Attitude and Orbit Control (AOC) Subsystem

The Attitude and Orbit Control (AOC) subsystem is responsible for controlling both the orbit and the attitude of a spacecraft. The orbit defines the path of the satellite through space, while the attitude defines its orientation. Orbit control ensures that the satellite remains in, or is transferred to, the correct orbital position to provide the required services, while attitude control prevents uncontrolled tumbling and maintains correct pointing of antennas, sensors, and solar arrays.

Orbit control is required to compensate for orbital perturbations and to perform orbit transfers or station-keeping maneuvers. These functions are achieved primarily through the use of thrusters.

Attitude control involves sensing the current orientation of the spacecraft, determining any deviation from the desired attitude, and applying corrective control. Attitude determination may use Earth sensors, Sun sensors, star trackers, radio-frequency sensors, and gyroscopes. Attitude control is commonly implemented using either spin stabilization or three-axis stabilization, with control torques provided by actuators such as reaction wheels, control moment gyros, or thrusters.

In many spacecraft, attitude determination and control functions are combined and referred to as the Attitude Determination and Control Subsystem (ADCS).