The subjects of radio astronomy are astronomically large, but the signals they produce are astronomically weak by the time they reach Earth. These emissions are measured in Janskys, named for the father of radio astronomy, Karl Jansky. A Jansky is based on 0.00000000000000000000000001 watts - and that's a big signal at Green Bank. Even a musical greeting card playing at the base of the telescope could produce anomalous spikes in the data of an unlucky astronomer trying to study stellar gases. If the interference is strong enough, the telescope's ultrasensitive first amplifier - cooled by liquid helium to minimize internal noise - shuts down.
Although just about any electronic or electromechanical device can blind Green Bank's telescope, the biggest culprit in the first category is the observatory itself. After all, it's a high tech operation crammed with sophisticated electronics and PCs. Green Bank director Jewell believes that some of the steps taken to mitigate interference at the facility may someday be adopted in the wider world, such as innovative circuit board designs and extensive shielding. The cafeteria's microwave oven is kept in a shielded cage. Large chambers designed to absorb radio waves - including a 5,000-square-foot conference room - have been built to make sure that, as Sizemore tells it, "radiation generated in the building stays in the building." Outside, spark plugs are notorious radio-frequency emitters, so Green Bank maintains a fleet of diesel-powered, electronics-free '69 Checker cabs and '70s Dodge trucks.
Needless to say, keeping the Quiet Zone quiet is getting progressively harder.
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