Get a behind the scenes look with the high-tech tour

Suzanne Stewart
Staff Writer

One of the great things about the Green Bank Observatory is that the public has access to nearly all areas. The Science Center is open for visits and there are regular guided bus tours to see all the telescopes on the campus.

For those who want a more in-depth look at the operations and mechanics of what goes on at the GBO, they offer the once a month High Tech Tour. 

That tour, on the second Thursday of each month, is guided by a GBO engineer who will take you through the engineering department and into the Green Bank Telescope control room. The electrical engineers take turns guiding the tour and explaining what goes into operating and maintaining the GBT.

Two of those engineers are Bob Simon and Jason Ray.

Welcome to the RF Lab

Simon is in the microwave department and has been at the observatory for 41 years. He works in the radio frequency lab that designs and maintains the receivers used on the GBT to collect information.

When an astronomer makes a proposal for a project on the GBT, Simon and the microwave department design a receiver that is installed in the observation room on the arm of the telescope.

“All of our receivers are cryogenic,” Simon said. “Basically, that just means we operate near absolute zero. Temperature wise, we’re just above minus 430-degree Fahrenheit when this is in operation.”

All the receivers operate like this due to the sensitivity of the wavelengths being collected from outer space.

Simon compared it to the radio in your car. If you are driving in Roanoke, Virginia, the radio station K92 comes in clear. As you drive further away from Roanoke, the signal becomes weaker. The best way to keep that clear signal is to physically move closer to the source.

Since the Earth cannot physically be moved closer to the stars and galaxies being observed, the receivers collecting the observations must be more sensitive.

“The cryogenics does that,” he said. “Our electronics get much more sensitive as we cool it down physically.”

Once the project is underway and Simon and crew are working on the receiver design, they have all the components made on site in the machine shop. Again, due to the sensitivity, the parts have to be very precise and have to be manufactured perfectly.

“You can see some of the things that they’re able to make,” Simon said, holding a cone shaped item for the receiver. “That starts life just as a hunk of aluminum on a lathe. We have really talented machinists, and we have very high end milling machines and lathes that can do this within a thousandth of an inch of accuracy.”

Parts of the receiver are covered with gold plating due to a worry about thermal and electrical conductivity. Gold works well in near absolute zero temperatures and does not compromise the information collected.

Simon first became interested in electronics as a child watching his dad tinker in his workshop. He recalls HeathKits, kits that allowed individuals to build their own clock radio or other electronic device.

“It would give you instructions on how to put it together,” he said. “Some things were simple; some were complicated.”

Simon grew up in the Bridgeport area and attended Fairmont State College where he earned an electronics degree. When it came time to find a job, he didn’t have the luxury of searching the internet. Instead, there were binders at the college, all filled with information for job placement.

Simon looked up electronics and electrical engineering and found a listing for the National Radio Astronomy Observatory in Green Bank. He sent out a résumé and was called in for a job interview.

“We were starting a new program or new project here called VLBA – Very Long Baseline Array – so they were looking to hire some staff to fill some of that work,” he said. “That’s what got me hired here. They hired a few people working on this VLBA project, so I was here working on that.”

After that project, there was another one and then another one, and 41 years later, Simon is still working on projects in the engineering department.

On to the Digital Lab

Just down the hall from the radio frequency lab is the digital lab, where Ray works.

The digital department is responsible for monitoring and controlling all the moving parts of the GBT. Whether it’s the panels in the dish, the sub reflector or the track under the entire instrument, the digital department is on it.

“The digital group is responsible for a lot of different things like the systems that make the telescope move,” Ray said. “We call those the Servo systems. We have how it rotates in azimuth and the big dish tips down in elevation. 

“The active surface is another system,” he continued. “The telescope is so big that when you tip it down, the shape of the dish changes. Mostly, due to gravity, it basically collapses down on itself some. That’s bad because you have to have a nice parabolic shape to get the signals to bounce correctly from the dish up into the receivers.

