Dec 31

Day 6: Sunshield Booms begin to deploy

Portside boom now completely deployed. Credit: NASA

What’s up with Webb Home

1-1-22 UPDATE

Last night NASA posted,”Engineers began to deploy the second (starboard) mid-boom at 6:31 p.m. EST and completed the process at about 10:13 p.m. EST.”

Congratulations to the team! Both the port and starboard booms are now deployed and Webb is shining like a diamond. Next is tensioning!

Today saw the beginning of one of the most difficult Webb deployments so far, the sunshield rollout. The Webb telescope observes in ultraviolet light and needs to be kept very cold in order to collect the faint light from distant galaxies. A key component to keep the telescope cold is Webb’s sunshield. This large structure, the size of a tennis court, is made up of 5 layers of very thin material.  


The sunshield consists of five layers of a material called Kapton. Each layer is coated with aluminum, and the sun-facing side of the two hottest layers (designated Layer 1 and Layer 2) also have a “doped-silicon” (or treated silicon) coating to reflect the sun’s heat back into space. 

The sunshield is deployed by two booms, or arms, that pull it out outward from its stowed configuration.  Today, the first boom (the “port” side) pulled half of the sunshield out from its stowed position; the deployment was completed at 4:49 pm EST.

In the next stage, the second boom (the “starboard” side) will be moved.

And, we are not done for tonight! NASA just announced:

Shortly before 6:30 p.m., the team decided to proceed with deploying the starboard mid-boom tonight, and the initial steps of that deployment began just after 7 p.m.

Once both sides are fully deployed, the sunshield will then be pulled tight (or “tensioned”) to separate the layers from one another. It is these layers, and the gaps between them, that provide maximum thermal protection for the telescope and its sensitive equipment.