Control Moment Gyroscopes of the ISS
<ul><li>The preferred method of attitude control is the use of Control Moment Gyroscopes (CMGs), sometimes called gyrodynes in other programs, mounted on the Z1 Truss segment. Each CMG has 98-kilogram (220-pound) flywheel that spins at 6,600 revolutions per minute (rpm). The high-rotational velocity and large mass of the flywheel allow a considerable amount of angular momentum to be stored. Each CMG has gimbals such that the flywheels can be repositioned. As the flywheel is repositioned, the resulting force orients the ISS. Using multiple CMGs permits the ISS to be moved to new attitudes or permits the attitude to be held constant.</li>
<li>The advantages of this system are that it relies on electrical power generated by the solar arrays and that it provides smooth, continuously variable attitude control. CMGs are; however, limited in the amount of angular momentum they can provide and the rate at which they can move the station. When CMGs can no longer provide the requisite energy, Russian segment thrusters are used.</li></ul>
NASA
2015-06-25
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