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Electro emissive (Esther) devices are thin sheets, whose infrared emissivity can be varied reversibly by electrical charging. Bonded to external surfaces of spacecraft radiators, they allow active control of the heat radiated to space while consuming negligible electrical energy. Due to the very low mass and power consumption of that novel component for space craft thermal control, considerable cost savings in development and operation can be achieved. In the current phase of the development the performance of the Esther devices, achieved in the laboratory, is optimised (where necessary) and consolidated. The applied processes of the thin film technology and the internal structure and materials of the different layers have been optimised w.r.t. reproducibility and stable performance. The manufacturing and the functional test of the Esther devices has been standardised and a number of prototypes were produced (about 200).

The redesign of the international Space Station Freedom (SSF) and funding constraints in the ESA member states caused a redirection of the development effort for the Attached Pressurised Module (APM). For the ECLSS the most important changes are the reduction in length of the module in order to make it compatible with the ARIANE V capabilities and the more severe cost constraints. As a result new concepts for the cabin loop were investigated leading to a decrease in cabin loop power consumption, mass and volume and a reduced development effort due to a lower number of items. In the previous concept a module internal loop with a flow rate of 864m3/hr and an Intermodule Ventilation (IMV) flow rate for air revitalisation to the station with 240m3/hr were installed. The revised boundary conditions with a reduced overall massflow rate of 540m3/hr allows the combination of the cabin loop and the IMV with limited impact on the total power consumption.

The pressurized modules use water and air coolant circuits to remove the dissipated heat from the sources and to transport it to the heat sink. The advantage of the water loops is to provide a high heat removal capability at low power consumption well suited for high specific heat loads i.e. assemblies with high dissipation and small volume. Air coolant circuits offer a higher flexibility to account for different shapes of the equipments and for changes in the configuration of the loop. Thus they are better suited for assemblies with lower dissipation and do not impose as much design restrictions on assemblies as water loops. But they have a higher specific power demand compared to water loops. In the Columbus pressurized modules avionics air loops and cabin air loops are installed. Both of them belong to the Environmental and Life Support Subsystem (ECLSS).