Spacecraft electric propulsion

{{Short description|Type of spacecraft propulsion using electrical energy to accelerate propellant}} {{distinguish|Field propulsion|Reactionless drive}} {{Use dmy dates|date=September 2020}} [[File:Lorentz force on charged particles in bubble chamber - HD.6D.635 (12000265314).svg|thumb|The Lorentz force acting on fast-moving charged particles in a bubble chamber. The Lorentz force plays a key role in several electric propulsion technologies, including Hall-effect thrusters, magnetoplasmadynamic thrusters, and pulsed plasma thrusters.]] [[File:Xenon hall thruster.jpg|thumb|A 6 kW xenon Hall thruster in operation at the NASA Jet Propulsion Laboratory.]]

'''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, but the limited electrical power available aboard spacecraft yields much lower thrust, making electric propulsion unsuitable for launch from Earth's surface and better suited to long-duration in-space maneuvers.<ref name="Choueiri FP 2004" />{{rp|8}}<ref name="NASA Lewis FP 1966" />{{rp|6}}

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.<ref name="Myers NASA Electromagnetic Propulsion 1993" />{{rp|1-8}} Radio-frequency and electron cyclotron resonance ion engines form a further subclass that avoids physical electrode contact with the propellant plasma.<ref name="Kuninaka IEPC 2009" />{{rp|2}}<ref name="Lob Giessener FP 2008" />{{rp|40}}

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.<ref name="Choueiri FP 2004" />{{rp|4,8,11}} 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.<ref name="Camilleri EP 2017" />{{rp|1,4}}<ref name="Kozubsky SPD Trudy MAI 2012-12-10" />{{rp|2-3}} 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.<ref name="Brophy JPL SPT Russia 1992" />{{rp|1}}<ref name="Arrighi NASA Deep Space 1 2019-12-18" /> Later milestones include Dawn's ion-propelled orbits of Vesta and Ceres, BepiColombo's high-performance gridded ion thruster system, and Psyche's first use of Hall Effect thrusters in interplanetary space.<ref name="JPL Dawn mission" /><ref name="ESA BepiColombo electric 2018" /><ref name=":0" />

==Background and history== [[File:Konstantin Tsiolkovsky 1908-1909.jpg|thumb|Konstantin Tsiolkovsky in 1911 predicted that electricity may some day propel vehicles.]]

Traditional rocketry has dominated aerospace propulsion in the 20th and early 21st centuries.<ref name="NASA History of Rockets" /> Conventional rockets achieve motion by expelling mass, most commonly the combustion output from chemical propellants to generate thrust via Newton's third law, which is the familiar rocket launch with explosive flame and smoke beneath it.<ref name="Sutton Rockets 2017" />{{rp|5-6}} Electric propulsion developed as a parallel track for spacecraft propulsion, focusing on electrical and electrostatic methods of accelerating propellant rather than relying solely on chemical combustion.<ref name="Choueiri FP 2004" />{{rp|8}}

===1900s to the 1950s=== [[File:Origin of Marshall Space Flight Center (MSFC) (9131100).jpg|thumb|Hermann Oberth (center), with (l-r) Ernst Stuhlinger, Holger Toftoy, Wernher von Braun, and Robert Lusser at Marshall Space Flight Center. Oberth is credited with defining electric propulsion concepts as a "serious and worthy pursuit in astronautics".]]

Early antecedents of electric propulsion emerged by the early 20th century. Konstantin Tsiolkovsky writing in 1911 included an early published statement of the basic electric-propulsion idea: using electricity to increase the velocity of ejected particles. Tsiolkovsky wrote:<ref name="Choueiri FP 2004" />{{rp|4}}

{{Blockquote|It is possible that in time we may use electricity to produce a large velocity for the particles ejected from a rocket device.}}

Early work on electrostatic acceleration dates to Robert H. Goddard, whose 1917 patent application (granted 1920) Edgar Choueiri has described in ''Journal of Propulsion and Power'' as the first documented electrostatic ion accelerator intended for propulsion.<ref name="Choueiri FP 2004" />{{rp|8}} In his 1918-1919 manuscript ''"To whomsoever will read in order to build"'', Yuri Kondratyuk discussed electric propulsion in the context of cathode rays and described thrust from electrically discharging and repelling material particles, alongside a schematic that Choueiri noted may be the "first conceptualization of a colloid thruster".<ref name="Choueiri FP 2004" />{{rp|10}} Hermann Oberth's 1929 book ''Wege zur Raumschiffahrt'' defined, in Edgar Choueiri's assessment, 'for the first time publicly and unambiguously' that related propulsion concepts were 'a serious and worthy pursuit in astronautics'.<ref name="Choueiri FP 2004" />{{rp|11}}

During the interwar period, early electric-propulsion work began moving from theory toward experiment. Valentin Glushko joined the Gas Dynamics Laboratory in Leningrad in 1929, and by 1933 with staff developed an early electric thruster prototype, an electrothermal approach intended for spacecraft propulsion.<ref name="Choueiri FP 2004" />{{rp|11}} The device was likely the first electric thruster to ever be studied on a thruster stand, and was the first electrothermal thruster ever built.<ref name="Choueiri FP 2004" />{{rp|11-12}}

According to Choueiri, early thinking and experimentation in related propulsion research focused mainly on electrostatic concepts, but the first laboratory electric thruster was electrothermal and the first electric thruster to fly in space was a mostly electromagnetic pulsed plasma device.<ref name="Choueiri FP 2004" />{{rp|8}} After the 1930s, related electric-propulsion research reached a lull in public published activity for over a decade through and after World War II.<ref name="Choueiri FP 2004" />{{rp|12}}

The postwar period saw growing institutional interest in electric propulsion within both military and civilian research programs. The first clear postwar reappearance of these propulsion concepts in open scientific literature was in December 1945, in the ''Journal of the American Rocket Society'', where the term "ion rocket" was first coined by Herbert Radd.<ref name="Choueiri FP 2004" />{{rp|12}}<ref name="Radd ARS 1945" />{{rp|28-29}} In 1947 at Fort Bliss, Wernher von Braun encouraged Ernst Stuhlinger to investigate his spacecraft propulsion ideas, telling Stuhlinger, "I wouldn't be a bit surprised if one day we flew to Mars electrically!"<ref name="Choueiri FP 2004" />{{rp|13}}

===1960s-1970s=== During the 1960s through the 1970s, electric and electromagnetic propulsion matured experimentally, with some systems flying in limited operational roles.<ref name="Myers NASA Electromagnetic Propulsion 1993" />{{rp|1-2}}<ref name="Sutton Rockets 2017" />{{rp|10-11,623}} Electric propulsion research during this period expanded across multiple countries and institutional settings.

