The proposed research plans to provide a fundamental understanding of the behavior of light secondary attachments and equipment in large space structures under a variety of microgravity loading conditions. One main objective is to develop passive and active vibration control strategy for sensitive on-board equipment. Responses of light secondary systems and equipment aboard large flexible space structures and spacecrafts with or without vibration control devices will be analyzed. These systems and equipment will be subjected to acoustics, on-board moving (rotating) instrumentation, lift-off, micrometeroid impacts and maneuvering and deployment loadings. Deterministic and probabilistic techniques, as well as, digital simulations will be used in these analyses. The nature of tuning of secondary systems to space structures with passive or active vibration control devices will be critically examined. Particular attention will be given to performance analyses of frictional dampers for passive vibration control of equipment aboard space structures.