Numerical study on effects of a module-scale crater on lunar plume-surface interaction

During lunar landings, impact craters and other complex terrains may intensify dust dispersion produced by plume-surface interaction, posing disturbances and threats to lunar modules. This study investigates the interaction between rocket plume of the Chang’E-5 module and a module-scale crater using the direct simulation Monte Carlo method. The results show that a steep crater significantly changes near-field flow structures, leading to the formation of a large recirculation bubble beneath the nozzle. The recirculation bubble increases regolith erosion on the crater wall and entrains dust particles into the nozzle, which can cause severe damage to the engine and other devices. Meanwhile, as the crater steepens, the deflection angle of the gas flow significantly increases, elevating pressure and heat flux on the module surface. The maximum inclination angle of lunar dust also increases, seriously blocking the landing visibility. For less steep craters, although the plume deflection and dust dispersion are less severe, the total erosion flux is higher according to Roberts erosion model, implying more damage to the module. This study reveals the significant effects of a module-scale crater on the lunar plume-surface interaction and can serve as a reference to predict and mitigate threats of extreme terrains to lunar missions. (Figure presented.)