All spacecraft in low earth orbit are subject to hypervelocity impacts by meteoroids and orbital debris. Recent studies have shown that the nature of a spacecraft wall perforation can range from a flat hole with a jagged edge (i.e. a so-called cookie-cutter hole) to a hole accompanied by bulging, cracking and petalling. If a cracking event were to occur on-orbit, unstable crack growth could develop, which could lead to an unzipping of an impacted pressurized spacecraft module. It is therefore imperative to be able to determine whether or not a spacecraft wall perforation will be accompanied by either petalling or cracking. This paper presents the results of a study whose objective was to develop an empirical model that could be used to determine whether a spacecraft wall perforation would be in the form of a petalled hole or a cookie-cutter hole. The model consists of a petalling limit function that predicts the onset of petalling in terms of impact conditions and spacecraft wall system geometry. The model is used to show that the perforation of a spacecraft wall with an enhanced shield will always be accompanied by petalling and cracking, while the perforations of a Whipple-type spacecraft wall may or may not be petalled and cracked, depending on impact conditions.
