With Webb Telescope’s Mid-Booms Extended, Sunshield Takes Shape

"With the successful extension of Webb's second sunshield mid-boom, the observatory has passed another critical deployment milestone," NASA announced Friday, adding that the sunshield "now resembles its full, kite-shaped form in space..." The completion of the sunshield cover and mid-boom deployments over the past two days marks a critical milestone for Webb: all 107 membrane release devices associated with the sunshield deployment — every single one of which had to work in order for the sunshield to deploy — have now successfully released. Webb has 178 of these 'non-explosive actuators' in all; 107 were used to keep the sunshield safe and folded prior to deployment... While the deployments took longer than expected today, that was due to the operations team moving forward with caution and according to the protocols they laid out for dealing with unpredictable situations... The two mid-boom arms are now locked in their final position. They will hold the sunshield membranes in their proper place, as the team turns to the final stage in the sunshield's deployment: tensioning. In the coming days, the team will separate and then individually tension each of the five sunshield layers, stretching them into their final, taut shape. This will create space between the membranes to allow heat to radiate out, making each successive layer of the sunshield cooler than the one below... Sunshield tensioning will take at least two days but may take longer, due to the complexity of the process and the flexibility built into the timeline. Universe Today shares a video showing the complexity of the sunshield operation. Long-time Slashdot reader necro81 writes that "Unlike other nail-biting JWST events like the rocket launch, something of this size and complexity has never been attempted in space. "After this, the telescope's optics will be in the shade forevermore, and can begin cooling to the frigid operating temperature needed to detect infrared light."

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