With NASA’s goal to land the next human on the lunar surface in the next few years, it has become vitally important that we have a better understanding of how future landing spacecraft will interact with the unique properties of regolith—the layer of loose, unconsolidated dust and rock on the lunar surface—which can cause hazards like visual obstructions, particulate clouds, and cratering of the landing zone. Researchers from the Fluid Dynamics Branch at NASA’s Marshall Space Flight Center are performing plume-surface interaction (PSI) simulations between lander engine plumes and unprepared regolith surfaces, and have developed new tools to provide predictive PSI environments for various NASA projects and missions including the Human Lander System (HLS), Commercial Lunar Payload Services (CLPS), and future Mars landers. These tools allow the researchers to determine how to best meet the simulation and time requirements for each project by varying model fidelity. The highest fidelity tool is the Gas Granular Flow Solver (Loci/GGFS) that models gas-particle multi-phase interactions to predict regolith cratering and ejection of particles into the immediate surroundings of the lander. At its highest fidelity, it can model microscopic regolith particle interactions with a particle size/shape distribution that statistically replicates actual regolith; however, to be most effective with today’s computing resources, it is currently run using only one to three equivalent particle sizes/shapes. The team also incorporated engineering models into their software suite to create production-ready hybrid tools with reduced fidelity. At the lowest fidelity, the computational fluid dynamics (CFD) code Loci/CHEM+DIGGEM can predict crater depth over time by relating local CFD-predicted surface shear stresses to a model of erosion mass flux.
Quick Facts
A high-fidelity PSI model is extremely computationally intensive. Our PSI toolset follows a fidelity cascade that allows us to support our customers’ needs today with current agency computing power, but we have strategically designed our tools to grow incrementally in fidelity as NASA’s computing capacities increase.
- With more powerful lander engines, risks for mission due to cratering and particle ejection during vehicle ascent and descent will be significantly greater than during the Apollo missions. The tools being developed are already being used to predict cratering and visual obscuration on upcoming CLPS and HLS missions, as well as for long-term lunar site planning.
- In addition to the high-fidelity Loci/GGFS and low-fidelity Loci/CHEM tools, the team at NASA Marshall is working on integrating static porous medium and dynamically eroding porous medium models to increase the fidelity of simulations by including gas diffusion into the soil, which can change the nature of the erosion.
- Without access to resources at the NASA Advanced Supercomputing facility, it would not be possible to run these simulations, which can require over 200-million-cell meshes, runtimes on the order of weeks, and can generate terabytes of data.
- Future source code optimization and increases in computing resources will allow NASA researchers to make better use of the more computationally intensive, higher fidelity tools for lunar mission planning, while still maintaining production-level runtimes.
Researchers
- Jason Howison, NASA Marshall Space Flight Center Please enable Javascript to see email address.
- Jeff West, NASA Marshall Space Flight Center Please enable Javascript to see email address.
More Information
- Overview of the Predictive Simulation Capability Element of the Plume Surface Interaction Project
- Design of a Subscale, Inert Gas Test for Plume-Surface Interactions in a Reduced Pressure Environment
- Overview of Predictive Simulation Capability Development for Crater Evolution and Ejecta in Continuum/Rarefied Flows
- Continuum-Rarefied Modeling of Plume-Surface Interaction in Low-Pressure Environments