Northrop Grumman Aerospace Systems of Redondo Beach, Calif., said Oct. 28 that the James Webb Space Telescope’s optical telescope element passed its critical design review, clearing the way for final manufacturing and integration of all subsystems.

The optical telescope element will serve as the eye of the James Webb Space Telescope (JWST) and includes a 6.5-meter primary mirror, all associated mirrors and support structures.

Northrop Grumman is the lead contractor for JWST, a nearly $5 billion space-based observatory NASA expects to launch in June 2014 aboard an Ariane 5 rocket paid for by the European Space Agency.

Scott Willoughby, Northrop Grumman’s JWST program manager, said in a statement that completion of the optical telescope element’s critical design review allows the team to finish building the optical telescope subsystems, integrate them and deliver the completed optical telescope element for integration with the rest of the observatory.

The optical telescope element subsystems already in full production include the primary mirror segment assemblies, secondary mirror assemblies and an aft optical assembly containing the tertiary mirror and fine steering mirror, according to a Northrop Grumman press release.

The second batch of three lightweight Beryllium flight mirror segments is nearly finished with cryotesting at NASA’s Marshall Space Flight Center, Huntsville, Ala. The first batch of cryotested mirrors have been delivered to Tinsley Laboratories in Richmond, Calif., for polishing. Eighteen flight mirror segments in all will undergo a series of cryotests and polishing.