7. 2. 6 FLIGHT MECHANICS 7. 2. 6.1 STATION KEEPING Station keeping requirements for the SPS thermal conversion concept will basically be the same as those for the photovoltaic concept, described in subsection 7.1. 5.1. Both concepts will be subject to the same type of disturbances, although the magnitude of the aerodynamic and solar pressure perturbations will be different because of different areas and masses. A separate analysis has not been conducted for the thermal conversion concept. 7. 2. 7 ATTITUDE CONTROL SUBSYSTEM 7. 2. 7.1 GROUND RULES/GUIDEL1NES For the thermal conversion system, the ground rules and guidelines are identical to those given in subsection 7.1.6.1. Here, of course, the Z body B axis in the reference attitude is normal to the plane of the concentrator array. 7. 2. 7. 2 ATTITUDE CONTROL COORDINATES The attitude control coordinates are identical to those given in subsection 7.1. 6. 2, with the plane of the solar array replaced by the plane of the concentrator array. 7. 2. 7. 3 OPERATIONAL ATTITUDES The reference operational attitude discussion presented in subsection 7.1. 6. 3 for the photovoltaic conversion system also applies to the thermal conversion system. However, the alternate operational attitude with X perpendicular to the orbit plane is not acceptable with fixed facets in the B solar concentrators, and the axis of the thermal conversion system must be maintained in alignment with the solar vector to an accuracy of ±1°. 7. 2. 7. 4 DISTURBANCE TORQUES The gravity gradient torques are the predominant external disturbances. Peak values of the gravity gradient torques are:
RkJQdWJsaXNoZXIy MTU5NjU0Mg==