[[File:SERT-1 spacecraft.jpg|thumb|left|SERT-1 was the first ion engine NASA spacecraft, launched on July 20, 1964.]] In West Germany, electric-propulsion development also proceeded from 1960 at German Aerospace Center (DLR) institutes in Stuttgart and Braunschweig and at the University of Giessen.<ref name="Lob Giessener FP 2008" />{{rp|37}} At Gießen, Horst Löb's group began development of radio-frequency ion thrusters of the RIT type, which use radio frequency fields rather than physical electrodes to ionize propellant, starting with the conception, laboratory model, and first tests of the RIT-10; the prototype was further improved through the 1960s and transferred to industry for qualification in 1970.<ref name="Lob Giessener FP 2008" />{{rp|41}} A June 1960 decree of the Central Committee and Council of Ministers (No. 715-296), declassified after the Soviet period, directed the development of "space electric rocket engines".<ref name="USSR Decree 715-296 1960" />{{rp|1-2}} This included ion and electroplasma thrusters with target specific impulse of 5,000-10,000 seconds, a measure of propellant efficiency, assigning work to OKB-1, the Kurchatov Institute, and other named bureaus as part of a broader 1960-1967 Soviet Union space development plan.<ref name="USSR Decree 715-296 1960" />{{rp|27}}<ref name="Sutton Rockets 2017" />{{rp|50}} In 1964, Ernst Stuhlinger published ''Ion Propulsion for Space Flight'', characterized by Choueiri as the first comprehensive book on electric rocket technology, marking the field's transition into a serious engineering discipline.<ref name="Choueiri FP 2004-2" />{{rp|2-3}}

On 20 July 1964, two electrostatic ion engines were tested in space in the Space Electric Rocket Test (SERT I), and the mercury electron-bombardment engine produced thrust in flight.<ref name="NASA Lewis FP 1966" />{{rp|13}} SERT I was the first spacecraft to incorporate electric propulsion; its mercury electron bombardment ion engine, which ionizes mercury vapor by bombarding it with electrons and then accelerates the resulting ions electrically, ran for 31 minutes, becoming the first electric engine to operate in space.<ref name="Camilleri EP 2017" />{{rp|1,4}} A 1966 NASA Lewis Research Center overview stated that electric-propulsion spacecraft then under study could not be expected to take off from Earth and therefore would need to be launched to Earth orbit by chemical rockets before beginning low-thrust operation.<ref name="NASA Lewis FP 1966" />{{rp|6}} The 30 November 1964 Zond 2 mission to Mars from the Soviet Union marked the first planetary use of electric propulsion.<ref name="Myers NASA Electromagnetic Propulsion 1993" />{{rp|1}} Following the Zond 2 demonstration, pulsed plasma thruster development was transferred from the Kurchatov Institute to OKB Fakel, whose "Globus" pulsed propulsion unit flew in 1968.<ref name="Kozubsky SPD Trudy MAI 2012-12-10" />{{rp|2}}<ref name="Kazeev PPT Trudy MAI 2012-12-10" />{{rp|1}} The follow-on Space Electric Rocket Test II (SERT II), launched on 3 February 1970, was the first long-duration operation of ion thrusters in space; its two mercury electron-bombardment engines accumulated over 5 months and 3.5 months of continuous operation respectively, and after intermittent restarts, one thruster logged over 11 years of total operation through 1981.<ref name="Arrighi NASA SERT II 2024" />

Alongside ion engine development, a distinct line of electromagnetic thruster research was advancing in the Soviet Union. In the 1960s, A. I. Morozov proposed the stationary plasma thruster (SPT), a Hall-effect device that accelerates ionized propellant using perpendicular electric and magnetic fields.<ref name="Morozov PMTF 1968" />{{rp|19}}<ref name="Kozubsky SPD Trudy MAI 2012-12-10" />{{rp|3}} Within decades, hundreds would fly in space.<ref name="Kozubsky SPD Trudy MAI 2012-12-10" />{{rp|2,6}}

The first SPT was tested in orbit aboard a Meteor spacecraft in 1972, with corrective propulsion units operating on further Meteor missions through 1980.<ref name="Kozubsky SPD Trudy MAI 2012-12-10" />{{rp|2-3}}

===1980s=== Commercial electrothermal propulsion entered operational satellite service during this period. Hydrazine resistojets, electric thrusters that heat propellant before expelling it, began commercial geostationary north-south orbital station-keeping, used to maintain orbital position, with Intelsat V in 1980.<ref name="Martinez-Sanchez Pollard EP Overview 1998" />{{rp|688-689}}

===1990s=== [[File:Deep Space 1 clean (PIA04242).png|thumb|Artist concept of Deep Space 1 firing its ion thrusters in space.]]

The end of the Cold War opened access to previously restricted Soviet electric propulsion technology. U.S. electric propulsion specialists traveled to Russia in 1991 to evaluate the Russian SPT-100 at the Scientific-Research Institute of Thermal Processes in Moscow and at Fakel in Kaliningrad using U.S. instrumentation.<ref name="Brophy JPL SPT Russia 1992" />{{rp|1}} Brophy's subsequent JPL report said the measured performance appeared close to the advertised values, and noted claims that more than fifty lower-power SPT units had already flown on Russian spacecraft.<ref name="Brophy JPL SPT Russia 1992" />{{rp|1,4}}<ref name="Brophy Barnett Sankovic AIAA SPT-100 1992" /> The report laid out a second program phase in which thrusters would be brought to the United States for testing toward possible Western use.<ref name="Brophy JPL SPT Russia 1992" />{{rp|1,4}}<ref name="Sankovic Hamley Haag SPT-100 LeRC 1993" />{{rp|1}} That work fed into the later Ballistic Missile Defense Organization Russian Hall Electric Thruster Technology (RHETT) effort to move Hall thruster technology toward Western operational use.<ref name="Sankovic Caveny RHETT 1997" />{{rp|1}}<ref name="NRC USAF Propulsion 2006" />

Electric-propulsion work matured across the decade. Hydrazine-based arcjet rockets were deployed in 1993 on Telstar 401, extending electrothermal electric propulsion into higher-performance commercial geostationary use.<ref name="Hoskins Aerojet 2013" />{{rp|1-3}}

Alongside these experimental programs, electric propulsion was also entering routine commercial service. Commercial electric propulsion also entered Western geostationary satellite operations in the 1990s, as Hughes Boeing 601HP communications satellites began using gridded xenon ion thrusters (XIPS) for station-keeping in 1997.<ref name="Flightglobal XIPS 2000" /><ref name="Brophy success EP 2022" />{{rp|3}} After initial Russian usage from the 1970s, beginning in the 1990s qualified SPT units entered service on American and European spacecraft as well.<ref name="Kozubsky SPD Trudy MAI 2012-12-10" />{{rp|2,6}} European electric propulsion programs reached similar milestones in the years that followed. The Gießen RIT line later reached flight application on the European Space Agency's Artemis satellite, launched in 2001, which carried two German RIT-10 thrusters for station-keeping.<ref name="Lob Giessener FP 2008" />{{rp|42}} By the late 1990s, ESA was already positioning solar electric primary propulsion as a key technology for future deep-space missions through SMART-1, whose PPS-1350-G Hall thruster was later developed in the CNES Stentor satellite program and adapted from a geostationary station-keeping design.<ref name="Racca SMART-1 1998" />{{rp|50-59}}<ref name="Dumazert PPS-1350-G 2003" />{{rp|1-2}}<ref name="Koppel SMART-1 EPS 2004" />{{rp|1,7}}

By the late 1990s, electric propulsion had moved from experimental and military programs into routine commercial satellite operations, particularly for geostationary station-keeping, orbit raising, and related orbit-control maneuvers.<ref name="Brophy success EP 2022" />{{rp|3}}<ref name="Flightglobal XIPS 2000" /><ref name="Sutton Rockets 2017" />{{rp|624-625}} Deep Space 1 became the first U.S. space mission to use an ion thruster as its primary means of propulsion through 1998, validating NASA's NSTAR solar electric propulsion system in long-duration flight.<ref name="Arrighi NASA Deep Space 1 2019-12-18" />

===21st century=== [[File:Artist's impression of the SMART-1 mission ESA199399.jpg|thumb|Artist's impression of the SMART-1 mission.]]

