Abstract: Spacecraft transfer orbit operations include separating a spacecraft from a launch vehicle, while in a launch vehicle transfer orbit. The spacecraft includes a propulsion subsystem and a spacecraft controller that controls the spacecraft in a three-axis stabilized mode. With the spacecraft continuously in the three-axis stabilized mode, one or more orbit raising maneuvers are performed by firing either or both of a chemical thruster and an electric thruster firing. Any two consecutive orbit raising maneuvers are separated by a respective intervening coast period. While in the three-axis stabilized mode, the spacecraft does not rotate about any axis at a rate greater than 0.1 degree/sec and dumping of momentum stored in a reaction wheel system is avoided.

Abstract: Position control methods are described for satellites and spacecraft for controlling transition from thruster control to momentum wheel control in a three-axis stabilized spacecraft. Transition from a high-bandwidth, high-torque thruster-controlled stationkeeping (SK) mode to a low bandwidth, low torque momentum wheel On-Orbit Mode is carried out. Usually a unique threshold entry method to automatically initiate the transition mode at the point with the most favorable dynamics. Also, the disclosed method eliminates the use of nutation in conjunction with a deadbeat thruster sequence to correct the spacecraft attitude to improve pointing performance and significantly shorten the time spent in the transition mode.