How do you steer spacecraft?

Answer 1

Generally in space, one needs to use small rockets to change orientation of the spacecraft. Often called Thrusters in the movies, on real spacecraft they are called the Reaction Control System (RCS).

Most spacecraft RCS can be used with thrusters in opposition (causing rotation) in the 3 axes: pitch, yaw and roll. The same RCS can be used in a coordination fashion to move the spacecraft up/down, forward/backward and right/left. This is called translation.

Another way to steer spacecraft is through the use of a gyroscope. Some satellites use gyroscopes to keep the satellite pointed in the same orientation.

Answer 2

Spacecraft are steered using thrusters or reaction control systems that adjust the direction of the spacecraft by changing its momentum. This momentum change in turn alters the spacecraft's trajectory. Additionally, spacecraft can also use gravity assists from planets or other celestial bodies to adjust their trajectory.