Northrop Grumman Corp. delivered the first mirror segment for NASA’s James Webb Space Telescope, Northrop Grumman announced. The segment was sent to Tinsley Laboratories, where it will undergo high-precision grinding, aspheric polishing and testing at ambient temperatures to tolerances as tight as 20 nanometers.

After initial polishing, and testing at NASA’s Marshall Space Flight Center in Huntsville, Ala., the mirror segments will be shipped to Ball Aerospace where they will be mounted onto a lightweight, actuated assembly and undergo functional and environmental testing.