Accessibility links

Green Bank Radio Telescope Probes the Universe - 2002-04-22


From the dawn of time humans everywhere have looked into the night sky and wondered such things as where did the earth come from, when did the universe begin and will it ever end? While the science of astronomy has helped create calendars, measures of time and mathematical systems, it has yet to answer those age old questions. Scientists hope a new telescope at the National Radio Astronomy Observatory, might bring the world one step closer to the answers.

Fifteen-year-old Carrie Bishop loves astronomy. So for her week-long spring recess from school, her family made the seven-hour drive from Canton, Ohio, down to Green Bank, West Virginia, to visit the world's most sophisticated radio telescope. "I'm really into science and I saw it on the map," she says. "It looked like something new and something different, a lot of fun."

Unlike other facilities, the National Radio Observatory doesn't have optical telescopes. Instead, it has eight radio telescopes, which detect and record celestial radio waves. Guide Cara Rose says many of the 30,000 visitors who come here each year are disappointed when they learn they won't actually be seeing outer space, but it doesn't take them long to realize how interesting radio astronomy can be. "With radio astronomy, what it allows us to do that's different than optical is study a source that does not emit a visible spectrum," she says. "For instance, a source that has cooled down. Stars are very hot and very bright visibly, but if the source has cooled down, it's more likely to emit a radio signal than visible light. So optically, we may never see that source, but it could exist there. So by using the radio telescope, we can actually detect it and study it."

During a slide presentation, Ms Rose explains that even though they're called radio waves, they can't be heard. In order to study them, scientists assign different colors to a radio wave's intensity. Then they can print out a computerized image of the phenomenon. Since the Observatory opened in 1956, research has been conducted on everything from the Big Bang, the cataclysmic explosion many scientists believe launched our universe 15 billion years ago, to black holes, those strange relics of collapsed stars that are so dense, even light can't escape their gravitational pull.

After the show, Ms. Rose takes the Bishops on a bus tour of the observatory grounds.

Only diesel-fueled vehicles are allowed in the telescope area. Because they have no spark plugs, they emit only low-level radio waves, which don't interfere with the scientists' work. "They chose Green Bank primarily because we're in a very rural area here and we have a very low population and things like household appliances, car engines and microwaves can cause interference to radio astronomy. So man-made interference is minimal," she says.

Along the tour route, Ms. Rose shows the Bishops the first antenna used to detect radio waves, the first radio telescope used to search for signals of extra terrestrial life, and the prototype for the telescope depicted in the 1997 Movie, "Contact."

But the main attraction is the Green Bank Telescope, built two years ago. "The Green Bank telescope is the world's largest fully steerable radio telescope," she says. "The dish is 100 by 110 meters and it stands 150 meters. The telescope is also the largest moveable structure on land. The moveable weight is 7.2 million kilograms."

Although the telescope, which looks like a gigantic gleaming white satellite dish, covers nearly a hectare, control of its mechanical movement is extremely precise. Because it's moveable, it can view 85 percent of the sky, more than any other radio telescope. Until scientists are sure its accuracy will stay consistent, it will be used for less important projects. For example, it has already mapped the cloud-covered surface of the planet Venus.

Scientist Jay Lockman says he was honored to be chosen as one of only a hundred people to work fulltime at the Observatory. He's mapping the edge of the Milky Way Galaxy. "The Milky Way is our own home galaxy and it has an atmosphere, a gas that is in between the stars," he says. "I'm interested in the transition between the gas in the Milky Way and whatever else is out there in the universe. The power of the telescope can be used to search for extremely faint radio emissions from the gas."

This year alone, the telescope has detected three new pulsars, remnants of massive stars which have exploded… mapped a new image of the Orion Nebula… and discovered that the Milky Way has an abundance of matter left over from the early universe, which should help unravel the mysteries of the Big Bang.

Mr. Lockman says that because the observatory is a non-profit educational facility, telescope time is loaned out, freely, which means he often gets to meet and sometimes work with scientists from all over the world. "There were astronomers from the Soviet Union coming here to use these telescopes all the way through the Cold War. From China, from Japan, certainly Argentina recently, Europe of course," he says. "So it really has a reputation as an international facility in many ways. If you're interested in astronomy, quite quickly you'd hear the name Green Bank."

The Observatory has an on-site dormitory for visiting scientists, who typically spend an average of 50 observation hours a year at the facility. But you don't have to be a world-renowned astronomer to use the telescopes. Teachers may also use the observatory for class projects… something Carrie Bishop can't wait to tell her classmates. "It made radio waves a lot easier to understand than (how) my teacher explains it and how the book puts it," she says. "I think I'll do better in school now."

Testing of the new Green Bank Radio Telescope will soon be finished. Astronomers predict that once it is operating full-time, the telescope will enable them to peer farther into deep space than ever before, sparking a wave of important discoveries about the nature and origins of the universe. Student Carrie Bishop hopes that someday, she'll be one of the scientists making those discoveries.

XS
SM
MD
LG