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A-4.4 Attitude Maneuver Planning

Figure A-5 describes the DFD associated with the Plan Attitude Maneuvers application. The data stores labeled Orbit Ephemeris, Attitude Ephemeris, and Quality Assessed EU Measurands provide data needed to evaluate the current state and health of the vehicle (see Figure A-2, the overall DFD for Mission Planning). The Mission Planning Requirements data store shown in Figure A-2 describes mission requirements, objectives, and constraints on attitude maneuvers. The text below describes the data flow for the Plan Attitude Maneuvers application.

Evaluate Vehicle State - This function accepts the desired attitude along with the attitude maneuver planning activity. Then, it performs monitoring and assessment of the spacecraft's orbital and attitude state as well as the health and status of on-orbit subsystems via telemetry. Key among these parameters will be the status of on-board propellant available for maneuvers as well as the status of the power and thermal management subsystems.

Generate Maneuver Parameters - Based on the vehicle's state (as specified by the Evaluate Vehicle State process), the desired attitude, and constraints on attitude maneuvers, this process determines the parameters for executing an attitude maneuver (e.g., burn epoch, maneuver duration, thruster commands, and time delay). These parameters are stored in the Attitude Maneuver Parameters data store for use by other applications. Prediction of the post-maneuver vehicle state is also performed and recorded.

Figure A-5. Plan Attitude Maneuvers data flow diagram.