The radar system protecting America (and Canada too!)

In the far north of Canada and the US, in some of the most remote locations on the planet, is a chain of radar stations with one job: to detect an oncoming attack from over the north pole.

But how did that chain get built? And when? Let's find out?

Historical precedent: Chain Home radar line, United Kingdom (WWII)

Before WWII, the British government quietly constructed a chain of radar stations in the south of their country. The new technology would prove vital in the war to come, detecting incoming German bombers with enough time to scramble defending fighters. In their turn the Germans built their own radar defences that allowed the Luftwaffe to target Allied bombers, often exacting horrific casualties.

1940s - 1950s: The Cold War

Soon after the end of WWII, as it began to look as if the next big conflict would be with the Soviet Union, American and Canadian military planners decided it would make sense to, first, create an integrated North American defence network, and build a chain of radar stations modelled on the radar networks built by the British and Germans during the war. Of course, the scale of the North American version was vastly more challenging in terms of size and terrain.

The first attempt was the Pine Tree radar line, mostly along the US-Canada border. The most likely air attack route from the USSR would have been over the north pole, so the radar was built for that. Unfortunately, the tech for this first line wasn't great; they had a lot of trouble making it work properly. Plus as jet technology developed quickly, it became apparent they'd need more lead time, so they decided to build another line further north.

The Mid-Canada line was built to supplement the Pine Tree line. Built mostly in the northern areas of Canada's western provinces as well as northern Ontario and Quebec, it was even more challenging to build and operate. With stations built in remote, inaccessible areas unconnected by roads, keeping them supplied was a massive (and expensive) undertaking. Yet it was still a very flawed system that didn't work very well. Luckily, advancing technology allowed the construction of yet another chain of radar stations even further north.

The Distant Early Warning or DEW line was an extraordinary feat of technology and constructions. Running several hundred kilometres north of the arctic circle, most of it ran along the shore of the Arctic Ocean, then along Baffin Island and northern Greenland (the station pictured here was in Greenland). This radar line was around 3,000 miles long (just under 5,000km), and was built in some of the harshest conditions the planet has to offer. The stations could only be supplied by air in wintertime, requiring an even larger continent-spanning logistical network. For a time it was supplemented by seaborne radar picket vessels in the Pacific and Atlantic Oceans, keeping North America snugly wrapped in a protective radar shield that never slept.

Unfortunately, by the time it was finished in the late 1950s, the DEW line was already obsolete. Why? Because advancing technology meant the emerging threat of Soviet attack came from ICBMS -- Intercontinental Ballistic Missiles. They still flew over the pole, but moved so fast that not only would they be incredibly hard to detect, but the time to react would be so limited that literally every second would count. The answer? To build yet another chain of radar stations.

The good news for builders of BMEWS -- Ballistic Missile Early Warning System -- was that it would only require the construction of three radar stations, in Alaska, Greenland and the UK. The bad news was that building a vast network capable of detecting and tracking a mass nuclear missile attack by, potentially, thousands of incoming missiles, with zero time for analysis and double-checking (total flight time of a Soviet ICBM from launch to impact would be 10-30 minutes) would push the limits of detection and computing technology.

They were able to make it work, but it was very tricky, often triggered by innocent phenomena such as flocks of birds or even a moonrise. Any one of these mistakes might easily have triggered a mistaken nuclear retaliation attack by the US military, but somehow humanity avoided that catastrophe.

The network was run by NORAD -- the North American Aerospace Defence Command. This is a military structure headquartered at Colorado Springs, Colorado. It was, and remains, a joint Canadian-US military command. They never sleep, keeping an eye on all potential threats -- and ready to activate nuclear retaliation. Starting in the 1960s, the radar lines were supplemented by satellite systems equipped to detect missile launches and nuclear explosions.

The DEW line and its predecessors were shut down after the Cold War ended, being replaced by the Solid State Phased Array Radar System (SSPARS) in 2001. This uses stations located at the old BMEWS sites, in addition to some new ones. North America is still wrapped snug in a protective radar blanket.

The Soviets never were able to build a comparable radar chain; they simply didn't have the resources. Some radar sites were quite notable, however, the most well-known, codenamed Duga, being the source of an annoying, repeating electromagnetic signal nicknamed the "Russian Woodpecker." Radio manufacturers literally had to design "woodpecker blankers" in their circuit boards to block it out. The site located near the former Chernobyl Nuclear Power Plant still stands, but has been inactive for decades. It is the site of avid urban explorers, It really is a huge structure, around 150 metres (around 500 feet) high. The Soviets tried to "outflank" the BMEWS system by developing a FOBS missile technology -- Fractional Orbital Bombardment System. These missiles, instead of flying over the north pole, would briefly enter orbit, fly over the south pole, and attack the US from its unguarded south flank. However the FOBS system required much smaller warheads, and were made obsolete by the American addition of satellite tracking to its detection systems. Plus there were still nuclear submarines, which could launch nukes with flight time of only 5-10 minutes.

Most of the shut-down radar sites have been dismantled. And of course they required a massive clean-up effort costing around half a billion dollars. But there are still a few that are still standing, abandoned, and you can visit them -- if you can get to them.