Abstract: Apparatus and methods for attitude control of a space vehicle. The space vehicle includes a reaction wheel subsystem and a propulsion subsystem for attitude control. A slew controller for the space vehicle detects a failure of the reaction wheel subsystem. To perform an attitude slew, the slew controller identifies a pair of thrusters in the propulsion subsystem that will rotate the space vehicle about a desired axis. The slew controller determines burn parameters for the pair of thrusters, and initiates the burns to perform the desired attitude slew.

Abstract: A system and method are disclosed for an innovative spacecraft (S/C) safing methodology. The system and method use wheel momentum to perform a rotisserie rotation so that the spacecraft can slew at a fast rate in a controlled fashion in order to keep the spacecraft power safe and maintain telemetry and command (T&C) coverage. The system and method involve a reaction wheel system and a spacecraft control processor (SCP). The SCP is in communication with the reaction wheel system. The SCP is operable to determine a rotisserie axis, and take the cross product of the rotisserie axis and a momentum vector to result in a unit vector. The SCP is further operable to slowly slew the spacecraft about the unit vector through an angle until the rotisserie axis aligns with the momentum vector, and rotate the spacecraft about the rotisserie axis to keep the spacecraft power safe.

Abstract: Spacecraft control modules can steer a spacecraft during a slew maneuver. The spacecraft control modules can receive a target attitude for the spacecraft slew maneuver. An angle between a current attitude and the target attitude may be determined. A smooth attitude offset profile with respect to a steering frame may be established from the current attitude to the target attitude. A smooth attitude command may be generated from the smooth attitude offset profile. The smooth attitude command may be applied to an attitude control module of the spacecraft.

Abstract: A system and method are disclosed for an innovative spacecraft (S/C) safing methodology. The system and method use wheel momentum to perform a rotisserie rotation so that the spacecraft can slew at a fast rate in a controlled fashion in order to keep the spacecraft power safe and maintain telemetry and command (T&C) coverage. The system and method involve a reaction wheel system and a spacecraft control processor (SCP). The SCP is in communication with the reaction wheel system. The SCP is operable to determine a rotisserie axis, and take the cross product of the rotisserie axis and a momentum vector to result in a unit vector. The SCP is further operable to slowly slew the spacecraft about the unit vector through an angle until the rotisserie axis aligns with the momentum vector, and rotate the spacecraft about the rotisserie axis to keep the spacecraft power safe.

Abstract: Spacecraft control modules can steer a spacecraft during a slew maneuver. The spacecraft control modules can receive a target attitude for the spacecraft slew maneuver. An angle between a current attitude and the target attitude may be determined. A smooth attitude offset profile with respect to a steering frame may be established from the current attitude to the target attitude. A smooth attitude command may be generated from the smooth attitude offset profile. The smooth attitude command may be applied to an attitude control module of the spacecraft.

Abstract: A method, apparatus, article of manufacture, and a memory structure for designing a robust controller. The method comprises the steps of determining a plant model G of the system dynamics; bounding system dynamics unmodeled by the plant model G of the system dynamics by a weighting function W; applying a transform to an augmented plant model T having the plant model G and the weighting function W; defining a controller {tilde over (F)} from the transformed plant model T; and applying an inverse of the transform to the controller {tilde over (F)} defined from the transformed plant model and the weighting function W to generate the robust controller F.

Abstract: A system and method to enhance attitude estimation for transfer orbit maneuvers of a spinning satellite includes a transfer orbit earth sensor that can receive and convert an infrared radiance to an analog signal. The analog signal is provided to a hardware chord processor and an analog-to-digital converter. The hardware chord processor determines an earth chord length based on the analog signal. The analog signal is sampled in the analog-to-digital converter to provide a digital signal to a digital earth sensor pre-processor, which reshapes the digital signal to provide a pre-processed signal having nearly distinct peaks. A software chord processor is provided with the pre-processed signal. The software chord processor locates the peaks in the pre-processed signal and determines an earth chord length.

Abstract: A method, apparatus, article of manufacture, and a memory structure for designing a robust controller. The method comprises the steps of determining a plant model G of the system dynamics; bounding system dynamics unmodeled by the plant model G of the system dynamics by a weighting function W; applying a transform to an augmented plant model T having the plant model G and the weighting function W; defining a controller {tilde over (F)} from the transformed plant model T; and applying an inverse of the transform to the controller {tilde over (F)} defined from the transformed plant model and the weighting function W to generate the robust controller F.