Atmosphere-breathing electric propulsion, or air-breathing electric propulsion, shortly ABEP, [1] is a propulsion technology for spacecraft, which could allow thrust generation in low orbits without the need of on-board propellant, by using residual gases in the atmosphere as propellant. Atmosphere-breathing electric propulsion could make a new class of long-lived, low-orbiting missions feasible.
The concept is currently being investigated by the European Space Agency (ESA), [2] the EU-funded BREATHE project at Sant'Anna School of Advanced Studies in Pisa and the EU-funded DISCOVERER project. [3] Current state-of-the-art conventional electric thrusters cannot maintain flight at low altitudes for any times longer than about 2 years, [4] because of the limitation in propellant storage and in the amount of thrust generated, which force the spacecraft's orbit to decay. The ESA officially announced the first successful RAM-EP prototype on-ground demonstration in March 2018. [5]
An ABEP is composed by an intake and an electric thruster: rarefied gases which are responsible for drag in low Earth orbit (LEO) and very low Earth orbit (VLEO), are used as the propellant. [6] [7] This technology would ideally allow S/Cs to orbit at very low altitudes (< 400 km around the Earth) without the need of on-board propellant, allowing longer time missions in a new section of atmosphere's altitudes. This advantage makes the technology of interest for scientific missions, military and civil surveillance services as well as low orbit even lower latency communication services than Starlink.
A special intake will be used to collect the gas molecules and direct them to the thruster. The molecules will then be ionized by the thruster and expelled from the acceleration stage at a very high velocity, generating thrust. The electric power needed can be provided by the same power subsystems developed for the actual electric propulsion systems, likely a combination of solar arrays and batteries, though other kind of electric power subsystems can be considered. An ABEP could extend the lifetime of satellites in LEO and VLEO by compensating the atmospheric drag during their time of operation. The altitude for an Earth-orbiting ABEP can be optimised between 120–250 km. [8] This technology could also be utilized on any planet with atmosphere, if the thruster can process other propellants, and if the power source can provide the required power, e.g. sufficient solar irradiation for the solar panels, such as Mars and Venus, otherwise other electric power subsystems such as a space nuclear reactor or radioisotope thermoelectric generator (RTG) have to be implemented, for example for a mission around Titan.
The first studies considering the collection and use of the upper atmosphere as propellant for an electric thruster can be found already in 1959 with the studies on the propulsive fluid accumulator from S. T. Demetriades. [9] [10] [11] [12]
In the development of atmosphere-breathing ion engines, a notable extension of Child's Law led to its implementation in the ABEP concept in 1995. [13] [14] Originally, Child's Law modeled the flow of charge between an anode and a cathode with the assumption that the initial velocity of ions was zero. This assumption, however, is not applicable to ion thrusters operating in low Earth orbit, where ambient gas enters the ionization chamber at high velocities.
Buford Ray Conley provided a generalization of Child's Law that accounts for a non-zero initial velocity of ions. This adaptation has been significant for the theoretical modeling of ion propulsion systems, particularly those that operate in the rarefied conditions of low Earth orbit.
The generalization of Child's Law has implications for the design and efficiency of atmosphere-breathing ion thrusters. By accounting for the high-velocity ambient gas that enters the ionization chamber in low Earth orbit, the modified law allows for more accurate theoretical modeling. Once the ambient gas is ionized in the chamber, it is electromagnetically accelerated out of the exhaust, contributing to the propulsion of the spacecraft.
ESA's RAM-EP, designed and developed by SITAEL in Italy, was first tested in laboratory in May 2017. [15] [16] [17]
The Institute of Space Systems at the University of Stuttgart is developing the intake and the thruster, the latter is the RF helicon-based Plasma Thruster (IPT), [18] [19] which has been ignited for the first time in March 2020, see IRS Uni Stuttgart Press Release. Such a device has the main advantage of no components in direct contact with the plasma, this minimizes the performance degradation over time due to erosion from aggressive propellants, such as atomic oxygen in VLEO, and does not require a neutralizer. Intake and thruster are developed within the DISCOVERER EU H2020 Project.
