Development of On-board Space Computer Systems

This paper describes the functions, characteristics, requirements, and design approaches of the on-board computers for seven space vehicles—Saturn I, Orbiting Astronomical Observatory, Gemini, Saturn IB, Saturn V, Skylab, and Space Shuttle. The data contained in this paper represent an encapsulation of sixteen years of space-borne-computer development. In addition, the evolution of computer characteristics such as size, weight, power consumption, computing speed, memory capacity, technology, architectural features, software, and fault-tolerant capabilities, is summarized and analyzed to point out the design trends and the motivating causes. The evolution in utilization of the on-board computers; their interface with sensors, displays, and controls; and their interaction with operators are summarized and analyzed to show the increasing role played by computers in the overall space-vehicle system.