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Two-phase capillary loops are being extensively studied as heat collection and rejection systems for space applications as they appear to satisfy several requirements like low weight, low volume, temperature control under variable heat loads and/or heat sink, operation under on ground and micro gravity conditions, simplicity of mounting and heat transfer through tortuous paths. In 1998–2000 Alenia defined and Lavochkin Association developed the Deployable Radiator on the base of honeycomb panels, axial grooved heat pipes and Loop Heat Pipe. It was designed for on-ground testing.

The results of the thermal tests performed on the OLYMPUS Large Telecommunication Satellite Heat Pipe Radiators are presented. The test set-up maintained the Heat Pipes horizontal, the dissipation and thermal characteristics of electronic units being simulated by thermal dummies. The tests were divided in three phases with different temperatures of the chamber cryogenic shrouds to simulate the worst steady (equinox) cold case and investigate a fictitious extreme cold case (end of eclipse steady state) and an equivalent hot case. The results testify the adequacy of the Radiator design and the agreement between analytical predictions and temperatures measured during the test.

The results are presented of a thermal balance test performed at subsystem level on the thermal model of EURECA (EUropean REtricvable CArrier) in the ESTEC LSS Vacuum Chamber. The test article, thermally representative of the most relevant items of the flight unit, was equipped both with “passive” thermal control hardware (MLI blankets, heaters) and “active” thermal control hardware (fluid loop, cold plates, radiators). This test consisted of several phases with different functioning conditions. Solar lamps and heated plates were used to reproduce solar, albedo and IR fluxes. The analysis of the test results confirmed the adequacy of the thermal control design, in particular, of the key items of the fluid loop and MLI, while an extensive correlation campaign validated the thermal mathematical model.

Two-phase capillary loops are being extensively studied as heat collection and rejection systems for space applications as they appear to satisfy several requirements like low weight, low volume, temperature control under variable heat loads and/or heat sink, operation on ground and 0-g, simple mounting and heat transfer through tortuous paths. A Deployable Radiator with Loop Heat Pipe (LHP) with a heat transport capability of 1500 W has been defined and conceived by Alenia, and developed by Lavochkin Association under Alenia contract. In this paper a detailed description of the Deployable Radiator (and of its 1000 W LHP precursor) is presented, with emphasis on the areas that required research activities to improve performances. First test results are presented and discussed.