Sputnik Arming Key in Space Race
This metal arming key is the last remaining piece of the first artificial satellite to orbit the Earth. It prevented contact between the batteries and transmitters until Sputnik was prepared for launch. A pin mounted on the launch vehicle served the same purpose until the satellite separated from the launcher in orbit. Only then did Sputnik begin to transmit the distinctive "beep, beep, beep" heard round the world.