- Two solid rocket boosters provide the main thrust to lift the
space shuttle off the pad. They are the largest solid-propellant
motors ever flown, the first designed for reuse.
- Each SRB has four hold-down posts securing it to the launch
- A sequence of events occurs within a few seconds before launch,
leading up to SRB ignition and liftoff.
Electrical Power Distribution
- The orbiter supplies power to the SRBs.
Hydraulic Power Units
- Each SRB has two self-contained independent hydraulic power
Thrust Vector Control
- Each SRB has two hydraulic gimbal actuators that provide the
force and control to gimbal the nozzle for thrust vector control.
SRB Rate Gyro Assemblies
- Each SRB has two RGAs that provide attitude data to the orbiter
computers during ascent.
- Explosive bolts separate the SRBs from the external tank when
fuel has been expended.
Range Safety System
- The vehicle has three RSSs, one in each SRB and one in the external
tank. If the vehicle violates a launch trajectory red line, the
ground can command them to self-destruct.
SRB Descent and Recovery
- 295 seconds after they separate from the vehicle, both SRBs
fall into the Atlantic Ocean, where they are recovered for reuse.