The effect of thin deployable construction elements of the international space station on the probability of its hull penetration by meteoroids and orbital debris

When calculating the probability of hull penetration by meteoroid and orbital debris (M/OD) for some of the International Space Station (ISS) modules (e.g. FGB, Service module, cargo vehicle “Progress”), one has to take into account their additional shielding produced by ISS deployable construction elements (such as solar panels, radiators), which decrease M/OD penetrating probabilities. The lack of developed calculation methods of accounting for this effect has arisen the necessity to investigate the law— governed nature of particle fragmentation process accompanying high velocity penetration of thin barriers, as well as to elaborate techniques for correct calculation of the probability of no penetration (PNP) of module pressure wall. The results of thorough analysis of the theoretical and experime ntal published data as well as of data obtained in joint NASA and RSA experimental program on particle fragmentation are presented in this report in the form of normalized analytical correlation between the fragment maximum size and impact parameters. On the basis of above mentioned particle fragmentation law, the method of module hull ballistic limit curves (BLC's) recalculation is determined, which include the effect of thin barriers greatly distanced from the module hull. This BLC's are used for module PNP calculations with the help of modified version of NASA BUMPER code. The special subroutines accounting for PNP changes due to the particle collisions with ISS deployable construction elements are introduced in the BUMPER algorithm. The results of the Service module PNP calculations with account for its “shadowing” by solar panels and radiators are presented.