Radar Tubes for Defense
The launch of Sputnik 1 in 1957 proved that Soviet missiles armed with nuclear weapons could reach the United States. In response, Americans established an integrated system of radar stations to detect missiles in flight. The Ballistic Missile Early Warning System included large stations in Alaska, Greenland, and England. The radar waves were generated by devices called klystron tubes. Though tubes are no longer used, the stations remain in operation today.