Computers in Spaceflight: The NASA Experience
- Chapter Four -
- Computers in the Space Shuttle Avionics System -
[133] The DPS on the Shuttle orbiter reflects the state of software engineering in the 1970s. Even though the software was admittedly the key component of the spacecraft, NASA chose the hardware before the first software requirement was written. This is typical of practice in 1972, but less so now. NASA managers knew that time and money spent on detailed software requirements specification and the corresponding development of a test and verification program would save millions of dollars and much effort later. The establishment of a dedicated facility for development was an innovative idea and helped keep costs down by centralization and standardization. A combination of complete requirements, an aggressive test plan, a decent development facility, and the experience of NASA, Rockwell, Draper, and IBM engineers in real-time systems was enough to create a successful Shuttle DPS.
Even as the system took shape, NASA managers looked to the future of manned spacecraft software. Increased automation of code and test case generation, automated change insertion and verification, and perhaps automated requirements development are all considered future necessities if development costs are to be kept down and reliability increased. In the 1980s, a new opportunity for software development and hardware selection presents itself with NASA's long-awaited Space Station. NASA has another chance to adopt updated software engineering techniques and, perhaps, to develop others. Success in space is increasingly tied to success in the software factory.

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