Page 226 - Satellite Communications, Fourth Edition

206 Chapter Seven

Figure 7.6 HS 376 spacecraft. (Courtesy of Hughes Aircraft Company
Space and Communications Group.)

7.3.2 Momentum wheel stabilization
In the previous section the gyroscopic effect of a spinning satellite was
shown to provide stability for the satellite attitude. Stability also can
be achieved by utilizing the gyroscopic effect of a spinning flywheel,
and this approach is used in satellites with cube-like bodies (such as
shown in Fig. 7.2, and the INTELSAT V type satellites shown in Fig.
1.1). These are known as body-stabilized satellites. The complete unit,
termed a momentum wheel, consists of a flywheel, the bearing assem-
bly, the casing, and an electric drive motor with associated electronic con-
trol circuitry. The flywheel is attached to the rotor, which consists of a