WE ARE PROPOSING FOR FY20 FUNDS TO CONTINUE DEVELOPMENT OF A GRID FREE RAREFIED GAS DYNAMICS (RGD) MODEL FOR SIMULATION OF HEAT FLOW IN THE UPPER THERMOSPHERE AND EXOSPHERE REGIONS OF PLANETARY ATMOSPHERES. IN THE TYPICAL RAREFIED GAS DYNAMIC APPROACH A GRID IS REQUIRED TO RESOLVE THE LOCAL MEAN FREE PATH (MFP 1/NS N DENSITY -COLLISION CROSS-SECTION) TO OBTAIN STEADY STATE SOLUTIONS OF NON-EQUILIBRIUM (NOT MAXWELLIAN) GAS FLOW IN THIS TRANSITIONAL REGION (