Shuttle Reaction Control System
A Reaction Control System (RCS) is responsible for attitude control and steering by the use of thrusters. The RCS system is capable of providing small amounts of thrust in any desired direction or combination of directions. An RCS is also capable of providing torque to allow control of rotation (pitch, yaw, and roll). This is in contrast to a spacecraft's main engine, which is only capable of providing thrust in one direction, but is much more powerful. This is an up-close view of the RCS thrusters in the nose of a Space Shuttle.