Background

A societal concern

Lightning is a fascinating albeit destructive manifestation of nature. Estimates on the average number of persons killed by lightning every year range from 6000 to as many as 24000 worldwide. Lightning is also the cause of power outages, forest fires electronic and infrastructure damages, amounting to billions of euro a year, making it a major societal concern.

A 300 years old protection…

Although lightning protection techniques have seen considerable progress in the past, the best external lightning protection to date is still based on the concept of the lightning rod, invented by Benjamin Franklin almost 300 years ago. This kind of passive control of lightning by a metallic rod is widely used for the external protection of fixed installations. However, there are many situations where a large bulky permanent structure is not conceivable (gathering of crowds, temporary storage of dangerous material, rockets on their launching pad, proximity protection of landing lanes in airports). Easily deployable active rods then become necessary.

The lightning rocket: a complex and perilous technique

Small rockets pulling grounded conducting wires have been used to trigger lightning for many decades, the first reported successful attempt being in 1960. The success rate of this technique varies largely from one location to another and it depends on the stage of the thunderstorm and the electric field on the ground at the moment of the triggering attempt. Although mobile launch pads have been built, they are usually fixed and the number of rockets available is typically limited to 5 to 10 rockets. In addition, the small rockets fall to the ground regardless of whether the attempt was successful or not, creating a risk situation for/endangering personnel and equipment on the ground.