Technology demonstration of large stable cryogenic composite structures for JWST

摘要

The need for JWST's metering structure to be stable over time while at cryogenic temperatures is derived from its scientific objectives. The operational scenario planned for JWST provides for the optical system to be adjusted on regular intervals based upon image quality measurements. There can only be a limited amount of optical degradation between the optical system adjustments in order to meet the scientific objectives. As the JWST primary mirror is segmented, the structure supporting the mirror segments must be very stable to preclude degradation of the optical quality. The design, development and, ultimately, the verification of that supporting structure's stability rely on the availability of analysis tools that are credibly capable of accurately estimating the response of a large structure in cryogenic environments to the nanometer level. Validating the accuracy of the analysis tools was a significant technology demonstration accomplishment. As the culmination of a series of development efforts, a thermal stability test was performed on the Backplane Stability Test Article (BSTA), demonstrating TRL-6 status for the design, analysis, and testing of Large Precision Cryogenic Structures. This paper describes the incremental development efforts and the test results that were generated as part of the BSTA testing and the associated TRL-6 demonstration.