Aligning the Primary Mirror Segments of the James Webb Space Telescope

Engineers at NASA’s Johnson Space Center in Houston used light waves to align the James Webb Space Telescope’s mirror segments to each other, so they act like a single, monolithic mirror in the cryogenic cold of the center’s iconic Chamber A. Part of the Webb telescope’s ongoing cryogenic testing in Chamber A at Johnson includes aligning, or “phasing,” the telescope’s 18 hexagonally shaped primary mirror segments so they function as a single mirror. All of these segments must have the correct pos