While Chas and I were snowboarding in West Virgina, we visited the National Radio Astronomy Observatory in Green Bank. They have an enormous radio telescope — the largest moving structure on land, they claim. It’s built out of over 2,000 panels, and at the meeting of every 4 panels is a motor so that those panels can be adjusted relative to each other to produce a perfect reflecting surface.
The receiving equipment is mounted above the dish, and is kept around 15 Kelvin all of the time with liquid hydrogen. The electronics are all hand-made on-site, and mounted in brass. Brass is the only metal they have that will not shatter at operating temperatures.
Interesting fact: The area is covered by the National Radio Quiet Zone. It is 13,000-square miles of almost total radio wave silence. This only applies to ground-based transmitters; DirectTV and other satellites still blanket the area with transmissions.
They are absolutely ruthless about limiting interference. They have crews that will trace down any type of oscillating interference in the surrounding areas. They actually repair or replace old appliances for homeowners in the valley. No digital cameras are allowed within a safety zone, but regular film ones are. In fact, they have a large number of old vehicles in their fleet, not because they can’t get new ones, but because new ones are filled with electronics. They can only use diesel vehicles because diesels don’t need spark plugs, which generate RF interference.
When we took the tour, the guide did a physics demo with a Faraday cage, and a digital camera. Way cooler and more informative than any of the Physics classes I took in school.
I wonder if there’s a lower incidence of cancer among people who live in this area. Might be interesting to do a study and settle all the “OMG THERE’S RADIO WAVES IN YOUR HEAD, GIVIN YOU CANCERS”.
Also, you might be interested to know that there is allegedly a large chunk of ECHELON located down the street.