Soviet thruster design was introduced to the West in 1992 after a team of electric propulsion specialists, under the support of the Ballistic Missile Defense Organization, visited Soviet laboratories. Some 100–200 engines completed missions on Soviet and Russian satellites. Hall-effect thrusters operated on Soviet satellites from 1972 until the late 1990s, mainly used for satellite stabilization in north–south and in east–west directions. Īn alternate form of electric propulsion, the Hall-effect thruster, was studied independently in the United States and the Soviet Union in the 1950s and 1960s. This test was followed by an orbital test, SERT-2, in 1970.

It successfully operated for the planned 31 minutes before falling to Earth.

Suborbital tests were conducted during the 1960s and in 1964, the engine was sent into a suborbital flight aboard the Space Electric Rocket Test-1 (SERT-1). It was similar to a gridded electrostatic ion thruster and used mercury for propellant. Kaufman in 1959 at the NASA Glenn Research Center facilities. Ī working ion thruster was built by Harold R. The idea appeared again in Hermann Oberth's Wege zur Raumschiffahrt (1929 Ways to Spaceflight), where he explained his thoughts on the mass savings of electric propulsion, predicted its use in spacecraft propulsion and attitude control, and advocated electrostatic acceleration of charged gasses. The technique was recommended for near-vacuum conditions at high altitude, but thrust was demonstrated with ionized air streams at atmospheric pressure. The first person who wrote a paper introducing the idea publicly was Konstantin Tsiolkovsky in 1911. For these reasons, spacecraft must rely on other methods such as conventional chemical rockets or non-rocket launch technologies to reach their initial orbit. An ion engine cannot usually generate sufficient thrust to achieve initial liftoff from any celestial body with significant surface gravity. MIT has created designs that are able to fly for short distances and at low speeds at ground level, using ultra-light materials and low drag aerofoils. Ion thrust engines are generally practical only in the vacuum of space as the engine's minuscule thrust cannot overcome any significant air resistance without radical design changes, as may be found in the ' Atmosphere Breathing Electric Propulsion' concept. Īpplications include control of the orientation and position of orbiting satellites (some satellites have dozens of low-power ion thrusters), use as a main propulsion engine for low-mass robotic space vehicles (such as Deep Space 1 and Dawn), and serve as the propulsion thruster for crewed spacecraft and space station (Tiangong). The Dawn spacecraft broke the record, with a velocity change of 11.5 km/s (7.1 mi/s), though it was only half as efficient, requiring 425 kg (937 lb) of xenon. The Deep Space 1 spacecraft, powered by an ion thruster, changed velocity by 4.3 km/s (2.7 mi/s) while consuming less than 74 kg (163 lb) of xenon. Ion thrusters in operation typically consume 1–7 kW of power, have exhaust velocities around 20–50 km/s ( I sp 2000–5000 s), and possess thrusts of 25–250 mN and a propulsive efficiency 65–80% though experimental versions have achieved 100 kW (130 hp), 5 N (1.1 lb f). Temporarily stored electrons are reinjected by a neutralizer in the cloud of ions after it has passed through the electrostatic grid, so the gas becomes neutral again and can freely disperse in space without any further electrical interaction with the thruster.īy contrast, electromagnetic thruster ions are accelerated by the Lorentz force to accelerate all species (free electrons as well as positive and negative ions) in the same direction whatever their electric charge, and are specifically referred to as plasma propulsion engines, where the electric field is not in the direction of the acceleration. Ion thrusters are categorized as either electrostatic or electromagnetic.Įlectrostatic thruster ions are accelerated by the Coulomb force along the electric field direction. It creates thrust by accelerating ions using electricity.Īn ion thruster ionizes a neutral gas by extracting some electrons out of atoms, creating a cloud of positive ions. A prototype of a xenon ion engine being tested at NASA's Jet Propulsion Laboratory (2005)Īn ion thruster, ion drive, or ion engine is a form of electric propulsion used for spacecraft propulsion.

Uses of krypton