Large retractable appendages in spacecraft

This is the first comprehensive review of large spacecraft appendages that are both deployable and retractable. Its aim is to gather information on retraction-specific issues, to guide the design, development, and ground testing of retractable appendages for future spacecraft. Following a survey of existing retractable booms and masts, solar arrays, and antennas, including examples of special latching systems, an extensive investigation of the in-orbit performance of appendages that were deployed and retracted in space during the last 25 years has been carried out. Remarkably, almost all appendages that had deployed successfully could also be retracted and, despite widespread concern about total reliance on electric motors for deployment and retraction, the evidence shows that practically all electric motors have performed well.