Hugoniots and Shock-melting Criteria for Solid and Porous H2o Ice

Introduction. Knowledge of the dynamic response of planetary minerals such as H2O ice is required to model and interpret mutual collisions and impact craters. The Hugoniot of H2O ice describes the dynamic strength and possible shock-compressed states, which determine the mechanical and thermodynamic work done during an impact event. Previous studies [1, and references within] of the shock properties of ice were centered at ~263 K for terrestrial applications. Because ices on most planetary surfaces exist at ambient temperatures much below 263 K, we conducted a detailed study of the shock response of solid ice Ih at 100 K and ~40 % porous ice at ~150 K to derive Hugoniots that are applicable to most of the solar system. Solid Ice Results. The wave profiles record twoand three-wave shock fronts (e.g., Fig. 1a), where each wave represents a different shock process. The present (100 K) and previously published (263 K) ice data are combined to derive five distinct regions on the ice Hugoniot: elastic shocks in ice Ih, ice Ih deformation shocks, and shock transformation to ices VI, VII and liquid water. The Hugoniot is expressed as linear fits between shock velocity, U , and the jump in particle velocity, S p u ∆ , for each wave in the shock front.