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Abstract:
NTT Corporation reports the world's first successful triggering and guiding of natural lightning using a drone during experiments conducted between December 2024 and January 2025 in Shimane Prefecture, Japan. By monitoring electric field fluctuations near thunderclouds and deploying a drone trailing a conductive wire connected to a ground switch, they actively induced a lightning strike to the drone. Key innovations demonstrated include a specialized lightning protection cage, capable of shielding commercial drones from direct strikes (tested up to 150 kA), and an electric field manipulation technique to initiate the discharge. Despite minor melting on the cage, the drone survived the strike and continued flying. NTT aims to leverage this "lightning drone" technology to protect cities and infrastructure from lightning damage, estimated at ¥100-200 billion annually in Japan, and explore future applications like lightning energy harvesting.
NTT's Breakthrough: Triggering and Guiding Lightning with Drones
Background: Lightning causes significant damage (¥100-200 billion annually in Japan) to infrastructure, and traditional lightning rods have limitations in coverage and applicability (e.g., wind turbines, large venues).
Goal: NTT is developing "drone-triggered lightning" technology to actively initiate and guide lightning strikes safely away from vulnerable areas using drones.
Experiment Conducted: Lightning triggering experiments using drones were performed at 900m elevation in Hamada City, Shimane Prefecture, from December 2024 to January 2025.
Methodology: Ground-based field mills monitored electric field strength. When high, a drone equipped with a lightning protection cage and trailing a conductive wire was flown to 300m altitude. A ground switch then connected the wire to the earth.
First Successful Triggering (Dec 13, 2024): Activating the ground switch caused a rapid local electric field change (over 2000V measured between wire and ground just before), successfully triggering a natural lightning strike to the drone.
Drone Survivability: The drone, protected by its custom cage, withstood the direct lightning strike (evidenced by sound, flash at winch, and partial melting of the cage) and remained operational, continuing stable flight.
Key Technology 1: Lightning Protection Cage: NTT developed a conductive metal cage mountable on commercial drones. It shields internal components by redirecting lightning current and uses radial distribution to cancel damaging magnetic fields. It withstood 150 kA artificial lightning tests (>98% of natural lightning strength).
Key Technology 2: Electric Field Triggering: The system uses the drone, wire, and ground switch to intentionally create a rapid, localized increase in the electric field, actively encouraging a lightning discharge towards the drone at a controlled time.
Future Outlook: NTT plans to refine lightning prediction, drone triggering success rates, and understanding of lightning mechanisms. They aim to deploy "lightning drones" for active protection and explore the possibility of capturing and utilizing lightning energy.