W.Va. Observatory Scans the Universe for Radio Signals
Wednesday, November 19, 2008
How quiet is it in tiny Green Bank, W.Va.? It's so quiet you can hear clouds swirling around black holes in distant galaxies. So quiet you can detect collapsed stars the size of cities spinning like tops and make out planets revolving around faraway suns. Here, the National Radio Astronomy Observatory is shielded from human-created radio signals so astronomers can tune in to the music of the spheres. Here in the heart of a 13,000-square-mile, mountain-buffered "radio telescope national quiet zone" (established by the Federal Communications Commission 50 years ago today), silence is a virtue. Within a 10-mile perimeter of the observatory, cellphones are considered bad form. Not that they would work anyway, since the nearest cellphone tower is miles away.
It was a gorgeous fall day when I visited Green Bank, the drive passing through forests flickering with sunlight, then up and down five ridges and across narrow valleys splashed with farmland, meadows and little towns. After months of election news, I wanted a larger perspective, some real news about the Big Question: Are we alone?
My observatory tour started with a short film, followed by an entertaining talk from guide Steve Royer. He began by emphasizing how isolated this place is, how it was chosen precisely because of its lack of growth potential. In fact, the population of Pocahontas County, at under 9,000, is less now than it was 50 years ago. The site was also chosen for its proximity to Washington (close but not too close) and its location near the 38th parallel, which, because of the Earth's tilt, shows the most stars and therefore offers the fullest view of the galaxy.
Then it was time for amazing facts and figures. The telescopes here detect radio waves emitted from deep space; that is, waves between audio and infrared on the electromagnetic spectrum. In addition to possible alien radio and TV stations, lots of sources emit such waves: charged particles, heat and basically anything that oscillates. Because these waves are much longer than visible light waves, our eyes would have to be 30 feet in diameter to see them. Visible light waves are a hair's width; radio waves are three millimeters to three meters across.
With radio waves all around us, the observatory does its best to limit transmitters of any sort in the area, going to some surprising lengths. Only diesel vehicles are allowed near the big telescopes, since spark plugs can cause interference. An errant signal was once traced to a faulty electric fence in a nearby field; the observatory paid for a replacement. On another occasion scientists tracked a signal to an electric blanket in a local house. Not much could be done about another source: flying squirrels wearing radio collars. The squirrels, tagged in a study by the U.S. Fish & Wildlife Service, went wherever they pleased.
The tour continued on a minibus, taking in a kind of outdoor museum of radio astronomy. Among objects on display was the first radio telescope, built in 1937 by engineer Grote Reber in his own back yard outside Chicago and moved here. Elsewhere stood functioning radio telescopes of various sizes, each of them shaped like a huge satellite dish: a 45-foot-diameter instrument that found a black hole in the middle of the Milky Way and now tracks solar flares and spots, a 20-meter telescope that measures continental drift, a 140-foot telescope that first found polyatomic molecules in space, a 40-foot teaching telescope and an 85-foot scope that was used in the search for intelligent life beyond Earth. Starting in 1960, scientists such as Frank Drake and Carl Sagan worked here intermittently on this so-called Search for Extraterrestrial Intelligence, or SETI (which unfortunately rhymes with "yeti"), until funding was cut off by Congress in 1992. Now privately funded, the search has shifted its base of operations to California.
The road winds through a stand of long-needle pines, planted to absorb interference. Around a bend, looming like the giant ear that it is, stands the hulking GBT, the world's largest fully steerable radio telescope. The Robert C. Byrd Green Bank Telescope, or Great Big Thing to locals, rises 485 feet, its gleaming white dish as big as a football field. "Today," Royer tells us, "we're searching for red dwarf stars, the most prevalent stars in our galaxy." These older, colder stars may have planets, which are detectable from gravitational irregularities.
The GBT was built to replace a somewhat smaller telescope that collapsed one night in 1988. Metal fatigue made the whole structure buckle and fall, one beam spearing a toilet in a (luckily empty) restroom. The GBT was then built for about $80 million. Why? Practical purposes of radio astronomy have included new technology for TV reception and radar to improved weather prediction. Beyond this, radio astronomy continues to increase our knowledge of the universe and its origins.
We got out of the bus to stare at the telescope, sans digital cameras, which emit a signal. On the way back to the visitor center, Royer pointed out a cemetery. "That's where we bury people who use digital cameras at our GBT site," he said. It dates from the Civil War and holds the graves of people whose descendants still live in this unassuming county.
The give-and-take between observatory and community has made for a marriage of futuristic technology and rural hominess. More than 50 percent of the observatory's staff is from the surrounding county, more than 70 percent from the state.
Afterward, I wandered through the hands-on science center. There was a quote from Reber, who was 26 when he built the world's first radio telescope: "I was too young to know it wasn't possible." It was a good thought to carry back over the mountains and into the noisy world of not-so-big questions.