Vhf Antenna

Attitude Xyz
Fig. 19-17. GEOS-3 Spacecraft

The goal of the GEOS-3 acquisition sequence was to achieve mission mode and begin experimental operations as rapidly as possible. The mission constraints are given in Table 19-1. The initial attitude acquisition plan for the GEOS-3 was to activate the z axis electromagnet soon after spacecraft separation to achieve magnetic stabilization (Section 19.5.2), to extend the boom over a high northern latitude command station to achieve proper (pitchsaO) gravity-gradient stabilization, and, finally, to accelerate the wheel to achieve yaw stabilization. This procedure was abandoned because the large amplitude librations induced by the boom and wheel maneuvers coupled with the long system damping time constants

Table 19-3. GEOS-3 Attitude Acquisition Profile
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