Design of Test Set-ups and Thermal Analysis for Space Simulation Tests with Extreme Temperature Requirements 951677
Various test set-ups are described which illustrate how to obtain very hot and cold temperatures during thermal cycling with the additional requirement that at the extreme temperatures the specimens - in our case white painted antenna dishes- must be visible to perform distortion measurements.
In the cold case the number of thermal leaks or holes in the shroud must be small i.e. the effective shroud temperature shall be as low as possible.
If a solar simulator is used to irradiate the specimen in the hot case, the absorbed energy can be enlarged by using a removable curtain in front of the antenna, which changes the thermo-optical surface properties to higher αs/εH.
In the case of the CASSINI reflector the requirements for the cycle temperature are Tantenna= -160°C and + 150°C. The coating is white paint with αs/εH = 0.2/0.85 and it is not possible to insulate the rear side. More than 3000 Watt/m2 must be absorbed to obtain the high temperature in a space environment.
To fulfil these requirements various test set-ups will be discussed and analysed by thermal calculation. This includes a thermal model for infrared quartz tube heaters. The result is a test set-up with infrared heaters mounted on a shroud with special coating.