The scoop on the ﾑscopes
In the 50s, the United States entered a race. It may not be as famous as the race to put a man on the moon, but it was a race that left a lasting impression on Pocahontas County.
The race was to dominate in the exploration of radio astronomical research, a field the U.S. feared it was already behind in researching.
Developers scouted locations for the perfect place to create the National Radio Astronomy Observatory to stay ahead of the race.
The possible locations were narrowed down to three places: Massanutten and Deerfield, Virginia, and Green Bank, West Virginia.
On December 13, 1955, the Steering Committee selected Green Bank as the ideal spot for the observatory and construction of the site began in 1958.
Fifty-one years after construction began on the first telescope, the Green Bank NRAO is now home to 10 telescopes, not including the scope that fell.
So, letﾒs meet the residents of the NRAO. The telescopes.
The Howard E. Tatel Radio Telescope, better known as 85-1, is the first telescope to be constructed. It is one of three 85-foot telescopes at the NRAO. The 85-1 made many strides at the NRAO in the research of radio astronomy. It is best known for its use in Project Ozma, Frank Drakeﾒs first search for extraterrestrial intelligence.
The 85-1 is named for Tatel, who worked for the Carnegie Institute Department of Terrestrial Magnetism in the 1950s and collaborated with the Blaw-Knox Company of Pittsburgh, Pennsylvania to design a telescope for DTM.
The scope was used for measuring surface temperatures of Venus and the Moon and studies of Jupiterﾒs radiation belts. 85-1 was joined by the two other 85-foot telescopes in the mid 60s and became the fixed element in the three-element Green Bank Interferometer (GBI).
The GBI, three scopes working together as one, was used to study the rotation of Earth and monitoring of variable sources between 1978 and 1994.
Although the 85-1 had a life expectancy of 20 years, it is still in operation as part of the GBI.
Green Bank Pulsar Monitoring Telescope 85-3
Along with being one-third of the GBI, the 85-3 has been used since 1989 for monitoring pulsar timing and brightness for scientists at Princeton, Berkeley and Oberlin College.
An estimated 35 pulsars are observed every day by the 85-3.
Forty Foot Telescope
The Forty Foot Telescope was constructed in the early 60s. It was created for the purpose of determining if radio sources are variable. It is believed to be the first completely automated telescope.
In 1987, after sitting dormant for 20 years, the scope was recommissioned for use as an educational telescope. Students from fifth grade to graduate school use the scope to investigate the universe.
The 43 Meter (140 Foot) Telescope
Dedicated in 1965, the 140 Foot retired from service as an NSF user-instrument in 2002. The largest equatorial telescope in the world, the 140 Foot returned to service in 2008 as part of a collaborative project with MIT (Massachusetts Institute of Technology).
The 140 Foot is visible in the horizon along with the Robert C. Byrd Green Bank Telescope.
The 300 Foot Telescope
The 300 Foot was completed in 1962 is more famous for its demise than its works. The 300 Foot contributed greatly to the study of radiation undetectable by the eye. The first ﾓinvisibleﾔ radiation to be explored by the 300 Foot was the radio radiation.
On November 5, 1988, the 300 Foot collapsed due to the sudden failure of a large gusset plate in the box girder assembly that formed the main support of the antenna. The collapse was so large that many residents of Green Bank said they heard and even felt the impact of the fallen dish.
Green Bank 20-meter Telescope
Completed in 1994, the 20-meter Telescope was funded by the US Naval Observatory and was part of the National Earth Orientation Service telescope network and the USNO Navy Network, participating in a global program of Earth Orientation VLBI measurements in cooperation with the International Earth Rotation Service and with the NASA Space Geodesy program.
The program was discontinued in 2000 due to budget cuts, but the 20-meter is still in use by the NRAO. Experiments performed by the 20-meter are designed to measure small wobbling motions of the Earthﾒs polar axis and irregularities in the Earthﾒs rate of rotation in reference to positions of quasars.
The data is used for studies of continental drifts and for world-wide navigation systems.
Robert C. Byrd Green Bank Telescope
The new kid on the block, the GBT is the star of the NRAO. Completed in 2000, the worldﾑs largest fully steerable radio telescope is a one-of-a-kind telescope with a unique design unlike the other scopes in Green Bank. Instead of having a receiver arm meeting in the center of the dish, the arm is off to one side.
The design allows incoming radiation to meet the surface directly because the aperture is unblocked and increases the amount of useful area in the dish.
The first of its kind, the size of the GBT will never be duplicated. Instead, the NRAO plans to construct clusters of smaller telescopes to equal the power of one large scope.
The massive structure, which I have to remind everyone that Iﾒve been to the top of, has made huge strides in the study of radio astronomical research because of its size and design.
The Jansky Antenna
A full-scale replica of the antenna created by the ﾓFather of Radio Astronomy,ﾔ Karl Jansky, is on display at the entrance of the NRAO.
Although the antenna is for display only, it is important to know its history as well as its namesake.
Jansky began his career at the Bell Telephone Laboratories in Holmdel, New Jersey, in 1928. He was assigned the job of investigating the sources of static that would interfere with radio voice transmissions.
His antenna was designed to receive radio waves at a frequency of 20.5 MHz and was mounted on a turntable to allow it to rotate in any direction.
As he studied the static, he identified three types: nearby thunderstorms, distant thunderstorms and a faint steady hiss of unknown origin. Through further research, he discovered that the hiss was coming from the Milky Way.
With this knowledge, Jansky requested that Bell Labs build a 100-foot dish antenna so he could continue his investigation of the Milky Way. Bell Labs denied his request and assigned Jansky to a new project.
His study of radio astronomy was discontinued indefinitely.
If Jansky was the father of astronomy, then Grote Reber was its uncle or cousin. In 1933, Reber learned of Janskyﾒs findings and was influenced to study radio astronomy.
Because of the Great Depression, Reberﾒs attempts to work with Jansky at Bell Labs were denied because the company couldnﾒt afford to hire him. Instead of giving up, he decided to study radio astronomy on his own.
Reber singlehandedly built a radio telescope in his backyard in Wheaton, Illinois, in 1937. He built the telescope in his free time while working a full-time job at a radio company in Chicago.
Using his scope, Reber did the first systematic survey of radio waves from the sky. He continued Janskyﾒs exploration of the Milky Way and published results from his observations in both engineering and astronomy journals.
In the early 60s, Reber donated his telescope to the NRAO and supervised its assembly there. It was put on a turntable allowing it to point in any direction, but it is there mainly as an historical monument.
Most residents may know this scope as the red, white and blue telescope because it was painted in patriotic colors for the United States bicentennial.
The Ewen-Purcell Horn
Another antenna that serves as a display, The Ewen-Purcell Horn was used by Harold Ewen and Edward Purcell in the first detection of the 21 centimeter emission from neutral hydrogen in the Milky Way in 1951 at Lyman Laboratory of Harvard University.
Purcell received a $500 grant from the Rumford Fund of the American Academy of Arts and Sciences for the cost of materials for building the antenna, waveguide and electronic components.
It took Ewen and Purcell one year from receipt of the grant to detect the line emission.
Dutch astronomers followed Ewenﾒs frequency switching technique and two months later successfully detected the line.
Australian astronomers also detected the line soon after.
Observation of the 21 centimeter line remains a very integral part of radio astronomy to this day, resulting in a more detailed understanding of the interstellar medium in our galaxy and in the study of external galaxies.