On July 9, 1962, the United States launched a Thor rocket armed with a W49 thermonuclear warhead up to an altitude of around two hundred and fifty miles over the Pacific and detonated it.  It took thirteen minutes for the missile to reach its predesignated altitude before the 1.45 megaton explosion illuminated the night sky for hundreds of miles in every direction.  The missile, designated Starfish Prime, remains the biggest bomb ever detonated in space to this day.

Scientists were poised to study the effects of radiation at high altitudes on Johnston Island below.  Twenty-seven smaller rockets were launched alongside Starfish Prime to measure the effects of the detonation, but none of them, nor the scientists involved, were prepared for what would occur as a result of the explosion.

The flash created by the explosion as seen through heavy cloud cover from Honolulu nearly 900 miles away. (WikiMedia Commons)

In the near vacuum of space, free electrons were hurled from the explosion in every direction and faced no atmospheric impedance.  Instead, they formed a brief but powerful, electromagnetic pulse that caused power outages and other electrical issues on the Hawaiian Islands, nearly a thousand miles away.  At least six satellites orbiting near the explosion were lost despite the distance seeming so insurmountable that the U.S. government hadn’t even considered the likelihood of such damage occurring.   Scientists had discovered that high altitude detonations of nuclear weapons could disrupt the flow of electricity in devices thousands of miles away from the point of detonation.  Starfish Prime was not just a nuclear weapon, it was a weaponized EMP (electromagnetic pulse).

“To our great surprise and dismay, it developed that Starfish added significantly to the electrons in the Van Allen belts,” Atomic Energy Commission Glenn Seaborg wrote in his memoirs. “This result contravened all our predictions.”

In the scope of threats to our way of life, few things should be more concerning than the prospect of a foreign nation using this method to cripple the infrastructure of the United States.  If a 1.45 megaton bomb could knock out electronics a thousand miles away, imagine what a warhead the size of the Soviet Tsar Bomba would do if detonated in low orbit above us.  Its 50-megaton yield would render the entire U.S. power grid a thing of the past.  Cars wouldn’t start.  Phones wouldn’t work.  The blackout would be all encompassing and permanent.

The threat of an EMP being detonated above us isn’t only a Russian one.  According to Dr. William Graham, who served as a science advisor to President Reagan and was a member of the Department of Defense’s Science Board, the threat could easily come from North Korea or Iran.

Unlike strategic nuclear strikes that require elaborate targeting systems and rocket technology, an EMP strike would only need to reach high altitude airspace above the U.S.  According to Graham, an rocket delivering a nuclear warhead could be fired from a simple container ship.  In July of 2014, ISIS claimed that even they currently have one captured Scud missile in their possession that could theoretically do the job.  North Korea’s missile program could feasibly deliver the payload effectively even from their own shores.

In 2008, a federal commission assigned to study EMPs and their possible damage to the infrastructure of the United States concluded that an attack on the American power grid could result in killing a whopping ninety percent of Americans over a twelve-month span.  Our growing dependence on technology for things like communication, transporting goods, and extending the shelf life of supplies would result in Americans starving in the dark.  The real damage would likely be self-inflicted as people grew desperate and started fighting among themselves.  To a large extent, a single (large enough) EMP detonation could wipe the United States, as we know it, off the map.