日本における雷の影響
Hello, everyone. SCIEN-SPOT is a podcast that shines a spotlight on the latest scientific technology from Japan.
Your host is REN from SCIEN-TALK.
So, what comes to mind when you hear the word, lightning?
Summer skis, sudden flashes, roaring thunder, and sometimes a terrifying natural phenomenon that brings significant damage.
Indeed, lightning strikes are one of the natural phenomena that cause immense harm to human society.
For instance, they can lead to widespread power outages due to damage to power facilities,
harm to communicative equipment, building fires, and even accidents that result in loss of life.
In Japan, the estimated damage is between 100 to 200 billion Japanese yen annually,
and the countermeasures have been a long-standing challenge.
Of course, for a long time, the traditional method for lightning protection has been lightning rods, which you might be familiar with.
These are installed on rooftops of buildings and tall structures to attract lightning and safely channel it into the ground, thereby protecting the surroundings.
However, these lightning rods have a limited range of protection.
Moreover, there are many cases where installing a lightning rod itself is physically or economically difficult,
such as for window turbines, outdoor event venues, or construction sites.
It's almost likely they can only intercept lightning if it's a fixed target.
Thunder clouds often move and cut the obscurity on the lightning.
NTTの革新的な技術
NTT, a major Japanese company, has taken on this long-standing challenge with a fresh perspective.
They announced a groundbreaking technology called drone-induced lightning,
which involves actively inducing lightning using drones and guiding it to a safe location.
This is a revolutionary shift in thinking, moving from simply waiting for lightning to strike to controlling lightning,
a concept that feels straight out of science fiction.
NTT aims to protect cities and critical infrastructure from lightning damage with these flying lightning rods,
ultimately striving for a society with zero lightning damage.
This is a highly ambitious endeavor to minimize the impact of lightning on social infrastructure and safeguard people's lives.
Guiding lightning with drones might sound like something out of science fiction,
but NTT has successfully demonstrated this visionary technology with acting lightning, marking a world first.
What exactly does this experiment entail?
Let's get to the core of it.
This groundbreaking experiment took place from December 2024 to January 2025 in the mountainous areas of Hamada City,
Shimane Prefecture, at an altitude of 900 meters, a prime environment for lightning generation.
First, NTT's research team meticulously observed the increase in electric field strength as thunder clouds
approached using a specialized device called a field mill, which can measure atmospheric electric field strength in real time.
NTTの雷耐性技術
Just before lightning strike, the electric condition in the air changed dramatically.
When the electric field strength reached a certain level, indicated a high probability of lightning,
the star or the show made its appearance.
NTT flew a specialized drone equipped with their uniquely designed lightning-resistant cage to an altitude of 300 meters.
This lightning-resistant cage is one of the key technologies for drone-induced lightning.
Imagine this, how do you prevent the drone from being destroyed if lightning strikes it directly?
NTT devices are designed that essentially encases the drone in the lowest metallic shield.
This cage works by bypassing the large current that flows when lightning strikes directly,
preventing the interval electronic components from malfunctioning and failing.
Furthermore, by making the lightning current flows radically across the cage's surface,
its cleavage cancels out the powerful magnetic fields generated by the current, minimizing their impact on the drone.
It's like a judo master skillfully deflecting the energy of a lightning attack.
NTT's preliminary tests showed that this drone could withstand artificial lightning strikes of up to 150 kA,
which is 5 times the average natural lightning strikes and cover over 98% of natural lightning events, without any issues.
This truly makes it an impenetrable body capable of enduring even the most intense lightning.
ドローンによる雷の誘発技術
Next, let's look at the technology for activity-inducing lightning.
The conductive wire is attached to the flying drone, connecting it to the ground.
At the optimal moment, when the electric field under the thunder cloud is high,
a high-voltage switch installed on the ground is operated to rapidly connect the drone to the ground.
At this precise moment, the electric field strength around the drone changes dramatically.
This rapid change acts almost like the drone, with its wire pulling the trigger on a large mass of energy.
This is the thunder cloud powerfully encouraging lightning to strike.
Then, on that fateful day of December 13, 2024, as the thunder cloud approached and the field mill observed a rise in electric field strength,
the drone was flown and the wire was connected to the ground.
As a result, a large current flowed through the wire and simultaneously the surrounding electric field strength changed significantly.
Furthermore, it was confirmed that a voltage of over 2,000 V was generated between the wire and the ground just before the lightning was induced.
And at that very moment, lightning was induced towards the drone, simultaneously with the induction,
a loud blasting sound, light emission from the winch part, and partial melting of the drone's lightning-resistant cage were observed.
But most importantly, the drone equipped with the lightning-resistant cage contributed to fly stably even after being directly struck by lightning.
NTTの雷誘起技術の革新
This success marks a world-first achievement in inducing lightning using a drone.
It represents a significant advance of NTT's long-standing expertise in protecting communication infrastructure from lightning.
This achievement by NTT demonstrates a new possibility for dealing with the powerful natural phenomenon of lightning,
not just being a participant but actively controlling.
This is expected to greatly advance research into the yet unexplained mechanism of lightning generation.
This technology paves the way for protecting cities, critical infrastructure, and human lives from lightning damage,
contribute to the realization of a society without lightning damage.
NTT plans to continue research to further increase the success rate of this drone-induced lightning
and also engage in more forward-looking research and development,
including methods to store and utilize the immense energy from induced lightning.
Perhaps the day will come when lightning is no longer just a disaster but a new source of energy.
That's all for today's Science Spot.
This spot is broadcasted daily on weekday mornings in both Japanese and English.
I hope today's discovery has changed how you view lightning even just a little.
I'd love for you to listen to the podcast and post your notes and thoughts with the hashtag Science Spot.
See you next time.
