Webb is beginning to resemble the form it will take when it is fully deployed - now that the mission operations team has successfully deployed and latched into place the observatory's forward and aft Unitized Pallet Structures.

The team began working through the deployment of the forward pallet this morning, concluding at approximately 1:21 p.m. EST. The team then moved on to the aft pallet deployment, completing the process at approximately 7:27 p.m. EST. While the actual motion to lower the forward pallet from its stowed to its deployed position took only 20 minutes, and the lowering of the aft pallet took only 18 minutes, the overall process took several hours for each because of the dozens of additional steps required.

These include closely monitoring structural temperatures, maneuvering the observatory with respect to the sun to provide optimal temperatures, turning on heaters to warm key components, activating release mechanisms, configuring electronics and software, and ultimately latching the pallets into place.

The unfolding of the pallets marks the beginning of Webb's major structural deployments and also the beginning of the sunshield deployment phase - which will continue through at least this Sunday, Jan. 2.

The planned timeline of these deployments is laid out here but could change as the operations team gets deeper into the schedule.

Forward Pallet Structure Lowered
Earlier Tuesday's afternoon the Webb mission operations team concluded the deployment of the first of two structures that hold within them Webb's most unpredictable and in many ways complicated component: the sunshield.

The structures - called the Forward and Aft Unitized Pallet Structures - contain the five carefully folded sunshield membranes, plus the cables, pulleys, and release mechanisms that make up Webb's sunshield. The team completed the deployment of the forward pallet at approximately 1:21 p.m. EST, after beginning the entire process about four hours earlier. The team will now move on to the aft pallet deployment.

The deployment of the forward pallet required several hours of the mission operations team carefully walking through dozens of steps - only one of which was the actual motor-driven deployment to move the pallet from its stowed position to its deployed state. The lowering of the forward pallet also marks the first time that structure has conducted that movement since it underwent its final unfolding and deployment test in December 2020 at Northrop Grumman Space Park in Redondo Beach, California.

The deployment of the pallet structures begins what will be at least five more days of necessary steps to deploy the sunshield - a process that will ultimately determine the mission's ability to succeed. If the sunshield isn't in place to keep Webb's telescope and instruments extremely cold, Webb would be unable to observe the universe in the way it was designed.

The steps involved - outlined here - will continue after today with the extension of the Deployable Tower Assembly, followed by the release of the sunshield covers, the extension of the mid-booms, and finally the tensioning of the five Kapton layers of the sunshield itself.

As the deployment of the sunshield will be one of the most challenging spacecraft deployments NASA has ever attempted, the mission operations team built flexibility into the planned timeline, so that the schedule and even sequence of the next steps could change in the coming days.

Related Links
James Webb Space Telescope
Stellar Chemistry, The Universe And All Within It

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