As each piece of the James Webb Space Telescope is built, it has to be tested rigorously, but the telescope at some point needs to be tested as a whole. Webb, though, is enormous, standing several stories tall. To make sure that the observatory will work in deep space, NASA has to use its biggest thermal vacuum chamber, the one here at the Johnson Space Center in Houston, Texas. 

Hi, Mary. 

Hi. 

I understand you can tell us more about what you guys are doing with this chamber. 

We embarked on a rather large construction project to get our thermal vacuum chamber ready for the James Webb Space Telescope. This chamber has a lot of history stemming back from Apollo times. The chamber itself was actually built in the 1960s to get ready for the space race. 

We see a nice wide angle of this. Can we get a closer view of what's really going on in there? 

We can go inside and take a closer look. 

Mary, why are you taking us out here? 

Well, these are the original liquid nitrogen tanks that we used for the testing of Apollo, and it contains all the liquid nitrogen we need to make the chamber below 300 degrees Fahrenheit. 

What are we going to see next? 

We're going to look at some of the things we've had to remove from the Apollo testing to get ready for James Webb, and go up to the fifth level. 

Solar lamps were part of testing for the Apollo. The vehicle needed to have a high intensity heat source on one side at a time. Some of them will be closed off, and some of them will be used to pass in new piping for helium. 

The helium was for what? 

The helium will supply, basically, like, a big soup can inside of the can of the chamber, which is going to make the chamber cold. 

Colder than the 300 degrees below zero that Apollo had to face? 

Colder than the nitrogen temperatures we had for Apollo. It'll make it-- it'll go below 400 degrees for the James Webb Space Telescope. 

Here we are at the fifth level entrance to the chamber, and I'll let our lead for test operations tell you what we have to do for the vehicle inside the chamber. 

As you can see, there's some work going on here. This scaffolding has just been erected. We're about to get ready to start installing the helium shroud. We have to mask up anything when we're done. There could be a crack or what we call a stray light path into the interior of the chamber. Any heat sources, any light sources, those would all affect the proper operation of the telescope. 

So we're down on the ground level? 

This is it. This is the floor of the chamber. What you're actually standing on now used to be an old Apollo lunar turntable. This part of the floor used to rotate, and that's one of the things that's been changed for James Webb. 

The mechanism that turned the floor had an oil based seal. Contamination is a risk for it, so that's been replaced and welded. The floor doesn't turn anymore. 

So now, you can see how NASA's past is paving the way for NASA's future. Thanks for joining us for another edition of Behind the Webb. 

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