Thermal analysis and testing of a spaceborne passive cooler

Thesis

This thesis describes the thermal design and thermal testing of the development model radiative cooler for the Composite Infra-Red Spectrometer (CIRS) due for launch on the Cassini spacecraft in 1997. The radiative cooler is used to cool the instrument's Focal Plane Assembly (FPA) to approximately 80K. The FPA holds two arrays of HgCdTe detectors for the mid infra-red spectrometer of the instrument which covers the wavelength range 7μm to 17μm. The FPA is mounted from the optics on a titanium alloy tripod and is cooled conductively by the radiator via a flexible link and a cold finger. A range of thermal models of the system have been developed ranging from a simple, analytical model to a finite difference numerical model. A calorimeter was designed to perform heat leak measurements on samples of Multi- Layer Insulation (MLI) blankets to determine the number and type of shields required for the MLI blanket covering the back of the cooler radiator. A test facility incorporating a vacuum system, a space simulator target, and a simulator for the CIRS instrument was designed and constructed for testing the assembled cooler. Various configurations of the Development Model (DM) CIRS cooler were tested as components became available and the results obtained compared to the thermal model predictions. It was found that the cooler will attain a temperature of 80K in operation, but with less excess cooling power than predicted by the thermal models.

Authors: Jones, G; Calcutt, S; Jones, Graham

• Publication date: 1994
• Type of award: DPhil
• Level of award: Doctoral
• Awarding institution: University of Oxford
• Language: English
• Subjects: Thermal analysis; Design and construction; Research; Space vehicles