SMART-1, launched in 2003, demonstrated solar electric primary propulsion in flight for ESA and carried the Hall thruster system that had been developed from late-1990s European work on commercial electric-propulsion applications and deep-space mission preparation.<ref name="Koppel SMART-1 EPS 2004" />{{rp|1,7}}<ref name="Racca SMART-1 1998" />{{rp|50-59}}

While electric-propulsion research and deployment continued, new systems were also launched into space. Hayabusa was launched by the Japan Aerospace Exploration Agency in 2003, propelled by electrodeless plasma thruster technology.<ref name="Kuninaka IEPC 2009" />{{rp|2}}<ref name="Nishiyama IEPC 2011" />{{rp|2}} By 2012, more than 270 Hall-effect SPT units had operated on over 60 Russian spacecraft.<ref name="Kozubsky SPD Trudy MAI 2012-12-10" />{{rp|2,6}} NASA's Dawn became the first spacecraft to orbit an object in the main asteroid belt at Vesta in 2011, and the first to orbit a dwarf planet at Ceres in 2015. Its ion propulsion system made Dawn the only spacecraft ever to orbit two extraterrestrial destinations.<ref name="JPL Dawn mission" /><ref name="NASA Dawn dwarf planet 2015" /> ESA's GOCE in 2009<ref name="ESA GOCE intro" /><ref name="ESA GOCE drag free" /> and JAXA's Super Low Altitude Test Satellite "TSUBAME" (2017-2019) marked later electric-propulsion milestones by demonstrating continuous drag compensation and ion-engine-supported super-low-altitude operations in very low Earth orbit.<ref name="JAXA TSUBAME transition 2019" /><ref name="JAXA TSUBAME end 2019" />

ESA and JAXA's BepiColombo, launched in 2018, marked a later major milestone in solar electric propulsion when its Solar Electric Propulsion System began in-flight commissioning in November 2018, in what ESA described as the first in-flight operation of the most powerful and highest-performance electric propulsion system flown on any space mission to date.<ref name="ESA BepiColombo mission" /><ref name="ESA BepiColombo electric 2018" />

In November 2023, Psyche became the first spacecraft to use Hall effect thrusters in interplanetary space, beyond the Earth-Moon system. The spacecraft uses its electric thrusters for both primary propulsion and momentum control and carries no chemical propulsion system. It is scheduled to enter orbit around the asteroid (16) Psyche in 2029.<ref name=":0" />

==Definitions== [[File:Orbion Hall-effect thruster firing on krypton.jpg|thumb|A Hall-effect thruster fires on krypton in a lab.]] Spacecraft electric propulsion is generally classified by how electrical energy is used to accelerate propellant: electrothermal systems heat propellant before expansion, electrostatic systems accelerate ions through electric fields, and electromagnetic systems accelerate plasma through the interaction of electric currents and magnetic fields.<ref name="Myers NASA Electromagnetic Propulsion 1993" />{{rp|1-8}}<ref name="Sutton Rockets 2017" />{{rp|647-649}} Over time, the boundaries between these classes have sometimes been drawn differently in surveys and program literature, especially for devices that combine more than one acceleration mechanism.<ref name="Choueiri FP 2004" />{{rp|4,8}}

Within electric and electromagnetic propulsion, thrust is generated by accelerating and expelling propellant using electric or magnetic fields rather than by coupling to an external environment.<ref name="Myers NASA Electromagnetic Propulsion 1993" />{{rp|1-2,5-8}} Examples include electrostatic ion engines, Hall-effect thrusters, pulsed plasma thrusters, magnetoplasmadynamic thrusters, pulsed inductive thrusters, electrothermal thrusters, and radio-frequency or electron-cyclotron-resonance ion engines.<ref name="Myers NASA Electromagnetic Propulsion 1993" />{{rp|1-8}}<ref name="Morozov PMTF 1968" />{{rp|19-22}}<ref name="Kuninaka IEPC 2009" />{{rp|2}}<ref name="Lob Giessener FP 2008" />{{rp|40}}

Conservation of momentum remains a fundamental requirement because these systems close momentum through exhaust rather than through external fields or media.<ref name="Sutton Rockets 2017" />{{rp|647-649}}<ref name="Myers NASA Electromagnetic Propulsion 1993" />{{rp|1-2}}

==Types== [[File:Hayabusa2 Ion thruster.jpg|thumb|Rendering of Hayabusa 2's ion propulsion system in use.]]

A wide range of electric propulsion methods have been proposed or demonstrated. Spacecraft electric propulsion is commonly grouped into electrothermal, electrostatic, and electromagnetic systems according to how electrical energy is used to heat, ionize, and accelerate propellant.<ref name="Myers NASA Electromagnetic Propulsion 1993" />{{rp|1-8}}<ref name="Sutton Rockets 2017" />{{rp|647-649}} Electric propulsion is most useful in missions where propellant efficiency matters more than rapid acceleration. In practice it has been used for geostationary station-keeping, orbit raising, deep-space probes, precision attitude and position control, and drag compensation in Earth orbit.<ref name="Sutton Rockets 2017" />{{rp|624-625}} These advantages come with operational tradeoffs: low-thrust transfers can require longer maneuver times and, in some cases, higher total delta-v than impulsive chemical maneuvers, so combined chemical-electric mission profiles remain common when transfer time is constrained.<ref name="Martinez-Sanchez Pollard EP Overview 1998" />{{rp|695-696}}<ref name="Sutton Rockets 2017" />{{rp|625}}

===Demonstrated=== Various electric and electromagnetic propulsion approaches and systems have achieved experimental validation, flight heritage, or sustained engineering development.

====Electric and electromagnetic with carried propellant==== [[File:Front and rear views of the PIT MkVI thruster during the re-assembly process.png|thumb|Front and rear views of the PIT MkVI pulsed inductive thrusters during their assembly process.]]

Three families of electromagnetic thruster, pulsed plasma thrusters (PPTs), magnetoplasmadynamic thrusters (MPD), and pulsed inductive thrusters (PIT), rely on strong fields.<ref name="Sutton Rockets 2017" />{{rp|647–649}}<ref name="Myers NASA Electromagnetic Propulsion 1993" />{{rp|1–2}} The three differ in lifetime, efficiency, and power scaling, but share advantages common to electromagnetic acceleration: high specific impulse, precision suitable for satellite positioning, robustness, high power processing capability, and relatively simple system-level scaling with available spacecraft power.<ref name="Myers NASA Electromagnetic Propulsion 1993" />{{rp|1}}

PPTs are the only electromagnetic thrusters used on operational satellites.<ref name="Myers NASA Electromagnetic Propulsion 1993" />{{rp|1,8}} Solid-propellant PPTs first flew in the Soviet Union in 1964 and in the United States in 1968; they initiate an arc discharge across a solid fluorinated polymer bar, ablating a small amount of propellant and accelerating it by the Lorentz body force.<ref name="Myers NASA Electromagnetic Propulsion 1993" />{{rp|1-2}} Their compact, low-power, pulsed configurations make them suited to satellite positioning and drag compensation, unlike later concepts that rely on inductive or steady-state operation.<ref name="Myers NASA Electromagnetic Propulsion 1993" />{{rp|1,4}}

