The impingement of rocket plume on untreated regolith on extraterrestrial bodies poses risk to the landing performance and assets located in close proximity. In Phase I of the proposed work, Outward Technologies will develop and test a numerical modeling framework for simulating plume-regolith interactions through coupled Discrete Element Method (DEM) and Computational Fluid Dynamics (CFD) codes. This work builds on Outward Technologies' unique capabilities for simulating irregularly shaped grains in DEM and efficiently modeling large volumes of lunar regolith with stochastic distributions applied for soil size fractions, grain shapes, and soil compaction. The proposed framework will include 1) a grain-based DEM model of lunar regolith to capture the physics-based soil mechanical response and grain-grain collisions, 2) a two-way coupled CFD/DEM solver for simulating plume-regolith interactions, and 3) a damage calculator for mapping the pitting induced by soil ejecta impacting a target surface. These tools will be developed using Python routines applied to open-source software YADE. Phase I will be used to demonstrate code functionality with preliminary analyses on regolith-plume interactions and ejecta-induced damage to advance the proposed technology from TRL 2 to 3. In Phase II, the framework will be extended to a two-way coupled DEM/CFD simulator for plume-regolith interactions and the DEM inputs will be calibrated to match the mechanical response of lunar regolith observed from experimental tests, thereby increasing the TRL from 3 to 5. The proposed approach is computationally challenging but, given its accuracy and high fidelity, will lead to a robust method of 1) evaluating landing stability and cratering physics across a range of potential ground conditions and landing systems; 2) designing landing pads and protective berms; 3) determining placement of structures relative to lander locations; and 4) identifying ideal placements of sensors on landers.
NASA applications include the prediction of plume-induced cratering, ejecta dynamics, and rate of ejecta-induced damage on lander hardware and on nearby structures. These increased capabilities reduce risk for future NASA missions by evaluating:
-The selection of landing sites on the Moon, other planetary bodies, and asteroids
-Landing visibility threshold requirements
-Protocols for lander sensor data reliability during descent
-Sensor systems, lander shields, landing pads, and preventive berms
-Placement of structures relative to landing sites
Landing on untreated soil is one of the most pervasive logistical problems for military aviators such as helicopters and vertical landing jet aircraft. The ejecta can cause drops in visibility while eroding the aircraft equipment. The proposed computational tool allows for efficient design of landing systems and mitigating shields, ensuring the safety of pilots, aircraft, and nearby assets.