This paper compares, in detail, the two major spacecraft thermal analysis computer codes: TRASYS (Thermal Radiation Analysis System) and SSPTA (Simplified Shuttle Payload Thermal Analyzer) when applied to two sophisticated spacecraft systems, namely, SMRM (Solar Maximum Repair Mission) and Astro-1/UIT (Ultraviolet Imaging Telescope) in conjunction with the SINDA (System Improved Numerical Differencing Analyzer) thermal code.
The status of TRASYS-to-SSFTA and SSPTA-to-TRASYS translating programs at Fairchild Space Company are discussed, and a methodology for the development and analysis of spacecraft thermal math models is presented using the general-purpose interactive graphics package PDA-PATRAN-G, TRASYS, SSPTA, SINDA, and numerous in-house-developed translating programs.
The orbital absorbed energies and the internode radiation conductors generated by TRASYS and SSPTA, for the aforementioned spacecraft systems, are systematically compared.
An error, concerning the TRASYS preprocessor interpretation of the number of steps around an orbit, in the ORBGEN card is detected and corrected. Discrepancies, within the TRASYS, are noted when the shadow factors are internally calculated as opposed to being interpolated from the shadow tables. A special-purpose small model is developed in order to examine the above effects.