Design and development of the truss assembly fixture for Space Station assembly operations

The Truss Assembly Fixture (TAF) is a critical piece of flight support equipment (FSE) that will be deployed from the Orbiter payload bay (PLB) and utilized by astronauts to assemble the first sections of the Space Station. The TAF provides a base for assembly operations and also augments extravehicular activities (EVA) to minimize assembly timelines. The TAF utilizes several different mechanical systems to deploy itself and to position astronauts, equipment assemblies, and the Space Station during assembly operations. This paper describes the TAF design evolution based on the state of on-orbit assembly technology and the Space Station design. The main design requirements (e.g., launch packaging, station control, and astronaut reach) and constraints (e.g., astronaut mobility and EVA time) are identified, and interfacing systems (i.e., Orbiter and Station systems) are discussed. The results of testing performed to date, including full-scale engineering mockup evaluations in both laboratory and underwater neutral buoyancy environments, are also discussed. The efforts of the work performed to date have produced a design that minimizes on-orbit EVA time required to assemble the Space Station and provides an easily positionable platform for astronauts during assembly operations. The TAF preliminary design has been completed and validated through test simulations, and a baseline has been established for the design, development, test, and evaluation phases.