Militaries around the world work extremely hard to keep their latest innovations secret, for obvious reasons. But this secrecy can spark intense curiosity and speculation among members of the public. Every so often, military secrets are released, if only many decades after they were invented.
One such example is Fogbank – a secret material used in the production of nuclear warheads. Its manufacture was so highly classified that details of the process were lost. So, when a fresh batch of the material was needed to refurbish old warheads, the US National Nuclear Security Administration was forced to spend a lot of time and money to rediscover the process.
Although its existence is now public knowledge, the exact nature of Fogbank still remains classified. Arms experts believe it’s an aerogel material, designed to become superheated plasma when the weapon’s fission stage is detonated, which then triggers the final, fusion-stage detonation of the weapon. Fogbank was first manufactured in Tennessee between 1975 and 1989. After the final batch of warheads was produced, the facility was deactivated.