redOrbit Staff & Wire Reports — Your Universe Online
The massive backplane that will help hold the James Webb Space Telescope´s primary mirror in place as it scans the night sky is now one step closer to completion, NASA officials announced on Friday.
The recent assembly of the primary mirror backplane support structure wing “is another milestone that helps move Webb closer to its launch date in 2018,” said Geoff Yoder, the telescope program´s director at the US space agency´s headquarters in Washington.
The wing assemblies were designed and constructed by aerospace and defense products supplier ATK at their Utah facility, where they are now scheduled to undergo testing. They have 900 separate parts, each of which were made from lightweight graphite composite materials using advanced fabrication techniques, NASA officials explained.
They will enable the mirror — itself built from 18 pieces of beryllium — to be folded and fit within a 16.4-foot fairing on board a rocket. The mirror will then unfold to 21 feet in diameter once the telescope is transported into space. The center section of the backplane was completed last April, and now that the wings have been finished, all that remains is to build the support fixture that will be home to an integrated science instrument module.
Ultimately, technicians will connect the wings and the center to the rest of the observatory.
“We will measure the accuracy down to nanometers — it will be an incredible engineering and manufacturing challenge,” explained Bob Hellekson, ATK’s Webb Telescope program manager. “With all the new technologies that have been developed during this program, the Webb telescope has helped advance a whole new generation of highly skilled ATK engineers, scientists and craftsmen while helping the team create a revolutionary telescope.”
The fully assembled primary mirror backplane support structure will weigh over 2,000 pound and will measure roughly 24 feet by 21 feet, according to the space agency. It needs to be extremely stable so that it does not alter the shape of the primary mirror, as well as hold the instruments in a precise position in relation to the rest of the telescope. Furthermore, according to NASA, when the successor to the Hubble Space Telescope is operating in extremely cold conditions (360 degrees below zero to 406 degrees below zero Fahrenheit), the backplane cannot vary more than 38 nanometers, or about one one-thousandth the diameter of a human hair.
“Our ATK teammates demonstrated the thermal stability on test articles before building the wing assemblies with the same design, analysis, and manufacturing techniques. One of the test articles ATK built and tested is actually larger than a wing,” Charlie Atkinson, the deputy Webb Optical Telescope Element manager for Northrop Grumman in Redondo Beach, California, said. “The mirrors are attached to the wings, as well as the rest of the backplane support structure, so the alignment is critical. If the wings distort, then the mirror distorts, and the images formed by the telescope would be distorted.”
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