Eric Schlosser - Command and Control

Donald Quarles was one of the leading skeptics at the Pentagon, eager to cut costs and avoid the unnecessary duplication of weapon systems. No longer secretary of the Air Force, he was the second-highest-ranking official at the Pentagon, rumored to be Eisenhower’s choice to become the next secretary of defense. And then Quarles suddenly died of a heart attack, amid the long hours and great stress of his job. Funding of the Titan II was soon approved, largely due to the size of its warhead. General LeMay didn’t care much for the Atlas, Titan, or Minuteman — missiles whose only strategic use was the annihilation of cities. But the Titan II, with its 9 megatons, was the kind of weapon he liked. It could destroy the deep underground bunkers where the Soviet leadership might hide, even without a direct hit.

One of the many challenges that the designers of the Titan II faced was how to bring the warhead close to its target. The Titan II’s rocket engines burned for only the first five minutes of flight. They provided a good, strong push, enough to lift the warhead above the earth’s atmosphere. But for the remaining half hour or so of flight, it was propelled by gravity and momentum. Ballistic missiles were extraordinarily complex machines, symbols of the space age featuring thousands of moving parts, and yet their guidance systems were based on seventeenth-century physics and Isaac Newton’s laws of motion. The principles that determined the trajectory of a warhead were the same as those that guided a rock thrown at a window. Accuracy depended on the shape of the projectile, the distance to the target, the aim and strength of the toss.

Early versions of the Atlas and Titan missiles had a radio-controlled guidance system. After liftoff, ground stations received data on the flight path and transmitted commands to the missile. The system eventually proved to be quite accurate, landing about 80 percent of the warheads within roughly a mile of their targets. But radio interference, deliberate jamming, and the destruction of the ground stations would send the missiles off course.

The Titan II was the first American long-range missile designed, from the outset, to have an inertial guidance system. It didn’t require any external signals or data to find a target. It was a completely self-contained system that couldn’t be jammed, spoofed, or hacked midflight. The thinking behind it drew upon ancient navigational rules: if you know exactly where you started, how long you’ve been traveling, the direction you’ve been heading, and the speed you’ve been going the whole time, then you can calculate exactly where you are — and how to reach your destination.

“Dead reckoning,” in one form or another, had been used for millennia, especially by captains at sea, and the key to its success was the precision of each measurement. A poor grasp of dead reckoning may have led Christopher Columbus to North America instead of India, a navigational error of about eight thousand miles. On a ship, the essential tools for dead reckoning were a compass, a clock, and a map. On a missile, accelerometers measured speed in three directions. Spinning gyroscopes kept the system aligned with true north, the North Star, as a constant reference point. And a small computer counted the time elapsed since launch, calculated the trajectory, and issued a series of instructions.

The size of the guidance computer had been unimportant in radio-controlled systems, because it was located at the ground station. But size mattered a great deal once the computer was going to be carried by the missile. The Air Force’s demand for self-contained, inertial guidance systems played a leading role in the miniaturization of computers and the development of integrated circuits, the building blocks of the modern electronics industry. By 1962 all of the integrated circuits in the United States were being purchased by the Department of Defense, mainly for use in missile guidance systems. Although the Titan II’s onboard computer didn’t rely on integrated circuits, at only eight pounds, it was still considered a technological marvel, one of the most powerful small computers ever built. It had about 12.5 kilobytes of memory; many smart phones now have more than five million times that amount.

The short-range V-2 had been the first missile to employ an inertial guidance system, and the Nazi scientists who invented it were recruited by the Army’s Redstone Arsenal after the Second World War. They later helped to give the Jupiter missile an impressive Circular Error Probable — the radius of the circle around a target, in which half the missiles aimed at it would land — of less than a mile. But the longer a missile flew, the more precise its inertial guidance system had to be. Small errors would be magnified with each passing minute. The guidance system had to take into account factors like the eastward rotation of the earth. Not only would the target be moving toward the east as the world turned, but so would the point from which the missile was launched. And at different latitudes, the earth rotates at slightly different speeds. All these factors had to be measured precisely. If the missile’s velocity were miscalculated by just 0.05 percent, the warhead could miss its target by about twenty miles.

The accuracy of a Titan II launch would be determined early in the flight. The sequence of events left no room for error. Fifty-nine seconds after the commander and the deputy commander turned their keys, the Titan II would rise from the silo, slowly at first, almost pausing for a moment above the open door, before shooting upward, trailed by flames. About two and a half minutes after liftoff, at an altitude of roughly 47 miles, the thrust chamber pressure switch would sense that most of the oxidizer in the stage 1 tank had been used. It would shut off the main engine, fire the staging nuts, send stage 1 of the missile plummeting to earth, and ignite the stage 2 engine. About three minutes later, at an altitude of roughly 217 miles, the guidance system would detect that the missile had reached the correct velocity. The computer would shut off the stage 2 engine and fire small vernier engines to make any last-minute changes in speed or direction. The vernier engines would fire for about fifteen seconds. And then the computer would blow the nozzles off them and detonate an explosive squib to free the nose cone from stage 2. The nose cone, holding the warhead, would continue to rise into the sky, as the rest of the missile drifted away.

About fourteen minutes later, the nose cone would reach its apogee, its maximum height, about eight hundred miles above the earth. Then it would start to fall, rapidly gaining speed. It would fall for another sixteen minutes. It would reach a velocity of about twenty-three thousand feet per second, faster than a speeding bullet — a lot faster, as much as ten to twenty times faster. And if everything had occurred in the right order, at the right time, precisely, the warhead would detonate within a mile of its target.

In addition to creating an accurate guidance system, missile designers had to make sure that a warhead wouldn’t incinerate as it reentered the atmosphere. The friction created by a falling body of that size, at those speeds, would produce surface temperatures of about 15,000 degrees Fahrenheit, hotter than the melting point of any metal. In early versions of the Atlas missile, the nose cone — also called the “reentry vehicle” (RV) — contained a large block of copper that served as a heat sink. The copper absorbed heat and kept it away from the warhead. But the copper also added a lot of weight to the missile. The Titan II employed a different technique. A thick coating of plastic was added to the nose cone, and during reentry, layers of the plastic ablated — they charred, melted, vaporized, and absorbed some of the heat. The cloud of gases released by ablation became a buffer in front of the nose cone, a form of insulation, reducing its temperature even further.