Engineering:Electrically powered spacecraft propulsion

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Short description: Type of propulsion system
6 kW Hall thruster in operation at the NASA Jet Propulsion Laboratory

An electrically powered spacecraft propulsion system uses electrical, and possibly also magnetic fields, to change the velocity of a spacecraft. Most of these kinds of spacecraft propulsion systems work by electrically expelling propellant (reaction mass) at high speed.[1]

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.[2] Due to limited electric power the thrust is much weaker compared to chemical rockets, but electric propulsion can provide thrust for a longer time.[3]

Electric propulsion is now a mature and widely used technology on spacecraft. Russia n satellites have used electric propulsion for decades.[4] (As of 2019), over 500 spacecraft operated throughout the Solar System use electric propulsion for station keeping, orbit raising, or primary propulsion.[5] In the future, the most advanced electric thrusters may be able to impart a delta-v of 100 km/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.[2][6] An electric rocket with an external power source (transmissible through laser on the photovoltaic panels) has a theoretical possibility for interstellar flight.[7][8] 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.[9]


The idea of electric propulsion for spacecraft was introduced in 1911 by Konstantin Tsiolkovsky.[10] Earlier, Robert Goddard had noted such a possibility in his personal notebook.[11]

Electrically powered propulsion with a nuclear reactor was considered by Tony Martin for interstellar Project Daedalus in 1973, but the approach was rejected because of its thrust profile, the weight of equipment needed to convert nuclear energy into electricity, and as a result a small acceleration, which would take a century to achieve the desired speed.[12]

The first demonstration of electric propulsion was an ion engine carried on board the SERT-1 (Space Electric Rocket Test) spacecraft.[13][14] It launched on 20 July 1964 and operated for 31 minutes.[13] A follow-up mission launched on 3 February 1970, SERT-2. It carried two ion thrusters, one operated for more than five months and the other for almost three months.[13][15][16]

By the early 2010s, many satellite manufacturers were offering electric propulsion options on their satellites—mostly for on-orbit attitude control—while some commercial communication satellite operators were beginning to use them for geosynchronous orbit insertion in place of traditional chemical rocket engines.[17]


Ion and plasma drives

These types of rocket-like reaction engines use electric energy to obtain thrust from propellant. Unlike rocket engines, these kinds of engines do not require nozzles, and thus are not considered true rockets.[citation needed]

Electric propulsion thrusters for spacecraft may be grouped into three families based on the type of force used to accelerate the ions of the plasma:


Main page: Engineering:Ion thruster

If the acceleration is caused mainly by the Coulomb force (i.e. application of a static electric field in the direction of the acceleration) the device is considered electrostatic. Types:


The electrothermal category groups devices that use electromagnetic fields to generate a plasma to increase the temperature of the bulk propellant. The thermal energy imparted to the propellant gas is then converted into kinetic energy by a nozzle of either solid material or magnetic fields. Low molecular weight gases (e.g. hydrogen, helium, ammonia) are preferred propellants for this kind of system.

An electrothermal engine uses a nozzle to convert heat into linear motion, so it is a true rocket even though the energy producing the heat comes from an external source.

Performance of electrothermal systems in terms of specific impulse (Isp) is 500 to ~1000 seconds, but exceeds that of cold gas thrusters, monopropellant rockets, and even most bipropellant rockets. In the USSR, electrothermal engines entered use in 1971; the Soviet "Meteor-3", "Meteor-Priroda", "Resurs-O" satellite series and the Russia n "Elektro" satellite are equipped with them.[18] Electrothermal systems by Aerojet (MR-510) are currently used on Lockheed Martin A2100 satellites using hydrazine as a propellant.


Main page: Physics:Plasma propulsion engine

Electromagnetic thrusters accelerate ions either by the Lorentz force or by the effect of electromagnetic fields where the electric field is not in the direction of the acceleration. Types:

Non-ion drives


A photonic drive interacts only with photons.

Electrodynamic tether

Main page: Physics:Electrodynamic tether

Electrodynamic tethers are long conducting wires, such as one deployed from a tether satellite, which can operate on electromagnetic principles as generators, by converting their kinetic energy to electric energy, or as motors, converting electric energy to kinetic energy.[19] Electric potential is generated across a conductive tether by its motion through the Earth's magnetic field. The choice of the metal conductor to be used in an electrodynamic tether is determined by factors such as electrical conductivity, and density. Secondary factors, depending on the application, include cost, strength, and melting point.


