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The Advanced Comm~~nications Technology Satel lite (ACTS) is a major NASA conununications program involved in the development of a high technology experimental satellite for commercial use. Its conununications capability includes a basebandswitched, time division multiple access (BBS TDMA) system, which operates in the 30/20-GHz frequency bands in conjunction with an on-board baseband processor and scanning beams. This paper addresses the network control architecture of the BBS-TDMA system. After a brief system overview, key network control elements, including the TDMA frame structure, acquisition and synchronization, demand assignment, and fade control, are described. The onboard baseband processor plays the preeminent role in the BBS-TDMA systrm, and its control aspects are discussed in detail. The paper also includes a description of the ACTS ground subsystem, consisting of the master control station and the TDHA terminals.

A simple estimator is developed for determining in flight the accuracies of vector attitude sensors. The estimator is unbiased and independent of the configuration of the sensors. In addition, the estimator requires neither an a priori estimate of sensor accuracies nor an estimate of the spacecraft attitude. A covariance analysis of the estimator is given. Data from the Magsat mission is analyzed as a example. A simple algorithm for estimating attitude sensor misalignments, which is independent of any knowledge of the spacecraft attitude, is also presented. This misalignment estimator is applied to in-flight data from the Solar Maximum Mission.

Covers advancements in spacecraft and tactical and strategic missile systems, including subsystem design and application, mission design and analysis, materials and structures, developments in space sciences, space processing and manufacturing, space operations, and applications of space technologies to other fields.