How does a spacecraft change its direction in space?

A spacecraft changes its direction in space by using thrusters or reaction control systems that expel propellant in the opposite direction of the desired movement. This principle is based on Newton's third law of motion, which states that for every action, there is an equal and opposite reaction. By firing thrusters in specific directions, the spacecraft can achieve controlled maneuvers, adjusting its trajectory or orientation as needed. Additionally, larger spacecraft may use main engines for significant course changes.