The article discusses the physical aspects and assumptions in the formulation of the gas dynamics and thermal physics models in conditions of "Luna - Resource" spacecraft landing on the Moon surface. It was proposed to divide the problem into two stages: calculation of the gas phase and determination of trajectories and heating of particles of lunar dust. The use of the continuum equations and not taking into account the reverse effect of particles on gas was substantiated. The calculation results of parameters impingement exhaust jet of spacecraft propulsion system with Moon surface are given. It was obtained that a reverse external force is added to the streamlined surfaces equal to 196 N, the gas temperature at the bottom of the cargo compartment reaches 2000 K, and the calculated heat flux was 400 kW. The trajectories of the particles of lunar dust was determined and it was found that with a size of 1 μm the distance of their flight range was 3.5 km.