The space shuttle is controlled largely by five on-board computer systems. Bugs in these systems' software can cause mission failure, loss of vehicle, even loss of life. Because each shuttle flight is unique, each requires changes to thousands of lines of computer code. Since fiscal year 1981, the National Aeronautics and Space Administration (NASA) has spent more than $324 million developing, testing, and implementing shuttle software to support commercial projects, scientific research, and defense missions. Software has never been reported as a major problem in shuttle operations.
Effective software is essential to the success and safety of the Space Shuttle, including its crew and its payloads. The on-board software continually monitors and controls critical systems throughout a Space Shuttle flight. At NASA's request, the committee convened to review the agency's flight software development processes and to recommend a number of ways those processes could be improved. This book, the result of the committee's study, evaluates the safety, oversight, and management functions that are implemented currently in the Space Shuttle program to ensure that the software is of the highest quality possible. Numerous recommendations are made regarding safety and management procedures, and a rationale is offered for continuing the Independent Verification and Validation effort that was instituted after the Challenger Accident.