Mirror Segment for James Webb Space Telescope Delivered for Polishing

Manufacturing of the James Webb Space Telescope (JWST) progressed further with the delivery of the telescope’s first mirror segment for grinding and polishing in late September. Northrop Grumman Corporation is NASA Goddard Space Flight Center’s prime contractor for the space observatory, leading the design and development effort.

Tinsley Laboratories in Richmond, Calif., will perform high-precision grinding, aspheric polishing and testing at ambient temperatures on the mirror segment, which is an engineering development unit. The mirrors will be polished to tolerances as tight as 20 nanometers, or less than one millionth of an inch.

After initial polishing, the segments will be tested at roughly minus 400 degrees Fahrenheit (near absolute zero) in a cryogenic test chamber at NASA’s Marshall Space Flight Center in Huntsville, Ala., and returned to Tinsley for further refinement and polishing. The entire polishing process takes about two-and-a-half years.

“We’re using new manufacturing techniques and new facilities to produce unprecedented lightweight precision optics for the Webb Telescope,” said Martin Mohan, JWST program manager at Northrop Grumman’s Space Technology sector. “That the mirror segments are moving smoothly through a process with such rigorous specifications is a tribute to the manufacturing team’s expertise.”

Tinsley is part of a larger mirror-manufacturing team, led by Northrop Grumman’s principle lead optical contractor, Ball Aerospace & Technologies Corp. The team also includes Brush Wellman Inc., which recently completed making nineteen 500-pound hexagonal mirror blanks from beryllium, and Axsys Technologies Inc., which is now machining and etching the blanks.

The mirror segment is the first engineering unit to go through manufacturing and is being used to help fine-tune manufacturing techniques and equipment. Eighteen primary mirror segments, two secondary mirrors and a tertiary mirror will follow at Tinsley’s new Large Optics Manufacturing Facility. The 19th segment will be held as a spare.

When work is completed at Tinsley, the mirrors will be shipped to Ball Aerospace where they will be mounted onto a lightweight, actuated strong-back assembly and undergo functional and environmental testing. The final optical verification at cryogenic temperatures will then be performed by Ball Aerospace at Marshall Space Flight Center.

Following its launch, JWST will peer into the infrared at great distances to search for answers to astronomers’ fundamental questions about the birth and evolution of galaxies, the size and shape of the universe and the mysterious life cycle of matter. The space-based Observatory will reside in an orbit 940,000 miles from Earth at the L2 Lagrange point.

Tinsley is a subsidiary of SSG Precision Optronics, Inc. of Wilmington, Mass., and has performed optical work on NASA’s Great Observatories including the Hubble Space Telescope and the Spitzer Space Telescope. SSG Precision Optronics is a developer of major telescope and other opto-mechanical systems for spaceflight environments for both defense and civil applications.

Northrop Grumman Corporation is a global defense company headquartered in Los Angeles, Calif. Northrop Grumman provides technologically advanced, innovative products, services and solutions in systems integration, defense electronics, information technology, advanced aircraft, shipbuilding and space technology. With more than 125,000 employees, and operations in all 50 states and 25 countries, Northrop Grumman serves U.S. and international military, government and commercial customers.