On July 7, 2011, as Space Shuttle Atlantis sat on the launch pad just one day before it was due to make the final voyage of NASA’s 30-year Shuttle program, lightning struck. Twice.
The crucial questions for engineers and officials hoping to keep the launch on schedule were: where exactly did those strikes hit, and were they close enough to do any damage to the Shuttle’s electrical systems?
There were two systems monitoring lightning activity around Kennedy Space Center in 2011: the local Cloud-to-Ground Lightning Surveillance System (CGLSS) operated by the Air Force, which has a base nearby, and the National Lightning Detection Network (NLDN), a nationwide detection system owned and operated by a private company.
According to CGLSS, both lightning events struck pad A at Launch Complex 39, where Atlantis was waiting for launch. Neither system had a great track record at Kennedy—NASA investigations had determined they reported only 70 to 80 percent of lightning strikes and were prone to reporting strikes in locations where they did not actually occur.
Nevertheless, a launch, especially one with crew on board, cannot go forward when there is any question the spacecraft may have been damaged. “Problems on the ground are fixable, but if you launch something that has been compromised, you can get into a lot of trouble,” emphasizes Carlos Mata, who was the lightning subject matter expert at Kennedy for more than a decade before moving into the private sector.
In previous cases, a storm like this, with strikes so close, would have certainly demanded a delay while engineers retested potentially affected systems.
“And the retest could take a long time depending on which systems are involved. Several days to a week,” explains Kevin Decker, an engineer at Kennedy.
That is exactly why NASA had already begun working on a new lightning monitoring system focused directly on the launch pads, Mata says, “to make sure that if lightning struck within a certain radius, we will detect it. Period.
“We also wanted to be able to accurately locate it, but that was a secondary requirement.”
The new system incorporated a suite of high-speed cameras designed to capture visual evidence of any lightning striking the pad directly or nearby. The cameras are mounted on three lightning protection towers, as well as on the vehicle assembly building seven miles away, explains Decker, who serves as NASA’s lead design engineer on the system. The cameras’ overlapping fields of view ensure that, wherever there is a strike, images will be recorded by multiple cameras.
The towers also serve to support a lightning protection system for the launch vehicle. Wires are strung between the towers and down to the ground, providing a preferential place for lightning to strike and a path for the current to travel away from the vehicle on the pad.
Around a wider perimeter, there are electromagnetic field sensors installed at ground level, Decker adds. The electromagnetic sensors record the electric and magnetic fields generated by the lightning to measure both the intensity and strike location. “If you had a strike near the road leading up to the pad, for example, each of the electric field sensors would experience the field at slightly different times. And because we know how fast electric fields travel, we can actually triangulate within several meters of where that strike hit.”
In 2011, this system was not yet fully installed, but the cameras on the lightning protection towers were already operational and mounted at pad B, less than two miles from pad A, where Atlantis sat ready for launch. So when the storm hit, “the electromagnetics folks came to me and said, ‘Carlos, did you see anything?’” Mata recalls.
Indeed, the cameras had captured both strikes. Still pictures and video were able to show the bolts hitting nearby but not directly on the pad. As a result, STS-135 was not scrubbed that afternoon and took off the next day.
Mata spent several years fine-tuning the system at Kennedy. At NASA’s request, he built it almost entirely from off-the-shelf commercial components, but many needed to be modified and improved to meet his needs. For instance, he says, they modified the timing of the data acquisition system that records the outputs from the various sensors to better map lightning strikes that hit the ground in multiple places.
As the system improved, the lightning protection industry began to take note, and Mata was invited to speak about it at conferences and to industry groups around the country. In 2014, Mata visited a company in Connecticut, East Coast Lightning Equipment, and while there, he got to talking with the company owners.
“I told them I thought there was a commercial market for this,” Mata recalls. “And I think the light bulb went on. We started having conversations, and about two years later, Scientific Lighting Solutions LLC (SLS) was registered.”