Spacecraft electric propulsion

Spacecraft electric propulsion encompasses propulsion systems that use electric energy to accelerate and expel propellant, generating thrust through electric or magnetic fields. Their principal advantage over chemical rockets is much higher specific impulse, meaning greater propellant efficiency, at the cost of lower thrust that usually requires long-duration operation.

The main families of spacecraft electric propulsion include electrostatic devices such as gridded ion engines, Hall-effect thrusters, and colloid thrusters; electromagnetic devices such as pulsed plasma thrusters, magnetoplasmadynamic thrusters, and pulsed inductive thrusters; and electrothermal devices such as resistojets and arcjets. Radio-frequency and electron cyclotron resonance ion engines form a further subclass that avoids physical electrode contact with the propellant plasma.

Electric propulsion concepts date to Konstantin Tsiolkovsky's 1911 writings and Robert H. Goddard's 1917 electrostatic accelerator patent, with the first laboratory thruster built by Valentin Glushko at the Gas Dynamics Laboratory in 1933. The first electric engine operated in space aboard SERT-1 in 1964, and Hall-effect thrusters entered operational service on Soviet Meteor spacecraft in the 1970s. After the Cold War, Western researchers gained direct access to Soviet Hall thruster technology, and by the late 1990s electric propulsion had entered routine commercial geostationary satellite service and deep-space primary propulsion with Deep Space 1. Later milestones include Dawn's ion-propelled orbits of Vesta and Ceres, and BepiColombo's high-performance Hall thruster system, described by the European Space Agency as the most powerful electric propulsion system flown to date.