The Thin Aluminum Line

Supersonic airplanes and a screen of radar stood ready during the cold war to avert the end of the world.

The Soviets' first atomic bomb test in 1949, in background, prompted tense aerial duels between (top to bottom) Soviet Tu-95 bombers, F-101s, and F-102s. Bottom: The blast effects of a one megaton bomb exploding over Pittsburgh. (David Peters; Sources: NASM (SI Neg. #85-16420); NASM (SI Neg. #1B44791); SOVFOTO)
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To explore ways to make North American nuclear defense less porous, the Massachusetts Institute of Technology in 1952 convened a Summer Study Group. It started with the idea of creating a radar net around the northern fringe of North America.

The system the scientists created became a massive joint undertaking by the United States and Canada and relied on groundbreaking computer technology to manage information. To develop it, MIT created an air defense lab that later morphed into the Lincoln Laboratory, which remains famous for research in missile defense, space surveillance, and civilian air traffic control. The brains of the information management system would be called the Semi-Automatic Ground Environment, or SAGE.

Centrally located digital computers would monitor data from a picket line of new-generation radars, then vector interceptors toward targets. Surface-to-air missiles, as well as interceptors from southern U.S. bases, would also engage the Soviet bombers as the battle spread south. The MIT group estimated that such a system could exterminate 60 or 70 percent of the attackers.

Offense-minded officials in the Air Force were not impressed. Although the Battle of Britain in World War II had demonstrated that

contemporary interceptors guided by ground radar were more effective than fighters patrolling

on their own, pilots preferred keeping command and control in the cockpit.

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.

About Carl A. Posey

Novelist and award-winning science writer Carl A. Posey was the author of seven published novels, a number of non-fiction books, and dozens of magazine articles. He was a licensed pilot and an Air & Space magazine contributor for more than 30 years, beginning with its second issue in 1986. Posey died on February 9, 2018.

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