Spacecraft propulsion refers to the methods used to move spacecraft through space. Unlike cars or airplanes that rely on air, spacecraft must operate in the vacuum of space, where traditional engines can't work. Instead, they use various propulsion systems, such as chemical rockets, which burn fuel to create thrust, or ion thrusters, which use electricity to accelerate ions for movement. These propulsion systems allow spacecraft to travel vast distances, whether it's reaching the Moon, exploring Mars, or venturing beyond our solar system. Each type of propulsion has its advantages and disadvantages, influencing mission design and the spacecraft's capabilities.