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🔎 Ion Engine – Definition and Explanations


Testing of a xenon ion engine, in a laboratory in the Jet Propulsion Laboratory (JPL)

A ion engine is an engine that produces its propulsive force by projecting ions at very high speed (We distinguish 🙂. Its principle has already been thought out at the beginning of the XXe century and it is used at the beginning of the XXIe century for the space flight (Spaceflight is the movement of a spacecraft in and through space. Spaceflight is…).

Operation of the ion engine

In a engine (A motor (from the Latin mōtor: “the one who moves”) is a device…) ion, the fuel (A fuel is a fuel that powers a heat engine. This transforms…) is not burned but ionized. The ions then released pass through two strongly electrically charged grids and thus undergo a acceleration (Acceleration commonly refers to an increase in speed; in physics,…). The strength (The word force can designate a mechanical power over things, and also, metaphorically, a…) acceleration of the ions causes a reaction force of meaning (SENS (Strategies for Engineered Negligible Senescence) is a scientific project which aims to…) opposite: it is the strength of propulsion (Propulsion is the principle that allows a body to move in its surrounding space….) of the ion engine.

The ions collect their electrons just before leaving the engine, in order to maintain the neutrality of charge (The payload represents what is actually…) from vehicle (A vehicle is a mobile machine, which makes it possible to move people or loads from one…) and ejected fuel.

It’s the xenon (Xenon is a chemical element, symbol Xe and atomic number 54. The…) (a gas (A gas is a set of atoms or molecules very weakly bound and…) rare) which is used as “fuel”. Speak past (The past is first of all a concept linked to time: it is made up of the whole…)the sodium (Sodium is a chemical element, symbol Na and atomic number 11. It is a…) and mercury have been tested, but these materials erode the engine.

The electrical energy necessary for the ionization of the fuel and the acceleration of the released ions is obtained thanks to solar panels. In the future (Futurs is a science fiction collection from Éditions de l’Aurore.)nuclear reactors will probably also be used to provide this energy (In common sense, energy designates everything that allows you to do work, make energy, etc.).


Ion engines, due to their low thrust (In aerodynamics, thrust is the force exerted by moving air…), are not suitable for launching space vehicles. For this, the engines of rocket (Rocket may refer to:) conventional are still needed. But, in principle, as soon as the space vehicle (A space vehicle or spacecraft or spacecraft is understood to mean a vehicle allowing to…) has reached space, the ion engine can take over.

The ion engine can work for a very long time without stopping, if necessary for years. With its help, extremely distant destinations, such as Jupiter, can be reached much faster.

First test, very conclusive, in 1998

The ion engine was extensively tested for the first time by the unmanned space vehicle Deep Space 1 (Deep Space 1 is the first space probe of NASA’s New Millenium program, whose objective…). The latter was launched by the NASA (The National Aeronautics and Space Administration (“National Administration of…) on October 24, 1998. Its primary purpose was to test a certain number (The notion of number in linguistics is treated in the article “Number…) new astronautical techniques, including the ion engine.

By the end of the mission, the speed of Deep Space 1 had increased, thanks to the ion engine, from 4.5km/safter using only 81.5 kilograms fuel. With a conventional engine and using as many combustible (A fuel is a material which, in the presence of oxygen and energy, can…)the vehicle would have undergone barely a tenth of this acceleration.


The following telecommunications satellites are equipped with ion thrusters:

  • Astra 2A built by Boeing (Boeing (official name in English The Boeing Company) is one of the largest manufacturers…)
  • Inmarsat (Inmarsat (for International maritime satellite organization) is a company of…) 4 and Intelsat (Intelsat, Ltd. is the leading provider of satellite telecommunications services. The…) X-02 built by Astrium.

The varying forces of attraction of the Moon (The Moon is Earth’s only natural satellite and the fifth largest satellite in the world…) and Sun (The Sun (Sol in Latin, Helios or Ήλιος in Greek) is the star…) involve regularly making corrections to path (The trajectory is the line described by any point of a moving object, and…) in order to maintain this type of satellite (Satellite may refer to:) on the good orbit (In celestial mechanics, an orbit is the trajectory drawn by a body in space…). The amount (The quantity is a generic term of metrology (account, amount); a scalar,…) of fuel that can be carried is limited, but because ion engines are very economical, the duration of the mission can be increased.

the satellite (Satellite may refer to:) Artémis (Advanced Relay and Technology Mission Satellite) was saved from a bad launch (failure partiel (The partial word can be used as:) ofAriadne 5 (Ariane 5 is a European Space Agency (ESA) launcher, developed to place…)on July 12, 2001, which had placed it in an orbit more than twice lower than that planned, 17,000 km ofaltitude (Altitude is the vertical elevation of a place or object relative to a level…) at theapogee (An apogee (from the Greek apogeios: far from the earth; apo: far + gê:…) instead of 36,000). Propelled by its ion engines which had not yet been designed for this purpose, because intended for simple orbit corrections once at the desired altitude and position, it reached the desired altitude after 18 month (The month (From lat. mensis “month”, and formerly in plural “menses”) is a period of time…).

Space probes

The space probe (A space probe is an unmanned spacecraft sent by man to…) SMART-1 (367 kg, including 52 kg of Xenon to be ejected) from the European Space Agency (ESA) also had an ion engine. Launched on September 28, 2003 on a geostationary orbit (The geostationary orbit, abbreviated GEO (geostationary orbit) is an orbit…) (36,000 km), it carried out higher and higher terrestrial orbits, then on November 15, 2004, its first orbit around (Autour is the name that the avian nomenclature in the French language (update) gives…) from the moon. To reach the Moon distant only from 385,000 kmshe traveled 100 million kilometers (The meter (symbol m, from the Greek metron, measure) is the basic unit of length of the System…) while consuming only 60 liters of fuel thanks to its remarkably efficient engine. For nearly two years it carried out many lunar orbits, then as planned crashed on the Moon on September 3, 2006. This probe (A space probe is an unmanned vessel sent by humans to explore more closely…) put a lot more time (Time is a concept developed by human beings to apprehend the…) than a space vehicle equipped with a conventional (chemical) engine, but it is much more economical and therefore costs much less, because the load to be put into orbit is considerably reduced.

The Japanese space probe Hayabusa, launched on May 9, 2003, is equipped with a ion engine (An ion engine is an engine that produces its propulsive force by projecting ions at…). It is the first to have (almost) succeeded in landing on the Itokawa asteroid on November 19, 2005. Its ion propulsion (An ion engine is based on the acceleration of charged particles (ions) via a field…) allowed him to come back Earth (Earth is the third planet in the Solar System in order of distance…) Sunday, June 13, 2010 at 1:51 p.m. GMT (3:51 p.m. in hour (Time is a unit of measurement:) French) with possibly samples from the asteroid, having traveled about 300 million kilometers and more than 31,000 cumulative hours of operation.

Future space flights, very far from the sun

NASA is working on the development of an ion engine that will be powered by a nuclear reactor (A nuclear reactor is a device in which a chain reaction is…). This would make the use of the ion engine possible for spaceflight at very great distances from the Sun, where photovoltaic panels can no longer provide enough energy.