A spacecraft trajectory refers to the path that a spacecraft follows as it travels through space. This path is determined by various factors, including the spacecraft's initial velocity, the gravitational forces of nearby celestial bodies, and any propulsion maneuvers performed during the flight. Understanding trajectories is crucial for missions to reach specific destinations, such as planets or moons. To calculate a spacecraft's trajectory, engineers use mathematical models and simulations. These calculations help ensure that the spacecraft arrives at its target efficiently and safely. Trajectories can be influenced by gravity assists from planets or moons, which can alter the spacecraft's speed and direction without using additional fuel.