MPDs generate thrust through the Lorentz force produced by the interaction of discharge currents with self-induced or externally applied magnetic fields, and have been investigated for both quasi-steady and steady-state spaceflight applications.<ref name="Myers NASA Electromagnetic Propulsion 1993" />{{rp|5}} MPD thrusters have also flown in space in experimental regimes.<ref name="Myers NASA Electromagnetic Propulsion 1993" />{{rp|8}}

The PIT concept originated in the late 1960s and evolved through successive experimental designs focused on performance scaling, circuit optimization, and propellant compatibility.<ref name="Myers NASA Electromagnetic Propulsion 1993" />{{rp|7}} PITs were developed to overcome the erosion and lifetime limitations of electrode-based systems by inducing plasma currents through time-varying magnetic fields, accelerating neutral propellants without physical contact between conductors and plasma.<ref name="Myers NASA Electromagnetic Propulsion 1993" />{{rp|8}} No PIT system has flown in space, but the thruster class remains of interest for high-efficiency, long-duration propulsion with minimal material degradation, particularly in missions requiring flexible propellant selection and reduced contamination risk.<ref name="Myers NASA Electromagnetic Propulsion 1993" />{{rp|7}}

Electron cyclotron resonance thrusters (ECR) use electron cyclotron resonance, in which microwaves transfer energy to electrons spiraling in a magnetic field, to ionize and accelerate a gaseous propellant (commonly xenon), particularly in ionospheric or high-altitude environments. ECRs using electron cyclotron resonance with microwave discharge have flown in space, most notably as the μ10 ion engine system on JAXA's Hayabusa and Hayabusa2 asteroid missions.<ref name="Kuninaka IEPC 2009" />{{rp|2}}<ref name="Nishiyama IEPC 2011" />{{rp|2}}

Stationary plasma thrusters (SPT), also called Hall-effect thrusters, accelerate ionized propellant (typically xenon) using perpendicular electric and magnetic fields and a circulating electron current.<ref name="Morozov PMTF 1968" />{{rp|19-22}} The concept was proposed by A. I. Morozov in the early 1960s, and a 1968 paper on near-wall conductivity in strongly magnetized plasma provided key theoretical grounding for the discharge channel physics.<ref name="Morozov PMTF 1968" />{{rp|19}} The first SPT was tested in space aboard a Meteor spacecraft launched in December 1971, with orbital firings conducted between February and June 1972; subsequent corrective propulsion units operated on further Meteor missions through 1980.<ref name="Kozubsky SPD Trudy MAI 2012-12-10" />{{rp|3}} By 2012, more than 270 SPD-70 and SPD-100 thrusters had operated on over 60 Russian spacecraft, and beginning in the 1990s qualified SPT units entered service on American and European spacecraft as well.<ref name="Kozubsky SPD Trudy MAI 2012-12-10" />{{rp|2}}

The Gießen RIT line used a radio-frequency, electrode-less xenon discharge, a design Löb described as avoiding electrode-related wear while offering high efficiency and high exhaust velocity.<ref name="Lob Giessener FP 2008" />{{rp|40}}

===Development and testing=== [[File:IPT-plasma-jet.jpg|thumb|RF Helicon-based Plasma Thruster (IPT) prototype operating on nitrogen.]] These are concepts under active engineering development or testing that adapt electric or electromagnetic propulsion principles for new operational regimes.

====Environment-fed electric propulsion==== Atmosphere-breathing electric propulsion is a concept in which a spacecraft collects residual atmospheric particles in very low Earth orbit, ionizes them, and accelerates them electromagnetically instead of carrying all propellant onboard. A 2018 European Space Agency technology demonstration was described as the first firing of an air-breathing electric thruster using collected atmospheric molecules as propellant, but no such system has yet flown in space.<ref name="ESA airbreathing 2018" />

Related operational milestones in very low Earth orbit preceded true atmosphere-breathing concepts. ESA's Gravity Field and Steady-State Ocean Circulation Explorer (GOCE), launched on 17 March 2009, became the first-ever mission to fly drag free in low Earth orbit using an electric propulsion system that continually compensated atmospheric drag.<ref name="ESA GOCE intro" /><ref name="ESA GOCE drag free" /> JAXA's Super Low Altitude Test Satellite (SLATS) "TSUBAME", launched on 23 December 2017, transitioned to ion-engine orbit-keeping operations in April 2019 and later demonstrated maintenance of six orbital altitudes between 271.1 and 181.1 km, validating super-low-altitude Earth observation operations.<ref name="JAXA TSUBAME transition 2019" /><ref name="JAXA TSUBAME end 2019" />

==Selected milestones== The following table summarizes selected systems and mission milestones in spacecraft electric propulsion, including both flight-proven applications and developmental concepts discussed in this article.

