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70-448: An ion thruster , ion drive , or ion engine is a form of electric propulsion used for spacecraft propulsion . An ion thruster creates a cloud of positive ions from a neutral gas by ionizing it to extract some electrons from its atoms . The ions are then accelerated using electricity to create thrust . Ion thrusters are categorized as either electrostatic or electromagnetic . Electrostatic thruster ions are accelerated by

140-623: A B.S. degree in mechanical engineering from Northwestern University . After college he joined the National Advisory Committee for Aeronautics (NACA), the predecessor of NASA , working on turbo jet engines at the Lewis Research Center (now NASA Glenn) in Cleveland . He then moved to a group studying electric space propulsion. After concluding that a Von Ardenne source was insufficient, he developed

210-408: A car to highway speed in vacuum. The technical characteristics, especially thrust , are considerably inferior to the prototypes described in literature, technical capabilities are limited by the space charge created by ions. This limits the thrust density ( force per cross-sectional area of the engine). Ion thrusters create small thrust levels (the thrust of Deep Space 1 is approximately equal to

280-399: A cylindrical anode and a negatively charged plasma that forms the cathode. The bulk of the propellant (typically xenon) is introduced near the anode, where it ionizes and flows toward the cathode; ions accelerate towards and through it, picking up electrons as they leave to neutralize the beam and leave the thruster at high velocity. The anode is at one end of a cylindrical tube. In the center

350-523: A free flying VASIMR test being discussed by Ad Astra instead. An envisioned 200 MW engine could reduce the duration of flight from Earth to Jupiter or Saturn from six years to fourteen months, and Mars from 7 months to 39 days. Under a research grant from the NASA Lewis Research Center during the 1980s and 1990s, Martin C. Hawley and Jes Asmussen led a team of engineers in developing a microwave electrothermal thruster (MET). In

420-491: A higher exhaust speed (operate at a higher specific impulse ) than chemical rockets. Due to limited electric power the thrust is much weaker compared to chemical rockets, but electric propulsion can provide thrust for a longer time. Electric propulsion was first demonstrated in the 1960s and is now a mature and widely used technology on spacecraft. American and Russian satellites have used electric propulsion for decades. As of 2019 , over 500 spacecraft operated throughout

490-416: A hole in its chamber. A neutralising electron gun would produce a tiny amount of thrust with high specific impulse in the order of millions of seconds due to the high relativistic speed of alpha particles. A variant of this uses a graphite-based grid with a static DC high voltage to increase thrust as graphite has high transparency to alpha particles if it is also irradiated with short wave UV light at

560-443: A large percentage of the energy needed to run ion drives. The ideal propellant is thus easy to ionize and has a high mass/ionization energy ratio. In addition, the propellant should not erode the thruster to any great degree, so as to permit long life, and should not contaminate the vehicle. Many current designs use xenon gas, as it is easy to ionize, has a reasonably high atomic number, is inert and causes low erosion. However, xenon

630-684: A paper introducing the idea publicly was Konstantin Tsiolkovsky in 1911. The technique was recommended for near-vacuum conditions at high altitude, but thrust was demonstrated with ionized air streams at atmospheric pressure. 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. A working ion thruster

700-482: A prescribed duration) or unsteady (pulsed firings accumulating to a desired impulse ). These classifications can be applied to all types of propulsion engines. 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. A chemical rocket imparts energy to the combustion products directly, whereas an electrical system requires several steps. However,

770-615: A propellant. 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: A photonic drive interacts only with photons. 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. Electric potential

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840-407: A roughly constant magnetic field in the source tube (supplied by solenoids in the prototype), but the magnetic field diverges and rapidly decreases in magnitude away from the source region and might be thought of as a kind of magnetic nozzle . In operation, a sharp boundary separates the high density plasma inside the source region and the low density plasma in the exhaust, which is associated with

910-439: A series of protruding cusps, or Taylor cones . At a sufficiently high applied voltage, positive ions are extracted from the tips of the cones. The electric field created by the emitter and the accelerator then accelerates the ions. An external source of electrons neutralizes the positively charged ion stream to prevent charging of the spacecraft. Pulsed inductive thrusters (PITs) use pulses instead of continuous thrust and have

980-406: A sharp change in electrical potential. Plasma properties change rapidly across this boundary, which is known as a current-free electric double layer . The electrical potential is much higher inside the source region than in the exhaust and this serves both to confine most of the electrons and to accelerate the ions away from the source region. Enough electrons escape the source region to ensure that

