Ion propulsion systems are a type of spacecraft propulsion that use ions, or charged particles, to generate thrust. These systems work by accelerating ions using electric fields and then expelling them at high speeds. This process creates a small but continuous force, allowing spacecraft to gradually build up speed over time, making them efficient for long-duration missions. Unlike traditional chemical rockets, which rely on burning fuel, ion propulsion systems consume much less propellant. This efficiency enables missions to travel further into space, such as those undertaken by NASA and ESA for exploring distant planets and asteroids.