NASA’s James Webb Space Telescope aft-optics subsystem (AOS) has passed performance testing at Ball Aerospace & Technologies Corp., setting another optical milestone. Since last May, the AOS — a precision beryllium rectangular optical bench that houses the tertiary and the fine steering mirror installed at the center of the Webb’s primary mirror — has undergone thermal, vibrational and cryogenic testing to demonstrate its ability to withstand the rigorous vibration environment of the rocket launch and to remain precisely aligned to function at the extremely cold space temperatures. Ball Aerospace Technician Robin Russell inspects the Webb Telescope aft-optics subsystem during mirror integration acitivites. The aft-optics bench, made of lightweight beryllium like the mirrors, holds Webb’s tertiary and fine steering mirrors. The installed, gold-coated tertiary mirror can be seen in the background. Courtesy of Ball Aerospace. “Completing aft-optics system performance testing is significant because it means all of the telescope’s mirror systems are ready for integration and testing,” said Lee Feinberg, NASA optical telescope element manager for the James Webb Telescope at Goddard Space Flight Center in Greenbelt, Md. The AOS is surrounded by a shroud that eliminates stray light and by two large radiator panels that keep the assembly cold. The subsystem collects and focuses the light from the secondary mirror and feeds it into the science instruments. The device is the final optical subsystem in the Webb’s optical telescope element to complete integration and test activities at Ball Aerospace, the principal subcontractor to Northrop Grumman for the optical technology and lightweight mirror system. In September, Ball began shipping the Webb’s 18 finished beryllium primary mirrors to NASA Goddard. (See: Ball Ships First Webb Telescope Mirrors) The remaining mirrors will arrive at Goddard in 2013, awaiting telescope integration in 2015. The Hubble Space Telescope successor is on track for an October 2018 liftoff. September 2009 artist conception of NASA’s James Webb Space Telescope. Courtesy of NASA. “Each optical element that Ball Aerospace builds for the Webb is extremely sophisticated,” said David L. Taylor, Ball Aerospace’s president and CEO. “The successful completion of another milestone brings us one day closer to the launch of NASA’s next major space observatory.” The AOS will remain at Ball Aerospace to be used in integrated testing with the flight actuator drive unit and AOS source plate assembly. For more information, visit: www.jwst.nasa.gov or www.ballaerospace.com To learn more about the optics of the James Webb Space Telescope, watch the Photonics Media free webinar, Photonics in Space Applications.