1050-403: A system consisting of 2 or 3 multi-aperture grids. After entering the grid system near the plasma sheath, the ions are accelerated by the potential difference between the first grid and second grid (called the screen grid and the accelerator grid, respectively) to the final ion energy of (typically) 1–2 keV, which generates thrust. Ion thrusters emit a beam of positively charged ions. To keep

1120-439: A test reported in 2010 showed erosion of around 1 mm per hundred hours of operation, though this is inconsistent with observed on-orbit lifetimes of a few thousand hours. The Advanced Electric Propulsion System (AEPS) is expected to accumulate about 5,000 hours and the design aims to achieve a flight model that offers a half-life of at least 23,000 hours and a full life of about 50,000 hours. Ionization energy represents

1190-421: A time, in contrast to the very short burns of chemical rockets. F = 2 η P g I sp {\displaystyle F=2{\frac {\eta P}{gI_{\text{sp}}}}} Where: The ion thruster is not the most promising type of electrically powered spacecraft propulsion , but it is the most successful in practice to date. An ion drive would require two days to accelerate

1260-655: 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 Russian "Elektro" satellite are equipped with them. Electrothermal systems by Aerojet (MR-510) are currently used on Lockheed Martin A2100 satellites using hydrazine as

1330-417: Is a spike that is wound to produce a radial magnetic field between it and the surrounding tube. The ions are largely unaffected by the magnetic field, since they are too massive. However, the electrons produced near the end of the spike to create the cathode are trapped by the magnetic field and held in place by their attraction to the anode. Some of the electrons spiral down towards the anode, circulating around

1400-411: Is accelerated by an oscillating electric and magnetic field, also known as the ponderomotive force . This separation of the ionization and acceleration stages allows throttling of propellant flow, which then changes the thrust magnitude and specific impulse values. A helicon double layer thruster is a type of plasma thruster that ejects high velocity ionized gas to provide thrust . In this design, gas

1470-578: 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: Electric propulsion systems can be characterized as either steady (continuous firing for

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1540-503: Is globally in short supply and expensive (approximately $ 3,000 per kg in 2021). Some older ion thruster designs used mercury propellant. However, mercury is toxic, tended to contaminate spacecraft, and was difficult to feed accurately. A modern commercial prototype may be using mercury successfully however, mercury was formally banned as a propellant in 2022 by the Minamata Convention on Mercury . From 2018–2023, krypton

1610-408: Is injected into a tubular chamber (the source tube ) with one open end. Radio frequency AC power (at 13.56 MHz in the prototype design) is coupled into a specially shaped antenna wrapped around the chamber. The electromagnetic wave emitted by the antenna causes the gas to break down and form a plasma. The antenna then excites a helicon wave in the plasma, which further heats it. The device has

1680-470: Is limited by several processes. In electrostatic gridded designs, charge-exchange ions produced by the beam ions with the neutral gas flow can be accelerated towards the negatively biased accelerator grid and cause grid erosion. End-of-life is reached when either the grid structure fails or the holes in the grid become large enough that ion extraction is substantially affected – e.g., by the occurrence of electron backstreaming. Grid erosion cannot be avoided and

1750-490: Is that the single cathode is replaced by multiple, smaller cathode rods packed into a hollow cathode tube. MPD cathodes are easily corroded due to constant contact with the plasma. In the LiLFA thruster, the lithium vapor is injected into the hollow cathode and is not ionized to its plasma form/corrode the cathode rods until it exits the tube. The plasma is then accelerated using the same Lorentz force . In 2013, Russian company

1820-630: Is the major lifetime-limiting factor. Thorough grid design and material selection enable lifetimes of 20,000 hours or more. A test of the NASA Solar Technology Application Readiness (NSTAR) electrostatic ion thruster resulted in 30,472 hours (roughly 3.5 years) of continuous thrust at maximum power. Post-test examination indicated the engine was not approaching failure. NSTAR operated for years on Dawn . The NASA Evolutionary Xenon Thruster (NEXT) project operated continuously for more than 48,000 hours. The test

1890-563: The Chemical Automatics Design Bureau successfully conducted a bench test of their MPD engine for long-distance space travel. Electrodeless plasma thrusters have two unique features: the removal of the anode and cathode electrodes and the ability to throttle the engine. The removal of the electrodes eliminates erosion, which limits lifetime on other ion engines. Neutral gas is first ionized by electromagnetic waves and then transferred to another chamber where it

1960-546: The Coulomb force along the electric field direction. 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. By contrast, electromagnetic thruster ions are accelerated by the Lorentz force to accelerate all species (free electrons as well as positive and negative ions) in

