In 2018, when the James Webb Space Telescope begins capturing infrared images emitted from the dawn of the universe at its station a million miles out in space, Utahns can proudly note that the 21-foot-diameter, 12-foot-deep backplane that supports the telescope’s 18 hexagonal mirrors was made in Utah by ATK at its Space Components Division’s facility in Magna.
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What’s more, the beryllium used to make the mirrors was mined and processed in Utah’s west desert. Beryllium is lighter and stronger than glass, and the Beehive state happens to be one of the only sources of concentrated beryllium in the world.
ATK program manager Bob Hellekson says ATK has been working on the telescope for about 11 years. One of the company’s challenges was inventing a backplane that could support the parabolic shape of the mirrors without expanding or contracting more than 38 nanometers–about 1/1,000th the thickness of a human hair–during the 14-day excursions when the camera shutters are open. As it sits in a balanced position between the gravity of the Earth and the gravity of the Sun, the telescope will experience temperatures ranging from 80 degrees Fahrenheit on the bottom side closest to the sun to -400 degrees Fahrenheit on the top side that faces away from the sun. So the challenge for ATK was to engineer carbon fiber composite structures that could experience such temperature extremes without expanding or contracting more than 38 nanometers. For reference, if the mirror were enlarged to span from Los Angeles to New York City, the tolerance for error would be less than one inch.
“This is totally state of the art,” says Hellekson. “This is ground-breaking technology to take a structure of this size with this kind of stability requirements down to -400 degrees Fahrenheit.”
At the peak of production, between 150-200 ATK workers, most of them located in Utah, helped engineer, test and manufacture the 10,000 components that make up the backplane and supporting structures for the telescope. In addition to the telescope structure, ATK is also providing cryogenic testing, the mirror actuators and systems engineering. While the $200 million contract for ATK Space Components Division’s portion of the $8 billion-dollar telescope is one of the largest contracts in the company’s satellite history, the company actually has its hand in nearly every satellite that goes into space.
ATK’s Magna location happens to be a global center of satellite work serving NASA, military, commercial and civil satellite applications. In fact, Hellekson says his organization is typically working on 10-15 different satellite systems at any given time. Nearly all the satellite structures the company makes involve a carbon fiber composite material known as prepreg; however, the company occasionally makes satellite structures from aluminum. For the Webb Telescope, ATK used state-of-the-art material sciences and advanced fabrication techniques. The composite parts attach in many cases to precision metallic fittings, made of precision materials such as invar and titanium that provide interfaces with other elements of the observatory.
Thin and Strong
He notes that composite structures are advantageous over metal because they are thin and strong, but lightweight. “If the backplane was a metallic structure it would be too heavy to launch,” he says. “We are at the capacity of rockets right now.”
ATK shipped the James Webb Space Telescope’s primary mirror backplane in August. The backplane will undergo extreme cryogenic thermal testing in a vacuum chamber at NASA’s Marshall Space Flight Center in Alabama, where it will be exposed to the temperature of deep space. The backplane will then travel to the Northrop Grumman Aerospace Systems facility in Redondo Beach, Calif., in early 2014 before NASA and Northrop Grumman ready the observatory for its 2018 launch. ATK has also delivered other components of the telescope to Northrop Grumman and NASA.
Because the telescope is the largest single satellite structure to be launched into space, the backplane and other components will have to be folded into the cargo space of a French Ariane 5 rocket. Once in orbit, the telescope’s backplane will unfold itself thanks to the folding “wings” designed by ATK. After the wings move into place, Hellekson says each of the mirrors has six “push me, pull me” actuators that will shape the mirrors into one uniform parabolic mirror. He adds that it took years of “hard science” to determine that the design was scalable into a world-class telescope.
The James Webb Space Telescope is a joint project of NASA, the European Space Agency and the Canadian Space Agency. It was designed to replace the highly successful Hubble Space Telescope that was launched in 1990. The Webb Telescope will be the most advanced astronomical system available to science–100 times more powerful than the Hubble Telescope with a 700 percent larger mirror. And while the Webb Telescope’s mirror is significantly larger than Hubble’s, its overall weight will actually be lighter than Hubble because of the ultra-thin, ultra-lightweight beryllium mirror segments, a new technology that was not available when Hubble was built.
What’s more, the Webb Telescope’s sunshield, which is the size of a tennis court, will have an SPF rating of more than 1 million, Hellekson muses.
Scientists hope images from the telescope will lead to new discoveries and unravel many of the mysteries of the universe. Themes the telescope will focus on include the assembly of galaxies, the birth of stars and what is called “First Light and Reionization” that occurred 13.7 billion years ago.