Some proposed propulsion methods apparently violate currently-understood laws of physics, including:[20]

Steady vs. unsteady

Electric propulsion systems can be characterized as either steady (continuous firing for a prescribed duration) or unsteady (pulsed firings accumulating to a desired impulse). These classifications can be applied to all types of propulsion engines.

Dynamic properties

Electrically powered rocket engines provide lower thrust compared to chemical rockets by several orders of magnitude because of the limited electrical power available in a spacecraft.[3] A chemical rocket imparts energy to the combustion products directly, whereas an electrical system requires several steps. However, the high velocity and lower reaction mass expended for the same thrust allows electric rockets to run on less fuel. This differs from the typical chemical-powered spacecraft, where the engines require more fuel, requiring the spacecraft to mostly follow an inertial trajectory. When near a planet, low-thrust propulsion may not offset the gravitational force. An electric rocket engine cannot provide enough thrust to lift the vehicle from a planet's surface, but a low thrust applied for a long interval can allow a spacecraft to maneuver near a planet.

See also


  1. Mazouffre, Stéphane (2016-06-01). "Electric propulsion for satellites and spacecraft: established technologies and novel approaches". Plasma Sources Science and Technology 25 (3): 033002. doi:10.1088/0963-0252/25/3/033002. ISSN 0963-0252. 
  2. 2.0 2.1 Choueiri, Edgar Y. (2009) New dawn of electric rocket Scientific American 300, 58–65 doi:10.1038/scientificamerican0209-58
  3. 3.0 3.1 "Electric versus Chemical Propulsion". Electric Spacecraft Propulsion. ESA. 
  4. "Electric Propulsion Research at Institute of Fundamental Technological Research". 16 August 2011. 
  5. Lev, Dan; Myers, Roger M.; Lemmer, Kristina M.; Kolbeck, Jonathan; Koizumi, Hiroyuki; Polzin, Kurt (June 2019). "The technological and commercial expansion of electric propulsion". Acta Astronautica 159: 213–227. doi:10.1016/j.actaastro.2019.03.058. 
  6. "Choueiri, Edgar Y. (2009). New dawn of electric rocket". 
  7. "Google Scholar".,5. 
  8. Geoffrey A. Landis. Laser-powered Interstellar Probe on the Geoffrey A. Landis: Science. papers available on the web
  9. Boyle, Alan (2017-06-29). "MSNW’s plasma thruster just might fire up Congress at hearing on space propulsion" (in en-US). 
  10. Palaszewski, Bryan. "Electric Propulsion for Future Space Missions (PowerPoint)". Electric Propulsion for Future Space Missions. NASA Glenn Research Center. 
  11. Choueiri, Edgar Y. (2004). "A Critical History of Electric Propulsion: The First 50 Years (1906–1956)". Journal of Propulsion and Power 20 (2): 193–203. doi:10.2514/1.9245. 
  12. "PROJECT DAEDALUS: THE PROPULSION SYSTEM Part 1; Theoretical considerations and calculations. 2. REVIEW OF ADVANCED PROPULSION SYSTEMS". Archived from the original on 28 June 2013. 
  13. 13.0 13.1 13.2 Administrator, NASA Content (14 April 2015). "Glenn Contributions to Deep Space 1". 
  14. Cybulski, Ronald J.; Shellhammer, Daniel M.; Lovell, Robert R.; Domino, Edward J.; Kotnik, Joseph T. (1965). "Results from SERT I Ion Rocket Flight Test". NASA. 
  15. NASA Glenn, "SPACE ELECTRIC ROCKET TEST II (SERT II)" (Accessed 1 July 2010)
  16. SERT page at Astronautix (Accessed 1 July 2010)
  17. de Selding, Peter B. (20 June 2013). "Electric-propulsion Satellites Are All the Rage". SpaceNews. 
  18. "Native Electric Propulsion Engines Today" (in ru). Novosti Kosmonavtiki. 1999. 
  19. NASA, Tethers In Space Handbook, edited by M.L. Cosmo and E.C. Lorenzini, Third Edition December 1997 (accessed 20 October 2010); see also version at NASA MSFC; available on scribd
  20. "Why Shawyer's 'electromagnetic relativity drive' is a fraud". 

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