Project Mogul was a mid-20th century classified U.S. Army Air Force operation that focused on detecting sound

waves that were generated by nuclear weapons tests conducted by the Soviets.

This project lasted from 1947 until the beginning of 1949, and there was a lot of

weapons testing going on at that point.

As World War II came to an end, both the U and USSR were polishing their guns and refining their weapons of mass destruction

in preparation for what seemed like an inevitable conflict between the two still-standing global powers,

who had seemingly incompatible approaches to and beliefs about, pretty much everything. So the US was trying to figure out how to keep tabs on the Soviet's activities in this department,

and it was discovered that way up high in the sky, in the upper atmosphere,

there's a zone in which the combination of air pressure and temperature attributes

reduce the speed of sound, which in turn means sound waves travel great distances.

The net effect of those atmospheric circumstances at that specific height is that if you're able to listen to that layer of air in just the right way,

you can, with a reasonable degree of certainty, figure out when someone else, even on the other side of the planet,

has detonated a massive bomb, like an atomic bomb, and you might even be able to figure out where, the magnitude of the bomb, and so on.

This project made use of experimental balloons, which were armed with microphones and transmitters,

that could capture globe-spanning sound waves at that high altitude and then transmit that data back to the ground, where researchers would be keeping tabs and documenting these anomalies.

In order to function properly, these balloons needed to stay way up in the upper atmosphere, stable for long periods of time.

And that required additional tech wizardry that helped them track their altitudes and

adjust their ballast levels as appropriate.

And it also required that these balloons were quite resilient.

And the initial versions were made from clusters of smaller rubber balloons all linked together, but the program soon

moved on to large polyethylene plastic balloons instead, as they were less prone to leaks

and more overall durable. This program was ultimately sunsetted when a more reliable

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