The Webb telescope will experience intense forces as it launches into space. To ensure that the different parts of the observatory won't suffer damage during this stage of the mission, engineers shake them rigorously. These two- to three-week-long vibration tests are performed on each of Webb's 18 primary mirror segments and the secondary, tertiary, and fine-steering mirrors. Engineers test the mirror's optics before and after each vibration test to confirm that the simulated launch left the mirror surface unscathed, without deformation or structural changes.
NASA and Mary Estacion (STScI)
Publication: November 30, 2011