Intakes have been designed in multiple studies, and are based on free molecular flow condition and on gas-surface interaction models: based on specular reflections properties of the intake materials, high efficiencies can theoretically be achieved by using telescope-like designs. With fully diffuse reflection properties, efficiencies are generally lower, but with a trapping mechanism the pressure distribution in front of the thruster can be enhanced as well. [20]
The UK-based start-up NewOrbit Space has been developing an air-breathing electric propulsion system since 2021, achieving several milestones in the process. Notably, NewOrbit became the first in the industry to successfully operate and neutralize an ion engine entirely on atmospheric air in a vacuum chamber. Initial testing results have shown a specific impulse of 6,380 seconds, with the engine accelerating incoming air to speeds exceeding 200,000 km/h. This breakthrough enables the propulsion system to generate enough thrust to overcome atmospheric drag in very low Earth orbit, allowing sustainable spacecraft operation at altitudes below 200 km. [21] [22]
Busek Co. Inc. in the U.S. patented their concept of an Air Breathing Hall Effect Thruster (ABHET) in 2004, [23] and with funding from the NASA Institute for Advanced Concepts, started in 2011 a feasibility study that would be applied to Mars (Mars-ABHET or MABHET), where the system would breathe and ionize atmospheric carbon dioxide. [24] The MABHET concept is based on the same general principles as JAXA's Air Breathing Ion Engine (ABIE) or ESA's RAM-EP. [25]
Spacecraft propulsion is any method used to accelerate spacecraft and artificial satellites. In-space propulsion exclusively deals with propulsion systems used in the vacuum of space and should not be confused with space launch or atmospheric entry.
In spacecraft propulsion, a Hall-effect thruster (HET) is a type of ion thruster in which the propellant is accelerated by an electric field. Hall-effect thrusters are sometimes referred to as Hall thrusters or Hall-current thrusters. Hall-effect thrusters use a magnetic field to limit the electrons' axial motion and then use them to ionize propellant, efficiently accelerate the ions to produce thrust, and neutralize the ions in the plume. The Hall-effect thruster is classed as a moderate specific impulse space propulsion technology and has benefited from considerable theoretical and experimental research since the 1960s.
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.
A pulsed plasma thruster (PPT), also known as a Pulsed Plasma Rocket (PPR), or as a plasma jet engine (PJE), is a form of electric spacecraft propulsion. PPTs are generally considered the simplest form of electric spacecraft propulsion and were the first form of electric propulsion to be flown in space, having flown on two Soviet probes starting in 1964. PPTs are generally flown on spacecraft with a surplus of electricity from abundantly available solar energy.
A pulsed inductive thruster (PIT) is a form of ion thruster, used in spacecraft propulsion. It is a plasma propulsion engine using perpendicular electric and magnetic fields to accelerate a propellant with no electrode.
The Variable Specific Impulse Magnetoplasma Rocket (VASIMR) is an electrothermal thruster under development for possible use in spacecraft propulsion. It uses radio waves to ionize and heat an inert propellant, forming a plasma, then a magnetic field to confine and accelerate the expanding plasma, generating thrust. It is a plasma propulsion engine, one of several types of spacecraft electric propulsion systems.
Thruster may refer to:
Field-emission electric propulsion (FEEP) is an advanced electrostatic space propulsion concept, a form of ion thruster, that uses a liquid metal as a propellant – usually either caesium, indium, or mercury.
