Using discrete event simulation to model fluid commodity use by the space launch system

In May 2013, NASA requested a study to develop a discrete event simulation (DES) model that analyzes the launch campaign process of the Space Launch System (SLS) from an integrated commodities perspective. The scope of the study includes launch countdown and scrub turnaround and focuses on four core launch commodities: hydrogen, oxygen, nitrogen, and helium. Previously, the commodities were only analyzed individually and deterministically for their launch support capability, but this study was the first to integrate them to examine the impact of their interactions on a launch campaign as well as the effects of process variability on commodity availability. The model utilized the flow process modules in Rockwell Arena to simulate the commodity flows and calculate total use. The study produced a validated DES model that showed that Kennedy Space Center´s ground systems were capable of supporting a 48-hour scrub turnaround for the SLS.