POE density estimate overlap regions demonstrated a method of determining the consistency of the solutions. Gravity Recovery and Climate Experiment POE density estimates showed consistent results with the Challenging Mini−Satellite Payload POE density estimates.pagesENThis item is protected by copyright and unless otherwise specified the copyright of this thesis/dissertation is held by the author.Aerospace engineeringAtmospheric density estimatesChampGraceOrbit determinationPrecision orbit ephemeridesThermospheric and exospheric densityThesisopenAccess