Roughly the size of a basketball and weighing just 21 pounds, the Vanguard satellite struck an almost comical contrast to the rocket built to launch it: a three-stage, 72-foot, 22,000-pound behemoth. Despite its size, the satellite carried beneath its thin metal surface a range of sophisticated instruments developed to precisely measure the temperatures, pressures and lights it would encounter during orbit. The satellite’s diminutive tracking tool, known as Minitrack, was designed to detect meteorites and to follow the craft’s progress. It also gave the project’s overall monitoring system its name.
Once assembled in Washington, DC, the Vanguard 704 system occupied 1,700 square feet of an air-conditioned, humidity-controlled room at the computing center. Painted to match the program’s color pallet — primarily blue, orange and olive — the 704 and its components formed the heart of Minitrack. Once the satellite launched, Minitrack stations positioned around the world — from Fort Stewart, Georgia, to Lima, Peru — would alert the 704 as the craft passed overhead. The 704 would then relay location data to the Vanguard communications center and to the next Minitrack station along the path.
Originally designed for engineering and scientific applications, the 704 was more than up to the task. It employed a high-speed core memory system to execute calculations twice as fast as the initial 700 series release, the 701. Paired with an IBM-built cathode-ray tube (CRT) — a vacuum tube used to display images — the 704 translated the computer’s output into graphs, orbit trajectories, symbols, figures, numbers and words “just as they might appear on a television screen,” wrote IBM Poughkeepsie News in 1957.
By the time of the first satellite launch, another 704 (later upgraded to a 709) had been assembled in a low, windowless building a few thousand feet from the rocket’s launchpad in Central Florida. This system joined the effort to track potential impacts: monitoring the rocket’s aerial location throughout its flight, at the ready with a self-destruct mode in case of a sudden loss of power over an inhabited area. Utilizing data gathered directly from the missile, this second 704 computed speed and position as well as the exact instant when the missile’s final stage should be fired in order to launch the satellite into orbit.