ETD

• damage
• impact
• Jutzi
• meteorites
• moon
• porosity
• scaling
• simulations
• sph

This thesis tests whether impact-scaling relations calibrated on pristine, laboratory targets remain valid when applied to a surface already modified by a previous impact. Using a three-dimensional Smoothed Particle Hydrodynamics model (PySPH, with an added Tillotson equation of state, P-alpha porosity model, Weibull-Grady-Kipp fracture model, and non-reflective boundaries), a mare-like target of damaged, porous regolith over intact basalt is impacted twice: once to calibrate the crater-radius scaling relation, and five more times at different locations on the resulting surface. In all five cases, inverting the calibrated relation underestimates the true impact velocity by 15-52%, because the reworked, rarefied regolith cannot support a well-developed shock, reducing the energy reaching the excavation flow. The modified target thus behaves as an effectively different material, not a locally perturbed one. Applying a single calibration across an entire crater population may therefore bias ages inferred from heavily reworked, saturated surfaces toward being systematically too young.