[MUSIC PLAYING] Because the James Webb Space Telescope will be searching for the heat coming from faraway objects in the universe, the observatory needs to be kept cold. The layers of its sun shield will separate from each other, much like this fan does, in order to keep the Webb telescope from heating up. To find out more about how this is all going to work, we've come to Northrop Grumman in Redondo Beach, California. Jud, I see that a test is about to happen here. What's going on? 

Yes, we're about to deploy the second half of the sun shield membrane assembly to see how the whole system works together. We're trying to verify that the behaviors of the sun shield pan out like we expect them to. If there are problems with the deployment, then we know how to fix the problems before we get into our flight production. 

How representative is it of the flight sun shield? 

These are about 90% representative of the flight membrane articles. They have similar coatings. And for the most part, the overall construction of the membranes are identical. As we deploy the sun shield, it unfolds in a controlled, organized manner. And that's allowing us to keep the membrane assembly, or the sun shield, safe during deployment. 

After the membranes deploy all the way out, we are then going to tension the membranes. And that's going to actually cause the five layers of the membrane to separate. Our main concern right now is to test the membrane interaction with the subsystems of the sun shield to make sure everything's functioning as intended. 

So when this test is done, will it look like the pictures we've seen of Webb? 

Actually, it won't look exactly like the images. The overall shape and size of the memory should be close. There are some differences that we won't be able to replicate. Because we are deploying in 1g of gravity on Earth. We won't be able to realize the real shape until we get up into space, where it's 0g, or weightless environment. 

Well, thanks, Jud, for showing us what you guys do to test out the sun shield. 

Sure. You're very welcome, Mary. 

The observatory needs to be protected from heat sources like our own sun. The suntan lotions you and I use have a maximum sun protection factor of about 100 or so. The Webb telescope sun shield has an estimated SPF of 1 million. Thanks for joining us for this edition of Behind the Webb. 

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