2030-578: The Solar System use electric propulsion for station keeping , orbit raising, or primary propulsion. In the future, the most advanced electric thrusters may be able to impart a delta-v of 100 km/s (62 mi/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 . An electric rocket with an external power source (transmissible through laser on

2100-427: The photovoltaic panels ) has a theoretical possibility for interstellar flight . 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. The idea of electric propulsion for spacecraft

2170-480: The standard gravitational acceleration of Earth , and noting that F = m a ⟹ a = F / m {\displaystyle F=ma\implies a=F/m} , this can be analyzed. An NSTAR thruster producing a thrust force of 92 mN will accelerate a satellite with a mass of 1   ton by 0.092   N / 1000 kg = 9.2 × 10   m/s (or 9.38 × 10   g ). However, this acceleration can be sustained for months or years at

Ion thruster - Misplaced Pages Continue

2240-409: The 1960s and, since then, they have been used for commercial satellite propulsion and scientific missions. Their main feature is that the propellant ionization process is physically separated from the ion acceleration process. The ionization process takes place in the discharge chamber, where by bombarding the propellant with energetic electrons, as the energy transferred ejects valence electrons from

2310-606: The 1960s on board the Voskhod 1 spacecraft and Zond-2 Mars probe. The first test of electric propulsion was an experimental ion engine carried on board the Soviet Zond 1 spacecraft in April 1964, however they operated erratically possibly due to problems with the probe. The Zond 2 spacecraft also carried six Pulsed Plasma Thrusters (PPT) that served as actuators of the attitude control system. The PPT propulsion system

2380-740: The 200 kW RF generators for ionizing propellant. Some of the components and "plasma shoots" experiments are tested in a laboratory settled in Liberia, Costa Rica . This project is led by former NASA astronaut Franklin Chang-Díaz (CRC-USA). A 200 kW VASIMR test engine was in discussion to be fitted in the exterior of the International Space Station , as part of the plan to test the VASIMR in space; however, plans for this test onboard ISS were canceled in 2015 by NASA , with

2450-417: The ability to run on power levels on the order of megawatts (MW). PITs consist of a large coil encircling a cone shaped tube that emits the propellant gas. Ammonia is the gas most commonly used. For each pulse, a large charge builds up in a group of capacitors behind the coil and is then released. This creates a current that moves circularly in the direction of jθ. The current then creates a magnetic field in

2520-503: The anode and the cathode, closing the circuit. This new current creates a magnetic field around the cathode, which crosses with the electric field, thereby accelerating the plasma due to the Lorentz force. The LiLFA thruster uses the same general idea as the MPD thruster, though with two main differences. First, the LiLFA uses lithium vapor, which can be stored as a solid. The other difference

2590-399: The chamber walls through heat conduction and convection (HCC), along with radiation (Rad). The remaining energy absorbed into the gaseous propellant is converted into thrust . A theoretical propulsion system has been proposed, based on alpha particles ( He or 2 He indicating a helium ion with a +2 charge) emitted from a radioisotope uni-directionally through

2660-543: The correct wavelength from a solid-state emitter. It also permits lower energy and longer half-life sources which would be advantageous for a space application. Helium backfill has also been suggested as a way to increase electron mean free path. Ion thrusters' low thrust requires continuous operation for a long time to achieve the necessary change in velocity ( delta-v ) for a particular mission. Ion thrusters are designed to provide continuous operation for intervals of weeks to years. The lifetime of electrostatic ion thrusters

2730-403: The discharge chamber, microwave (MW) energy flows into the center containing a high level of ions (I), causing neutral species in the gaseous propellant to ionize. Excited species flow out (FES) through the low ion region (II) to a neutral region (III) where the ions complete their recombination , replaced with the flow of neutral species (FNS) towards the center. Meanwhile, energy is lost to

2800-520: 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 . These types of rocket-like reaction engines use electric energy to obtain thrust from propellant . Electric propulsion thrusters for spacecraft may be grouped into three families based on

2870-639: The electron bombardment source in 1958/1959, and was responsible for the development of two ion thrusters that were tested in space ( SERT-1 and SERT-II missions). The Kaufman ion source is now also used for other applications, such as ion implanters used in semiconductor processing. Kaufman was awarded a Ph.D. from Colorado State University (CSU) in 1970, and an Exceptional Scientific Achievement Award by NASA in 1971. He joined CSU as staff in 1974, then left academia in 1984 to work at Kaufman & Robinson, Inc., in Fort Collins, Colorado . He invented

