Simulation modeling for long duration spacecraft control systems

The authors describe the use of simulation and contrast it with analytical solution techniques for evaluation of analytical reliability models. They discuss the role of importance sampling in simulation of models of this type. They demonstrate the use of the simulator tool by applying it to a fault-tolerant hypercube multiprocessor intended for spacecraft designed for long-duration missions. The reliability analysis is used to highlight the advantages and disadvantages offered by simulation compared with analytical solution of Markovian and non-Markovian reliability models. It was performed to determine whether the assumption of Weibull decreasing failure rates (DFRs) for components of a fault-tolerant hypercube would significantly improve the ten-year system reliability estimate over that obtained assuming constant failure rates. Results show a substantial improvement indicating that a candidate architecture that would otherwise be considered inadequate could provide acceptable reliability after all