Shuttle Reviews: Design Certification Review (DCR)
In the Vehicle Assembly Building (VAB) at NASA's Kennedy Space Center, Space Shuttle Discovery is beginning its long, slow journey to Launch Pad 39B. First motion was at 2:04 p.m. EDT. The Shuttle comprises the orbiter, External Tank (ET) and twin Solid Rocket Boosters (SRBs). The Space Shuttle rests on the Mobile Launcher Platform, which is moved by the Crawler-Transporter underneath. The Crawler is 20 feet high, 131 feet long and 114 feet wide. It moves on eight tracks, each containing 57 shoes, or cleats, weighing one ton each.
A DCR consists of a board chaired by senior NASA officials that reviews all aspects of the design changes to ensure that they have been verified to meet program requirements and specifications. Each shuttle element will separately perform project level DCRs, which culminated in the shuttle program wide DCR in April 2005.
The DCR accomplishes basically two things. First, it re-establishes the baseline for hardware and math models relative to how well they satisfy the program requirements. Second, if hardware or math model fails to meet the requirements, it establishes the flight constraints in order to fly. Among some of the areas reviewed are the main propulsion systems, orbital maneuvering systems, auxiliary power unit, and hydraulics. The DCR is the culmination of all RTF activities.
To date, the space shuttle Program has only completed three DCRs in the history of the program -- before STS-1, after the Challenger accident, and after the substantial performance enhancements in 1996 when the shuttle system underwent significant change to the ET and ascent trajectory design. The fourth one was the return to flight DCR after the Columbia accident.
Boeing shuttle Integration tracked more than 80 changes for return to flight. Some of the major design changes include the ET bipod ramp redesign, bolt catchers for the Solid Rocket Boosters, debris mitigation and tolerance, OBSS, camera systems for launch, the shuttle roll maneuver, and the results of an integrated hazard review. System Integration performs shuttle system-wide analyses of these changes to understand their affects on vehicle structural loads, thermodynamics, propulsion, avionics, software, and ground processing.