The James Webb Space Telescope has successfully deployed all five layers of its tennis-court-sized sunshield, a requirement for the telescope’s science operations and the most tense part of its risky deployment.
Yesterday (Jan. 4), the difficult procedure, which required careful tensioning of each of the five hair-thin layers of the complex sunshield structure, was a complete success. Its completion came as a huge relief to the thousands of engineers who worked on the project over three decades, as well as the countless scientists around the world who are eagerly awaiting Webb’s groundbreaking observations.
“Yesterday, we did not think we were going to get through the first three layers,” Keith Parrish, the observatory manager for the James Webb Space Telescope, said in a live NASA webcast during today’s deployment. “But the team just executed everything flawlessly. We were only planning to do one yesterday, but that went so well. They said hey, can we just keep going? And we almost had to hold them back a little bit.”
A complex system of cables and motors pulling at the diamond-shaped sunshield’s corners was used to secure the right tension for each of the sunshield’s five layers.
The elaborate tightening of the sunshield’s diamond-shaped layers began on Monday (Jan. 3). NASA had expected that each layer would take one day to tension, but by the end of the first day, three layers had been successfully tensioned, with the final two tightened on Tuesday (Jan. 4).
The fourth layer was successfully deployed at 10:23 a.m. EST (15:23 GMT) as the telescope cruised 546,000 miles (879,000 kilometers) from Earth. The fifth layer was tensioned at 12:09 p.m. EST (1709 GMT) to cheers and applause from control teams.
“This is a really big moment, I just want to congratulate the entire team,” one of the operations managers could be heard saying in the web-stream upon confirmation of the fifth layer being completed. “We still have got a lot of work to do, but getting the sunshield deployed is really, really big.”
Because the James Webb Space Telescope is designed to study the universe at infrared wavelengths, or heat, it must be kept at extremely cold temperatures to prevent heat from Webb from obscuring its observations. The sunshield keeps Webb perfectly cold by reflecting both incoming solar radiation and heat from planet Earth.
Fully deployed, the sunshield will protect the telescope from the Sun’s radiation. It will reach a maximum of approximately 388K, approximately 233 degrees F, while keeping the instruments cold at a minimum of approximately 36K or around -394 degrees F. Credit: NASA
This sunshield deployment was thoroughly tested on Earth, but even the most sophisticated test lab cannot fully simulate the effects of weightlessness and other factors present in space. If something went wrong, the entire $10 billion mission, which took roughly three decades to build, could have been jeopardized.
The successful deployment of the sunshield means the Webb team can now proceed to the next nail-biting event: deploying the secondary mirror, a very important step. Later this week, engineers expect to be able to fold out the side wings on the folded up primary mirror.
After that, 5 1/2 months of setup still remain, including alignment of the telescope optics, and calibration of the science instruments. After that, Webb will deliver its first images.
How vulnerable us the sunshield to damage from meteorites etc?