Modeling Damage in Spacecraft Impacted by Orbital Debris Particles

Long-duration spacecraft in low Earth orbit such as the International Space Station (ISS) are exposed to high-speed impacts by pieces of debris from past Earth-orbiting missions. Among the hazards that accompany the perforation of a pressurized manned spacecraft are critical crack propagation in the inner wall of a multi-panel module wall system, crew hypoxia, and uncontrolled thrust due to air rushing out of the module inner wall hole. These phenomena are directly related to the hole diameter and crack lengths in a spacecraft inner wall following a performation. A new empirical model of hole diameter and maximum tip-to-tip crack length for some of the multi-wall systems being developed for the ISS is presented and discussed. The model is used to show that 1) hole diameters and crack lengths are directly related to the momentum of the impacting projectile, and 2) properly constructed hole size and crack length models based on data obtained at moderate impact velocities (i.e., approximately 6 to 7 km/s) can be used successfully to predict hole size and crack lengths at impact velocities exceeding 11 km/s.