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Atmosphere-Breathing Electric Propulsion, or Air-Breathing Electric Propulsion or RAM Electric Propulsion shortened as ABEP or RAM-EP, is a propulsion technology for spacecrafts, which could allow thrust generation in low orbits without the need of on-board propellant, as it uses the residual gases of the atmosphere as propellant. The conventional state-of-the-art electric thrusters do not allow yet to fly at low altitudes for long period of times, usually no more than 2 years (), because of the limitation in propellant storage and in the amount of thrust generated, which forces the spacecraft to decay. ==Principle of Operation== An ABEP is basically composed by an intake and an electric thruster: the principle of operation is to use the same rarefied gases which are responsible for the generation of the drag in LEO and VLEO (Low and Very Low Earth Orbit), as propellant (). The use of this technology would allow S/Cs to fly at very low orbits ideally without the need of on-board propellant, allowing longer time missions in a new section of atmosphere’s altitudes, interesting for scientific missions as well as military and civil surveillance services. A special intake will be used in order to collect the gas molecules and direct them, keeping their velocity and pressure values, to the thruster. The molecules will then be ionized by the thruster and then expelled from the nozzle at a very high velocity to generate 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, but other kind of electric power subsystems can be considered. An ABEP shall be able to extend the lifetime of satellites in LEO and VLEO by compensating the atmospheric drag during their time of operation. Not only Earth can be considered a suitable planet for this kind of propulsion but also other planets with atmosphere, first of all Mars. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Air-Breathing Electric Propulsion」の詳細全文を読む スポンサード リンク
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