The Thin Aluminum Line
Supersonic airplanes and a screen of radar stood ready during the cold war to avert the end of the world.
- By Carl Posey
- Air & Space magazine, January 2007
David Peters; Sources: NASM (SI Neg. #85-16420); NASM (SI Neg. #1B44791); SOVFOTO
(Page 3 of 10)
Critics in the Air Force and elsewhere likened the idea to the Maginot Line, whose redoubts had been deftly flanked by the German blitzkrieg, and derided MIT proponents as “Maginot boys.”
There was, however, a crucial difference. While France was defending against old threats, the proposed defensive system aimed to counter entirely new kinds of threats with the freshest technology. The system employed computer, radar, and aircraft designs that were then just gleams in the eyes of programmers, scientists, and engineers.
The project advanced in spite of its detractors. In 1957, the first SAGE control center was dedicated at McGuire Air Force Base in New Jersey; within four years 22 more centers were operating. SAGE monitored the airspace over Canada and all of the United States except Alaska. (Interceptors in Alaska received radar information relayed to them by North American Aerospace Defense Command.)
SAGE’s four-story, windowless blockhouses were not much to look at from the outside. Within the six-foot-thick concrete walls, however, were some of the world’s most advanced computers and communications gear. A 300-ton FSQ-7 computer filled the second floor, its 70 cabinets housing 58,000 humming vacuum tubes. The facilities had no heating; in winter, the vacuum tubes kept them warm.
On another floor, Air Force personnel sat in the soft blue light of communications and display consoles, watching for signs of war.
New radar picket lines were going up in the north. Begun in 1951, the Pinetree Radar Line by 1954 had 30 manned stations along the U.S.-Canada border at 49 degrees north latitude. A Mid-Canada Line, built in the late 1950s, provided a fence of eight main and 90 unmanned Doppler stations along the 55th parallel.
The most daunting feat, however, was raising the northernmost radar fence: the Distant Early Warning (DEW) Line, draped along the 70th parallel from western Alaska and the Aleutian chain eastward across Canada to Greenland. When President Dwight Eisenhower approved construction in February 1954, virtually the only structures north of the continent’s tree line were Inuit villages.
Just three years later, 58 stations were operational; the number would eventually grow to 70. Each main station had big AN/FPS-19 L-band search radar (or, in the two Greenland stations, a more powerful AN/FPS-20). Unattended AN/FPS-124 Doppler radars filled in the gaps, looking for low-flying targets.