ABSTRACT
The focus of this chapter is on the long-term wear and tear, or aging, of the mechanical subsystem of a spacecraft. The mechanical subsystem is herein considered to be the primary support structure (as in a skeleton or exoskeleton) upon which all other spacecraft systems rest, and the associated mechanisms. Mechanisms are devices that have some component that moves at least once in response to some type of passive or active control system. For the structure, aging may proceed as a gradual degradation of mechanical properties and/or function, possibly leading to complete structural failure over an extended period of time. However, over the 50 years of the Space Age, such failures appear to be unusual. In contrast, failures for mechanisms are much more frequent and may have a very serious effect on mission performance.1
