NASA’s new Webb space telescope opens its golden ‘eye’

The world’s most powerful telescope unfurled its final mirror today as it sped away to its final destination one million miles from earth. NASA completed the final step of the Webb telescope’s difficult two-week initiation process Saturday, unfolding the final 21-foot piece: its ‘golden eye.’ NPR science correspondent Joe Palca joins Hari Sreenivasan to explain more about the telescope, its design, and its purpose.

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  • Hari Sreenivasan:

    The most powerful telescope ever launched into space made another successful step on its journey to a point a million miles away from Earth today.

  • NASA Control:

    It's called a batwing.

  • Hari Sreenivasan:

    NASA engineers working with a global team sent the commands that unfolded the final wing of the 21-foot primary mirror, revealing 18 golden hexagons in a honeycomb-like structure.

  • NASA Control:

    Look at that, the primary mirror is successfully deployed. NASA scientists narrated the deployment process using a live animated visualization. There are no monitoring cameras onboard the James Webb space telescope.

  • NASA Control:

    And, liftoff.

  • Hari Sreenivasan:

    The mission began 14 days ago on Christmas morning from French Guiana.

    Earlier this afternoon, as more steps in the process were being finalized, I spoke with NPR Science Correspondent Joe Palca about the telescope and its mission.

    Joe, first question. How do you make something unfurl in a part of space that you can't see, you don't have a live camera feed of, how do you send instructions back and forth and get that feedback?

  • Joe Palca:

    The instructions go through something called the Deep Space Network, which is this collection of giant antennas on Earth. And the way you know what's happening is this thing is festooned with sensors, and in some cases they don't even need sensors. For example, they can tell the motor's running when they can see current is running through the motor, so they don't actually have to see that the motor is turning. They know that if it's drawing current, it's doing something. And if it wasn't, it wouldn't be moving.

  • Hari Sreenivasan:

    If everything goes right, you know, fingers crossed there's lots of steps still left in this. What will we see?

  • Joe Palca:

    You know, this thing was built for one purpose or originally conceived of for one purpose, which is to see light from the most distant galaxies and stars. And the reason you need this telescope and not something like the Hubble Space Telescope, is that those distant objects are moving away from us so fast that the light is being stretched out. It's in what's called the infrared. And so you can't see it. If you're looking at it's like night goggles, you can't see anything. But if you look through an infrared telescope, oh yes, there I see a star or a galaxy. And so that's why they built this. But the crazy thing is, is that since they conceived of it, people discovered, Oh, there's planets orbiting stars outside our solar system and we could look at those with this telescope. That's crazy. We can do that. They didn't design it for that, but now they can use it for that. The final thing I'll say about what they're going to find is, they don't know. And that's the cool thing. When you give scientists a new piece of equipment and say, check this out, see what you can do with it. They're going to come up with interesting observations, and I was saying the first example of that is Galileo. Like he built the telescope well, he was looking around. He didn't know what he was going to find. He pointed it at Jupiter and suddenly he discovered moons around Jupiter. He didn't build the telescope because he wanted to know if there were moons around Jupiter. Nobody knew. Yeah, but he built it and he found them.

  • Hari Sreenivasan:

    You have been covering this telescope for years now. It has gone through so many different setbacks and project delays, and to see that it's this close, I'm sure that the scientists that you're speaking to are, pardon the phrase, over the moon about this.

  • Joe Palca:

    Well, there's two groups of people that are over the moon. One are the scientists who have been thinking and planning and hoping and dreaming, and they have been coming up with ideas about how to use this for the last decade or more. But the other people who are just ecstatic are the engineers because this is a really, really complicated piece of equipment. And as you say, it went through a lot of iterations, a lot of setbacks and a lot of this stuff that had to work exactly properly to unfold it because it had to be folded up to fit inside the rocket that sent it into space. The unfolding process had to work right. There was no way to fix it. And so what do you do if you're an engineer? Well, you test and you test and you test and you test, and then finally say, Well, I think we've checked it out in as many ways as we can. Let's see if it works and then you do this, which is probably not the official sign for years. But I think there's a little bit of I hope we thought of everything because there's nothing we can do about it now.

  • Hari Sreenivasan:

    So you're one of the few reporters who've gone and seen this thing in person. Put the scale of it in perspective for us who haven't seen it in person. What's it like standing in front of it? And give us an idea of what that challenge is to get all of these mirrors focused in on one specific spot.

  • Joe Palca:

    What you're first struck by it. It's about two stories tall, so it's about as tall as a school bus standing on its end. And I saw the mirror portion of it, it hadn't been attached to the Sun Shield, which is even a more complex thing. But what I was struck by was how perfect the optics are because I saw it being. It was lifted up into the air and turned and as it turned, I could see things reflected in the mirror and it was astoundingly clear. I mean, this is not your bathroom mirror. This is like the most fantastic mirror. And it's gold, which also adds to a certain cachet. So they put a gold coating on it because that happens to be good at reflecting infrared light. And so it just really gives you a sense of size and majesty, I would say that's a good word for it.

  • Hari Sreenivasan:

    Joe Palca, NPR Science Correspondent Thanks so much.

  • Joe Palca:

    You're very welcome.

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