1. A distributed GPS or GNSS method of orbit modeling and propagation, comprising: (a) computing GNSS satellite force model parameters using a Predicted GPS (PGPS) Server; (b) delivering said GNSS satellite force model parameters and an initial GNSS satellite position and velocity to a Predicted GPS (PGPS) Client via a communications link, (c) generating within said Predicted GPS (PGPS) Client a predicted Orbital State Vector (OSV) comprising a satellite position and velocity, by propagating the initial satellite position and velocity provided by said Predicted GPS (PGPS) Server to a different time than the time of said initial satellite position and velocity, using said GNSS satellite force model parameters provided by said Predicted GPS (PGPS) server to said Predicted GPS (PGPS) Client; and (d) providing a local GPS or AGPS device with assistance data derived from said predicted Orbital State Vector (OSV) without requiring a real-time network connection; wherein said assistance data is derived by converting said predicted Orbital State Vector (OSV) into the so-called satellite navigation data model format and provided by said Predicted GPS (PGPS) Client to said GPS or AGPS device at a time and in a format required by said GPS or AGPS device.