{| class="wikitable sortable" style="width:100%;" |+ Selected milestones in spacecraft electric propulsion |- ! System / milestone ! Domain ! First demonstrated usage ! Date ! Vehicle / mission ! Maturity ! Remarks |- | Electrothermal thruster | Space | First electric thruster built and tested on a thruster stand | 1933 | Gas Dynamics Laboratory prototype (Valentin Glushko) | Ground tested | Carried propellant; first electric thruster ever studied on a stand.<ref name="Choueiri FP 2004" />{{rp|11-12}} |- | Electrostatic ion engine | Space | First electric propulsion spacecraft; mercury electron-bombardment engine operated 31 minutes | 1964 | SERT I (NASA) | Operational | Carried propellant; first electric engine to operate in space.<ref name="Camilleri EP 2017" />{{rp|1,4}}<ref name="NASA Lewis FP 1966" />{{rp|13}} |- | Pulsed plasma thruster (PPT) | Space | First electromagnetic thruster flown in space; first planetary use of electric propulsion | 1964 | Zond 2 (Soviet Union, Mars mission) | Operational | Carried propellant; solid-propellant PPTs also flew in the U.S. in 1968.<ref name="Myers NASA Electromagnetic Propulsion 1993" />{{rp|1-2}} |- | Pulsed inductive thruster (PIT) | Space | Successive experimental designs from MkI through MkVI focused on performance scaling and propellant compatibility | 1968 | PIT MkI–MkVI laboratory series | Ground tested | Carried propellant; developed to overcome electrode erosion limits of PPTs and MPDs; no flight to date.<ref name="Myers NASA Electromagnetic Propulsion 1993" />{{rp|7-8}} |- | Electrostatic ion engine (long-duration) | Space | First long-duration ion thruster operation in space; one thruster logged over 11 years of total operation | 1970 | SERT II (NASA) | Operational | Carried propellant (mercury); two electron-bombardment engines accumulated months of continuous thrust; validated long-life ion propulsion.<ref name="Arrighi NASA SERT II 2024" /> |- | Hall-effect thruster (SPT) | Space | First SPT tested in orbit; corrective firings on Meteor spacecraft | 1972 | Meteor (Kurchatov Institute / OKB Fakel) | Operational | Carried propellant (xenon); proposed by Morozov early 1960s; 270+ units flown on 60+ Russian spacecraft by 2012.<ref name="Kozubsky SPD Trudy MAI 2012-12-10" />{{rp|2-3}} |- | Electrostatic ion engine (primary propulsion) | Space | First U.S. space mission to use an ion thruster as its primary means of propulsion | 1998 | Deep Space 1 (NASA) | Operational | Carried propellant (xenon); validated NSTAR solar electric propulsion system in long-duration flight.<ref name="Arrighi NASA Deep Space 1 2019-12-18" /> |- | ECR ion engine | Space | μ10 microwave-discharge ion engine system | 2003 | Hayabusa (JAXA) | Operational | Carried propellant (xenon); also flew on Hayabusa2 (2014).<ref name="Kuninaka IEPC 2009" />{{rp|2}}<ref name="Nishiyama IEPC 2011" />{{rp|2}} |- | Hall-effect thruster (primary propulsion) | Space | First ESA mission to use solar electric propulsion as primary propulsion | 2003 | SMART-1 (ESA) | Operational | Carried propellant (xenon); PPS-1350-G Hall thruster developed from late-1990s European geostationary station-keeping designs.<ref name="Koppel SMART-1 EPS 2004" />{{rp|1,7}}<ref name="Racca SMART-1 1998" />{{rp|50-59}} |- | Electric propulsion (drag-free flight) | Space | First mission to fly drag-free in low Earth orbit using continuous electric propulsion | 2009 | GOCE (ESA) | Operational | Carried propellant; electric propulsion system continually compensated atmospheric drag throughout mission.<ref name="ESA GOCE intro" /><ref name="ESA GOCE drag free" /> |- | Electrostatic ion engine (dual-destination) | Space | First spacecraft to orbit two extraterrestrial destinations; first to orbit a body in the asteroid belt and first to orbit a dwarf planet | 2011 | Dawn (NASA) | Operational | Carried propellant (xenon); ion propulsion enabled orbit of Vesta (2011) and Ceres (2015).<ref name="JPL Dawn mission" /><ref name="NASA Dawn dwarf planet 2015" /> |- | Electrostatic ion engine (high-performance) | Space | Most powerful and highest-performance electric propulsion system flown on any space mission at time of commissioning | 2018 | BepiColombo (ESA / JAXA) | Operational | Carried propellant; Solar Electric Propulsion System began in-flight commissioning November 2018.<ref name="ESA BepiColombo mission" /><ref name="ESA BepiColombo electric 2018" /> |- | Atmosphere-breathing electric propulsion | Space | First ground firing of an air-breathing electric thruster (intake + thruster), including ignition using atmospheric propellant | 2018 | ESA TRP / Sitael RAM-EP ground test (simulated ~200 km environment) | Ground tested | ESA described this as a world-first firing of an air-breathing electric thruster concept using collected atmospheric molecules as propellant.<ref name="ESA airbreathing 2018" /> |- |Hall-effect thruster (interplanetary) |Space |First use of hall-effect thrusters in interplanetary space |2023 |Psyche (NASA) |Operational |Carried propellant (xenon); Hall thrusters fired for the first time in interplanetary space November 2023.<ref name=":0">{{Cite journal |last=Oh |first=David Y. |last2=Alonge |first2=Nora |last3=Bairstow |first3=Sarah H. |last4=Biswas |first4=Abhijit |last5=Chesko |first5=Carl |last6=Goebel |first6=Dan M. |last7=Imken |first7=Travis |last8=Na-Nakornpanom |first8=Arthur |last9=Nicholas |first9=Austin |last10=Snyder |first10=John Steven |last11=Johnson |first11=Ian |last12=Linggi |first12=Paul |last13=Lord |first13=Peter |last14=Malone |first14=Shane |last15=Pirkl |first15=Zack |date=January 2026 |title=Launch and Initial Checkout of the Psyche Spacecraft |url=https://arc.aiaa.org/doi/10.2514/1.A36329 |journal=Journal of Spacecraft and Rockets |volume=63 |issue=1 |pages=262–276 |doi=10.2514/1.A36329 |issn=0022-4650|url-access=subscription }}</ref> |}

==See also== {{Sister project links}}

* {{anl|Bussard ramjet}} * {{anl|Emerging technologies}} * {{anl|Field propulsion}} * History of aviation * History of rockets * History of spaceflight * {{anl|New Millennium Program}} * {{anl|Non-rocket spacelaunch}} * Timeline of aviation * Timeline of rocket and missile technology * Timeline of spaceflight

==References== {{US government sources}} <references>

<ref name="Arrighi NASA Deep Space 1 2019-12-18">{{Cite web|date=2019-12-18|title=NASA History: Deep Space 1 Validated the Promise of Ion Thrusters|last1=Arrighi |first1=Robert S.|authorlink1=|url=https://www.nasa.gov/history/nasa-history-deep-space-1-validated-the-promise-of-ion-thrusters/|url-status=live|website=NASA|archive-url=https://web.archive.org/web/20250228074222/https://www.nasa.gov/history/nasa-history-deep-space-1-validated-the-promise-of-ion-thrusters/|archive-date=2025-02-28}}</ref>

<ref name="Arrighi NASA SERT II 2024">{{cite web |last=Arrighi |first=Robert S. |title=NASA's SERT II: 'A Genuine Space Success Story' |url=https://www.nasa.gov/centers-and-facilities/glenn/nasas-sert-ii-a-genuine-space-success-story/ |website=NASA |date=2024-04-11|access-date=2026-03-11|archive-url=https://web.archive.org/web/20240411150901/https://www.nasa.gov/centers-and-facilities/glenn/nasas-sert-ii-a-genuine-space-success-story/|archive-date=2024-04-11}}</ref>

<ref name="Brophy Barnett Sankovic AIAA SPT-100 1992">{{cite conference | last1=Brophy | first1=John R. | last2=Barnett | first2=John W. | last3=Sankovic | first3=John M. | last4=Barnhart | first4=David A. | title=Performance of the Stationary Plasma Thruster: SPT-100 | conference=28th AIAA/SAE/ASME/ASEE Joint Propulsion Conference | location=Nashville, Tennessee | date=July 1992 | id=AIAA Paper 92-3155 | doi=10.2514/6.1992-3155 | url=https://electricrocket.org/IEPC/IEPC1993-091.pdf | publisher=American Institute of Aeronautics and Astronautics | archive-url= | archive-date=}}</ref>

<ref name="Brophy JPL SPT Russia 1992">{{cite report | last=Brophy | first=John R. | title=Stationary Plasma Thruster Evaluation in Russia | date=1992-03-15 | publisher=Jet Propulsion Laboratory | type=Summary report | id=JPL Publication 92-4; NASA-CR-192823 | url=https://ntrs.nasa.gov/citations/19930016017 | access-date=2026-03-09 | quote=A team of electric propulsion specialists from U.S. government laboratories experimentally evaluated the performance of a 1.35-kW Stationary Plasma Thruster (SPT) at the Scientific-Research Institute of Thermal Processes in Moscow and at 'Fakel' Enterprise in Kaliningrad, Russia. | archive-url=https://web.archive.org/web/20260227045357/https://ntrs.nasa.gov/api/citations/19930016017/downloads/19930016017.pdf | archive-date=2026-02-27}}</ref>

<ref name="Brophy success EP 2022">{{cite journal |last=Brophy |first=John R. |title=Perspectives on the success of electric propulsion |journal=Journal of Electric Propulsion |volume=1 |issue=1 |article-number=9 |year=2022 |doi=10.1007/s44205-022-00011-0|url=https://link.springer.com/article/10.1007/s44205-022-00011-0|doi-access=free }}</ref>

