Green Bank, WV, is home to a telescope that needs electromagnetic silence | Hacker News Reader

Green Bank, WV, is home to a telescope that needs electromagnetic silence

popularmechanics.com

52 pointsspking33 comments

Green Bank and the local town is a really cool place. It's a shame to see that some people are giving up on the attitude that's helped protect the telescope's ability to perform amazing science.

My undergrad work used some data from that telescope, and I've spent a few different weeks out on site at various times.

The article mentions the use of diesel vehicles, but neglects to mention that the presence of control electronics is making it harder and harder for the facility to use modern diesel vehicles as the radios, ECUs, and in many newer vehicles even the ignition system radiates vast (relatively speaking) amounts of unwanted radio. When I was there a decade ago, they were lamenting the loss of a couple late-60's or 70's model diesel trucks (see this short article from autoblog with images https://www.autoblog.com/2014/04/24/national-radio-astronomy...) that were just beyond further repair at that point.

I was friends with some summer interns out at GBT during late 2000s, and they mentioned how the student housing at the time didn't have computers, as it was in direct line-of-site of the telescope and the building wasn't shielded well enough. So they had a notepad on the fridge which was for "consulting the oracle" the next day. If the group had a question that required research/google, it was jotted down and they took turns looking it up the next day and emailing the group with the collected answers.

On another tangent, I've heard from some people out that way they're starting to run into some problems with people claiming to be "Electro-sensitive" seeking refuge in the town, then causing hell with the local population and in some cases even trying to blame the observatory for "transmitting". (note this claim is all hear-say from friends who worked there or know people who worked there)

Old diesel vehicles are horrific polluters.

It sounds like this telescope needs to be relocated to the Moon. There just aren't many places on this planet left where you can avoid EMI/RFI, and where anyone would want to live.

This unscientific and non data backed opinion simply isn't contributing towards meaningful dialogue.

But what about the post you're replying to?

Ultimately the telescope will have to find a way to cope with the modern EM environment. Moving off-planet does have some incredible advantages if the budget is there. Failing that, modern signal processing can work miracles, compared to what was available when the Green Bank site was commissioned. I assure you that forcing everyone in the vicinity to drive older diesel vehicles is not the right solution, whatever the problems may be.

In the 1990s, only the vehicles used on the observatory property were antique diesels. The people in the surrounding area drove normal cars and pickups. I imagine it is still the same.

This is exactly the case. There's a small perimeter zone around the sensitive telescopes where unshielded/unapproved vehicles are prohibited, unless otherwise scheduled for some reason. This small area is the only place where these antique diesels are in use. They are in no way forcing the people in the nearby towns to use diesels or anything of the sort.

The energy required to put anything on the Moon is immense. Meanwhile, pollution from rockets is not well understood yet: https://www.scientificamerican.com/article/how-much-air-poll.... Meanwhile, a telescope on the moon would be pointing at the sun (a very bright radio source, mostly due to proximity) for long periods at a stretch.

TLDR: the moon probably isn’t an ideal location.

> ...and in some cases even trying to blame the observatory for "transmitting"

But doesn't it transmit?

Most radio receivers use the superheterodyne principle, where the idea is to combine the signal from the antenna with another one that is generated by the receiver. As a result radio receivers tend to emit signals close to the frequency they are tuned for.

Note that I don't believe that electrosensitivity is anything but psychological. I am just curious to know if there is at least some truth in that statement.

Green Bank Observatory does not intentionally transmit, and any leakage would hardly exist for long, since the whole point is to listen to extremely weak signals.

However, a radio telescope differs from your usual radio receiver in that the stages are often separated by vast distances. I'm unfamiliar with the exact signal chain used in GBT, but I do have plenty of experience with a similar scale telescope, the Arecibo Radio Observatory.

A radio telescope will go to huge lengths to reduce the system noise of the receiving elements, including cryogenically cooling the receiver and first few stages of amplification. These signals will then often be brought down within a shielded enclosure (often within a shielded receiver room) and shifted into their intermediate frequency (IF) stage with a highly pure local oscillator (LO) signal and brought back down to the control/electronics building.

In the case of both GBT and Arecibo, that IF is brought down as modulated light over fiber optics, meaning that there is no RFI leakage possible on the transport. And at both, the conversion back to IF is done within a shielded room. At GBT, if I remember correctly, that room is within the Jansky Lab, which was designed as a shielded building.

All of this is to say that it's very unlikely that there is any signal at all transmitting out of the telescope system in any way.

Just noting that a superheterodyne receiver doesn't transmit on purpose, it's just mostly that it generates an internal frequency reference some multiple of the target frequency that has a tendency to leak out. For a normal radio this isn't too relevant as the signal isn't particularly strong or in a frequency range where it'll mess with anything.

