THE LOW EARTH ORBIT SPACE STATION WILL PRODUCE A LOCAL GAS CLOUD AND RESULTING CONTAMINATION GENERATED BY (1) OUTGASSING FROM NONMETALLIC MATERIALS, (2) EARLY DESORPTION FROM EXTERNAL SURFACES, (3) LEAKAGE OF THE CABIN ATMOSPHERE,(4) VENTING OF

THE LOW EARTH ORBIT SPACE STATION WILL PRODUCE A LOCAL GAS CLOUD AND RESULTING CONTAMINATION GENERATED BY (1) OUTGASSING FROM NONMETALLIC MATERIALS, (2) EARLY DESORPTION FROM EXTERNAL SURFACES, (3) LEAKAGE OF THE CABIN ATMOSPHERE,(4) VENTING OF CONDESNATES, AND (5) REACTION CONTROL PLUMES.THIS VERY LOW DENSITY GAS FLOW IS BEST MODELED USING MONTE CARLO METHODS. THE KEY TO USEFUL ENGINEERING PREDICTIONS WITH MONTE CARLO METHODS IS TO REALISTICALLY INCLUDE THE GASPHASE CHEMISTRY WHICH ULTIMATELY DETERMINES THE SURFACE CONTAMINATION STATE. THIS PROPOSED EFFORT IS DIRECTED TOWARD DETERMINING THE BEST WAY TO INCLUDE FINITE RATE CHEMISTRY IN MOTE CARLO RARIFIED GAS FLOW FIELD SOLUTIONS.