(Updated) First three layers of Webb telescope's sunshield fully tightened: Why the deployment is critical?

The five-layer sunshield keeps sunlight from interfering with the sensitive telescope instruments including the infrared cameras and mirrors. Each successive layer of the sunshield is positioned and separated with precision and is cooler than the one below.

The first three layers of NASA's James Webb Space Telescope's kite-shaped sunshield have been fully tightened, meaning they have been stretched into their final, taut shape. Tensioning for the remaining two layers is planned for tomorrow.

According to NASA, the tensioning process of the three layers, which are the closest to the Sun, took just over five and a half hours. Once fully deployed, the tennis court-sized sunshield will protect the telescope from the Sun's radiation.

"This was the hardest part to test on the ground, so it feels awesome to have everything go so well today. The Northrop and NASA team is doing great work, and we look forward to tensioning the remaining layers," said James Cooper, NASA's Webb sunshield manager, based at Goddard Space Flight Center.

The layers start coming and they don’t stop coming…Layers 2 and 3 are now complete! Tensioning for the final two layers of Webb’s 5-layer sunshield is planned for tomorrow. More: https://t.co/rD9IOD9gX4 #UnfoldTheUniverse pic.twitter.com/BaQKwd2MuO

— NASA Webb Telescope (@NASAWebb) January 4, 2022

The five-layer sunshield keeps sunlight from interfering with the sensitive telescope instruments including the infrared cameras and mirrors. Each successive layer of the sunshield is positioned and separated with precision and is cooler than the one below.

The tennis court-sized sunshield separates the powerful space observatory into a warm, sun-facing side, with the outermost layers having a modelled maximum temperature of approximately 383K (approx. 230 degrees F) and a cold side with the coldest layer having a modelled minimum temperature of 36K or around -394 degrees F).

The James Webb Space Telescope was launched on an Ariane 5 rocket from French Guiana on December 25, 2021. Touted as the world's largest and most powerful space science telescope, Webb will answer outstanding questions about the Universe and make breakthrough discoveries in all fields of astronomy. It will complement and extend the discoveries of the Hubble Space Telescope.

Update 1

The Webb team has completed the sunshield deployment following the tensioning of the fifth and final layer of the flagship telescope.