Webb Telescope Mirrors Ready for Testing

The supplementary mirrors that focus the light from the primary mirror into the science instruments on NASA's James Webb Space Telescope have been integrated into the aft-optics subsystem (AOS) by Northrop Grumman Corporation teammate Ball Aerospace, Northrop Grumman announced in a news release Monday.

The mirrors are now ready for the next level of testing.

"Our teammates at Ball have done an outstanding job on all the mirror optics, including this integration," said Scott Texter, Webb Optical Telescope Element manager, . "It's the last major effort in manufacturing Webb's large optical components and represents a significant milestone for the observatory."

Northrop Grumman is the central contractor charged with designing and developing the telescope for NASA's Goddard Space Flight Center in Greenbelt, Maryland.

Ball Aerospace & Technologies Corporation, located in Boulder, Colo., is the primary subcontractor for the Webb optical system's design and integration.

"This represents the last piece of a complex, precision-engineered optical puzzle that will deliver unprecedented images," said Jeff Sokol, AOS lead engineer, Ball Aerospace.

The recently integrated optics consist of the tertiary mirror and the fine steering mirror, comprising the telescope's AOS. The mirrors are enclosed within a precision beryllium rectangular structure called an optical bench, which is installed at the center of Webb's primary mirror.

In addition, the AOS is surrounded by a shroud to keep out stray light, as well as two large radiator panels to keep it cold.

This subsystem then collects and focuses the light from the Secondary Mirror and feeds it into the science instruments.

Integration was completed in November and December of 2011, and consists of attaching several smaller assemblies to the optical bench and then aligning the two mirrors to one another.

"The challenge is to get the two mirrors properly aligned and to know where they are at ambient temperatures," said Sokol. "It's very important to know where they will move to once they reach the telescope's hypercold operating temperature of 40 degrees Kelvin or -387 degrees Fahrenheit."

The AOS will soon undertake a series of tests that will show that it will withstand the rigorous vibration environment of the rocket launch and still be precisely aligned and function as it should at its cold operating temperature in space.

Testing is scheduled to begin in May.

The James Webb Space Telescope is a multibillion dollar satellite designed to replace the ageing Hubble Telescope.

Previously:

• Space Park Named Historic Site
• James Webb Telescope Construction Moves Forward