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An automated procedure has been developed for correlating thermal models with test or flight data. The procedure achieves model correlation by determining the best combination of changes to a model's linear and non-linear conductors in order to minimize the differences between model temperature predictions and measured data. This procedure has been developed for use with the SINDA Thermal analyzer program, but the methods are general and apply equally to other thermal programs, such as ESATAN. The method is based on Design Sensitivity and Optimization techniques and utilizes the solution sequences available in MSC/NASTRAN. The thermal model is reformulated into an equivalent structural model, which is then optimized using built-in MSC/NASTRAN routines to match specified results.

The SPAS (Shuttle Pallet Satellite) is a battery powered, 3-axis stabilized spacecraft which provides mechanical interface, power, command, low rate telemetry and high density data storage. A reconfigured SPAS for the SPAS III mission has been defined which includes new avionics and power subsystems, a modified communications subsystem, a Global Positioning System receiver, and a new sensor suite. The primary sensors are an IR (Infrared) Radiometer, an IR Spectrometer, a Multi-Spectral Imager/Spectrometer and two television cameras. The SPAS is deployed from the STS (Space Transportation System) orbiter for approximately four days, controlled with either ground or Astronaut commands, and then retrieved. Due to its externally mounted sensors and components, and widely varying possible orbital attitudes and mission conditions, the SPAS presented a challenging thermal design opportunity.

The TOPEX/Poseidon spacecraft is scheduled for launch in August 1992 aboard an Ariane 42P launch vehicle. The mission is a collaborative scientific venture between NASA and CNES. The primary objective is to perform precise measurements of the ocean surface topography by radar altimetry from a precision, circular orbit. The satellite consists of two major sections, the Multimission Modular Spacecraft Standard Bus and the Instrument Module. The IM accommodates seven instruments, the solar array, three communication antennae, and a variety of satellite support equipment. Thermal vacuum/thermal balance testing of the TOPEX/Poseidon was performed at the Goddard Space Flight Center between 24 March 1992 and 22 April 1992. Simulation of the space environment was accomplished in a vacuum chamber using IR heating/cooling plates to establish boundary temperatures.