Command and Control

how to bring the warhead close to its target: My description of ballistic missile guidance systems is based on a fine magazine article published more than half a century ago, Maya Pines, “The Magic Carpet of Inertial Guidance,” Harper’s, March 1962; a training manual for Titan II launch officers, “Missile Launch/Missile Officer (LGM-25): Missile Systems,” Student Study Guide 3OBR1821F/3121F-V1 through 4, Volume I of II, Department of Missile and Space Training, Sheppard Technical Training Center, September 1968; and an extraordinary book about how missiles hit their targets, Donald MacKenzie, Inventing Accuracy: A Historical Sociology of Nuclear Missile Guidance (Cambridge, MA: MIT Press, 1993).

burned for only the first five minutes of flight: During the booster phase, the first-stage engine of the Titan II fired for about 165 seconds; during the sustainer phase, the second-stage engine fired for about 125 seconds; and during the Vernier Stage, the two small solid propellant engines fired for about 10 seconds. See “Missile Launch/Missile Officer (LGM-25),” p. 3.

about 80 percent of the warheads within roughly a mile of their targets: Cited in MacKenzie, Inventing Accuracy, p. 122.

a leading role in the miniaturization of computers: See ibid., pp. 159–61, 206–7; Edwards, Closed World, pp. 63–65.

all of the integrated circuits in the United States: See MacKenzie, Inventing Accuracy, p. 207. In 1965, the Pentagon was buying 72 percent of the integrated circuits, and the proportion being used in military applications did not fall below half until 1967. See Table 6 in Gregory Hooks, “The Rise of the Pentagon and U.S. State Building: The Defense Program as Industrial Policy,” American Journal of Sociology, vol. 96, no. 2 (September 1990), p. 389.

It had about 12.5 kilobytes of memory: This is a rough estimate, used for the sake of simplicity. The Titan II missile’s onboard guidance computer could store 100,224 binary bits. They were stored on a magnetic drum memory assembly with 58 tracks. Each track held 64 words (or “bytes”) that contained 27 bits. For the sake of comparison, I have converted those 27-bit bytes into today’s more commonly used 8-bit bytes. By that measure, the Titan II onboard computer had about 12.5 kilobytes of memory. For the specifications of the computer, see “Missile Launch/Missile Officer (LGM-25),” p. 24. I am grateful to Chuck Penson, Bob Peurifoy, Richard Peurifoy, and Steve Peurifoy for helping me with these calculations.

more than five million times that amount: Many smartphones now have 64 gigabytes of memory. A gigabyte is equivalent to about 1 million kilobytes. The comparison between the 12.5-kilobyte memory of a Titan II computer and the 64-gigabyte memory of a smartphone is inexact. But it still conveys an important point: even the rudimentary computing device aboard the Titan II could guide a nuclear warhead almost halfway around the world with remarkable accuracy.

the first missile to employ an inertial guidance system: For the Nazi efforts in this field, see MacKenzie, Inventing Accuracy, pp. 44–60.

the Nazi scientists who invented it were recruited: Dr. Walter Haeussermann, who played a large role in developing the guidance system of the V-2, was brought to the United States under Project Paperclip and reunited with his former employer, Wernher von Braun. Haeussermann later worked on the guidance systems of the Redstone and Jupiter missiles, left the Army to work for NASA, later headed the Astrionics Laboratory at the Marshall Space Center, and helped devise the mechanisms that guided American astronauts safely to the moon. See Dennis Hevesi, “Walter Hauessermann, Rocket Scientist, Dies at 96,” New York Times, December 17, 2010.

Circular Error Probable… of less than a mile: See MacKenzie, Inventing Accuracy, p. 131.

miscalculated by just 0.05 percent: During the last fifteen minutes of the Titan II warhead’s reentry, it traveled at a speed of about 16,000 miles per hour. It would cover a distance of about 4,000 miles in those fifteen minutes. A measurement error of 0.05 percent would add or subtract about 20 miles from the distance traveled. For the speed of reentry, see Penson, Titan II Handbook, p. 169. Maya Pines made a similar calculation in “Magic Carpet of Inertial Guidance,” but with a somewhat different result.

The accuracy of a Titan II launch: My description of a Titan II missile’s launch, trajectory, and flight is based on information found in Penson, Titan II Handbook, pp. 118–39, 169; Stumpf, Titan II, pp. 177–78; and “Final Titan II Operational Data Summary,” Rev 3, TRW Space Technology Laboratories, September 1964, p. 3–1. Some of the numbers differ slightly in these sources. For example, Chuck Penson says the missile began to rise 58 seconds after the keys were turned; David Stumpf says 59.2 seconds. I have tried to convey the gist of how a Titan II launch would have unfolded. Penson’s account is especially vivid and detailed.