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| Sean Brady posted via Dennis DeBruler Polishing radio telescope bearing. This 17.5-foot hemispherical bearing is being machined to form the structural heart of the 140-foot (43-meter) telescope at the National Radio Astronomy Observatory (NRAO) in Green Bank, West Virginia, USA. When complete, it will support the full rotating weight of 2700 tons on a .005-inch thick oil film between it and the main hydrostatic pad supports. Cast by General Steel Industries it was then finished and polished by Westinghouse. Nearly 17 tons of metal were ground off during this process of getting the surface smooth with no bump more than .003 inches. The bearing still weighs in excess of 150 tons, and is one of the largest steel castings ever poured. Construction of the 140-foot telescope at Green Bank was completed in 1965. Sean Brady posted again Brian Peabody: Prosenjit Kumar Thakur The largest radio telescope at Greenbank is 100m, and is the largest fully-steerable telescope in the world. The offset mast is 485 feet [148m] high, the dish area is over 4 acres. Brian Peabody: Cecil Rivalto I was there two months ago, and it remains a radio-free zone, with pay phones along the nearby highway. The closer one gets to the telescopes, the more restrictive the electronics policy, with gasoline-engine vehicles limited to the visitor center parking lot. Those taking the (fascinating) tour of the facility have to turn off or surrender any electronics other than a pacemaker. Even my smartwatch was a no-no. I'm told that locals that want a microwave oven can use them only within an observatory-supplied Faraday cage. |
This telescope evidently has an equatorial mount because they talk about a polar shaft. I liked this old video because there was no background music, talking heads or platitudes. They also allowed some humor to sneak in. While this guy is hitting an aluminum girder with a hammer, the narration is "highly skilled craftsmen and very delicate construction equipment." At least the sledgehammer appears to have a rubber head.
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| 42:21 video @ 4:00 Making of the 140ft Radio Telescope |
And the narration during this scene was "everyone takes notice."
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| @ 15:27 |
I wish they labeled years on this timeline. I think this telescope is the one on the left. The next one has a date of 1962 and was 300'. At the time, it was the world's largest. The 100 meter one on the right side took a decade to build and went online in 2000.
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| 19:04 video @ 1:51 Seeing the Unseen [The Story of the Green Bank Telescope] |
The 300' telescope required major upgrades just a decade later, and it collapsed in 1988.
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| @ 2:47 |
After the development of using atomic clocks to synchronize data from multiple radio telescopes, I have wondered if a single dish telescope is obsolete. This video does explicitly say that the GBT (Green Bank Telescope) complements Alma and...
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| @ 11:44 |
... the very large array. The GBT was part of the recent detection of long gravity waves using pulsars. In fact, the first pulsars were found here.
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| @ 11:48 |
The observatory sets in a 13,000 square mile radio quiet zone that the FCC created in 1958. Not only are there no broadcast TV and radio in the area, but there is also no wi-fi nor microwave ovens. And I assume there are no cell phones. I read a few years ago about people coming to live here for health reasons because they felt radio waves made them sick. But I guess I didn't write any notes about Green Bank back then because I could not find them.
Indeed, there are no cell phones, they have pay phones along the roadside. [comments on Sean's second post]
It was a big deal when the local school was allowed to have WiFi like the other schools in the area.
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| GreenBankOvservatory The demand for the telescope is high enough that it operates 24 hours a day. So many homes were illegally using WiFi that they decided it was stupid to deprive the students of WiFi at 2.4GHz. And they now have a bigger problem with interference from phone and internet satellites. |
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| Kim Arbaugh posted Some of my very earliest memories was a cub scout field trip of about 65 miles to see the radio telescopes at Green Bank West Virginia. I was only about 5 years of age. My two elder brothers were Scouts. Some 40 years later, after a telecommunications career in the Coast Guard, I was an official visitor from 9-1-1 center Rockbridge County Virginia. Rockbridge County lies within the NARO Green Bank “Quiet Zone” and the FCC heavily regulates the output power of our Police, Fire and Rescue radios. I was privileged to go upon the 485 foot telescope structure and into the small receiver room above the middle of the 300 foot diameter dish. My 16 year old son was with me. Awesome experience. |
I developed an appreciation for how sparse this wilderness area is when I studied the "DGVR/C&O Bridge over Trout Run."
And the YouTube algorithm offered this video. The red square is the quiet zone.
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| 5:49 video @ 1:31 The Town Where Wi-Fi Is Banned: The Green Bank Telescope and the Quiet Zone "Power lines are buried 4' underground." Within a mile of the telescope, only diesel engines are allowed because spark plugs create interference. |
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