Some of the best ways to enhance training system effectiveness, whether for the International Space Station Crew or the war fighter, are to make sure (a) the training systems fidelity meets the training needs, (b) the training capability is fielded on time, and (c) the simulation investment yields a corresponding improvement in performance. Reuse of system-level simulation models can be a major contributor to the successful development of cost-effective, high-fidelity training systems on an aggressive schedule.

In this paper, three system-level simulation reuse case studies are presented based on experience to date in the development of NASA's Space Station Training Facility (SSTF) at the Johnson Space Center in Houston, Texas. Case studies include (a) the Boeing/Rocketdyne-provided Electrical Power Simulation (EPSIM), (b) the NASA Automation and Robotics Division-provided TRICK robotics systems model, and (c) the Russian Space Agency-provided Russian Segment Trainer. In each case, there was an initial tendency to dismiss simulation reuse candidates based on an apparent obvious lack of suitability. A careful examination of reuse potential, based on a more structured assessment of architectural and requirements-oriented representations of the reuse candidates, revealed significant reuse potential.

These assessments revealed a business case that pointed to a higher-fidelity end product, available on a faster timeline and at a fraction of the cost of "developing the system simulation models from scratch." This paper describes the detailed objective assessment and the corresponding implementation and verification that resulted in major quality, schedule, and cost benefits for NASA. These concepts should be directly applicable for use in the development of military training systems.