Kennedy Space Center: Innovative Non-Conductive Fall Protection
Electronically non-conductive ladder fall protection system makes working on lightning towers at NASA’s Kennedy Space Center safer and more efficient.
- By Jesse Peters, Mikaela McShane
- Sep 01, 2019
Launch Complex 39B at NASA’s Kennedy Space Center underwent renovations and upgrades to accommodate NASA’s Space Launch System (SLS) and the Orion crew capsule. The newly updated pad will support Artemis 1, formerly Exploration Mission-1, the first in a series of increasingly complex missions that will enable human exploration of the Moon and Mars, and other efforts for the Artemis Program.
However, to successfully send the first woman and next man to the Moon, Pad 39B must mitigate a natural threat—lightning. The height of the launch vehicles and the location of the pad on the coast of Central Florida’s Cape Canaveral means there is high risk of lightning strikes which could result in serious damage to the launch vehicle and the pad.
According to the Lightning Advisory Panel for America’s Space Program, “Lightning—both natural and artificially-initiated or ‘triggered’ discharges—is still the primary weather hazard to spaceflight operations.” Concurrently, Florida has been identified by the National Lightning Detection Network as the state with the greatest concentration of cloud-to-ground lightning flashes per square kilometer, making lightning strike prevention a doubly serious concern at the launch pads at Kennedy on Florida’s Space Coast.
After leaving the Vehicle Assembly Building, the SLS rocket and Orion spacecraft and the mobile launcher will travel atop a crawler-transporter, one of the massive tracked vehicles capable of transporting 18 million pounds, to Pad 39B. Once there, the launch vehicle can sit on the launch pad for serval weeks, leaving it open to lightning strikes and ensuing damage. The lightning protection towers surrounding the launch vehicle are critical to the continued safety of the launch vehicle and timeliness of launches. Technicians at Kennedy are continually monitoring the launch vehicle for signs of potential damage from induced electrical transits from local lightning events.
Lightning Protection Systems
A lightning protection system larger than any that has previously existed is now being utilized at the Florida spaceport. Lightning protection systems have continued to be adapted and upgraded as the space program has developed. Apollo era systems utilized a bonded structure that drew current through the structure. For the space shuttle, the system consisted of a lightning mast at the top of the pads service structure with two catenary wires, diverging currents into the ground.
The system that was put in place during the end of the 2000’s featured large cables strung between three 594-foot-tall steel and fiberglass towers. These catenary wire systems are prominent in the skyline above the launch area. The lightning protection systems also feature analysis systems that will allow launch managers to track and study the lightning strikes that do occur, helping prevent delays in the launch schedule. There are now expansive databases of local lightning data that can be utilized to predict and react to weather patterns.
The lightning protection systems prevent damage to the launch vehicles, but there is still the matter of protecting individuals who maintain and service the towers. The technicians who keep the lightning protection systems in working order have to be able to access the inside of the towers.
Need for Non-Conductive Fall Protection
Jesse Peters, a mechanical engineer at the center, was given the task of redesigning the fall arrest system. The new system is a more user-friendly, fully non-conductive fall protection safety restraint system. As Peters began to research potential options for replacing the existing system, he found that there were no off-the-shelf options available on the commercial market. Electrically non-conductive fall protection systems were previously unavailable. This technology creates a safe, easily integrated alternative to traditional fall arrest systems that utilize metal and other conductive materials.
“This project was initially started because our operations personnel who regularly work on the tower identified the lightning tower mast ladders as a safety hazard, due to the lack of a fall arrest system,” Peters said. “I was brought in to address this need for a safer system but we soon discovered no commercial solutions were available that would satisfy the requirement for the permanently installed system to be electrically non-conductive. This user need drove the design of the electrically non-conductive ladder fall protection system.”
Peters worked with one of the operations engineers, Mike Wisnom, to develop and test the new materials that would comprise the system. The design centered on the incorporation of the SurLoc fiberglass rail. After Wisnom found this piece, Peters was able to design the rest of the system around it, creating the first fully non-conductive fall arrest system.
This design has broad application across the industry, where an electrically non-conductive fall protection system is needed. The design and integration of this system are widely applicable to other industries and users. There are a number of potential applications in telecommunication towers, radio towers, chemical processing plants, oil and gas platforms, harsh corrosive marine environments and catenary lightning protection systems.
“After he found the rail, I designed the mounting hardware to install the rail onto the towers,” Peters said. “I had to get tower climbing certifications and fall protection training and climb the tower and take measurements.”
After obtaining measurements, Peters drafted the initial design and created finite element models to simulate structural loads and generated presentations for NASA who approved the structure. Instead of relying fully on computer models, Peters chose to build a small section of the fall protection system and test it on heavy equipment by hanging weights off of it. This test was performed to verify that fall protection design requirements were met, as this is a safety tool they wanted to be certain would work exactly as designed.
After the successful load test, the specifications were given to one of the machine shops at Kennedy and the components were fabricated. Wisnom and his operations group were tasked with installing the new system in the field. The installation process involved a tremendous amount of strategic planning and coordination. The elevator only goes up to 450 feet, so access to the top section of the mast requires individuals to climb a ladder inside the tower shaft. In order to install a fall protection system in the top 100 feet of the inner shaft of a 500-foot lightning tower, a great deal of preparation must precede the actual installation.
The equipment first had to be transported to the bottom of the lightning mast, then the operations team had to go inside of the mast to install the components of the system. This aspect is particularly challenging once the team reached the higher sections of the tower. Considering the height of the tower, the necessity of continuous ventilation to mitigate dust hazards and the inherent difficulty of working in a confined space, this team faced a particularly daunting challenge.
The operations group worked diligently to ensure all of the work was completed in the safest way possible. This featured the use of Personal Protective Equipment (PPE), including full face respirators and Tyvek suits for the fiberglass dust/fibers.
“We also have a fan at the bottom, pulling air from the mast. The fan is connected to eight-inch diameter ducting that the guys have to position near the elevation they’re working at so it can exhaust the dust from the area,” Wisnom said. “The work is at heights, so they’re using fall protection and work position lanyards for themselves and lifting whatever material they need (rails, rungs, bolts, etc..) up to elevation with rope.”
The installation involved removing 23 fiberglass ladder rungs, and replacing them with acetyl resin rungs, and removing the fiberglass bolts that mount the ladders to support channels. Finally, the 106-foot fiberglass rail was installed in 11 sections and spliced together.
This newly installed ladder system is fully OSHA compliant; at Kennedy, safety is the number one concern.
The novelty of the new design comes from its material make up. Until recently, all fall protection systems were comprised of electrically conductive components. In this case, electrically non-conductive fiberglass was used to design the ladder fall protection system for the lightning tower fiberglass mast. An existing ladder skate and rail system, comprised of a permanently installed fiberglass rail and removable skate, was adapted for this purpose by designing and fabricating non-conductive mounting hardware.
This new improvement to the lightning protection system is the newest of many innovative improvements that have been made since the genesis of the lightning protection systems at the launch pads. Kennedy is dedicated to continuously improving safety and efficiency.
The Technology Transfer Office at Kennedy is working to transfer this technology to other industries, in order to achieve the widest possible utilization of the technology and its benefits.
This article originally appeared in the September 2019 issue of Occupational Health & Safety.