ATTITUDE AND ORBIT CONTROL SUBSYSTEM

Satellite Communications Glossary

Satellite Communications — Attitude and Orbit Control Subsystem

 

 

 

 

 

 

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Information on Attitude and Orbit Control Subsystem

The path of the satellite through space is called its orbit; the orientation of the satellite in space is called its attitude. Control of the orbital path is required to ensure that the satellite is in the correct location in space to provide the services required of it. Attitude control is essential on the spacecraft to prevent the satellite from tumbling in space and to ensure that the antennas remain pointed at a fixed point on the Earth’s surface. These functions are the responsibility of the Attitude and Orbit Control Subsystem.
     Orbit control is required to correct for perturbation forces, and to transfer orbits, or orbital location. The major means of changing orbits or to move or maintain current location are to fire the thrusters.
     A basic attitude control system comprises three elements: an ability to sense the current attitude of the platform, an ability to compute errors between current attitude and desired attitude, and some mechanism by which the attitude error can be controlled and corrected.
     Spacecraft attitude can be determined by one or more of the following sensors: Earth sensors, Sun sensors, star trackers, radio frequency sensors, or gyroscopes. Once errors in attitude are detected, control is then exercised through one of a number of stabilisation methods. There are two main stabilisation methods: two-axis, or spin stabilisation; and three-axis stabilisation. Other techniques exist, the most useful of which is gravity-gradient stabilisation.


Other topics in our resources on Satellite Communications related to Attitude and Orbit Control Subsystem include: 
 
  • Communications Subsystem
  • Antenna Subsystem
  • Power Subsystem
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  • Structural Subsystem
  • Thermal Control Subsystem
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  • Tracking Telemetry and Command Subsystem (TT&C)
  • Thrust Subsystem

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