Both sides of the James Webb Space Telescope sunscreen are raised vertically in preparation for folding the sunscreen layer. Credit: NASA / Chris Gunn
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Engineers working on NASA’s James Webb Space Telescope have successfully folded and charged sunshades on the next million-mile (about 1.5 million km) journey, which begins later this year.
The sunshade – a five-layered diamond-shaped structure the size of a tennis court – is specially designed to fold around the sides of the telescope and within the boundaries of the launch vehicle, Ariane 5.Now folding is complete at Northrop Grumman on Redondo Beach, California, the sunshade will remain in its Compact form. during the launch and the first few days of the observatory will be spent in space.
Sun protection is designed to protect the telescope’s optics from any heat sources that could interfere with its vision, and is one of the Webb’s most important and complex components. Because Webb is an infrared telescope, mirrors and sensors must be kept in extremely cold temperatures to detect faint heat signals from distant objects in the universe.
In space, one side of the sun’s shield will always reflect light and background heat from the sun, earth, and moon. The thermal model shows that the maximum temperature for the outer layer is 383 K, or about 230 degrees Fahrenheit. Meanwhile, the other side of the sun visor will always face deep surfaces, with the coldest layer having a minimum temperature of 36 K, or around minus 394 degrees Fahrenheit.
When fully used, the telescope’s sunshade measures 70 feet by 47 feet (21 meters by 14 meters). When stored inside the missile for launch, the folded sun visor would encase in a very narrow area among other observatory structures to accommodate the confined space inside the missile enclosure which has a diameter of 18 feet (5.4 meters).
During the process of folding the sunshade for the James Webb Space Telescope, the engineering team carefully folded each layer in a zigzagging pattern to create an accordion-like pile of film on either side of the telescope. Credit: NASA / Chris Gunn
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“There’s nothing really like what we’re trying to achieve by folding the sun visor the size of a tennis court, but it’s like packing a parachute,” said Jeff Sheesum, chief engineer of solar surveillance design at Northrop Grumman. “Just as a skydiver needs its parachute to be properly packed in order to fully open and successfully return to the ground, Webb needs to store his sun visor in an ideal way to make sure it also opens completely and maintains its shape, in order to successfully sustain it in the required operation. temperature.”
The process of folding sunscreen for a month starts with five layers as evenly as possible. In its diffused state, the Sun Shield resembled a multi-layered silver ship, so its naturally curved surface added to the complexity of its movement. Then, the layers are lifted vertically and supported on a special support device so that they can be properly held so that they can be folded. Then the engineering team carefully folded each layer in a zigzag pattern to create an accordion-like stack of membranes on either side of the telescope.
The first layer of sun protection is two thousandths of an inch (0.005 cm) thick, while the other four layers are one-thousandth of an inch. For the team, the internal challenge was accurately folding this thin layer. The folding process must also take into account components such as 90 different pull cables for sunscreen, which must be stored in a certain way to ensure the sunshade spreads smoothly.
With the sunshade folding process successfully completed, the engineering team prepares the sun visor for its complex application in outer space. The sun’s shield will open at the end of the telescope’s first week in space after launch, enlarging it to its full size and then separating and fastening each of its five layers. This open procedure and stress test was completed for the last time on Earth in December 2020.
“Think about it backwards; we want the diffused sunshade to achieve the specified shape so that we get the performance we need. The entire folding process has been designed with that in mind. We have to fold neatly and carefully in the same way at all times, to ensure that we get the performance we need. “, Chief engineer sunvisor at NASA’s Goddard Space Flight Center in Greenbelt, Maryland:” The exposure happened exactly as we wanted. “
The James Webb Space Telescope released its main mirror in March 2020. A folded sun visor appears in this image. Credit: Northrop Grumman
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For example, one of the more complex aspects of the folding process involves the alignment of membrane piles. Each layer of sun protection contains hundreds of deliberate holes, which are deliberately arranged to avoid transmitting light and heat to the optical elements of the telescope when the sun visor is fully installed. These holes should be lined up during folding so that the web technician can insert a “pin” through the holes in each membrane unit. 107 “pins,” or membrane-releasing devices, will help to limit the coating when launched, but remove them to reveal the sun’s shield once the telescope is in space.
“This is a very systematic process that we use to make sure everything aligns correctly,” said Mark Roth, chief engineer of Northrop Grumman. “Our team has gone through several training sessions, and we’ve applied many lessons from the previous time we did this process, culminating in the last sunscreen fold.”
Over the next three months, engineers and technicians will complete stockpiling and secure the packed sunshades. This process will include installing a film removal device, equipping and securing all sun protection cables, and a storage cover for the sun protection film. It will also include storage of sun protection “sleeves” – middle sleeve kits – that will extend the sun visor horizontally outward during installation, as well as two structural pallets that hold the sun visor in place.
In addition, the observatory will undergo a final mirror deployment process before being shipped to the launch site in French Guiana, South America.
The protective layer of the sun is fully integrated into NASA’s James Webb Space Telescope
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Provided by NASA’s Goddard Space Flight Center
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quote: NASA’s Webb telescope packs sunscreen for a million-mile flight (2021, April 7) Retrieved April 7, 2021 from https://phys.org/news/2021-04-nasa-webb-telescope-sunshield-million. html
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