Software Architecture of the NASA Shuttle Ground Operations Simulator - SGOS

The SGOS executive and its subsystems have been an integral component of the Shuttle Launch Safety Program for almost thirty years. It is usable (via the LAN) by over 2000 NASA employees at the Kennedy Space Center and 11,000 contractors. SGOS supports over 800 models comprised of several hundred thousand lines of code and over 1,000 MCP procedures. Yet neither language has a for loop!! The simulation software described in this paper is used to train ground controllers and to certify launch countdown readiness.