Numerical simulations of hypervelocity collisions scenarios against a large satellite

This paper describes a set of numerical simulations of hypervelocity collisions involving the ESA LOFT spacecraft, with CubeSat impactors ranging from 1 U to 48 U and diverse collision scenarios. The study was done with the purpose to investigate (1) the transition between sub-catastrophic and catastrophic collision with increasing impactor's kinetic energy, and (2) the effect of impact point and encounter configuration on the collision severity.The simulations were performed with the new semi-empirical Collision Simulation Tool developed by CISAS-University of Padova (prime contractor) and etamax GmbH in the framework of an ESA contract recently completed. The CST makes possible to model a large variety of collision scenarios with spacecraft design details included, and is capable to provide statistically accurate impact fragments distributions with low computational expense. It is shown that (1) the ratio between the kinetic energy of the impactor and the mass of the target (Energy-to-Mass Ratio, EMR) is not sufficient to discriminate between sub-catastrophic and catastrophic impacts, and (2) the damage suffered by the target and the number of collision fragments are limited when impacts are not central and the ratio between impactor size and target size is small. In particular, results suggest that the NASA Standard Breakup Model overpredicts the fragments for glancing impacts and/or small impactors, showing that both the impact point and the size of the impactor at a given energy play a significant role to determine the severity of the event.