“You can think of it as being out of focus.”

To get the telescope in focus when it moves, there are adjusters underneath the panels that can move the panels and create the perfect parabolic shape. There are 2,209 of them.

“If you think about the floor as the surface of the dish and the tiles are the panels, everywhere four corners come together is one of these,” Ray said of the adjusters. “So, we can adjust this up or down, plus or minus an inch to correct that shape.”

The digital department also monitors vibrations and the weather for safety reasons. If the wind speed is too high, it can be dangerous to have the telescope in certain positions.

They also monitor snow patterns and freezing temperatures. The telescope can operate when there is snow in the dish, but only on the low frequency. If there is going to be a large snowstorm, the telescope will be moved to a certain angle to keep it from collecting too much snow which could in turn damage the panels.

Digital processing is also a large portion of the work done by Ray and his colleagues. The department uses circuit boards designed by the University of California and can change the software for each specific project on the GBT.

“The heart of it is underneath this fan,” Ray said, holding the circuit board. “It’s called the FPBA. That stands for Field Programmable Gate Array. You can think of it as a blank slate of digital logic. It saves you from having all these circuit boards and wires and interconnects. You can just have it programmed on this little chip.”

The circuit boards form a spectrometer called VEGAS – Versatile Green Bank Astronomical Spectrometer. It has eight circuit boards and replaces the GBT spectrometer which had 100 circuit boards.

“That’s just how versatile this chip allows us to be,” Ray said. “When we process signals, we channelize them into a number of channels, basically. If you want really fine resolution, you’ll use something that has a million channels. It will break something down into a million increments.

“If you’d like to get faster data rates, for instance, you may only have sixteen channels instead of a million,” he continued. “We have designs for these that range from sixteen channels up to a million in every increment to the power of two.”

Ray was the one who wrote the personalities that go into creating those channels.

“Then, of course, you do all that processing, and you transmit the results over to a computer, and then they can process them further there or just store the results on a disc,” he said.

Ray is a native of Pocahontas County and, like Simon, his interest in electronics was sparked by his dad.

“My dad worked for the phone company for forever, so he was always tinkering on electronic stuff at home,” he said. “That kind of made me interested in it. Then when I got in the high school, they had electronics class with Mr. [Gary] Beverage, and I took that.”

Ray went on to get a degree in electrical engineering and was lucky to come back home for his career.

“I didn’t really have expectations that I would end up here because I wasn’t sure – it didn’t seem like a lot of jobs were available back then,” he said. “But the timing was right for another engineer to retire right when I was graduating, so I ended up filling his position and I’ve been here ever since.”

There are a total of eight engineers in the electronics division at the GBO.

On to the control room

After the engineer takes the group through the electronics department, they head upstairs to the GBT control room, where the telescope operators monitor more than a dozen screens as they collect data from the telescope.

Catherine Tounzen has been a telescope operator for a year now and first learned about the observatory when she was in college. The physics department does an annual spring trip to use the 40-foot educational telescope.

“I came here twice, and I never really thought about working here, but after I graduated, I just so happened to look through the listings and here I am.”

There are times when an operator is in the control room when the tour arrives and visitors can learn more about their positions, as well. If the room is empty, the engineer leading the tour will explain what the control room does.

“We talk about the signals and where they come from the GBT on the fiber into the computers,” Ray said. “It’s also good with an operator up here so they can always talk about what’s going on and what they’re observing.”

Each High Tech Tour is different because each engineer has their own way of explaining things and their own personal experiences to share. Simon said he lets the tour participants help lead his discussion and welcomes lots of questions when he’s the guide.

The tour is a more intimate and interactive way to see a part of the observatory that is usually not on display. It takes place on the second Thursday of each month, 3:30 to 5 p.m. and is open to up to 15 people.

The tour costs $25 per person and requires advance booking on the observatory website.

For more information on the tour or to book your ticket, visit https://greenbankobservatory.org/events/high-tech-tour-441/