STEVE INSKEEP, HOST:
Let's turn our gaze now beyond the clouds and up to space. The space agency NASA has been working to assemble a huge mirror. They intend this to be the centerpiece of a huge telescope. It'll be far more powerful even than the famous Hubble Space Telescope. NPR's Geoff Brumfiel has been watching this come together at NASA's Goddard Space Flight Center in Maryland.
GEOFF BRUMFIEL, BYLINE: Inside a giant building here sits a hulking metal tank the size of a small house.
LAURA BETZ: This is where the heart of the telescope is inside right now.
BRUMFIEL: NASA's Laura Betz is taking me on a tour to see pieces of the new telescope called the James Webb Space Telescope. In this tank are it's delicate cameras and instruments. They're being subjected to conditions similar to what they will experience when they're launched into deep space.
BETZ: So it's very, very cold.
BRUMFIEL: While engineers test this hardware, the telescope's massive mirror is being built in a neighboring facility that's essentially a giant, ultra-clean gymnasium. We can't go inside for risk of contamination. But we meet crew chief Dave Simm at an observation deck, where we can see the mirror below.
BETZ: And here's Dave.
DAVE SIMM: Hi, how are you?
BRUMFIEL: Nice to meet you.
SIMM: Good to see you again.
BETZ: Good to see you.
BRUMFIEL: Simm's normally in there assembling it. When he is, he has to wear a white bunny suit that covers every inch of his body.
SIMM: The only thing exposed is your eyes.
BRUMFIEL: For months now, he's been working 10-hour shifts. His job is to take 18 hexagonal mirror segments, each about the size of a coffee table, and attached them to the telescope's cob-web frame. When everything is done, the mirror will look like a giant golden satellite dish, two stories high. Simm points to a table covered in books filled with assembly instructions.
SIMM: Each one of those notebooks down there is for one mirror.
BRUMFIEL: And we should say, each one of those notebooks is about the size of a phone book.
BRUMFIEL: So it's a - it's a little more involved than IKEA furniture.
SIMM: Yeah, definitely.
BRUMFIEL: Or at least the instructions are more thorough.
SIMM: (Laughter). They're more thorough, correct.
BRUMFIEL: And everything has to be by-the-book. At $8 billion, the Webb telescope will be one of the most expensive things NASA has ever built. Its segmented mirror is so big that once in space, it will have to unfold like an elaborate piece of origami. And to make observations, it needs to be a million miles from Earth - so far that no astronauts could fix it if it breaks. So why is NASA building this thing? The answer, says astronomer John Mather, is pretty simple.
JOHN MATHER: Every time we build a bigger or better piece of equipment, we find something astonishing.
BRUMFIEL: Webb is designed to capture light from the first stars and galaxies, light that's been traveling for billions of years across the universe. It will probe the atmospheres of potentially habitable planets outside the solar system. Mather is the telescope's project scientist at NASA, and he's pretty sure it's going to do other things too, things we haven't even thought of.
MATHER: When Galileo pointed his little bitty telescope at the sky, he saw there are mountains on the moon. There's satellites of Jupiter. There's spots on the sun. And none of that was known. It was all a surprise. And we're pretty sure we're going to get some big surprises because it always happens.
BRUMFIEL: But before Webb can discover its surprises, workers are going to have to finish putting the telescope together. Even after they complete the mirror, there's still quite a few instruction manuals to go. It won't launch until 2018. Geoff Brumfiel, NPR News.
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