Muzzle That Microwave! Welcome to Radio Quiet Zone

[Guest guest]

http://reuters.com/news_article.jhtml?type=sciencenews & StoryID=1260775

Muzzle That Microwave! Welcome to Radio Quiet Zone

Last Updated: July 28, 2002 10:12 PM ET

By Deborah Zabarenko

GREEN BANK, West Virginia (Reuters) - Welcome to the National Radio Quiet

Zone. Feel free to shout, play the tuba or let out a primal scream. Just

don't think about using a microwave oven.

One stray zap from a microwave -- or a car's sparkplugs, or even an electric

blanket -- in the heart of the 13,000 square mile zone could interfere with

science at the National Radio Astronomy Observatory at Green Bank, a patch

of forested Appalachia just west of the Virginia border.

The quiet that the zone is meant to protect does not refer to sounds humans

can hear; instead, it targets " noise " from human-made radio waves that might

blot out the faint radio signals from distant stars, galaxies and pulsars.

The newest instrument at Green Bank is the biggest: a radio telescope so

massive the Statue of Liberty, including the pedestal, could lie down on its

blindingly white observing surface with room to spare. Its 43-story height

and 16 million pound of tilting, turning mass make it the largest thing on

land that moves.

This $79 million telescope is so sensitive, scientists worry that even the

computers they use to monitor its workings could give off enough radiation

to pollute the data.

Its control room, which has perhaps as many desktop computers as a

small-town travel agency, located two miles from the telescope, has windows

covered with copper mesh shades and doors as heavy as those on bank vaults

to shield against radio interference.

RULES OF THE ZONE

Not many people stay at the zone's center in Pocahontas County, chosen in

1958 because it had the sparsest U.S. population density east of the

Mississippi and the surrounding mountains serve as natural radio wave

shields.

Those who live here, live by the rules of the zone.

This means, among other things, limited radio reception. Radio stations must

turn their transmitters away from the big telescopes at Green Bank so as

not to interfere with the instruments of the National Radio Astronomy

Observatory.

Cell phone towers are virtually non-existent. Wireless microphones are

forbidden. To get to the very middle of the installation, ordinary

petrol-powered vehicles are banned. Observatory staff use a fleet of

1960s-vintage diesel taxis and pick-up trucks, with no sparkplugs or modern

electronics.

" Interference is interference is interference, it doesn't matter where it

comes from, " said Wesley Sizemore, whose job it is to cut interference to a

minimum in the Quiet Zone.

FM radio stations and television transmitters are fairly easy, Sizemore said

in an interview; as long as they face away from the big telescopes, there is

no problem. And satellites overhead are usually transmitting at different

frequencies than those the scientists watch.

Garage-door openers and wireless microphones in the area close to the

telescopes can be problematic. So can a bad thermostat, normal power lines

or a heater's switch, Sizemore said. The most famous of the so-called

unintentional radiators was an old dog's heating pad.

NASTY DOG'S HEATING PAD

Sizemore generally gets a laugh from the tale of how he tracked broadband

interference to an elderly couple's home in the town of Green Bank, down the

road from the observatory.

" They had a little dog outside in the dog house and the dog was rather old, "

Sizemore said, chuckling at the memory. " I like most dogs, but this was an

exceptionally nasty little dog, so they had to kind of corral him while I

chased the interference. But I tracked it down to their dog house. "

The couple had given the dog an electric heating pad to lie on, but because

the pad was not meant to be used this way, it became defective and gave off

bursts of radio interference every few minutes, Sizemore said.

The solution was simple: the observatory got the dog a heating pad that was

made to be used outdoors.

" It cost us maybe $50...We're sitting here operating a radio telescope that

costs many hundreds or thousands of dollars an hour to operate and it was

basically receiving garbage, " Sizemore said. " So it's to our benefit and

it's good for public relations. Fifty dollars well spent. "

Some fixes are less basic. The nearby Snowshoe ski resort wanted to put in a

wireless local area network for their computers, but decided to hard-wire

the network instead to avoid interference.

SEEING THROUGH COSMIC DUST

There are other radio telescopes around the world -- one huge installation

is the Very Large Array in New Mexico, another is Arecibo in Puerto Rico --

but scientists believe Green Bank's big new telescope will be especially

sensitive to incoming cosmic signals.

Officially named for C. Byrd, the veteran senator famed for bringing

federal dollars to West Virginia, the new instrument is called simply GBT by

astronomers, short for Green Bank Telescope.

" The GBT will be such an enormous leap in sensitivity...a leap by factors of

10, which means a factor of 100 in observing time, " telescope scientist Jay

Lockman said in an interview. " So things which took many hours to detect

could be detected in seconds. "

When most people think of telescopes, they think of instruments that look at

the universe in waves of light. While these can produce startling and

beautiful images, they cannot see through the dust and gas of the cosmos, as

radio telescopes can.

One famous image made by the orbiting Hubble Space Telescope shows a

star-birth chamber known as the Pillars of Creation. Optical telescopes can

only see the chamber; radio telescopes can see inside it, Lockman said.

" The action is all inside, " Lockman said. " We can see that there are new

stars being born in there, but Hubble will never see it in a million years. "

He paused. " Well, maybe in a million years, but only because the stars will

have blown away the dust. "

LOUDEST PLACE IN QUIET ZONE

Ironically, one of the loudest places in the Quiet Zone is in the receiver

room at the top of the GBT. This is where incoming radio waves that have

been sensed by the big telescope's observing surface are channelled into

computers to be processed.

Ascent to the telescope's surface, which catches the incoming cosmic radio

waves, is done via a short flight of steps, an elevator and a long catwalk.

From there, another elevator goes up along a slanted track to the

instrument's towering sub-reflector, which bounces the radio waves down into

the reflector room.

A gentle chirping can be heard just outside the receiver room, but step

inside and the chirp escalates to a rhythmic mechanical shriek. This is the

sound of dewars, machines that remove as much of the atmosphere as possible

from the pipeline that carries incoming radio waves to computers to be

analyzed.

© Copyright Reuters 2002. All rights reserved.

www.reuters.com