Thermosphere Density Variability, Drag Coefficients, and Precision Satellite Orbits

Abstract : This research used precision orbit data to estimate neutral density along the orbits of the CHAMP, GRACE, and TerraSAR-X orbits. Comparisons with accelerometer data showed the precision orbit derived densities were more accurate than densities from the High Accuracy Satellite Model or from commonly used empirical density models. Additional research showed that the high frequency variations in density observed only be accelerometers have little effect on orbit propagation accuracy. CHAMP and GRACE precision orbit data were decimated to 8 and 15 minutes per orbit and had noise levels up to 100 m added to them to observe the effects of limited data of lower accuracy on density estimation. As expected, the accuracy decreased as higher levels of noise were added to the data, but the even with limited data of moderate accuracy, the estimated densities were of usable accuracy. The Direct Simulation Monte Carlo was used to estimate drag coefficients for the GRACE, Stella, and Starlette satellites. The resulting drag coefficients showed good agreement with existing drag coefficient techniques.