The Mirrors Of The World’s Most Powerful Telescope

Piece by piece, NASA is installing the segments of the James Webb Space Telescope’s mirror. One dozen of the 18 that comprise the primary mirror have been put together. Each hexagonal-shaped segment weighs 88 lb. (40 kg) and stands 4.2 ft. (1.3 meters) across. The rest of the mirrors should be in place within months.

The mirrors make up just one component of the massive James Webb Space Telescope. They are being installed on the structure, which was lowered by a crane onto the yellow optical assembly stand.  

The first flight mirror, made of ultra-lightweight beryllium, was fitted onto the telescope structure in November. Ball Aerospace of Boulder, Colorado, is a subcontractor to Northrop Grumman on optical technology and the mirror system.

 

Each mirror must fit onto the telescope structure with extreme precision—smaller than the width of a human hair. Harris Corp. is installing the mirrors. 

A robotic arm installs a mirror segment onto the telescope’s structure. The structure must keep each mirror segment precisely aligned during the space launch and the telescope’s journey through frigid temperatures in space. 

When it all comes together, a secondary mirror will face the primary mirror. The secondary mirror, also convex, is designed to unfurl in space. Teams of engineers are working to ensure the arms holding the secondary mirror will line up properly. The tripod that holds the secondary mirror folds out from the telescope’s backplane, which was made at Northrop Grumman’s facility in Redondo Beach, California. The backplane supports the primary mirror segments as well as the Integrated Science Instrument Module (ISIM) and other telescope optics.