Shuttle Reference Manual Operational Improvements and Modifications

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Many of the changes and upgrades in the space shuttle systems and components were under way before the 51-L accident as part of NASA's continual improvement and upgrade program. However, NASA has taken advantage of the space shuttle program downtime since the accident to accelerate the testing and integration of these improvements and upgrades as well as fixes required as a result of the accident.

Orbiter
The following identifies the major improvements or modifications of the orbiter. Approximately 190 other modifications and improvements were also made.

Space Shuttle Main Engine Margin Improvement Program
As early as 1983, engineers designed modifications to the SSMEs, improving margin and durability.

SSME Flight Program
In the first 25 flights, three off-nominal SSME conditions were detected. A major upgrade ensured these problems would not be repeated.

Solid Rocket Motor Redesign
Based on the recommendations of the "Presidential Commission on the Space Shuttle Challenger Accident," new design criteria were assessed and implemented for the solid rocket motors.