This past Friday I was in Green Bank, WV shooting a segment for a PBS program I’m working on called “Big or Small - Measure it All!” Green Bank is home to the National Radio Astronomy Observatory, and these things (that is, radio telescopes) need to be in an area with ‘quiet skies.’ Since the people who actually do live in B.F.E. think that Green Bank is in the boonies, I guess you could say their skies are quiet. Also, very very dark at night.
Anyway, the big kahuna at the NRAO is the Green Bank Telescope - that’s ‘the GBT’ to Ph.Ds in the know - one of the largest radio telescopes in the world. Even more impressive is that the GBT is the planet’s largest movable object on land. The thing weighs 16,000,000 lbs. In nine minutes, it can spin 360° on its azimuth (that is, spin like a very large, slow top). Making that feat even more incredible, this is accomplished by the use of only eight 20 horsepower DC motors. I had no idea one horse could move 100,000 pounds. On top of that, the dish itself can be tilted from looking straight up to looking 5° off the horizon.

What did we do there, you ask? Well, we shot in the control room, which was interesting enough. The entire room is sheated in copper (behind the drywall), the window screens are copper connected to the room sheathing, and the door is also wrapped in copper, with a copper threshold. All this to shield the telescopes in the installation from any RF (radio frequency) noise from the computer equipment. Any motor vehicles heading towards the telescopes must be diesel powered, as regular engines with their spark plugs cause interference. Oh, and no cell towers or wifi allowed in the valley where the NRAO is located. Causes some problems with the locals.

It didn’t move like this while I stood on it.

So we drove out to the GBT, which was over a mile away but looked like it was next door because it’s so friggin’ huge. The telescope is down for maintenance right now - they’re replacing the circular track that it spins on - but they obliged us by tilting the dish from looking straight up to its most vertical position. The position they use when they need to dump snow off of its two acres of surface area. The operator we talked to told us he’s known it to take upwards of 20 minutes to dump all of its snow load.

Once we’d gotten a great shot of the tilting, we were taken up to the top of the feed-arm. That’s the part that sticks waaaaay up there. This meant an elevator ride up to a catwalk - one of those that’s basically a steel grate, so you can look all the way to the ground - a walk to another elevator, then a ride up into the sky. We stepped out to find ourselves hundreds of feet above the ground. One of the NRAO people we were with suggested that we could point our camera down at the surface of the dish and he’d walk out on it to give a sense of scale. I asked (okay, I kinda begged) if I could go along too. Ever since we started talking about shooting at this telescope, I’ve wanted to shoot the open to the program while standing on the dish. And we did it!

We took the elevator back down to a lower level and walked out on the surface. I have to say - two acres of white metal looks even bigger when you’re standing on it. We had to be careful to walk on the seams. The dish is made of over 2,000 individual panels, all of them controlled by servos in order to keep them positioned properly. This thing is so big and heavy that gravity would cause it to sag if they didn’t have a way to maintain its shape.

The red dot is the camera. The green dot is me. Not to scale. Well, the dots aren’t to scale, but everything else is.

The metal is painted with an infrared-scattering paint. If it wasn’t, well…picture a magnifying glass focusing sunlight on an ant, only the magnifying glass is 100 meters by 110 meters and the ant is the feed-arm. The drawback to us on the dish was that it was a sunny day and the infrared was scattering onto us. Got a little toasty out there.

We finished up the shoot with a shot of me starting with the telescope at my back and the camera very far away. I walked directly toward the lens and delivered my last line. Sped up, it’s going to be a cool ending to the show and will give the kids a sense of the massive size of this thing.

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