Research in software allocation for advanced manned mission communications and tracking systems

Abstract

An assessment of the planned processing hardware and software/firmware for the Communications and Tracking System of the Space Station Freedom (SSF) was performed. The intent of the assessment was to determine the optimum distribution of software/firmware in the processing hardware for maximum throughput with minimum required memory. As a product of the assessment process an assessment methodology was to be developed that could be used for similar assessments of future manned spacecraft system designs. The assessment process was hampered by changing requirements for the Space Station. As a result, the initial objective of determining the optimum software/firmware allocation was not fulfilled, but several useful conclusions and recommendations resulted from the assessment. It was concluded that the assessment process would not be completely successful for a system with changing requirements. It was also concluded that memory requirements and hardware requirements were being modified to fit as a consequence of the change process, and although throughput could not be quantitized, potential problem areas could be identified. Finally, inherent flexibility of the system design was essential for the success of a system design with changing requirements. Recommendations resulting from the assessment included development of common software for some embedded controller functions, reduction of embedded processor requirements by hardwiring some Orbital Replacement Units (ORUs) to make better use of processor capabilities, and improvement in communications between software development personnel to enhance the integration process. Lastly, a critical observation was made regarding the software integration tasks did not appear to be addressed in the design process to the degree necessary for successful satisfaction of the system requirements