When you read the letters “GPS,” chances are you think of that little device in your car, whose computerized female voice helps you get from point A to point B.

Do $30 GPS Jammers Pose Threat to National Security?

But if our GPS systems go down today, absolute chaos would ensue, according to this fascinating article in the New Scientist. Why? Because GPS technology permeates almost every aspect of our plugged-in lives. Consider what happened in San Diego a few years ago when the GPS signals were disrupted:

In the tower at the airport, air-traffic controllers peered at their monitors only to find that their system for tracking incoming planes was malfunctioning. At the Naval Medical Center, emergency pagers used for summoning doctors stopped working. Chaos threatened in the busy harbour, too, after the traffic-management system used for guiding boats failed. On the streets, people reaching for their cellphones found they had no signal and bank customers trying to withdraw cash from local ATMs were refused. Problems persisted for another 2 hours.

Or what happened at Newark’s International Liberty Airport last year when GPS signals were jammed-up:

Airport controllers had installed a new GPS-based landing system, so that aircraft could approach in bad visibility. But it was shutting itself down once or twice a day. It took several months to find the culprit.

The culprit was a “GPS jammer,” a small plastic device which can be bought for as little as $30 online. This device can knock out GPS signals from miles away. As it turns out, a trucker on the New Jersey turnpike had installed a GPS jammer in his car to avoid paying a GPS-operated toll. He drove past the Newark airport twice a day, causing the havoc described above.

Do $30 GPS Jammers Pose Threat to National Security?

These devices, above, are illegal in the United States, the UK, and elsewhere, and for good reason: such a small device, it can cause such a large amount of damage. The main reason for this is that GPS signals are incredibly weak:

“The problem is that the GPS signal is very weak. It’s like a car headlight 20,000 kilometres away,” says consultant David Last, former president of the UK’s Royal Institute of Navigation. You can’t boost the signal any further because of the limited power supply on a satellite.

Last has first-hand experience of how easy it is to block a GPS signal, and the effects it can have on modern technology. In 2010, he conducted an experiment in the North Sea, aboard the THV Galatea, a 500-tonne ship.

Do $30 GPS Jammers Pose Threat to National Security?

The Galatea is the pride of its fleet, with all the latest navigation equipment. Last wanted to find out how it would cope without GPS. So he used a simple jamming device that overwhelmed the GPS signal by broadcasting noise on the same frequency as the satellites.

Beyond being a nuisance, GPS jammers pose a serious national security threat. After all, car thieves and criminals have already used jammers to evade the law. And from the examples above, we know that GPS jammers can interfere disastrously with air-traffic control, hospital emergencies, and our major methods of communication. With that in mind, it’s frightening to imagine a terrorist getting his hands on one of these.

Watch a GPS jammer at work below. You’ll see that the once the jammer is plugged in, the six satellite fixes on the screen go dead.

While we all rely on technology, this story reminds us how vulnerable we are when technology fails. Let’s hope that some innovative engineer will create a device sometime soon that will jam-up the jammers.