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The capillary pumped loop permits to solve one of the problems of the three axis stabilised satellite: the thermal control of dissipating equipment functionally placed inside the satellite core or on the earth panel and which have to be connected to the North and South radiator panels. This problem has been solved on previous programmes by heavy and non-flexible solutions (U shaped heat pipe networks for example), the capillary loop may offer the following advantages: on-ground test, at system level, without orientation constraints, possibility of active temperature control, easy integration in the satellite body. But this new technology has to be investigated and some specific problems (starting phase for example) have to be solved before the implementation in an operational satellite.

The TURKSAT Ku-Band Telecommunication program constitutes for Aerospatiale the successful result of technical, financial and time schedule challenges. After an overview of the Turksat mission, the system constraints assigned to the thermal control will be explained including the thermal control description of the satellite. The main interest for the thermal control of Turksat consists on one hand in the Protoflight development program, on the other hand in the starting point for the large scale application of Aerospatiale heat pipes on commercial satellite. The last part of the paper will deal with the good correlation between what was expected and what has been observed in flight, confirming the right selection for the development philosophy.

This paper presents the benefit for receiver thermal performance of installing heat pipes on top of the INTELSAT V - FM 15 antenna panel. The FM 15 spacecraft launched in January 1989 is identical in all respects to the FM 13 spacecraft launched in May 1988, except for the addition of three interconnection heat pipes on the external surface of the antenna panel. So this flight experiment is unique, because it allows a direct in-flight comparison between two identical spacecraft, one with, and one without heat pipes. Detailed thermal mathematical models have been developed to correlate the anticipated results obtained from INTELSAT V - FM 13 and FM 15 with those obtained from flight telemetry and to verify the level of heat transfer coefficients of the heat pipes.

The direct broadcasting television satellite TDF-1 has been launched on October 28th, 1988, by ARIANE flight V 26 from KOUROU, French Guyana. After the successful on orbit tests, the five television channels have been activated on the 15th of November. One of the key features of this satellite consists in the sophisticated design of the heat pipe network used for the thermal control of the telecommunication payload. This network is composed of 86 constant conductance heat pipes of different diameters, corresponding to a total cumulative length of about 120 meters, and arranged along the three axes of the spacecraft body. The paper describes the thermal control design of this satellite and summarizes the development plan selected in connection with the constraints linked with the heat pipe utilisation. The second part is an overview of the in-orbit performance of the thermal control system during the first Month of operational utilisation.

Future space stations and platforms will require a centralized thermal utility to provide temperature control of various heat sinks or sources. Its purpose is to transport large amounts of energy over long distances towards a heat rejection system, with very small temperature differences. The present paper deals with the heat rejection system. A concept of a multi-tubes condenser has been selected and designed, using ammonia as the working fluid. In order to support and confirm the modelization software, an experiment is set up with a one-tube condenser uniformly cooled, involving limited heat power, but representative of thermo-hydraulic conditions. This paper presents the test programme. Objectives are first to confirm the selected technology, and to assess internal operation from the measurements of the external temperature along the tube, and differential pressure drop.

The advantages of a space deployable radiator are among others to permit increase of dissipated power by enlarging the dissipative area from stowed to deployed configuration. The concept developed by AEROSPATIALE and CNES has also the advantage to permit reuse of existing platforms without necessity of an entirely re-designed architecture of the spacecraft. This concept is based essentially on: a deployable panel of hinged type where the power is spread over the surface by means of embedded heat pipes a thermal rotating joint coaxial with the panel hinge. The prototype model has a radiator panel of 800 × 600 mm with five embedded heat pipes and two radiative faces capability. In the hot case, corresponding at Summer or Winter Solstice for geosynchronous communication satellites the capability is about 160W, while the temperature of internal unit is maintained at + 30°C.