Development of a comprehensive physics-based model for study of NASA gateway lunar dust contamination

NASA is committed to landing humans again on the Moon by 2025 to a long-term goal of a sustaining presence. A major component of this mission is NASA's orbiting lunar outpost, Gateway, that will be subjected to the harsh environment of space during the planned 15-year lifespan in the Cis-Lunar environment. One aspect of this environment that is not well quantified is microscopic lunar regolith particles, or simply, lunar dust. Dust particles, most of which are smaller than the width of two human hairs and generally irregularly shaped, are widely influenced by the following electrostatic characteristics: volume resistivity, charge decay, chargeability, and dielectric properties of the dust. Such characteristics can allow the dust particles to collect electric charge from the surrounding environment, resulting in electrostatic interactions between the dust, electromagnetic fields, and electrically charged surfaces. Due to the nature of these fields, dust can collect on and contaminate charged surfaces. Lunar dust introduced into the Gateway environment by a lunar ascent vehicle element returning from the surface of the Moon presents risks to Gateway hardware such as radiators, solar arrays, external robotic systems, antennae, and docking mechanisms. To quantify this risk and inform NASA, International Partner, and Commercial Provider stakeholders, a comprehensive physics-based model is in development to investigate the interaction of charged lunar dust particles with the cis-lunar, deep-space environments, and spacecraft. It is comprised of a set of models of the space plasma and solar radiation environment and electromagnetic interaction of spacecraft and lunar dust. Spacecraft charging and plasma environment are solved using the opensource code from The French Aerospace Research Laboratory (ONERA) and the European Space Agency (ESA), known as Spacecraft Plasma Interaction Software (SPIS). The physics of particle charging and transport is modeled as an equilibrium implementation of Shifted-Orbital-Motion-Limited (SOML) theory which accounts for plasma flows and positive potential grains, using Siemens STAR-CCM + as the framework. Model validation includes lab experiments by NASA experts and academia, as well as future on-orbit dust detecting and dust collecting payloads on the exterior of Gateway. The results and analyses will inform Gateway Program system owners at risk for lunar dust contamination.