[MUSIC PLAYING] We're here at the Jet Propulsion Laboratory in Pasadena, California, home of Mars rovers. But it turns out the folks working here are doing a lot more than that. And I just happen to have here Dr. Mike Ressler. He is a MIRI project scientist. MIRI project Scientist-- a mouthful. What do you do in a nutshell? 

So MIRI is an instrument that will fly on the James Webb Space Telescope. And it's sensitive to infrared light rather than visible wavelengths. So we can see the heat from astronomical sources rather than the visible light that you see if you look through a telescope with your eyes. 

You are in charge of the production of the detectors? What exactly is the detector? 

The detectors are the sensors. So if you have a digital camera, there's a little electronic chip in the heart of the camera. And that's the sensor. It's what gathers the light from the lenses and converts it into a picture that you can look at it on your computer later on. So the instrument that we're working on does exactly the same thing. 

Let's take a look at it. And I think we have to get into bunny suits. Is that right? 

Well, smocks, to keep things clean. 

So much for getting my hair done today. One size fits all? 

Or one size fits none. 

Oh. 

We have a light source, basically a very sophisticated little light bulb, that's mounted in our test setup that's shining on the detector. And the detector is collecting light in steps. We can see that the detector is indeed very sensitive. It responds very well to light. By where it saturates, we can tell how bright a star we'll be able to look at once James Webb actually launches. 

All those bright spots are bright because they're supposed to be-- 

No bad pixels, no hot pixels-- everything's just as it should be. 

The detectors go through environmental tests. They're shaken and chilled to make sure they survive the rigors of space. 

So now it's time to do a final inspection of the unit to make sure nothing's happened to it while we were doing the testing. So we want to check it to make sure that nobody accidentally got a fingerprint on it. We want to make sure there are no broken wires or other damage to the unit. We want to make sure everything is just fine. So we're really wrapping up. And we're able to say this module is fully qualified and ready to go. 

The Mid-Infrared Instrument or MIRI has three detectors, all of which have to be precisely aligned with each other to within half the width of a human hair. Thanks for taking this tour with us Behind the Webb. 

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