Pathfinder value for integration and test of the Webb Telescope optical system

The James Webb Space Telescope has extended our knowledge of the universe since the first images appeared last year with optical performance reaching the diffraction limit. The optical alignment and quality were tested prior to launch at cryogenic temperatures with a complex test configuration for this unique telescope architecture. This article reviews the strategic choices for pathfinding the integration and test processes for this telescope and the lessons learned prior to integrating and testing the flight hardware, leading to a successful integration and test campaign of the flight telescope. The biggest lesson was learning the value of investing in pathfinding integration and test activities.