This was Project Argus. The idea had germinated in the panic after the launch of the Soviet Union's Sputnik satellite. In light of these surprising new capabilities, the US had a problem: how could it protect the country from an incoming nuclear warhead?
Armed with some wild physics, Nicholas Christofilos hatched an equally wild plan: turn the upper atmosphere into a force field across the US that would fry the electronics of incoming missiles. How? Explode nuclear weapons in Earth's magnetosphere to create a long-lived radiation belt that would degrade the missiles.
The first atomic detonation set off a luminous fireball, triggering a staggering blue-green aurora that captivated its audience. But beyond the pretty lights, it was a failure. The bombs did indeed produce many high-energy electrons, but it turned out that Earth's magnetic field wasn't strong enough to keep the electron shield from decaying.
Christofilos's ill-fated "death belt" is probably not what you think of when you think of DARPA ("Defense" was only added permanently in 1996). If you have heard of this Pentagon agency, you will know it as the place that brought you the internet, the laser and the stealth fighter. Sharon Weinberger's groundbreaking book The Imagineers of War, however, reveals how that mythology is the result of some pretty tight PR control by DARPA, exposing as much as she can of a far more uncomfortable truth.
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