Engineers working on NASA’s James Webb Space Telescope have successfully folded and packaged a sunshade for a million-mile (1.5-million-kilometer) expedition starting later this year.
The sunshade, a tennis court-sized five-layer diamond-shaped structure, was specially designed to fold up around both sides of the telescope and fit into the scope of the Ariane 5 rocket launch vehicle.The folding is now complete at Northrop. Grumman in Redondo Beach, California.The sunshade will remain in this compact form through launch and during the first few days the observatory will spend in space.
Designed to protect the telescope’s lenses from any heat source that could interfere with vision, the sunshade is one of Webb’s most important and complex components.Because Webb is an infrared telescope, mirrors and sensors need to be kept at a temperature. Extremely cold to detect faint heat signals from distant objects in the universe
In space, one side of the sunshade always reflects light and background heat from the Sun, Earth and Moon. Thermal models show that the highest temperature of the outermost layer is 383 Kelvin, or about 230 degrees Fahrenheit. At the same time, the other side of the windshield is always exposed to space, with the coldest layer having a simulated minimum temperature of 36 Kelvin, or about minus 394 degrees Fahrenheit.
The telescope’s sunshade measures almost 70 feet by 47 feet (21 meters x 14 meters) when stored in rockets for firing.The folding sunshades are loaded in the confined spaces between the other observatory structures to support it. Limited space within a rocket fairing that is 18 ft (5.4 m) in diameter
“There’s nothing quite like what we’re trying to achieve with a tennis court-sized sunshade. But it’s similar to packing a parachute, ”said Jeff Cheezum, Northrop Grumman’s sunshade design engineer, Jeff Cheezum. A sunshade is needed for perfect storage to ensure it opens perfectly and maintains its shape so that it can be maintained. Telescopes at the desired operating temperature “
The month-long process of folding the sunshade begins with laying five layers as flat as possible. In functional conditions, the windshield resembles a multi-layered silver boat, so the inherently bent surface adds a level of sophistication to the process. After that, the rack is raised vertically and fixed on a special support so that its folding can be properly restricted. The technician team then carefully folds each layer in a zigzag pattern to form an accordion membrane on either side of the telescope.
The first shade is two thousandths of an inch (0.005 centimeters) thick, while the other four is only one thousandth of an inch thick. For teams, the inherent challenge is the subtleties of folding such a thin layer. The folding process also takes into account components such as the Sunshield’s 90 different tension cables, which must be stored in a specific way to Make sure the sunshade works smoothly.
With the success of folding windshields, engineers have prepared windshields for complex applications in space. The sunshade unfolds at the end of the first week of the post-launch space telescope, stretched to its full size, and then separates and pulls each of the five layers of tension. This unfolding and tension test was completed for the last time on Earth in December 2020.
“Think back, we want the functional sunshade to a specific shape to achieve the desired performance. The entire folding process is designed with that in mind. Be careful in the same manner every time to be sure. Exposure takes place the way we want. “Said James Cooper, chief engineer of the windshield for NASA’s Goddard Space Flight Center in Greenbelt, Maryland.
For example, one of the most complex aspects of the folding process involves the arrangement of membrane stacks. Each layer of the sunshade contains hundreds of intended holes, which are deliberately positioned to avoid light and heat from transmitted to the optical components of the telescope when the sunshade is installed. full These holes must be lined up during folding so that Webb technicians can insert a “pin” through the holes in each membrane stack. The “pin” or 107 “membrane ejection device will suppress the opening. body But it will release to unfold the sunshade when the telescope is in space.
“It’s a very organized process that we use to make sure everything is organized properly,” said Marc Roth, Northrop Grumman’s head of mechanical engineering. Much has been learned from the previous times that we took this step, all of which ended with this final folding of the sunshade. “
Over the next three months, engineers and technicians will finish storing and securing the packed windshields. This process involves installing the membrane release device, installing and securing all of the sunshield cables, and storing the cover for the sunshield. It also includes the two “arms” storage of the sunshade, the Mid-Boom Assemblies, which extend the sunshade horizontally during use, including storing the entire pallet structure. Two that hold the sunshade
The observatory will undergo a final glass installation before being transported to the launch site in French Guiana South America.
The Sunshield layer is incorporated into NASA’s James Webb Space Telescope.
Service provided by NASA’s Goddard Space Flight Center.
Reference: NASA’s Webb Telescope holds a shield for the one million-mile expedition (2021, April 7) .Retrieved April 7, 2021 from https://phys.org/news/2021-04-nasa-webb-telescope-sunshield. -million.html
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