A propellant is a mass that is expelled or expanded in such a way as to create a thrust or another motive force in accordance with Newton's third law of motion, and "propel" a vehicle, projectile, or fluid payload. In vehicles, the engine that expels the propellant is called a reaction engine. Although technically a propellant is the reaction mass used to create thrust, the term "propellant" is often used to describe a substance which contains both the reaction mass and the fuel that holds the energy used to accelerate the reaction mass. For example, the term "propellant" is often used in chemical rocket design to describe a combined fuel/propellant, although the propellants should not be confused with the fuel that is used by an engine to produce the energy that expels the propellant. Even though the byproducts of substances used as fuel are also often used as a reaction mass to create the thrust, such as with a chemical rocket engine, propellant and fuel are two distinct concepts.
Laser propulsion is a form of beam-powered propulsion where the energy source is a remote laser system and separate from the reaction mass. This form of propulsion differs from a conventional chemical rocket where both energy and reaction mass come from the solid or liquid propellants carried on board the vehicle.
BepiColombo is a joint mission of the European Space Agency (ESA) and the Japan Aerospace Exploration Agency (JAXA) to the planet Mercury. The mission comprises two satellites launched together: the Mercury Planetary Orbiter (MPO) and Mio. The mission will perform a comprehensive study of Mercury, including characterization of its magnetic field, magnetosphere, and both interior and surface structure. It was launched on an Ariane 5 rocket on 20 October 2018 at 01:45 UTC, with an arrival at Mercury planned for on November 2026, after a flyby of Earth, two flybys of Venus, and six flybys of Mercury. The mission was approved in November 2009, after years in proposal and planning as part of the European Space Agency's Horizon 2000+ programme; it is the last mission of the programme to be launched.
The gridded ion thruster is a common design for ion thrusters, a highly efficient low-thrust spacecraft propulsion method running on electrical power by using high-voltage grid electrodes to accelerate ions with electrostatic forces.
MagBeam is the name given to an ion propulsion system for space travel initially proposed by Professor Robert Winglee of the Earth and Space Sciences Department at the University of Washington for the October 2004 meeting of the NIAC. MagBeam is different from a traditional electrostatic ion thruster in several ways, the primary one being that instead of the fuel and propulsion system being part of the payload craft, they are instead located on a platform held in orbit. It has also been suggested that the technology could be used to reduce the amount of space debris in orbit around Earth.
This is an alphabetical list of articles pertaining specifically to aerospace engineering. For a broad overview of engineering, see List of engineering topics. For biographies, see List of engineers.
The helicon double-layer thruster is a prototype electric spacecraft propulsion. It was created by Australian scientist Christine Charles, based on a technology invented by Professor Rod Boswell, both of the Australian National University.
The electrodeless plasma thruster is a spacecraft propulsion engine commercialized under the acronym "E-IMPAcT" for "Electrodeless-Ionization Magnetized Ponderomotive Acceleration Thruster". It was created by Gregory Emsellem, based on technology developed by French Atomic Energy Commission scientist Dr Richard Geller and Dr. Terenzio Consoli, for high speed plasma beam production.
A plasma propulsion engine is a type of electric propulsion that generates thrust from a quasi-neutral plasma. This is in contrast with ion thruster engines, which generate thrust through extracting an ion current from the plasma source, which is then accelerated to high velocities using grids/anodes. These exist in many forms. However, in the scientific literature, the term "plasma thruster" sometimes encompasses thrusters usually designated as "ion engines".
Spacecraft 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.
A Propulsive Fluid Accumulator is an artificial Earth satellite which collects and stores oxygen and other atmospheric gases for in-situ refuelling of high-thrust rockets. This eliminates the need to lift oxidizer to orbit and therefore brings significant cost benefits. A major portion of the total world payload sent into low Earth orbit each year is either liquid oxygen or water.
A thruster is a spacecraft propulsion device used for orbital station-keeping, attitude control, or long-duration, low-thrust acceleration, often as part of a reaction control system. A vernier thruster or gimbaled engine are particular cases used on launch vehicles where a secondary rocket engine or other high thrust device is used to control the attitude of the rocket, while the primary thrust engine is fixed to the rocket and supplies the principal amount of thrust.