This device allowed the Apollo 11 astronauts to determine the radiation in the crew compartment. It was fully portable, self-contained, and provided a direct reading of radiation dose rates. In the event of a radiation emergency (such as a solar flare) it could be used to find a habitable, low-dose region within the spacecraft.
Image Number: WEB13188-2013
Credit: National Air and Space Museum, Smithsonian Institution
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