<ref name="Camilleri EP 2017">{{cite report |last=Camilleri |first=Vincent |title=Electric Propulsion and Electric Satellites |website=Ann and H.J. Smead Department of Aerospace Engineering Sciences, University of Colorado Boulder |publisher=American Institute of Aeronautics and Astronautics |location=Boulder |date=2017-05-11 |url=https://www.colorado.edu/faculty/kantha/sites/default/files/attached-files/172038-172568_-_vincent_camilleri_-_may_11_2017_208_am_-_final_rp.pdf |archive-url=https://web.archive.org/web/20240422102207/https://www.colorado.edu/faculty/kantha/sites/default/files/attached-files/172038-172568_-_vincent_camilleri_-_may_11_2017_208_am_-_final_rp.pdf |archive-date=2024-04-22 |quote=The SERT 1 was not only the first electric satellite it was also the first spacecraft to incorporate any kind of electric propulsion. The SERT 1 launched on July 20, 1964 on the Scout X-4 rocket.}}</ref>

<ref name="Choueiri FP 2004">{{cite journal |last=Choueiri |first=Edgar Y. |author-link=Edgar Choueiri|title=A Critical History of Electric Propulsion: The First Fifty Years (1906-1956) |journal=Journal of Propulsion and Power |volume=20 |issue=2 |pages=193-203 |date=2004 |url=https://mae.princeton.edu/sites/g/files/toruqf7696/files/ChoueiriHistJPC04.pdf|archive-url=https://web.archive.org/web/20251004004258/https://mae.princeton.edu/sites/g/files/toruqf7696/files/ChoueiriHistJPC04.pdf|archive-date=2025-10-04|quote=The reader will soon note a measure of the vagaries of that evolution: while the earliest thoughts and experiments related to EP are almost all about electrostatic propulsion, the first laboratory electric thruster was electrothermal and the first electric thruster to ever fly in space was of the pulsed (mostly electromagnetic) plasma type.}}</ref>

<ref name="Choueiri FP 2004-2">{{cite conference |last=Choueiri |first=Edgar Y. |author-link=Edgar Choueiri |title=A Critical History of Electric Propulsion: Part II: 1957–1979 |conference=39th International Electric Propulsion Conference |location=Imperial College London |date=September 2025 |id=IEPC-2025-723 |url=https://alfven.princeton.edu/publications/pdf/choueiri-iepc-2025-723.pdf |publisher=Electric Rocket Propulsion Society|archive-url=https://web.archive.org/web/20260204200037/https://alfven.princeton.edu/publications/pdf/choueiri-iepc-2025-723.pdf|archive-date=2026-02-04}}</ref>

<ref name="Dumazert PPS-1350-G 2003">{{cite conference |last1=Dumazert |first1=Pierre |last2=Lagardere-Verdier |first2=Sophie |last3=Marchandise |first3=Frederic |last4=Koppel |first4=Christophe R. |last5=Garnero |first5=Pascal |last6=Balme |first6=Francois |title=PPS-1350-G Qualification Status |conference=28th International Electric Propulsion Conference |date=March 2003 |url=https://electricrocket.org/IEPC/0270-0303iepc-full.pdf|archive-url=https://web.archive.org/web/20260313153909/https://electricrocket.org/IEPC/0270-0303iepc-full.pdf|archive-date=2026-03-13}}</ref>

<ref name="ESA airbreathing 2018">{{Cite web|date=2018-03-05|title=World-first firing of air-breathing electric thruster|url=https://www.esa.int/Enabling_Support/Space_Engineering_Technology/World-first_firing_of_air-breathing_electric_thruster|website=European Space Agency|access-date=2026-03-03|archive-url=https://web.archive.org/web/20191109214349/https://www.esa.int/Enabling_Support/Space_Engineering_Technology/World-first_firing_of_air-breathing_electric_thruster|archive-date=2019-11-09}}</ref>

<ref name="ESA BepiColombo electric 2018">{{Cite web |date=2018-11-16 |title=Electric blue thrusters propelling BepiColombo to Mercury |url=https://www.esa.int/Enabling_Support/Space_Engineering_Technology/Electric_blue_thrusters_propelling_BepiColombo_to_Mercury |website=European Space Agency |access-date=2026-03-13 |archive-url=https://web.archive.org/web/20250704131809/https://www.esa.int/Enabling_Support/Space_Engineering_Technology/Electric_blue_thrusters_propelling_BepiColombo_to_Mercury |archive-date=2025-07-04}}</ref>

<ref name="ESA BepiColombo mission">{{Cite web |title=BepiColombo, Investigating Mercury's mysteries |url=https://www.esa.int/Science_Exploration/Space_Science/BepiColombo |website=European Space Agency |access-date=2026-03-13 |archive-url=https://web.archive.org/web/20260102041156/https://www.esa.int/Science_Exploration/Space_Science/BepiColombo |archive-date=2026-01-02}}</ref>

<ref name="ESA GOCE drag free">{{Cite web |title=GOCE achieves drag-free perfection |url=https://www.esa.int/Applications/Observing_the_Earth/FutureEO/GOCE/GOCE_achieves_drag-free_perfection |website=European Space Agency |access-date=2026-03-13 |archive-url=https://web.archive.org/web/20251123052511/https://www.esa.int/Applications/Observing_the_Earth/FutureEO/GOCE/GOCE_achieves_drag-free_perfection |archive-date=2025-11-23}}</ref>

<ref name="ESA GOCE intro">{{Cite web |title=Introducing GOCE |url=https://www.esa.int/Applications/Observing_the_Earth/FutureEO/GOCE/Introducing_GOCE |website=European Space Agency |access-date=2026-03-13 |archive-url=https://web.archive.org/web/20260224160918/https://www.esa.int/Applications/Observing_the_Earth/FutureEO/GOCE/Introducing_GOCE |archive-date=2026-02-24}}</ref>

<ref name="Flightglobal XIPS 2000">{{cite news |title=XIPS - efficient electric propulsion |work=Flight International |publisher=FlightGlobal |date=2000-01-31 |url=https://www.flightglobal.com/xips-efficient-electric-propulsion/30378.article |archive-url=https://web.archive.org/web/20250711223948/https://www.flightglobal.com/xips-efficient-electric-propulsion/30378.article|archive-date=2025-07-11}}</ref>

<ref name="Hoskins Aerojet 2013">{{cite conference |last1=Hoskins |first1=W. A. |last2=Polk |first2=J. E. |last3=Sankovic |first3=J. M. |last4=Curran |first4=F. M. |title=30 Years of Electric Propulsion Flight Experience at Aerojet Rocketdyne |conference=33rd International Electric Propulsion Conference |date=2013 |url=https://electricrocket.org/IEPC/7vc5f5xg.pdf|archive-url=https://web.archive.org/web/20250904053829/https://electricrocket.org/IEPC/7vc5f5xg.pdf|archive-date=2025-09-04}}</ref>

<ref name="JAXA TSUBAME end 2019">{{Cite web |date=2019-10-02 |title=JAXA terminates the operation of TSUBAME, a Super Low Altitude Test Satellite (SLATS) |url=https://global.jaxa.jp/press/2019/10/20191002a.html |website=Japan Aerospace Exploration Agency |access-date=2026-03-13 |archive-url=https://web.archive.org/web/20250708182432/https://global.jaxa.jp/press/2019/10/20191002a.html |archive-date=2025-07-08}}</ref>

