Webb telescope mirror work reflects well on Marshall Space Flight Center in Huntsville
Lee Roop | 
The Huntsville Times/Dave DieterTechnicians work on the mirrors of the James Webb Space Telescope following cryogenic temperature testing at Marshall Space Flight Center in Huntsville.
HUNTSVILLE, Alabama -- When NASA needed to perform critical tests on the mirrors for its next great space telescope, it turned to Huntsville's Marshall Space Flight Center.
Known for rocket propulsion, the center that engineered and managed the space shuttle's main engines, is also a grab bag of scientific and technical expertise and home to amazing facilities with varied technical and scientific abilities.
Consider the needs of the James Webb Space Telescope.
The heart of the $8 billion Webb is an array of 18 4-foot-wide hexagonal mirrors. They will ride to the telescope's ultimate destination 1 million miles from Earth folded up like an umbrella inside their transport rocket. Once there, they will unfold like an umbrella and focus faint, distant X-rays into a collecting chamber.
The telescope itself will "see" energy released by stars as far as 13 million light years from Earth. It will essentially look back to the beginning of the universe and answer key questions about the formation of the galaxies.
Because it will be so far from Earth, there will be no mission to fix Webb if it doesn't work. The mirrors must be right when they arrive at their final destination. To make sure they are, NASA decided to subject them to ingenious tests in a simulated space environment. Enter the Marshall X-ray & Cryogenic Test Facility.
The test facility is a house-size, cylindrical chamber resting on shock absorbers to prevent the smallest vibration of the mirrors.
During the tests, helium gas is pumped into the chamber to lower the temperature to almost minus 400 degrees Fahrenheit. Inside, the mirrors shrink or contract in the cold, just as they will in space. Technicians take detailed measurements of these changes.
Back outside the chamber, the mirrors are counter-polished so that when they are next in the chamber, and when they are in space, they contract to precisely the optics needed. A second round in the deep freeze proves that the counter-polishing worked.
Technicians from Ball Aerospace Co. in Boulder, Colo., actually handled the mirrors during each test, slow-walking them into and out of the chamber. The slightest bump or ding could have ruined the mirror surfaces made of strong, ultra-lightweight beryllium and coated with a thin gold surface.
Ball technicians also did the polishing. But the chamber itself is under Marshall control, and Marshall technicians managed each test series. When the tornadoes of April 27 shut down power to the center, Marshall technicians managed temporary power to keep a test going.
The mirrors aren't Huntsville's only contribution to Webb. A few miles from Marshall, technicians at ManTech International are producing five sunshields to protect Webb from the sun's heat.
Thinner than a human hair and the size of a tennis court, each test shield will take 18 months to build in a clean room at the ManTech International facility.
One contractor summed up the entire Webb project - and Huntsville's role - in a visit to Marshall this year.
"This is discovery and American ingenuity, something that's never been done before," said Scott Willoughby, project manager for the telescope's prime contractor Northrop Grumman.
It's also just another day for NASA in the Rocket City.