Planning Dynamic Simulation of Space Life Support 2009-01-2493

Dynamic modeling and simulation of recycling space life support is necessary to determine processing rates, buffer sizes, controls, and other aspects of systems design. A common approach is to develop an overall inclusive model that reflects nominal system operation. A full dynamic simulation of space life support represents many system elements in an inclusive model, but it cannot and should not include everything possible. A model is a simplified, partial, mathematical representation of reality. Including unnecessary elements makes the model complex, costly, and confusing. Models are built to help understand a system and to make predictions and decisions about it. The best and most useful models are developed to answer specific important questions. There are many possible questions about life support design and performance. Different questions are best answered by different models. Static spreadsheet analysis is a good starting point. Basic dynamic models show how the system can maintain its steady state design point. Dynamic models are especially suited for studying responses to failures and changes over time. There are many possible elements - processors, storage buffers, materials, events, and procedures – that could be included in a dynamic simulation of space life support. Changes or failures must be built into a model to illustrate their effects and plan corrective actions. The conclusion here is that a dynamic simulation of space life support should include all the major elements of the system, but should go beyond representing nominal operation to include potential failure modes and to behave realistically if a failure occurs. Based on the planning reported here, a dynamic simulation was made to understand failures in lunar surface habitat life support (Jones, 2009-01-2482).