<ref name="JAXA TSUBAME transition 2019">{{Cite web |date=2019-03-18 |title=Tsubame Transition to Orbit Keeping Operations |url=https://global.jaxa.jp/press/2019/03/20190318a.html |website=Japan Aerospace Exploration Agency |access-date=2026-03-13 |archive-url=https://web.archive.org/web/20240729151100/https://global.jaxa.jp/press/2019/03/20190318a.html |archive-date=2024-07-29}}</ref>

<ref name="JPL Dawn mission">{{Cite web|title=Dawn|url=https://www.jpl.nasa.gov/missions/dawn/|website=Jet Propulsion Laboratory|publisher=NASA}}</ref><ref name="NASA Dawn dwarf planet 2015">{{Cite web|date=2015-03-06|title=NASA Spacecraft Becomes First to Orbit a Dwarf Planet|url=https://www.nasa.gov/news-release/nasa-spacecraft-becomes-first-to-orbit-a-dwarf-planet/|website=NASA|archive-url=https://web.archive.org/web/20260313192250/https://www.nasa.gov/news-release/nasa-spacecraft-becomes-first-to-orbit-a-dwarf-planet/|archive-date=2026-03-13}}</ref>

<ref name="Kazeev PPT Trudy MAI 2012-12-10">{{cite journal |date=2012-12-10|last=Kazeev |first=M. N. |title=Импульсные плазменные двигатели в России |trans-title=Pulsed plasma thrusters in Russia |journal=Trudy MAI |issue=60 |language=ru |url=https://trudymai.ru/upload/iblock/e76/impulsnye-plazmennye-dvigateli-v-rossii.pdf?issue=60&lang=ru|archive-url=https://web.archive.org/web/20241122162927/https://trudymai.ru/upload/iblock/e76/impulsnye-plazmennye-dvigateli-v-rossii.pdf?issue=60&lang=ru|archive-date=2024-11-22|pages=1}}</ref>

<ref name="Koppel SMART-1 EPS 2004">{{cite conference |last1=Koppel |first1=Christophe R. |last2=Marchandise |first2=Frederic |last3=Estublier |first3=Denis |last4=Jolivet |first4=Laurent |title=The SMART-1 Electric Propulsion Subsystem In Flight Experience |conference=40th AIAA/ASME/SAE/ASEE Joint Propulsion Conference and Exhibit |date=2004 |url=https://sci.esa.int/documents/34677/36590/1567255180622-AIAA2004-3435-koppel-smart09.pdf|archive-url=https://web.archive.org/web/20250712045642/https://sci.esa.int/documents/34677/36590/1567255180622-AIAA2004-3435-koppel-smart09.pdf|archive-date=2025-07-12}}</ref>

<ref name="Kozubsky SPD Trudy MAI 2012-12-10">{{cite journal |date=2012-12-10|last1=Kozubsky |first1=K. N. |last2=Koryakin |first2=A. I. |last3=Murashko |first3=V. M. |title=История космических стационарных плазменных двигателей и их применение в России, США и Европе |trans-title=History of space stationary plasma thrusters and their application in Russia, the USA and Europe |journal=Trudy MAI |issue=60 |language=ru |url=https://trudymai.ru/upload/iblock/0e7/istoriya-kosmicheskikh-statsionarnykh-plazmennykh-dvigateley-i-ikh-primenenie-v-rossii_-ssha-i-evrope.-novye-vyzovy-dlya-statsionarnykh-plazmennykh-dvigateley..pdf?issue=60&lang=ru|archive-url=https://web.archive.org/web/20260309161639/https://trudymai.ru/upload/iblock/0e7/istoriya-kosmicheskikh-statsionarnykh-plazmennykh-dvigateley-i-ikh-primenenie-v-rossii_-ssha-i-evrope.-novye-vyzovy-dlya-statsionarnykh-plazmennykh-dvigateley..pdf?issue=60&lang=ru|archive-date=2026-03-09}}</ref>

<ref name="Kuninaka IEPC 2009">{{cite conference |last1=Kuninaka |first1=H. |title=Overview and Research Status of Microwave Discharge Ion Thruster System |conference=31st IEPC; American Institute of Aeronautics and Astronautics |publisher=International Electric Propulsion Conference (IEPC)| year=2009 |url=https://electricrocket.org/IEPC/IEPC-2009-267.pdf |archive-url=https://web.archive.org/web/20240415232026/https://electricrocket.org/IEPC/IEPC-2009-267.pdf |archive-date=2024-04-15 |page=1 |quote=The cathode-less electron cyclotron resonance ion engines, μ10, propelled the Hayabusa asteroid explorer, launched in May 2003, which is focused on demonstrating the technology needed for a sample return from an asteroid.}}</ref>

<ref name="Lob Giessener FP 2008">{{cite journal |last=Löb |first=Horst |title=Die Gießener Ionen-Raketentriebwerke |journal=Gießener Universitätsblätter |volume=41 |date=2008 |language=de |url=https://www.giessener-hochschulgesellschaft.de/download/GU/GU-41-2008.pdf |archive-url=https://web.archive.org/web/20260309172856/https://www.giessener-hochschulgesellschaft.de/download/GU/GU-41-2008.pdf |archive-date=2026-03-09 |department=Gießener Universitätsblätter is a 1918-founded science advocacy society of the University of Giessen. |pages=37-46}}</ref>

<ref name="Martinez-Sanchez Pollard EP Overview 1998">{{cite journal |last1=Martinez-Sanchez |first1=M. |last2=Pollard |first2=J. E. |title=Spacecraft Electric Propulsion-An Overview |journal=Journal of Propulsion and Power |volume=14 |issue=5 |year=1998 |pages=688-699 |doi=10.2514/2.5331 |url=https://stuff.mit.edu/afs/athena/course/22/22.033/www/references/oleg/JPP_14_5_Martinez.pdf|archive-url=https://web.archive.org/web/20170808200504/https://stuff.mit.edu/afs/athena/course/22/22.033/www/references/oleg/JPP_14_5_Martinez.pdf|archive-date=2017-08-08}}</ref>

<ref name="Morozov PMTF 1968">{{cite journal |last=Morozov |first=A. I. |title=Эффект пристеночной проводимости в хорошо замагниченной плазме |trans-title=Effect of near-wall conductivity in well-magnetized plasma |journal=Prikladnaya Mekhanika i Tekhnicheskaya Fizika |issue=3 |pages=19–22 |date=1968 |language=ru |url=https://www.sibran.ru/upload/iblock/e4b/e4bc310cd823283bde0b540da3218c35.pdf |archive-url=https://web.archive.org/web/20240527074525/https://www.sibran.ru/upload/iblock/e4b/e4bc310cd823283bde0b540da3218c35.pdf |archive-date=2024-05-27|quote=Однако существует класс плазменных систем, в которых аномальная проводимость, по крайней мере, частично, может быть объяснена иначе. К таким системам относятся, например, гомополяр, а также коробчатые и холловские ускорители (Translated: However, there is a class of plasma systems in which anomalous conductivity can, at least in part, be explained differently. Such systems include, for example, the homopolar discharge, as well as box-type and Hall accelerators.)}}</ref>

