Kennedy Space Center
July 30, 2002
KSC Develops Precision Launch Pad Lightning Detection Sensor With Potential Commercial Applications
A highly accurate but yet relatively inexpensive lightning detection system developed at Kennedy Space Center has been patented this month and has attracted the attention of the private sector.
"The system, known as the Sonic Lightning Locator (SOLLO), was developed to determine the precise ground-strike point of lightning," said John Madura, chief of the NASA-KSC Weather Office which funded SOLLO's development. Within a 1-mile radius, the system can pinpoint a cloud-to-ground lightning strike within about 15 feet.
"The Cape Canaveral Spaceport has one of the most comprehensive weather monitoring systems in the world, but this new sensor system offers unprecedented accuracy for lightning detection within a small area," Madura said.
"SOLLO was designed to provide more precise information for determining whether sensitive equipment at the launch pads has been exposed to the effects of a lightning strike," said Terry Willingham, chairman of the KSC Lightning Safety Assessment Committee. "We have sensors to help us determine when the vehicle is exposed to lightning, but we need a better way to determine whether sophisticated launch support equipment has been affected by electrical storms."
It could also be used to help judge whether a lightning strike may have had some effect on the Space Shuttle, a rocket or a payload on the launch pad. The sensor system is on a list of upgrades planned for implementation at KSC but not actually budgeted for operational installation at the pads until the research and development project is complete.
Dr. Pedro Medelius, an electrical design engineer with KSC Engineering Development contractor Dynacs, Inc., led the system invention effort. Medelius has been involved with lightning research since 1983 and has designed various instruments to monitor electromagnetic fields and their effects. Stan Starr, also of Dynacs at KSC, developed the models for the mathematical algorithms used to determine the location of the lightning strike.
SOLLO is being tested using "rocket-triggered lightning" at the University of Florida's International Center for Lightning Research and Testing located at Camp Blanding, an Army National Guard facility in north Florida near Starke. A high-tech version of Ben Franklin's key-on-a-kite-string experiment, a small composite rocket, about 4-feet tall with a spool of thin copper-Kevlar wire attached to it, is launched from an elevated platform when electric fields on the ground reach a high level. As the rocket reaches about 2,000 feet, a lightning strike occurs initiated by the trailing wire which is vaporized by the strike.
The SOLLO system utilizes both the electric field generated by the lightning strike and the thunder impulse received at multiple sensors to precisely locate the attachment point to ground. The main advantage of testing the sensor system with triggered lightning is that the location of the lightning strike is known, since it normally occurs at the point where the wire trailing the rocket is connected to the ground. This can be used to test and verify the accuracy of the sensors and their associated mathematical algorithms.
"What makes the SOLLO system unique is that it uses both the electric field and the thunder to help determine the precise location of the strike," Medelius said.
The detector consists of an electric field antenna and four sensors surrounding it set twenty feet apart. It uses a "time of arrival" system, which compares the precise differences in time between when the lightning's effect is first detected at the electric field antenna and when the thunder arrives at the four receiver sensors. This occurs at each sensor at different times, depending how far each is from the strike within a one-mile area.
The new spaceport technology offers many potential benefits to the public, as well as to private industry concerned about the cost of expensive high-tech equipment. Potential users include airports, utilities, insurance companies, golf courses, and amusement parks. Several companies are investigating licensing the technology through KSC's Technology Commercialization Office.
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