Ion thruster - Misplaced Pages Continue

2940-426: 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

3010-425: The ions varies, but all designs take advantage of the charge / mass ratio of the ions. This ratio means that relatively small potential differences can create high exhaust velocities. This reduces the amount of reaction mass or propellant required, but increases the amount of specific power required compared to chemical rockets . Ion thrusters are therefore able to achieve high specific impulses . The drawback of

3080-553: The ions. Electric power for ion thrusters is usually provided by solar panels . However, for sufficiently large distances from the sun, nuclear power may be used. In each case, the power supply mass is proportional to the peak power that can be supplied, and both provide, for this application, almost no limit to the energy. Electric thrusters tend to produce low thrust, which results in low acceleration. Defining 1 g = 9.81 m / s 2 {\displaystyle 1g=9.81\;\mathrm {m/s^{2}} } ,

3150-692: The late 1990s, mainly used for satellite stabilization in north–south and in east–west directions. Some 100–200 engines completed missions on Soviet and Russian satellites. 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. Ion thrusters use beams of ions (electrically charged atoms or molecules) to create thrust in accordance with momentum conservation . The method of accelerating

3220-405: The liquid flows through and an accelerator (a ring or an elongated aperture in a metallic plate) about a millimeter past the tube end. Caesium and indium are used due to their high atomic weights, low ionization potentials and low melting points. Once the liquid metal reaches the end of the tube, an electric field applied between the emitter and the accelerator causes the liquid surface to deform into

3290-404: The low thrust is low acceleration because the mass of the electric power unit directly correlates with the amount of power. This low thrust makes ion thrusters unsuited for launching spacecraft into orbit, but effective for in-space propulsion over longer periods of time. Ion thrusters are categorized as either electrostatic or electromagnetic . The main difference is the method for accelerating

3360-416: The other for almost three months. 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. By

3430-459: The outward radial direction (Br), which then creates a current in the gas that has just been released in the opposite direction of the original current. This opposite current ionizes the ammonia. The positively charged ions are accelerated away from the engine due to the electric field jθ crossing the magnetic field Br, due to the Lorentz force. Magnetoplasmadynamic (MPD) thrusters and lithium Lorentz force accelerator (LiLFA) thrusters use roughly

3500-520: The plasma in the exhaust is neutral overall. The proposed Variable Specific Impulse Magnetoplasma Rocket (VASIMR) functions by using radio waves to ionize a propellant into a plasma, and then using a magnetic field to accelerate the plasma out of the back of the rocket engine to generate thrust. The VASIMR is currently being developed by Ad Astra Rocket Company , headquartered in Houston , Texas , with help from Canada -based Nautel , producing

3570-474: 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)

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3640-428: The propellant gas's atoms. These electrons can be provided by a hot cathode filament and accelerated through the potential difference towards an anode. Alternatively, the electrons can be accelerated by an oscillating induced electric field created by an alternating electromagnet, which results in a self-sustaining discharge without a cathode (radio frequency ion thruster). The positively charged ions are extracted by

3710-531: The propellant to minimize storage volume. Electrically powered spacecraft propulsion Spacecraft electric propulsion (or just electric propulsion ) is a type of spacecraft propulsion technique that uses electrostatic or electromagnetic fields to accelerate mass to high speed and thus generating thrust to modify the velocity of a spacecraft in orbit. The propulsion system is controlled by power electronics . Electric thrusters typically use much less propellant than chemical rockets because they have

3780-471: The propellants. Given the practical weight of suitable power sources, the acceleration from an ion thruster is frequently less than one-thousandth of standard gravity . However, since they operate as electric (or electrostatic) motors, they convert a greater fraction of input power into kinetic exhaust power. Chemical rockets operate as heat engines , and Carnot's theorem limits the exhaust velocity. Gridded electrostatic ion thrusters development started in

3850-559: 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. Applications 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 serving as propulsion thrusters for crewed spacecraft and space stations (e.g. Tiangong ). Ion thrust engines are generally practical only in

3920-721: 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 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 ). 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 . The Dawn spacecraft broke

3990-407: The same idea. The LiLFA thruster builds on the MPD thruster. Hydrogen , argon , ammonia and nitrogen can be used as propellant. In a certain configuration, the ambient gas in low Earth orbit (LEO) can be used as a propellant. The gas enters the main chamber where it is ionized into plasma by the electric field between the anode and the cathode . This plasma then conducts electricity between

