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This paper documents the Space Station Freedom (SSF) Active Thermal Control System (ATCS) performance during approach/departure, berthing, and deberthing operations. Recommended fixed radiator orientations and radiator orientations as a function of the (β angle were used for SSF flights MB5 through UF-1. Radiator rotation restrictions impacting ATCS performance included plume loads during proximity operations, minimum clearances from the Shuttle post-mating, visual cues required for mating and/or SSF remote manipulator system, attitude perturbations, number of Orbital Replacement Units (ORUs) deployed and thermal radiator rotation joint bending moment response. Three thermal models (TEA, ALPHA and TAURUS) performed the analyses on the MB5 through UF-1 mission builds. The study was divided into three parts pertaining to approach/departure, berthing, and deberthing.

This study assessed Active Thermal Control System Central Thermal Bus radiator rotation profiles for the Space Station Freedom in Local Vertical/Local Horizontal, two Torque Equilibrium Attitudes (MB11 and MB17), Arrow and Gravity Gradient modes while maintaining radiator angular velocities and accelerations under 45 degree/minute and 0.01 degree/sec2, respectively. To determine the thermal influence of the Flex Hose Coupler (FHC), cases ran with the ±105° radiator orientation restriction as imposed by the coupler. The study used hot thermal environments and End-Of-Life panel properties. The model used was structured to produce radiator profiles that are as close as possible to an instantaneous and local minimum environment without violating the maximum angular rotation imposed. The results from all the investigated cases indicate that the radiator should be allowed to rotate between -167° (Gravity Gradient mode) and 207° (Arrow mode).