Spacecraft electric propulsion

Spacecraft electric propulsion (or just electric propulsion) is a type of spacecraft propulsion technique that uses electrostatic or electromagnetic fields to accelerate mass to high speed and thus generating thrust to modify the velocity of a spacecraft in orbit.^[1] The propulsion system is controlled by power electronics.

Electric thrusters typically use much less propellant than chemical rockets because they have a higher exhaust speed (operate at a higher specific impulse) than chemical rockets.^[1] Due to limited electric power the thrust is much weaker compared to chemical rockets, but electric propulsion can provide thrust for a longer time.^[2]

Electric propulsion was first demonstrated in the 1960s and is now a mature and widely used technology on spacecraft. American and Russian satellites have used electric propulsion for decades.^[3] As of 2019^[update], over 500 spacecraft operated throughout the Solar System use electric propulsion for station keeping, orbit raising, or primary propulsion.^[4] In the future, the most advanced electric thrusters may be able to impart a delta-v of 100 km/s (62 mi/s), which is enough to take a spacecraft to the outer planets of the Solar System (with nuclear power), but is insufficient for interstellar travel.^[1][5] An electric rocket with an external power source (transmissible through laser on the photovoltaic panels) has a theoretical possibility for interstellar flight.^[6][7] However, electric propulsion is not suitable for launches from the Earth's surface, as it offers too little thrust.

On a journey to Mars, an electrically powered ship might be able to carry 70% of its initial mass to the destination, while a chemical rocket could carry only a few percent.^[8]