4060-432: The spacecraft from accumulating a charge, another cathode is placed near the engine to emit electrons into the ion beam, leaving the propellant electrically neutral. This prevents the beam of ions from being attracted (and returning) to the spacecraft, which would cancel the thrust. Gridded electrostatic ion thruster research (past/present): Hall-effect thrusters accelerate ions by means of an electric potential between

4130-412: The spike in a Hall current . When they reach the anode they impact the uncharged propellant and cause it to be ionized, before finally reaching the anode and completing the circuit. Field-emission electric propulsion (FEEP) thrusters may use caesium or indium propellants. The design comprises a small propellant reservoir that stores the liquid metal, a narrow tube or a system of parallel plates that

4200-437: The type of force used to accelerate the ions of the plasma: 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

4270-741: 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. The Massachusetts Institute of Technology (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. An ion engine cannot usually generate sufficient thrust to achieve initial liftoff from any celestial body with significant surface gravity . For these reasons, spacecraft must rely on other methods such as conventional chemical rockets or non-rocket launch technologies to reach their initial orbit . The first person who wrote

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4340-572: The vehicle from a planet's surface, but a low thrust applied for a long interval can allow a spacecraft to manoeuvre near a planet. Harold R. Kaufman Born in Audubon, Iowa , USA, in 1926, Kaufman grew up in Evanston, Illinois , a suburb of Chicago . He trained in electrical engineering during World War II through an electronic technician program in the US Navy. After the war ended, he took

4410-454: The weight of one sheet of paper) compared to conventional chemical rockets , but achieve high specific impulse , or propellant mass efficiency, by accelerating the exhaust to high speed. The power imparted to the exhaust increases with the square of exhaust velocity while thrust increase is linear. Conversely, chemical rockets provide high thrust, but are limited in total impulse by the small amount of energy that can be stored chemically in

4480-591: Was built by Harold R. Kaufman in 1959 at the NASA Glenn Research Center facilities. It was similar to a gridded electrostatic ion thruster and used mercury for propellant. Suborbital tests were conducted during the 1960s and in 1964, and the engine was sent into a suborbital flight aboard the Space Electric Rocket Test-1 (SERT-1). It successfully operated for the planned 31 minutes before falling to Earth. This test

4550-426: Was conducted in a high-vacuum test chamber. Over the course of the test, which lasted more than five and a half years, the engine consumed approximately 870 kilograms of xenon propellant. The total impulse generated would require over 10,000 kilograms of conventional rocket propellant for a similar application. Hall-effect thrusters suffer from strong erosion of the ceramic discharge chamber by impact of energetic ions:

4620-599: Was followed by an orbital test, SERT-2, in 1970. On the 12 October 1964 Voskhod 1 carried out tests with ion thrusters that had been attached to the exterior of the spacecraft. An 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. Hall-effect thrusters operated on Soviet satellites from 1972 until

4690-543: Was introduced in 1911 by Konstantin Tsiolkovsky . Earlier, Robert Goddard had noted such a possibility in his personal notebook. On 15 May 1929, the Soviet research laboratory Gas Dynamics Laboratory (GDL) commenced development of electric rocket engines. Headed by Valentin Glushko , in the early 1930s he created the world's first example of an electrothermal rocket engine. This early work by GDL has been steadily carried on and electric rocket engines were used in

4760-414: Was tested for 70 minutes on the 14 December 1964 when the spacecraft was 4.2 million kilometers from Earth. The first successful demonstration of an ion engine was NASA SERT-1 (Space Electric Rocket Test) spacecraft. It launched on 20 July 1964 and operated for 31 minutes. A follow-up mission launched on 3 February 1970, SERT-2. It carried two ion thrusters, one operated for more than five months and

4830-754: Was used as a propellant for the first time in space, in the NPT30-I2 gridded ion thruster by ThrustMe , on board the Beihangkongshi-1 mission launched in November 2020, with an extensive report published a year later in the journal Nature . The CubeSat Ambipolar Thruster (CAT) used on the Mars Array of Ionospheric Research Satellites Using the CubeSat Ambipolar Thruster (MARS-CAT) mission also proposes to use solid iodine as

4900-486: Was used to fuel the Hall-effect thrusters aboard Starlink internet satellites, in part due to its lower cost than conventional xenon propellant. Starlink V2-mini satellites have since switched to argon Hall-effect thrusters, providing higher specific impulse. Other propellants, such as bismuth and iodine , show promise both for gridless designs such as Hall-effect thrusters, and gridded ion thrusters. Iodine

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