The effect of high-velocity impacts of meteoroids and space debris on the strength of glass in the windows of the International Space Station modules

The effect of meteoroid and space debris particles on spacecraft is one of the factors that have a significant impact on the reliable and safe operation of long-term manned space stations including the International Space Station (ISS). It is recognized that the required level of the ISS safety can only be achieved through the use of special protective aids (shields) in the module structures. It is impossible to use these shields on the windows of the ISS modules, since in the course of the mission some experiments involving imaging require that the windows stay open and their external panes are exposed to particles of micrometeoroids and space debris. In this connection, of special note is the estimate of the effects of the particle impacts on the damageability and the associated reduction in durability of the glasses, because only the understanding of the process of damage propagation can make it possible to predict the longevity of safe operation of windows and station as a whole. When the question of extending the station life was raised, the need arouse to conduct work to evaluate the probability of window glass failure in the presence of damage on glass surface. To address this problem, theoretical studies had to be conducted and confirmed through experiment. This paper presents the results of experimental and theoretical research in the strength of window glass damaged by particle impacts required for evaluating the remaining endurance. This research made it possible to provide a rationale, with a sufficient degree of confidence, for extending the life of windows on the Russian Segment of the ISS and determine their remaining life at an actual moment in time.