The James Webb Space Telescope is on its trek to a spot a million miles from Earth

MARY LOUISE KELLY, HOST:

The most powerful space telescope ever built has finally left the Earth. After years of delays, the James Webb Space Telescope lifted off from Europe's Spaceport in French Guiana on Christmas morning. Now, launch is just the start. The telescope has many a mile to go, both literally and figuratively before it's ready to operate. NPR science correspondent Joe Palca covered the launch and is here to give us an update on the mission.

And, Joe, I'm so excited to be talking to you about something other than COVID (laughter).

JOE PALCA, BYLINE: Yes, it's a nice break.

KELLY: It's refreshing. All right, so to the telescope. Tell us about those miles - the literal and figurative miles - that the Webb is going to have to travel. What's it up there to do?

PALCA: Well, the literal miles are the fact that it's traveling to a spot a million miles from Earth. It happens to be a spot where the gravity of the sun and the Earth balance each other out so the spacecraft can maintain the same position using a minimum of fuel. And it's going to take about a month for Webb to reach that spot. But there are a lot of steps to configure the telescope before it arrives. And if any single one of those steps fail, the telescope could be hobbled or worse, even become a piece of space junk.

KELLY: OK, I'm intrigued. A lot of steps. What - where do we start? What are the steps?

PALCA: Well, the telescope had to be folded up sort of origami-style to fit on the top of the Ariane rocket that carried it to space. And now it has to unfold. Now, and there's a lot of different parts that have to be moved into place. The first - NASA's Paul Geithner is deputy project manager for the Webb Telescope, and he says the first step was to extend the solar panels - the panel that the telescope needs for power. Next came the main antenna, so the telescope could communicate efficiently with Earth.

PAUL GEITHNER: Tomorrow, we'll start the big deployments.

PALCA: Geithner says tomorrow the telescope will begin to unfurl a giant sunshield that's critical for blocking out the sun.

GEITHNER: Most of the deployments have to do with the sunshield - most of the steps because that's where most of the complexity in deployment is.

PALCA: It's really complicated to get this thing to spread out to its size - its final size, about the size of a telescope. I've been trying to think of a good analogy, and it's a bit like taking a sail for a sailboat out of a box when it's been folded up and then hauling it up a mast all by remote control, you know, like, hundreds of thousands of miles from Earth. And the reason for blocking the sun out - it's crucial because the telescope is designed to work to measure infrared light, and its detectors have to be kept ultracold to work properly.

KELLY: Wow. It's a lot. OK, so is that it? Or is there more they need to do before they can actually see anything?

PALCA: Well, yeah, then they have to get the mirrors into place. The mirrors had two panels that were folded over. They're actually made up of 18 hexagonal mirrors made of beryllium and coated with gold. And when they're all aligned, they will create essentially one big mirror 21 feet across. That's big. And for comparison, the Hubble Space Telescope mirror is only eight feet across.

KELLY: And then once they get - if they get everything unfolded and working, what are scientists hoping to learn?

PALCA: Well, it's a pretty long list, but here are two examples. Jessica Spake is a research scientist at Caltech. She studies the atmospheres of planets orbiting stars outside our solar system. And she says Webb's huge mirror and infrared detectors will collect a ton of unprecedented data.

JESSICA SPAKE: We are seeing new molecules never seen before. And we're also going to be able to see much more signals, so much more planets will be available to study for us.

PALCA: And then another feature is that this telescope can look far into the past. Christina Williams is an assistant research professor at the University of Arizona. She says the Hubble Telescope can only see objects that were formed when the universe was already 400 million years old. The Webb will be able to see much earlier.

CHRISTINA WILLIAMS: I'm really excited to just see what's out there in this unexplored territory of the universe.

PALCA: Should be cool.

KELLY: Should be very cool.

Thank you, Joe.

PALCA: You're welcome.

KELLY: That is NPR's Joe Palca updating us on the progress of the most powerful space telescope ever built.

(SOUNDBITE OF KENNY SEGAL'S "LIMITED DAPS") Transcript provided by NPR, Copyright NPR.