NASA's Webb Telescope - Hubble's successor - gets its wings
16 March 2013
A massive backplane that will hold the primary mirror of NASA's James Webb Space Telescope nearly motionless while it peers into space, is another step closer to completion.
The latest milestone is the recent assembly of the support structure's wings, which enable the mirror - made of 18 pieces of beryllium - to fold up and fit inside a 5m fairing on a rocket, and then unfold to 6.4m in diameter after the telescope is delivered to space.
All that is left to build is the support fixture that will house an integrated science instrument module, and technicians will connect the wings and the backplane's centre section to the rest of the observatory. The centre section was completed in April 2012.
"This is another milestone that helps move Webb closer to its launch date in 2018," said Geoff Yoder, NASA's James Webb Space Telescope programme director.
Designed, built and set to be tested by ATK at its facilities in Magna, Utah, the wing assemblies are extremely complex, with 900 separate parts made of lightweight graphite composite materials using advanced fabrication techniques. ATK assembled the wing assemblies like a puzzle with absolute precision. ATK and teammate Northrop Grumman of Redondo Beach, California, completed the fabrication.
"We will measure the accuracy down to nanometers; it will be an incredible engineering and manufacturing challenge," said Bob Hellekson, ATK's Webb Telescope programme manager. "With all the new technologies that have been developed during this programme, 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 backplane must be very stable, both structurally and thermally, so it does not introduce changes in the primary mirror shape, and holds the instruments in a precise position with respect to the telescope.
While the telescope is operating at a range of extremely cold temperatures, the backplane must not vary more than 38 nanometers.
"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," said Charlie Atkinson, deputy Webb Optical Telescope Element manager for Northrop Grumman.
"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."
The James Webb Space Telescope is the successor to NASA's Hubble Space Telescope. It will be the most powerful space telescope ever built and observe the most distant objects in the universe, provide images of the first galaxies formed and see unexplored planets around distant stars. The Webb telescope is a joint project of NASA, the European Space Agency and the Canadian Space Agency.