(TNS) — Joshua Moore, an engineer and the technical and rope access program coordinator with Cumberland County-based Modjeski and Masters is used to inspecting large complex structures — primarily bridges.

But, every three years, Moore and a number of his colleagues head to the mountains of West Virginia for what he calls “a project of a lifetime.”

Modjeski and Masters, which is based in Silver Spring Township near Mechanicsburg, serves as the lead inspector of the National Science Foundation’s Robert C. Byrd Green Bank Telescope in Green Bank, West Virginia.

Officials say the Green Bank Telescope is the world’s largest fully steerable radio telescope. It is located at the Green Bank Observatory in a National Radio Quiet Zone. The zone was created by the federal government to provide a region to protect sensitive instrumentation from radio interference.

The observatory is home to multiple telescopes, but the centerpiece and largest instrument is the Green Bank Telescope.

“Scientists come from around the world to use the Green Bank Telescope, because it is the most accurate, versatile, large dish radio telescope in the world,” the observatory‘s website says. “Its suite of receivers covers 100 MHz to 100 GHz in frequencies, its processors can spot nanosecond timing differences in data, and it observes under radio-quiet skies. [It] can be used to do chemistry, physics, radar receiving, and astronomy, and has no equal in the world.”

The telescope collapsed in 1988 due to a sudden failure of a key structural element. A replacement was built but to prevent it from collapsing again, Modjeski and Masters was hired to develop an inspection plan and procedure.

The structure is overseen by the National Science Foundation. (It was previously overseen by the National Radio Astronomy Observatory.)

Modjeski and Masters began its inspections in 2003. They are performed on the telescope every three years. The company set up a database to be able to track the conditions of the parts that make up the structure.

The inspections typically last six to eight weeks, with teams of six people rotating in and out. Modjeski and Masters staff from about a dozen offices throughout the country participate in the inspections. That includes staffers from the Silver Spring Township headquarters and employees like Moore, who is at the New Orleans office.

“We’re extremely proud to have this long tenured relationship with this vital piece of science infrastructure,” Moore said. “We’ve been coming to Green Bank Observatory for over 20 years now. We really enjoy being able to contribute to the health of the structure. And also in some small part in the cutting edge of science. We’re happy that our expertise is utilized.”

The total structure of the Green Bank Telescope is about 450 feet tall and 330 feet wide. But it’s not just the size of the structure that makes this inspection complex. It’s the number of parts that need to be inspected. Moore said the project is “quite an undertaking.”

“For a structure like the Green Bank Telescope there’s a lot involved,” Moore explains. “The telescope itself has over 13,000 individual structural elements that we have to inspect. Every element is inspected hands-on, which means that an inspector is physically present at that moment and able to see the entire element. So, as you can imagine, that’s a lot of things to go look at.”

Moore said the telescope is comparable to a small skyscraper — a small skyscraper that’s constantly moving. It rotates 360 degrees, and it can also tilt forward and backward.

He said inspecting the telescope is different from, say, a large bridge project because there’s no vehicular traffic or railroad traffic on the structure; workers need to be able to withstand gravity and also the movements of the structure; and obviously it’s also built differently.

“If you think of the satellite dish you might have on your house, there’s a dish portion and then there’s some sort of receiver arm that links to the dish,” Moore said. “So the Green Bank Telescope is similar. There’s the reflector structure, is like the satellite dish on your house. That dish, if you will, has a diameter of 100 meters, about 330 feet, so like a football field-sized concave area that receives the radio wave. Then there’s an arm that comes up above that reflector to reflect the point that the radio waves self-reflect the ocean.”

There are also safety and access concerns. Moore said the structure in itself is a very unique access challenge because it wasn’t designed for someone to climb up and around it.

“We have devised methods to get to it,” he said. “And a lot of that involves rope access, which is using ropes to repel or climb.”

Part of the inspection aims to determine the health and functionality of the coating system. After an inspection in 2021, Modjeski and Masters recommended that the entire structure be repainted to protect the telescope’s structural integrity.

“The primary way that we can protect steel elements is by painting or coating, so that’s inherent in sort of the structural longevity of the object,” said Moore. “Coating on the Green Bank Telescope is very important to preserve it.”

The painting will involve a thorough blast cleaning to remove the existing paint and repainting with a three-coat zinc, epoxy, urethane coating system. An Ohio company will paint the telescope.

“Paint provides a protective barrier between the telescope’s structure and the elements, preventing corrosion and ensuring [its] strength and integrity,” the U.S. National Science Foundation said. “In particular, the feed arm was identified as a high priority for repainting. This part of the telescope extends high above the 100-meter dish, and holds vital components including the receivers and subreflector, which focus and process the radio waves observed by the telescope.”

The first phase of the project began in May and will be completed in September. This phase will include the feed arm and will cost $4.5 million. Moore said this phase will be followed by five more. Each is planned to take place during the summer for the next five years.

“Thanks to funding from the National Science Foundation, we’re able to begin the first phase of this maintenance project this year,” Anthony Remijan, interim director of the Green Bank Observatory, said in a news release. “The Green Bank Telescope is a cornerstone of the world’s astronomical research community. We are committed to preserving its integrity and ensuring it continues to serve the scientific community for the next generation of researchers.”

Moore said that there has been a maintenance coating program in place since the construction of the telescope. But Modjeski and Masters found that the coating was not really effective for the protection that the structure needed.

This will be the first complete cleaning and recoating of the structure that has occurred since it was constructed.

Moore said the project is “quite an undertaking”, but is a “pretty fulfilling and fun job to be on.”

“It’s very cool,” he said. “I’m a structural engineer, so obviously I like structures. I’m also an amateur astronomer. I’m also an avid outdoorsman. I get all three of those things when I work on this job. I get to climb on a really good structure that does really good science and I’m out in a beautiful outdoor setting. It’s awesome. It’s a project of a lifetime.”