A Zone of Silence
In a remote corner of West Virginia, a unique regulation creates a 13,000-square-mile bubble of technological quiet. The National Radio Quiet Zone (NRQZ) was established by the Federal Communications Commission in 1958. Its purpose is to shield the sensitive instruments at the Green Bank Observatory (GBO) and the Sugar Grove Station from radio frequency interference. Within this vast area, which also covers parts of Virginia and a sliver of Maryland, radio transmissions are heavily restricted by law.
The rules are strictest near the observatory. On the GBO property itself, gasoline-powered vehicles are forbidden because their spark plugs create electromagnetic interference; staff and visitors must use diesel-powered vehicles. Personal electronics like cell phones and devices with WiFi or Bluetooth must be completely powered off. Even microwave ovens are banned due to the faint radiation they emit. This electronically-muted area allows the observatory's telescopes to detect faint whispers from the cosmos that would otherwise be drowned out by the noise of modern civilization.
The Great Big Ear
The main instrument protected by this legally mandated silence is the Robert C. Byrd Green Bank Telescope (GBT). It is the world's largest fully steerable radio telescope. The GBT's dish is not a perfect circle; it measures 100 by 110 meters, giving it a collecting area of 2.3 acres. Standing 485 feet tall and weighing nearly 17 million pounds, the entire structure can pivot to point at 85 percent of the celestial hemisphere.
The GBT is powerful because is its active surface. The massive dish is covered by 2,004 aluminum panels. The position of these panels is constantly adjusted by 2,209 small motors, called actuators, to correct for deformations caused by the telescope's own immense weight as it moves. This system maintains a precise parabolic shape with an accuracy better than 50 micrometers—roughly the thickness of a human hair. This precision allows the GBT to operate effectively at frequencies up to 116 GHz. The telescope has been used to discover the most massive neutron star yet found, detect new molecules in interstellar space, and search for gravitational waves by timing the pulses from distant pulsars.