A new spin on FSF

@davesaddiction
Between 28 May and 7 October 1957 the US conducted Operation PLUMBBOB, as series of 29 nuclear tests. Most of the tests were intended to refine the weapon's design, to allow the development of smaller warheads for ICMBs and IRBMs, although several tests were for anti-aircraft and nuclear depth charges. Of the 29 tests, 2 were fizzles (the official term for a nuclear bomb that does not function correctly, resulting in a sub-nuclear yield. Plumbbob also tested weapons' effects against structures and soldiers.

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During Plumbbob, the first subterranean tests were conducted, with Pascal A being lowered down a 500 ft borehole, which was then plugged with a 7 foot thick concrete cylinder. The yield, anticipated to be only 1kg, turned out to be 50,000 times greater, registering 55t, creating a jet of fire that shot hundreds of feet into the sky, disintegrating the plug.
During the subsequent Pascal-B test on 27 August 1957, a 2,000 lb steel plate cap (a piece of armor plate) was welded over the borehole to contain the nuclear blast, even though scientists predicted it would not work. A high-speed camera, which took one frame per millisecond, was focused on the borehole because studying the velocity of the plate was deemed scientifically interesting. After the detonation, which was estimated at 300t, the plate appeared in only one frame, but this was enough to make an estimation of its speed: 66 km/s (41 mi/s; 240,000 km/h; 150,000 mph). {For comparison, the fastest manned vehicle, Apollo 10, reached just shy of 25,000mph.} The plate was never found; despite later claims that it was the first object launched into space, scientists believe compression heating caused the cap to vaporize as it sped through the atmosphere.