Advanced shields for manned modules

For manned space missions safety requirements for shielding against space debris and meteoroid impacts are particularly stringent, which leads to heavy structural configurations. In order to decrease the weight of shielding systems without compromising the protection offered, or in order to increase protection performance while maintaining constant weight, modern shield concepts have been evaluated in laboratory impact simulation experiments. In this paper, existing "Stuffed Whipple Shield" Protection Systems, such as those used on the US modules of the International Space Station, are described. These systems consist of an Al-bumper and a a so-called "stuffing layer" consisting of a combination of ceramic (Nextel) and aramid (Kevlar) fabrics. On the European ISS module (COLUMBUS), the stuffing consists of Nextel and a layer of Kevlar composite material. New concepts for various bumper and stuffing configurations have been evaluated by means of hypervelocity impact expe riments. Constant areal weight has been maintained for all shield configurations, allowing direct comparison. Results are presented for Alfoam sandwich bumpers and bumpers of TiAl super alloys. A number of material have been implemented as stuffing layers: Kevlar fabrics, Nextel fabrics combined with Kevlar fabrics, Kevlar fabrics combined with polyurethane foam. Protection effectiveness of the individual configurations is discussed. It was found that the Al-foam sandwich bumper leads to extended projectile fragmentation due to multi-shock effects in the Al-foam, which yields an increased protection performance at only a slight mass penalty. Furthermore, due to the cellular structure of Al-foam, a much stiffer structure (compared to conventional single-plate Al-bumpers) is obtained. This allows considerable weight savings as less reinforcement materials are needed to stiffen the structure. Therefore, the Al-foam concept was combined with Kevlar stuffing, leading to a truly innovative shielding syste