BMEWS - 510 Full Days - Tracking Radar

We tracker technicians spent the spring of 1961 assembling the components of the AN/FPS-49 Tracking Radar and its subsystems. We assembled, tested, modified, and retested our respective subsystems; My responsibility was the Tracking Radar Automatic Monitor (TRAM) system. In the early 1960s, tiny integrated circuit chips containing thousands of transistors, which are common today, were unknown. Each electronic cabinet was made up of row upon row of printed circuit cards, about 6 by 8 inches each, consisting of several, typically four, circuits of a given type. A flip-flop card, for instance, contained four flip-flops, each built of individual, discrete components, resistors, capacitors, diodes, and transistors. Each card plugged into a 64-pin connector, with wiring reaching the connectors from the rear of the cabinets. There were printed circuits on the individual cards, but the backplane was discretely wired, with wires running through plastic wiring channels and fanning out into the circuit card connectors above the channel. At each end of the cabinets, thick cables made connection to rows of connection blocks. In keeping with the precision of the rest of the BMEWS cabling, these cables fanned out to the connector blocks with wire bends all at the same radius, each wire marked with a wire number stamped on yellow tubing, slipped over the wire, and turned so that the numbers all faced outward. There were no dangling wires or kludges wired into the circuitry to spoil the view of order and perfection.

During the build-up of the tracker, I met the only person I've ever known with a photographic memory. In my opinion, George, an immigrant from the Ukraine, was an electronic genius. Like myself, he was an electronic technician. George would lay electronic logic diagrams out all over the TRAM room and patiently pencil in circuit installation and modifications details in red pencil. He would sometimes have several hundred square feet of diagrams laid out, all "D" size blueprints. While pencilling in a modification, he might shout, "This cannot work!" Walking over to the other side of the room, remembering intricate electronic details, he would explain to the engineers who developed the modification that the signal did this or that; then he would travel around over the diagrams, getting more and more excited as he'd explain how the signals would arrive at the point of the modification and how the mod kit as delivered would not work. Better still, he'd tell the engineers how to correct the mistake. Most of the engineers listened. George didn't make mistakes.

We watched as the steel erectors constructed the tracker antenna on the roof of our building inside the immense radome. The antenna mount was conical, about 20 feet in diameter tapering upward 40 feet to the mammoth azimuth bearing upon which the 105 ton antenna rotated. The azimuth bearing was a ball bearing, perhaps 10 feet in diameter, whose balls were about 4 inches in diameter. To move this mass, two electric motors, each producing 150 horsepower, were connected to the antenna through hydraulic transmissions nearly identical in design to the "Hydrostatic" transmission familiar today in lawn tractors. A similar arrangement, but with a single 150 horsepower motor and transmission, powered the elevation axis, rotating the antenna up and down through an arc of nearly 180 degrees. The hydraulic transmissions provided an infinite movement rate. Controlled by the MIPS computer, the antenna could move so slowly that movement was invisible to the eye, or accelerate at 32 degrees per second per second, to a maximum rate of 32 degrees per second. Movement this rapid was necessary to track multiple incoming targets, one after another, as would be the case during an attack. The slow precise movement was necessary to obtain the precision measurements needed to fine tune impact predictions and ultimately determine whether the U.S. would give a launch order of its own.

Slowly, but surely, the antenna erection was completed, the doors to the electronic cabinets were closed, transmitter and receiver tests were completed, and the TRAM console began showing green indicator lights. The tracker came to life, going online officially in the summer of 1961. The mammoth system's mechanical parts worked together with the precision of a fine watch, the transmitter sending 10 megawatts of energy into the heavens and incredibly sensitive receivers gathering signals from space junk or satellites upon command from the MIPS. Much of the tracker's time was spent tracking known pieces of space debris, developing a catalog of orbiting bits and pieces. At that time, the catalog was very small, perhaps a couple hundred items, taking perhaps ten pages of computer listings. Today, orbiting debris is more like a cloud of dust particles, counted in the hundreds of thousands of individual pieces, and presenting a hazard to space navigation. Perhaps the new BMEWS radars are still assisting in the cataloging of this debris.

At other times, the tracker, like the detection radar, was running simulations, ensuring that all components were working as they should. During a simulated missile attack, the tracker would rapidly switch from one simulated target to another, tracking each for about one or two seconds, then moving on. The movement of the antenna from target to target could be heard on the mezzanine below as a low growl, straining as it accelerated. If one watched the immense concrete antenna pedestal carefully during these movements, one could see the pedestal twist slightly in reaction to the torque exerted on the 105 ton mass above. The power, yet incredibly precise movement, of this mechanical giant was magical to me. I never ceased being awestruck with this, and always enjoyed going into the radome to watch the antenna move during the simulations.

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© Copyright 1996, Gene P. McManus, Baltimore, OH