Abstract: This paper illustrates something of a 'potpourri' of activities related to passive damping, some of them incidental to the main thrust of the investigations in question. This paper is not intended to provide a full review of space related European activities in this field. A wider perspective may be gleaned from other works. An issue in current project developments is the impact of in orbit spacecraft equipment induced structural vibrations. Such microvibrations can be of concern for experiments requiring zero gravity conditions or for telescopes where jitter can disturb the pictures. Clearly a similar problem can emerge for very high stability antennas. Many of the ongoing passive and active damping studies are related to suppressing the effects of such unwanted vibrations of which examples of the former are given here. In conducting terrestrial experiments, the presence of air and in particular radiation damping is unrepresentative. Investigations into the importance of air damping are illustrated. Some of the devices under development that can be used to suppress these unwanted vibrations are outlined. They usually involve modifications to the connecting mounts of the vibration inducing equipment or those of the vibration sensitive instrument. Other possible means of passively (or actively) attenuating the levels of vibration in the spacecraft structure are briefly considered. Despite the sensitivity of viscoelastic materials to changes in frequency and temperature, their use in some applications is still foreseen. Some allied work to check prediction tools is presented together with a review of earlier work that can be used to predict the damping provided by pinned and similar connections. !12
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