NACA physicists studying alpha rays in a continuous cloud chamber. A cloud chamber is used by Lewis scientists to obtain information aimed at minimising undesirable effects of radiation on nuclear-powered aircraft components. Here, alpha particles from a polonium source emit in a flower-like pattern at the cloud chamber's centre. The particles are made visible by means of alcohol vapour diffusing from an area at room temperature to an area at minus 78 degrees Centigrade. Nuclear-powered aircraft were never developed and aircraft nuclear propulsion systems were cancelled in the early 1960s. The National Advisory Committee for aeronautics (NACA) was established in 1915, and became NASA on 1 October 1958.
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