Figure D-4 shows the DFD for Determine Orbit. This function uses Screened, Edited Observations, along with data about the RGFs, physical parameters, and the current orbit ephemeris, to update the estimate of the orbit state. Any estimated parameters are stored in the Orbit Ephemeris data store. Other parameters (i.e., those not estimated but fundamental to force or measurement models) are stored in the Physical Parameters and RGF Database data stores. The following processes are identified:
Determine Orbit - Performs the actual state estimation using the tracking data and supporting data. The resulting state and statistics associated with the fit are placed back in the Orbit Ephemeris data store.
Assess Orbit Quality-This process evaluates the quality of the result of the orbit determination. This includes generating and evaluating various additional statistics associated with the fit.
Diagnose Orbit Conditions - This process identifies problems based on results of Assess Orbit Quality using the anomaly resolution rule base. If necessary, this process will make an entry in the Timeline data store requesting an orbit maintenance activity.