Momentum wheel is an emerging advance technology for attitude control systems of satellites being used now a days. Momentum wheel actually work on the principle of conservation of angular momentum. The whole thing consists of a wheel with a circuit attached having some kind of sensors. When these sensors detect some change in orientation of a satellite the wheelchair is rotated. When the wheel is rotated at high speed, angular momentum of high magnitude is generated and from newtons third law the satellite aft the wheel starts to rotate in opposite sense to that of wheel in order to nullify the angular momentum generated by the wheel. Thus whole process thus rotates the satellite in particular direction this changing it's orientation. Now if we employ three wheels in all the three axis we can easily control a satellite and it's orientation around the earth in its orbit. This as a whole is often referred to as attitude control system of a satellite.
