Not long time ago I was wondering how exactly is the robotic arm manipulating with JWST segment. I should see this:
The team uses a robotic arm called the Primary Mirror Alignment and Integration Fixture to lift and lower each of Webb's 18 primary flight mirror segments to their locations on the telescope structure. Each of the mirrors is made with beryllium, chosen for its properties to withstand the super cold temperatures of space. Each segment also has a thin gold coating to reflect infrared light. These mirror segments will function as one when the telescope is in orbit.
To precisely install the segments, the robotic arm can move in six directions to maneuver over the telescope structure. While one team of engineers maneuvers the robotic arm, another team of engineers simultaneously takes measurements with lasers to ensure each mirror segment is placed, bolted and glued perfectly before moving to the next.