December 31, 2008

WiFi And Cell Phone Interference Spoils Pulsar Research

Experts say the Green Bank Observatory in West Virginia is under an audio assault from wireless computers and other gadgets cluttering the same frequencies occupied by signals from neutron stars.

Wesley Sizemore is an interference hunter, vigilantly pursuing stray electromagnetic signals that bedevil researchers at the National Radio Astronomy Observatory, which sits on 13,000 square miles tucked away in the nation's only radio-free quiet zone.

He and other scientists at the observatory mostly investigate pulsar waves that have traveled through space for billions of years. They often pursue signals so weak they can be easily foiled by anything from power locks on cars to a broken wire inside a heating pad that kept a nearby dog warm in the winter.

"There was enough arcing inside the heating pad that it caught our attention," Sizemore said, telling what he affectionately calls "that damn dog story."

Sizemore has a specially equipped truck and gear that can pinpoint an interference source the size of a 50-cent piece which he used to tracked a doghouse about 10 miles from the observatory.

Fortunately, he bought a new heating pad and all was resolved, although not necessarily amicably.

"It was a nasty little dog," Sizemore said. "He wasn't real happy with me snooping around his doghouse, put it that way."

Astronomer Scott Ranson said collecting data in today's technology-dependent world is like trying to look at stars while a neighbor is shooting fireworks.

He added that his ongoing study of neutron stars has been destroyed more than once by bursts of interference. During one particularly frustrating episode his team was completely swamped with interference and their data was useless.

"We didn't know where it came from. It was there for several hours over a course of a few days."

During the 1950s, Congress and the West Virginia Legislature created national and state radio quiet zones to protect and promote the relatively new science of radio astronomy.

The resulting Green Bank Observatory is unique amongst other observatories because it features the world's largest steerable radio telescope. The ultra-sensitive scope, completed in 2000, is taller than the Statue of Liberty and heavier than a fleet of Boeing 747s, with a reflective dish that could hold 60,000 people.

"We have to have a radio-quiet environment for the radio telescope to work," assistant site director Karen O'Neil said at a recent open house at the observatory. "If we start to lose radio frequency bands, the point of having a telescope here diminishes rapidly."

For that reason, the observatory's official motto is "Stay Quiet to Promote Science".

Visitors to the site, must walk, bike or ride to the giant telescope in a diesel-powered bus because diesel motors rely on compression instead of spark plugs to ignite. Guests must turn off digital cameras and use film to take pictures.

Sizemore said to prevent interference, even the signals from space received by the telescope are sent to computers via fiber-optic cable rather than wirelessly. Inside the observatory, walls are lined with copper, and computer equipment is housed in metallic cages that block radiation and protect the telescope.

The observatory doesn't have control over electronic interference from passing planes or satellites but it can weigh in on the proposed placement or upgrade of any fixed transmitter within the 13,000-square-mile National Radio Quiet Zone.

Therefore, the researchers have the authority to crack down on wireless modems and speakers and cordless phones within the 10-mile radius of the West Virginia Radio Astronomy Zone.

While the scientists try to be good neighbors, residents have generally accepted the precautions taken to reduce electromagnetic noise, but some are starting to question the limitations placed on their tools of the digital age.

County Commission President James Carpenter, who lives within Green Bank's extra-restricted 10-mile radius, said they feel they're a bit discriminated against because they created the zone around their neighborhoods.

"Our children can't have a wireless computer when everybody else in the state can have one."

The observatory's staff wants to accommodate residents, but the day may come when researchers will have to start "knocking on doors and asking people to get off their wireless devices."

"Without interference protection we might as well close up shop and go home," said Sizemore.


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