Ion thruster

An electric spacecraft engine that accelerates ions to produce thrust, usually by expelling an onboard propellant such as xenon. It produces low thrust efficiently over long periods.

Electron bombardment ionization: A process in which energetic electrons collide with atoms and remove electrons, creating positive ions. Many ion thrusters create propellant ions by collisions with electrons emitted inside the discharge chamber.
Deep Space 1: A NASA technology-demonstration spacecraft launched in 1998 that used a xenon ion engine as its primary propulsion. It demonstrated ion propulsion in deep space, including an asteroid flyby and a comet encounter.
Chemical rocket engine: A rocket engine that produces thrust by releasing energy through chemical reactions in propellant. Chemical engines provide far greater thrust, while ion thrusters use propellant more efficiently.
Robert H. Goddard: An American rocket pioneer who proposed electrostatic acceleration of charged particles for space propulsion in the early twentieth century. His early proposal anticipated the central acceleration principle used by ion engines.
Hall-effect thruster: An electric propulsion device that uses crossed electric and magnetic fields to accelerate ions. It is a widely used thruster design that traps electrons with a magnetic field while accelerating ions.
Dawn (spacecraft): A NASA spacecraft that used ion propulsion to orbit the asteroid Vesta and dwarf planet Ceres. Its ion engines enabled one spacecraft to travel between and orbit two distant bodies.
Resistojet: An electric propulsion device that heats propellant electrically before expelling it through a nozzle. A resistojet heats neutral gas instead of ionizing and electrostatically accelerating it.
Hermann Oberth: A German-Romanian rocketry theorist whose 1929 book discussed electric propulsion for spaceflight. His writing helped bring electric spacecraft propulsion into early spaceflight theory.
Gridded ion thruster: An electric propulsion device that accelerates ions through electrostatic grids. Its perforated electrodes establish the potential difference that extracts and accelerates ions.
BepiColombo: A joint European-Japanese mission to Mercury that uses solar-electric propulsion during its interplanetary cruise. Its electric propulsion provides gradual trajectory changes on the long journey to Mercury.

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