As a bit of an aside: The intermediate frequency leaking is how the police can detect if you're using a radar detector (for avoiding tickets from speed cameras for instance). Of course listening to a faint signal like that is best done with a superheterodyne receiver, so there are radar detectors that detect if the police are using a radar detector detector nearby, which is then in turn of course called a radar detector detector detector.

wikipedia has some more info: https://en.wikipedia.org/wiki/Radar_detector#Counter_technol...

I actually interviewed for a position as a software developer at the GBO towards the end of my senior year in college. When describing the area to me, I distinctly recall the lead developer saying, "There is urban, suburban, rural, middle-of-nowhere and Antarctica. We are in between middle-of-nowhere and Antarctica". He also said the nearest grocery store was an hour away by car. Obviously the location was not for me, but they were doing some really exciting things.

Seems more like exactly “middle-of-nowhere” to me. It’s not like you can only get in or out for half the year, and even then, only by plane.

Heh. Everything I know about the Green Bank Telescope, I know from The Adventure Zone podcast, which set their second major story — Amnesty — there. If you've never tried it, I highly recommend it :-)

I used to work at the Very Large Array, which didn't have the same radio quiet zone that GBT did, so we were in charge of chasing visitors' cell phones down with a handheld spectrum analyzer and a small horn antenna. People became very uncomfortable when they're were being approached by a person holding a scientific instrument. https://n0ssc.blogspot.com/2013/05/what-im-up-to-at-vla.html

To be fair, you could hardly build a scientific device that looks more like a ray-gun than the thing in that picture!

I go camping in that area quite frequently. It’s almost certainly in my head but there’s something calming about it. It might just be fewer cars and planes overhead than, say, Canaan Valley to the north.

A friend and I had been talking about visiting NRAO/Green Bank for some years and in 2006 we finally decided on a weekend. When I went to look up some information on visiting, I discovered we had unknowingly picked their 50th anniversary weekend! It was a great trip and we got to see more than the usual tour. The drive out was beautiful (it was in the Autumn). The Bird Telescope is impressive.

United States National Radio Quiet Zone which also covers Sugar Grove.

https://en.wikipedia.org/wiki/United_States_National_Radio_Q...

There is a section of Interstate 81 where you can't tune into any radio stations. I believe that this installation is the reason for this "dead zone".

This is a really cool place to visit if you're ever passing by. We went about 1.5 hours out of our way to check it out one time and it did not disappoint.

The Great Courses series has course on radio astronomy hosted by Dr. Felix Goodman, an astronomer at Green Bank. One episode provides a close look at the telescopes located at GB including the big 400-foot dish. It's an interesting watch if you're interested in science and astronomy and want to know more about radio astronomy. The technology behind the telescopes is truly fascinating.

Observation: The Moon (in the near future) and Mars (in the far future) -- would be great places to install radiotelescopes that require electromagnetic silence...

There is also a NSA center in that area

Sugar Grove

What about the earths magnetic field? Is the telescope calibrated towards it already or is it too weak to influence humans on earth and only capable of influencing solar winds?

Depends on what you mean with influence, humanity has used magnetic compasses for a fairly long time.

The magnetic field itself doesn't vary fast enough to emit radiation at the frequencies the GBT observes at.

Obligatory Tom Scott video: https://youtu.be/eQEGPATQe5s

Would mandating 5Ghz help?

No, that just means restricting people to only using one colour for despoiling the canvas of nature.

Does it, though? The range of 5GHz networks is (fairly) significantly lower than 2.4GHz higher frequencies are more easily attenuated by buildings (and even air), so I'd perhaps wrongly expect it have less of an impact than 2.4GHz.

Maybe you can use it without interfering from slightly closer, but they have very sensitive receivers and loss of usable connection doesn't mean complete loss of signal.

It might actually be worse that the signal degrades quickly because that makes it harder to identify as artificial.

Ideally, you'd mandate wireless usage at 60 GHz. 60 GHz is strongly attenuated by oxygen in the air[0]. In fact some military satellites use it for secure communication between satellites because it's strongly attenuated by the atmosphere[0]. And while you would think that a band that is the most attenuated by oxygen in the air would be the absolute worst for wireless communication, there's oddly a wifi standard that uses it[2] for communication at speeds up to 7 Gbit/s. While the speed is high the range is only up to 10 meters and it doesn't penetrate walls. [0]https://cdn.everythingrf.com/live/atomspheric-absorption_636... [1]https://en.wikipedia.org/wiki/V_band#Uses [2]https://en.wikipedia.org/wiki/WiGig

Why does the title not match the actual title?

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