<ref name="Myers NASA Electromagnetic Propulsion 1993">{{cite report | title = Electromagnetic Propulsion for Spacecraft: Presented at the 1993 Aerospace Design Conference, Irvine, California, February 15–18, 1993 | last1= Myers |first1=Roger M. | publisher = Sverdrup Technology, Inc. for the NASA John H. Glenn Research Center at Lewis Field | date = February 1993 | type = Contractor Report | series = NASA Contractor Report Series | number = NASA-CR-191186 | location = Brook Park, Ohio | url = https://ntrs.nasa.gov/api/citations/19940008943/downloads/19940008943.pdf | archive-url = https://web.archive.org/web/20230610020741/https://ntrs.nasa.gov/api/citations/19940008943/downloads/19940008943.pdf | archive-date = 2023-06-10 | id = AIAA-93-1086; NASA-CR-191186; Accession 94N26441 | access-date = 2025-06-05}}</ref>

<ref name="NASA History of Rockets">{{Cite web|title=Brief History of Rockets|url=https://www.grc.nasa.gov/www/k-12/TRC/Rockets/history_of_rockets.html|url-status=live|website=NASA John H. Glenn Research Center at Lewis Field|archive-url=https://web.archive.org/web/20250930224445/https://www.grc.nasa.gov/www/k-12/TRC/Rockets/history_of_rockets.html|archive-date=2025-09-30}}</ref>

<ref name="NASA Lewis FP 1966">{{cite report|title=Propulsion for Deep Space|author=Electromagnetic Propulsion Division|institution=National Aeronautics and Space Administration, Lewis Research Center|location=Cleveland, Ohio|date=June 1966|id=NASA-EP-41|url=https://ntrs.nasa.gov/api/citations/19830077482/downloads/19830077482.pdf|archive-url=https://web.archive.org/web/20230307145947/https://ntrs.nasa.gov/api/citations/19830077482/downloads/19830077482.pdf|archive-date=2023-03-07}}</ref>

<ref name="Nishiyama IEPC 2011">{{cite conference |last1=Nishiyama |first1=K. |title=The Ion Engine System for Hayabusa2 |conference=32nd IEPC; American Institute of Aeronautics and Astronautics |publisher=International Electric Propulsion Conference (IEPC) |year=2011 |url=https://electricrocket.org/IEPC/IEPC-2011-309.pdf |archive-url=https://web.archive.org/web/20240415232027/https://electricrocket.org/IEPC/IEPC-2011-309.pdf |archive-date=2024-04-15 |page=2 |quote=An ion thruster consists of an ion source and a neutralizer both of which utilize microwave discharge with electron cyclotron resonance at a frequency of 4.25 GHz.}}</ref>

<ref name="NRC USAF Propulsion 2006">{{cite book | author=National Research Council | title=A Review of United States Air Force and Department of Defense Aerospace Propulsion Needs | date=2006 | publisher=National Academies Press | location=Washington, D.C. | isbn=978-0-309-10247-6 | doi=10.17226/11780 | chapter=5: Rocket Propulsion Systems for In-Space Operations and Missiles | url=https://nap.nationalacademies.org/read/11780/chapter/7 | access-date=2026-03-09 | quote=In 1990, the Science and Technology Directorate of the Ballistic Missile Defense Organization (BMDO) took the lead in identifying advanced spacecraft propulsion technology developed in the former Soviet Union with potential applications for U.S. government and commercial missions. It identified the Russian Hall thruster technology as being particularly promising. | archive-url= | archive-date=}}</ref>

<ref name="Racca SMART-1 1998">{{cite journal |last1=Racca |first1=G.D. |last2=Whitcomb |first2=G.P. |last3=Foing |first3=B.H. |title=The SMART-1 Mission |journal=ESA Bulletin |issue=95 |date=August 1998 |pages=50-59 |url=https://www.esa.int/esapub/bulletin/bullet95/RACCA.pdf|archive-url=https://web.archive.org/web/20050218205824/https://www.esa.int/esapub/bulletin/bullet95/RACCA.pdf|archive-date=2005-02-18}}</ref>

<ref name="Radd ARS 1945">{{cite journal |last=Radd |first=Herbert |title=A Survey of Spatial Problems: Some Tentative Solutions in Space Travel |journal=Journal of the American Rocket Society |issue=64 |date=December 1945 |pages=28-29 |doi=10.2514/8.4064 |url=https://arc.aiaa.org/doi/abs/10.2514/8.4064 |url-access=subscription |publisher=American Institute of Aeronautics and Astronautics}}</ref>

<ref name="Sankovic Caveny RHETT 1997">{{cite conference | last1=Sankovic | first1=John M. | last2=Caveny | first2=Leonard H. | last3=Lynn | first3=Peter | title=The BMDO Russian Hall Electric Thruster Technology (RHETT) Program: From Laboratory to Orbit | conference=33rd AIAA/ASME/SAE/ASEE Joint Propulsion Conference | location=Seattle, Washington | date=July 1997 | id=AIAA Paper 97-2917 | doi=10.2514/6.1997-2917 | publisher=American Institute of Aeronautics and Astronautics | url=https://arc.aiaa.org/doi/10.2514/6.1997-2917 | archive-url= | archive-date=| url-access=subscription }}</ref>

<ref name="Sankovic Hamley Haag SPT-100 LeRC 1993">{{cite report | last1=Sankovic | first1=John M. | last2=Hamley | first2=John A. | last3=Haag | first3=Thomas W. | title=Performance Evaluation of the Russian SPT-100 Thruster at NASA LeRC | date=January 1994 | publisher=NASA Lewis Research Center | type=Conference paper | id=IEPC-93-094; NASA-TM-106401 | url=https://ntrs.nasa.gov/citations/19940019157 | access-date=2026-03-09 | quote=Performance measurements of a Russian flight-model SPT-100 thruster were obtained as part of a comprehensive program to evaluate engineering issues pertinent to integration with Western spacecraft. | archive-url=https://web.archive.org/web/20240520191357/https://ntrs.nasa.gov/api/citations/19940019157/downloads/19940019157.pdf | archive-date=2024-05-20}}</ref>

<ref name="Sutton Rockets 2017">{{cite book| last1=Sutton| first1=George P.| last2=Biblarz| first2=Oscar| title=Rocket Propulsion Elements| edition=9th| publisher=Wiley| year=2017| isbn=978-1-118-75365-1| url=https://ftp.idu.ac.id/wp-content/uploads/ebook/tdg/DESIGN%20SISTEM%20DAYA%20GERAK/Rocket%20Propulsion%20Elements.pdf| archive-url=https://web.archive.org/web/20220612011026/https://ftp.idu.ac.id/wp-content/uploads/ebook/tdg/DESIGN%20SISTEM%20DAYA%20GERAK/Rocket%20Propulsion%20Elements.pdf| archive-date=2022-06-12}}</ref>

<ref name="USSR Decree 715-296 1960">{{cite web |title=Постановление ЦК КПСС и Совета Министров СССР №715-296 |trans-title=Decree of the Central Committee and Council of Ministers No. 715-296 |date=1960-06-23 |language=ru |url=https://www.kosmonavtika.com/bibliographie/documents/715-296.pdf|archive-url=https://web.archive.org/web/20170713051740/https://www.kosmonavtika.com/bibliographie/documents/715-296.pdf|archive-date=2017-07-13|pages=}}</ref>

</references>

{{Engineering fields}} {{Spacecraft propulsion}} {{Spaceflight}}

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