REDONDO BEACH, CA - The Northrop Grumman Corporation team developing the James Webb Space Telescope (JWST) reports successful testing of the software that will be used to bring the space observatory’s 18 mirror segments into alignment following launch. The test is a key step in verifying that the mirrors will produce clear images of the first stars and galaxies formed in the universe following the rough vibrations and disturbances during launch.
Conducted at the Keck Observatory in Hawaii in mid-June, the test demonstrated the accuracy of the coarse-phasing (or rough-focusing) mode developed for JWST’s Wavefront Sensing and Control System (WFS&C). Test data will be used to enhance the accuracy, reliability and speed of WFS&C software during commissioning. According to Northrop Grumman, the WFS&C provides the telescope’s “tuning ability,” and coarse phasing is one of several processes that will be used to achieve proper alignment for science operations following the space observatory’s deployment.
The tests were performed at the Keck Observatory because its twin 10-m telescopes, like JWST, feature large, actively controlled, segmented, hexagonal mirrors, and the same process used on the ground at Keck will be used in space to align JWST’s mirrors.
“Actively controlled segmented mirrors are the industry standard for large ground-based telescopes, but JWST will be the first space observatory to use deployable, active segmented mirrors,” said Martin Mohan, JWST program manager, Northrop Grumman Space Technology. “The success of this test gives us confidence that we’ll be able to adjust the telescope to meet the mission’s stringent science objectives.”
The test was conducted by Northrop Grumman’s teammate, Ball Aerospace & Technologies along with NASA’s Jet Propulsion Laboratory, using prototype hardware and flight software developed by Adaptive Optics Associates.
The WFS&C is designed to give the JWST the ability to reduce structural and optical deployment uncertainties through the use of electronics and motors. The system software processes images from a science camera to measure optical aberrations, then computes mirror motor commands to correct the aberrations, eliminating the massive and rigid structures required to maintain optical precision by traditional space telescopes.