Things That Go Bump in the Night

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Things That Go Bump in the Night

12/14/2007

By Doug Gale

effect of a high altitude burst would be "pumping" the Van Allen belt with a large number of bomb-induced electrons. The electrons will remain trapped in the belts for a year or more and destroy any unhardened satellites traversing the belts in low earth orbit. The first commercial communication satellite, Telstar, was a victim of Starfish Prime.

The Devil Is Always in the Details
In the "Black Friday" scenario the burst occurred 400 kilometers over Kansas. High enough to be above the horizon for almost all of the continental United States, but low enough to ensure that the intensity of gamma rays reaching that critical zone 20 to 40 kilometers above sea level was sufficient to generate a destructive EMP. But how bad would it really be? Most people, even Hawaiians, have never even heard of "Starfish Prime."

Predicting what would actually happen after a high altitude nuclear burst is complex. While an advanced degree in physics helps, it still isn't possible to account for all of the variables. For example, how effective is a car's metal body in shielding its computerized ignition system? The military has done extensive testing of military vehicles as part of their programs to harden military systems. But they didn't test my Honda--or if they did, I don't know the results.

Simulating an EMP without detonating a nuclear device is hard, and the size of objects that can be tested is limited to things like tanks and aircraft. There is no way other than computer simulation to test large systems. And unfortunately our cyber society is now based on large, complex, and geographically dispersed systems. The fact that my radio works doesn't mean that the national communications infrastructure will. Our only empirical data is from 1962, an era dominated by vacuum tube electronics and other components that were far more resistant to EMP than our modern integrated circuits, computers, and low earth orbit satellites. Stand-alone devices were the norm; complex networked systems were a rarity.

The good news is that it isn't easy to launch an EMP attack. A rogue state trying to execute the black Friday scenario faces some problems. (The assumption here is that a country with ballistic missile nuclear capabilities will refrain from an EMP attack because of their own vulnerability to a retaliatory nuclear strike from the United States.) First it needs a nuclear bomb. Unfortunately (for us) a primitive atomic bomb is actually more efficient than a modern hydrogen bomb in generating an EMP. Equally unfortunate is the fact that the strength of the EMP pulse only increases as the square root of bomb's yield. Thus a Hiroshima and Nagasaki class bomb might yield almost half the EMP of the 1.4 megaton Starfish Prime test. Stated in layman's terms that means the rogue state doesn't need a big bomb; a primitive a-bomb might work just fine.