Impacts of small objects regularly occur on the Moon, and have been observed to produce a characteristic optical flash upon impact. These impacts typically occur at hypervelocity (>10 km/s), and usually involve impactors less than ten meters in diameter. The details of the impact – such as impactor mass, speed, and composition, as well as orientation of the impact relative to the lunar surface normal – have important implications for both fundamental Solar System science and lunar exploration. However, extracting these characteristics from observations alone is challenging, and requires physics-based modeling to accurately predict the complex dynamics of the ejecta and its radiative evolution. Using CTH and ALE3D, numerical hydrocodes designed to model shock physics and material behavior at high strain rates, we conduct simulations of impacts into lunar regolith material, which provides detailed information on the state history of the material during the impact event. The ejecta formed in the impact is then postprocessed into a source term for the code HyperRISK, a numerical radiative transfer code that incorporates debris cloud evolution, which is then used to compute synthetic observations of the resulting impact flashes. These synthetic observations are compared with observations of actual lunar impact flash events and used to estimate their properties.
2021-04-07 08:00:00
