National Radio Quiet Zone

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It's not always best to let sleeping dogs lie. Consider the case of the heating pad and the radio telescope.

Several years ago, astronomers at the Green Bank Observatory in West Virginia detected some stray electrical signals that were interfering with their observations of the universe. Employees tracked the interference to a worn heating pad that a penned-up dog was sleeping on. The wiring was frayed just enough to create tiny electrical sparks. The observatory bought the dog a new pad, solving the problem.

Green Bank and a nearby Navy facility are protected from other types of radio interference by the National Radio Quiet Zone, which was created 50 years ago this week. Inside the 13,000-square-mile zone, there are strict controls on all types of interference, from radio and TV broadcasts to power lines to cell phones -- anything that might overpower the faint radio signals from distant stars and galaxies.

At the observatory itself, offices, computers, and even microwave ovens are shielded to block stray radio waves. And there's no cell phone or pager reception for miles. Orbiting satellites present a growing problem, but there's little the observatory can do to block them.

But when other sources of interference pop up, the observatory tracks them down. In one case, the culprit was a riding lawnmower at a nearby house. The owner agreed to finish his mowing later -- after an astronomical target had moved out of sight.

Script by Damond Benningfield, Copyright 2008

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