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The attitude and orbit control subsystem (AOCS) provides attitude information communications service equipment, and scientific instruments. Control is. An operating communications satellite system consists of Physical Structure. Attitude and Orbit Control System. (AOCS). Power System. Thermal Control. oriented framework for Attitude and Orbit Control System or AOCS of satellites. Understanding the case study requires some familiarity with the AOCS domain.

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These systems are partly on the satellite and partly at the controlling earth station. In addition, a solar aspect angle sqtellite the range must be maintained at all times. However, should any serious anomaly occur, such as a prolonged loss of contact, XMM-Newton will automatically enter a survival mode and wait for direct control to be re-established from Earth.

Attitude and orbit control system(AOCS) | Satellite Communication

By continuing to use the site you are agreeing to our use of cookies. Let X, Y and Z are another set of Cartesian axes. Note that this is not a bright source avoidance cone, but driven by requirements on the spacecraft’s alignment with respect to the Sun to ensure sufficient energy supply and thermal stability. Then, it will resolve that issue by bringing the satellite into the correct orbit.

Given XMM-Newton’s very specific orbit highly elliptical, irregular eclipse seasons, Sun avoidancethis required very complex hardwired logic within the unit.

It is usually composed of one or more antennas, which receive and transmit over wide bandwidths at microwave frequencies, and a set of receivers and transmitters that amplify and retransmit the incoming signals. The fully redundant AOCS represents some kg cimmunication electronics: Reaction wheel courtesy of MMS. All communications satellite derive their electrical power from solar cells.

Satellite Communication – AOC Subsystem

All eventual failures must be detected. We know that satellite may deviates from its orbit due to the gravitational forces from sun, moon and other planets.


So, the second gas jet will stop the motion of satellite in that axis direction. In this method, we can stabilize the satellite by using one or more momentum wheels. This drum is covered with solar cells.

In this method, the body of the satellite rotates around its spin axis. In general, it can be rotated at 30 to rpm in order to produce a force, which is of gyroscopic type.

The tracking system is located at this earth station and provides information on the range and the elevation and azimuth angles of the satellite.

These three axes define the altitude of satellite. This set of three axis provides the information about orientation of the satellite with respect to reference axes. A satellite which uses multiple frequency bands usually has four or more antennas. The power is used by the communications system, mainly in its transmitters, and also by all other electrical systems on the satellite. The receiver-transmitter units are known as transponders.

This method is called as three-axis method. Power systems and rockets are present in this drum. In this way, the AOC subsystem takes care of the satellite position in the right orbit and at right altitude during entire life span of the satellite in space. ESA’s X-ray space observatory targets distant X-ray sources for long periods often exceeding ten hours and one of the key requirements of the satellite is its very high pointing accuracy and stability.

Due to this, the spin axis gets stabilized and the satellite will point in the same direction. Before delivery for integration into the spacecraft, the AOCS system underwent several weeks of intensive testing, and subsequent System Validation Tests on the assembled satellite have confirmed its perfect operation.


Satellite Communication AOC Subsystem

The communication subsystem is the major part of the satellite. If there is any change in satellite orbit, then it sends a signal regarding the correction to Orbit control subsystem. The satellites, which perform this kind of operation are called as de-spin.

The direction of this motor will be opposite to the rotation of satellite body, so that the antennas point towards earth.

During launching phase, the satellite spins when the small radial gas jets are operated.

Altitude control subsystem takes care of the orientation of satellite in its respective orbit. Communication subsystem is placed on satellitte of the drum.

After this, the de-spin system operates in order to make the TTCM subsystem antennas point towards earth station. These forces change cyclically over a hour period, since the satellite moves around the earth. A vital requirement of the XMM-Newton mission is that its delicate science detectors must not be damaged by luminous sources in the sky.

The maximum rotation speed of the reaction wheels is rpm. Two types of transponder in use: Create your website today. This subsystem consists of rocket motors that are used to move the satellite back to the correct orbit when external forces cause it to drift off station and gas jets or inertial devices that control the attitude of the satellite. Attitude and orbit communicstion system AOCS. Following are the two methods to make the satellite that is present in an orbit as stable.

If there is a change in altitude of the satellite, then the angles between the respective axes will be changed.