Shuttle Reference Manual Solid Rocket Boosters

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Overview
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.

Hold-Down Posts
Each SRB has four hold-down posts securing it to the launch platform.

SRB Ignition
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 units.

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.

SRB Separation
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.