Applying HST lessons learned to JWST

The James Webb Space Telescope (JWST) is a 6.5 meter cryogenic observatory planned to launch in 2013. The observatory includes a three mirror anastigmat telescope with a deployed 18 segment primary mirror. Unlike the Hubble Space Telescope (HST), JWST will be difficult to service and therefore the development team needs to be highly confident the telescope will work after launch. Consequently, it is imperative that the team building JWST apply the lessons learned from the HST program so as to avoid repeating mistakes that led to a major optical error in HST. The purpose of this paper is to summarize what the JWST program is doing to apply the lessons learned from HST. It includes a summary of how the HST optical error was made, the lessons learned there from, and how the JWST program is applying these lessons to avoid the mistakes of the past and ensure correct JWST optical performance.