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Listening for Life
Thomas R. Fletcher
"Do you search for alien life?"
That was the first question asked by a 12 year-old boy--part of a visiting school group at the National Radio Astronomy Observatory in Green Bank. The movie Contact and other entertainment forms prompt such speculation. However, NRAO (funded by the National Science foundation) is about much more than searching for alien life.
Radio astronomy is a branch of astronomy in which celestial objects are studied by examining their emission of radio-magnetic radiation. It is a fairly recent science, with its earliest roots only going back to the 1930's. It was then that a researcher for Bell Laboratories, Karl G. Jansky, discovered a source of extraterrestrial radio waves originating near the center of the Milky Way Galaxy.
Grote Reber, an astronomer and radio engineer, is largely responsible for the development of radio astronomy. Prompted by Jansky's discovery, Reber built the world's first radio telescope in 1937. He did it right in his backyard in Wheaton, Illinois. The 31-foot in diameter, bowl-shaped telescope must have presented quite a backyard sight. I'm sure it provoked some strange looks and speculation by his neighbors. Why was 31-foot diameter the size chosen? His building project was limited by the length of the boards he could obtain at the local hardware store. Mr. Reber's invention served as the world's only radio telescope until after World War Two. Mr. Reber's telescope is now on display by the entrance to NRAO.
The new science of radio astronomy actually extended the range of astronomical observation beyond optical limitations. The cosmic radio emissions, so far as is known, arise from completely natural processes, and has allowed a mapping of our universe using those radio emissions.
Of course, the subject of extraterrestrial life grips the interest of many, and the Green Bank facilities have been used for that purpose. In fact, the SETI group (Search for Extra-Terrestrial Intelligence) completed a four-year project at Green Bank and has now moved its research to the Arecibo facility in Puerto Rico. SETI was started by NASA (National Aeronautics and Space Administration) in 1992. The foundation for SETI's work was laid by astronomer Frank Drake's radio survey of the stars competed in 1960 at the Green Bank NRAO facility. SETI has since completed many such star-mappings. SETI's goal is to examine the radio emissions coming from the nearest 1,000 stars that most resemble our sun.
Realistically speaking, the odds of discovering extraterrestrial life using this technology is fairly slim. The life forms would have to have been using radio and have been sending out a signal to be received. The Green Bank facility is primarily concerned with studying the naturally occurring radio signals of our universe, SETI is searching for manufactured signals.
The National Radio Astronomy Observatory was established in 1956. The Green Bank site in Deer Creek Valley was the first National Radio Astronomy Observatory facility. It was chosen for several reasons. A low population meant little radio interference. Surrounded by National Forest land, future population growth would always be limited. The mountains form a ring around the valley, creating a natural bowl-shape, blocking out man-made radio signals. Today the site hosts several working radio telescopes ranging in size from 40-foot in diameter to the 140-foot equatorially-mounted telescope. There are three 85-foot telescopes, which are often linked together and used as an interferometer (combining the signals received from all three so they act as one large telescope).
Then there is the big boy, The Robert C. Byrd Green Bank Telescope, the GBT, or as it is sometimes called the Great Big Telescope. Its dish is 100 by 110 meters and is the world's largest fully steerable radio telescope. The dish is larger than two side-by-side football fields–and seems to dwarf even the surrounding mountains. It is composed of 2004 panels, each corner-mounted on actuators that allow the panel positions to be adjusted, changing the dish configuration. A wheel and track design allows the 16,000,000 pound telescope the mobility to take in the entire sky above five degrees elevation. The receiver arm of the GBT stands higher than the Statue of Liberty.
There are 115 people who work at the facility, only 12 of which are astronomers. During the course of a year, however, up to 250 astronomers from all over the world use the Green Bank facility.
Located about 30 miles north of Marlinton on Route 92/28, the Green Bank site is a leading center for the growing science of radio astronomy. The site is open for daily tours in summer (Memorial Day – Labor Day) hours are daily 8:30 AM – 7:00 PM. Free public tours start at the top of each hour 9 AM – 5 PM. Fall hours, starting the Tuesday after Labor Day though October, open Wednesday – Sunday 8:30 AM – 7 PM. Winter & Spring Hours: November through the Friday before Memorial Day Wednesday – Sunday 10 AM – 5 PM. There are no limitations on simple film photography. However, advanced electronic and digital cameras are prohibited as they cause “radio pollution” that can ruin the data being collected by scientists. A trip to the Green Bank site makes a great family outing and the scenery along the way is gorgeous.
Tours begin with a brief lecture on the purpose and function of the observatory. A brief film then delves a little deeper into those same matters. A bus tour of the telescopes is then given. Tours are free, on an individual basis. Group tours can be arranged, for a fee. School groups are exempt from these fees.
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Text and Photos Copyright Thomas R. Fletcher / PROSE AND PHOTOS