With average heights of 58 meters or 190 feet, most orbital rockets are taller than large multistory buildings. Four towers surrounding the rocket at a launch complex, though, eclipse even the tallest launch vehicles.

The four towers around a rocket launchpad form part of the Lightning Protection System, which protects the launch vehicle from lightning strikes that can severely damage a rocket. The towers create a type of Faraday cage that shields the rocket from lightning and associated electromagnetic fields.

Lightning strikes the Earth’s surface approximately 100 times every second. That amounts to 3 billion lightning strikes a year.

With each lightning bolt capable of generating up to a billion volts of electrical energy (enough to power a 100-watt lightbulb continuously for 3 months) & reaching temperatures of 30 000° Celsius (54 000° Fahrenheit), it is a powerful and potentially deadly force.

As many readers will know or have experienced firsthand, lightning can cause severe damage to infrastructures and result in serious injury or even death.

Arianne 5 Lifts Off From Spaceport French Guiana
An Ariane 5 rocket lifts off from French Guiana with four lightning towers surrounding the launchpad.

As the following section will illustrate, this also poses a severe threat to orbital rockets on their launchpads. And, as will be illustrated, it is not just the lightning itself that poses a danger, but the environment created as a result of its presence.

(Learn more about lightning, how it is caused, the associated dangers, and its impact on the surrounding areas in this article.)

The Dangers Of Lightning To Orbital Rockets On A Launchpad

A rocket standing on a launchpad is especially susceptible to damage from lightning for a number of reasons. With an average height of 58 meters (190 feet), a modern rocket can easily be the tallest structure on a launchpad, surrounded by an otherwise very flat surface.

This makes it an easy target for potential lightning strikes, of which there are plenty at launch facilities like Kennedy Space Center in Florida and Europe’s Spaceport in French Guiana, which are located close to the Equator where thunderstorms are in abundance.

Unlike conventional aircraft designed to operate in Earth’s atmosphere, whose infrastructure is strengthened with several redundant systems in place to safeguard the plane from lightning and similar events, a rocket only spends a brief period of time in the atmosphere.

Lightning that struck the Apollo 12 launch site during its launch can clearly be seen reaching all the way down to the launch tower. The strike was caused by the Saturn 5 rocket itself as it flew through a highly charged column of air.

(Rockets are actually prone to damage from a variety of weather conditions. Learn more about the various atmospheric conditions that can impact a launch vehicle in this article.)

As a result, a rocket is designed to be just strong enough to withstand the dynamic forces (weight, thrust & drag) on it before entering orbit, as weight saving is always at the forefront. This means if struck, a rocket can sustain a substantial amount of structural damage.

Orbital launch vehicles also carry a large number of electronic equipment crucial for the vehicle to function, from navigation and guidance to keeping the astronauts on crewed spacecraft alive. This equipment is extremely sensitive to the slightest interference.

(A lightning bolt capable of generating a billion volts of electricity and reaching temperatures of 30 000° Celsius or 54 000° Fahrenheit has the ability to severely cripple or even completely destroy a rocket’s electronic equipment.)

Of all weather conditions, lightning is probably of the greatest concern to anyone involved with a rocket launch. This is not just because of the damage it can cause to the spacecraft and crew but also due to its unpredictability.

The probability of a lightning strike near a launch facility can be determined with a high degree of accuracy by measuring lightning activity in clouds around the launch site and measuring the amount of electricity present in the air (even in the absence of any clouds).

Even with the most accurate sensors and advanced forecasting models available, though, it is still impossible to determine precisely when and where lightning will strike. As a result, space agencies have a number of measures in place to guard against lightning strikes.

How Launch Complexes Protect Rockets From Lightning Strikes

The first and best line of defense a launch facility has against a potential lightning strike is the lightning towers surrounding a modern launchpad, like the four towers surrounding SpaceX’s Launch Complex 40 at Cape Canaveral in Florida, USA.

A SpaceX Falcon 9 rocket lifts off from Cape Canaveral
A SpaceX Falcon 9 rocket lifts off from Cape Canaveral in Florida with the white lightning masts on top of the four towers surrounding the launchpad towering over the launch vehicle.

These tall towers can be found at most major launch facilities around the world. From the Baikonur Cosmodrome, Russia’s launch facility in Kazakhstan, to Vandenberg Space Force Base in the United States – all are equipped with lightning suppression systems.

The system typically consists of 4 towers (although some launchpads make do with fewer towers), which are substantially taller than the rocket on the launchpad. This ensures that a lightning bolt will hit one of the towers instead of the launch vehicle.

Cylindrical-shaped masts, also known as “candlesticks,” are placed on top of each tower and act as insulators with a stainless steel cable running from the inside of each mast all the way to the ground, which redirects lightning safely away from the spacecraft.

All towers are also interconnected with steel cables to further insulate and protect the rocket. It creates a type of Faraday cage that not only protects the vehicle from a direct lightning strike but also from the dangerous electromagnetic field generated by lightning.

What Is A Faraday Cage?

A Faraday cage is a protective enclosure that shields an object from the electromagnetic field generated by another entity or event. It consists of a covering made from electrically conductive materials which enclose an object on all sides.

It can be a full enclosure, or as in the case of the original Faraday cage (named after its inventor, Michael Faraday), consists of a mesh of metal wiring enclosed around an object.

When an electrical current comes in contact with the cage, it is evenly distributed throughout the outside of the conductive enclosure of the cage/shield without entering or affecting any objects on the inside.

They are commonly used to protect objects and people from different types of electromagnetic radiation like microwaves and radio waves. In the case of rocket launch sites, it is used to shield spacecraft from the electromagnetic fields generated by lightning.

Conclusion

Orbital rockets are large vehicles that look quite robust while standing on a launchpad before liftoff. However, as this article illustrated, they are vulnerable to a variety of atmospheric conditions, specifically lightning, while standing on the launchpad.

(To learn more about exactly how large modern launch vehicles are, read more in this article about the average size of an orbital rocket, which also looks at the 30 biggest rockets in space exploration.)

A lightning strike can severely damage a launch vehicle’s structure, payload, and electronic equipment. For this very reason, rocket launch facilities make use of lightning protection systems like the four tall lightning towers typically found at a launch facility.

This article illustrated what these tall towers are, their makeup, and how they work to protect a rocket from a lightning strike and associated magnetic field while standing on the launchpad.

This article was originally published on headedforspace.com. If it is now published on any other site, it was done without permission from the copyright owner.

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