Mission Phases The safety analysis was conducted by evaluating each phase of the mission separately (Fig. 12). Each phase represents a change in configuration, location and activity which can affect the RTGs in the event of an accident. The phases as defined for the safety analysis are: Phase 0—prelaunch and launch. The prelaunch and launch phase begins with the initiation of loading the liquid propellant into the external tank and ends with liftoff. The duration is from eight hours before launch to launch (T—8 to T— 0). Phase 1—ascent. The ascent phase begins with liftoff of the Space Shuttle at T— 0 and continues until the solid rocket boosters are jettisoned at T+128 seconds. Phase 2—second stage. This is the period from 7+128 seconds until T+ 532 seconds when the first burn of the orbital maneuvering system engines begins. Included in Phase 2 are the remainder of the shuttle main engine burn and release of the external tank. Phase 3—on orbit. This phase starts with the first burn of the orbital maneuvering system at T+532 seconds and ends when the upper stage and spacecraft are deployed from the orbiter at T+6 h, 41 min, 24 s. The events include the first and second burns of the orbital maneuvering system for orbit attainment and circularization, the release of the upper stage/spacecraft and the firing of the orbiter reaction control system to move the shuttle away. Phase 4—payload deployment. The payload is deployed at T+6 h, 41 min, 24 s. For purposes of the safety analyses, this phase ends when the upper stage has attained Earth escape velocity even though the spacecraft has not yet been deployed.
RkJQdWJsaXNoZXIy MTU5NjU0Mg==