The orbital motion of a satellite exhibits an integrated response to the forces generated by the inhomogeneous mass distribution of the solid Earth/ocean/atmosphere system, the density of the atmospheric medium it traverses, and the size, orientation, temperature and material properties of the exposed satellite surfaces. Classical orbit determination methods, now sometimes referred to as dynamical methods, require modeling of the complete set of forces acting on an orbiting object. Through the application of the laws of motion, continuous orbit knowledge is obtained which encompasses both the tracked and untracked portions of the orbit. To develop improved and more complete conservative and non-conservative force models to support orbit determination, it is common to exploit the functional relationships between very precise observations of the satellite's motion and the underlying model parameters. Improvements in the inherent accuracy and global distribution of satellite tracking data have fundamentally driven this progress. The models required to support centimeter-level geodesy are generally more comprehensive and more complex than their predecessors. A parallel growth in computer technology has enabled extensive parameter recovery solutions to be performed and the application of the resulting models within orbit calculations.