Polaris

The Polaris project gave the IL team members the experience they needed for Apollo. The Polaris submarine was to launch nuclear missiles while submerged, requiring boosters with solid instead of liquid propellants to make the system simpler and safer. It also had to be extremely small (less than half the diameter of other missiles of the day). In 1956 designing this miniature, precise inertial guidance system for Polaris became an IL project.10

The navy ran Polaris out of the Special Projects Office (SPO), which played a role of systems engineer similar to that played by TRW in the Atlas program. To manage the complexity of the Polaris program, SPO engineers developed the Program Evaluation and Review Technique, or PERT, a method of plotting and tracking complex schedules that survives to this day as a staple of project management, and which NASA and the IL team would see again as part of Apollo.11 Indeed SPO's role on Polaris became one model for NASA's management of Apollo.

On the Polaris project, Eldon Hall, a quiet, lanky Idaho farm boy with an intense interest in electronics, led the IL's Digital Development Group. Although the IL had previously built guidance systems with analog computers, Hall persuaded the navy to bet on a digital machine for Polaris, based on the accuracy of computations required.

The Polaris computer was digital, but not a general-purpose machine that could run any program from software. Rather, Polaris used a ''digital differential analyzer'' architecture that drew on the early mechanical computing technologies developed at MIT in the 1930s by Vannevar Bush. The original ENIAC computer built at the University of Pennsylvania used this architecture as well. It was in effect a digital implementation of an analog computer, where the equations were wired in between computing elements (in ENIAC, these routings could be changed and the computer reprogrammed by rerouting cables, whereas in Polaris routings were fixed by the wiring of the machine). The Polaris computer integrated the accelerations measured by the inertial system through a series of difference equations, repeatedly adding and multiplying (and combining with the submarine's position and velocity) to get the missile's position. The computer used these data to issue commands to steer the missile along the desired trajectory. A new idea developed at the IL, called ''Q-guidance,'' allowed much of the computational load to be undertaken by ground-based digital computers ahead of time, enabling use of simpler machines in the missile itself.12

The Polaris electronics were not particularly complex, but making them work with the required reliability, robustness, and light weight challenged Hall and his IL engineers. They recognized the effective use of electronics to be as much about mechanical packaging as about circuit design.13 Hall explored new areas in construction, stacking modules like ''welded cordwood,'' and wire-wrapping the interconnections. Hall also designed the computer circuits so they all shared a single type of germanium transistor—effectively implementing the interchangeable-parts philosophy that had characterized mechanical manufacturing for more than a century. Transistors, barely a decade old at this point, could still be suspect in reliability, requiring rigorous qualification to be included in military hardware. In Hall's design, only one type of transistor would have to meet the intense testing and support criteria for the missile.

In the course of his work on Polaris, Hall visited the production line at Texas Instruments and met engineer Jack Kilby, who showed him a new invention: the integrated circuit, which incorporated several transistors on one semiconductor. Hall also visited the Fairchild Semiconductor company in California and met there with Robert Noyce; the company was working on making their integrated circuits scalable and robust.14 Hall then convinced the navy to incorporate the novel devices into the second-generation Polaris II computer. Again, Hall would build it out of a single component: a two-transistor NOR gate integrated circuit, sixty-four of them in all, costing $1,000 each.15

The first guided Polaris flight took place in July 1960. When the early Apollo studies were beginning at NASA, then, the MIT IL was achieving success in this high-profile, high-risk missile project.

Project Management Made Easy

Project Management Made Easy

What you need to know about… Project Management Made Easy! Project management consists of more than just a large building project and can encompass small projects as well. No matter what the size of your project, you need to have some sort of project management. How you manage your project has everything to do with its outcome.

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