Abstract: In 2017, the James Webb Space Telescope (JWST) underwent functional testing and optical metrology verification of the combined Optical Telescope Element and Integrated Science Instrument Module (OTIS) under cryogenic vacuum conditions in Chamber A at the Johnson Space Center. Maintaining flight-like thermal boundary conditions was a critical requirement for optical testing and required unique and challenging Ground Support Equipment (GSE) design solutions. Two such GSE systems, the Integrated…