JWST Cryo Fine Guidance Closed Loop Test Results

The James Webb Space Telescope uses the Fine Guidance Controller to achieve pointing accuracy to a millionth of a degree needed for its scientific observations. This closed loop controller includes the Fine Guidance Sensor (FGS) instrument, the Attitude Control System (ACS), and the Fine Steering Mirror (FSM), all working together to generate precise attitude updates every 64 ms to stabilize and point the Observatory. It was exercised for the first time with the flight hardware during the cryogenic test at Johnson Space Center.