Could a nuclear generated electromagnetic pulse kill your car?

Most of us know about the latest round of sabre-rattling, chest-thumping verbal exchanges between the USA and North Korea as they strive to convince each other their military weapons are biggest and best. Its familiar stuff, except for just recently when the subject of nuclear generated electromagnetic pulses reared its potentially devastating head.

Electromagnetic pulses (EMP) as a form of military weapon have of course been known about for years although information about them has been closely guarded.

An enemy could use EMP to destroy the electrical and electronic infrastructure of another country with massively debilitating effect. Anything from communications systems, power grids, electronic equipment, water and fuel services and much more could be disabled by an EMP attack.

However one element of modern life that may possibly withstand such an attack are the cars we drive.

But before delving into that, what is an EMP? The most familiar one to most of us is a lightening strike which in EMP parlance is classified as an E2 strike. Potentially very dangerous but usually controlled by surge protection technology so damage is minimised.

Nuclear generated EMP

In comparison to lightening, an EMP created by a high altitude nuclear device has the higher classification of E1 and is far more powerful.

Following such a nuclear detonation, gamma rays are released that start to absorb electrons from the atmosphere and both of these head towards earth. This is called the Compton Effect and the electrons combine with Earth’s electromagnetic field to generate extremely powerful magnetic waves.

The nuclear device prompting all this doesn’t need to be that big. In the early 1960s the USA tested a 1.5-megaton nuclear EMP in a study referred to as Starfish Prime above the Pacific Ocean. It caused electrical damage 900 miles away in Hawaii by disabling about 3% of the island’s street lighting.

However, if that same warhead had been exploded 200 miles above the US mainland the damage would have been far more. The strength of that EMP would have been up to 30,000Volts/metre because the Earth’s magnetic field has greater strength over the United States territory rather than the Pacific Ocean. And while on the subject of EMP strength, scientists today estimate that in the right location an E1 EMP could be as powerful as 50,000Volts/metre.

Wrecked Infrastructure

So having wrecked a substantial amount of what is considered modern infrastructure would a nuclear EMP attack also disable our cars? This is a tricky question to answer because even today the effects of a true nuclear EMP are difficult to accurately predict.

At the time of the Starfish Prime test cars were much simpler technically than today’s vehicles and the generally held view at that time was cars might stall but would probably start up and run normally.

Today opinions on the subject vary enormously. One view is that if your car has electronic fuel injection, anything computerised that controls your vehicle’s primary systems, a powertrain control module, ABS, electronic ignition or keyless ignition then your vehicle would be totally disabled by an E1 EMP of 50,000Volts/metre.

Sensitive Electronics

However, opposing that somewhat negative perspective is the view that many vehicles might survive an E1 EMP. Sensitive electronics may be shielded well enough to continue to operate. In effect, the metal parts of a car body could potentially act as a Faraday cage. And lets not forget that many electronic components used in cars have to operate in harsh, high temperature conditions and consequently are often of more robust design and are well protected.

However, the Faraday cage optimism is somewhat dented by the fact that if a car body did form a perfect cage then you wouldn’t be able to make phone calls from it.

Generally speaking the answer to whether our modern cars could stand up to an Electromagnetic Pulse attack comes down to just one thing; how strong is the attack.

Tests in the past have shown that car electronics subjected to an EMP of less than 25,000Volts/metre would not be effected. It is only when an EMP of E1 proportions (50kVm) strikes that serious problems could occur that would either totally disable the car or cause malfunctions on a car that was being driven that would inevitably result in a road traffic accident.

Tests have also shown that cars switched off at the time of a high power EMP would start and function close to normal.

So some drivers could find their cars were still working following a substantial EMP attack. The question is would they still be useful bearing in mind fuel would not be available because the electronics used in garage petrol pumps would be disabled and highway control systems such as traffic lights would be out. Add to that the fact highways would be jammed with dead cars and perhaps the overall answer to the headline question is don’t throw your bicycle away yet.

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