A simulation model for the analysis of Space Station gas-phase trace contaminants.

A simulation model for the analysis of gas-phase trace contaminants in the cabin air of the NASA Space Station Reference Configuration was developed at the NASA Langley Research Center. The model predicts changes in trace contaminant concentrations from both physical and chemical sources an sinks as a function of time. Simulations were performed in which values for relative humidity, temperature radiation intensity, pressure, and initial species concentrations were constrained to values for the parameters measured and modeled in the continental tropics at the Earth's surface. Species concentrations simulated using the model compared favorable with concentrations in the continental tropics which demonstrated that the chemical mechanism in the trace contaminant model approximates changes atmospheric species concentrations. The sensitivity of initial species concentrations to producing change in additional species concentrations was also assessed. Results from the model indicated that chemical reactions will be important in determining the composition of cabin air in the Space Station. It is anticipated that the trace contaminant model will be useful in assessing the impact of experiments a commercial operations on the composition of the cabin air in the Space Station.