Decoding the evolution of rear impact morphologies on the Hubble Space Telescope Solar Array

Front-back impact damage on glass faced I-IST solar cells generated by rear-incident impactors, has remained relatively unexamined in preference to front-incident phenomena. Representing in excess of one-third of the total damage on the retrieved I-IST solar array, front-back impacts are an important phenomena in the study of hypervelocity impacts in terms of scale, directional flux and their physical impact process. Preliminary analysis and comparison of 215 space and 41 laboratory generated impacts was performed. All front-back morphology classes observed on HST solar array were successfully reproduced by experimentation and their theorised progressive evolution with impactor energy verified. The rear-incident ballistic limit of the target was established. Spallation demonstrated a dependence with cone crack angle implying relevance to indentation fracture mechanics. Provisional damage equations were formulated on a morphology class basis.