Lifetime[ edit ] 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.
Links to other sites on electric propulsion Overview There are various ways of using electricity to thrust propellants, rather than using chemical explosion as in launch rockets. Electric thrusting of propellants is useful only for interorbital transportation, not launch from the Earth's or Moon's surface.
There are two electric propulsion techniques used in space today: Some American interorbital satellites today use electric "ion drive" for stationkeeping.
Ion drive is a simple and fairly mature technology. Ion drive can just as easily be used as the primary means of interorbital propulsion for delivering cargoes, and has been projected in future scenarios for space industrialization as a competitive kind of reusable interorbital vehicle.
The Deep Space 1 probe, launched on October 24,was the first vehicle to depend upon electric ion drive for all of its propulsion needs, to perform a close flyby of an asteroid. The Russians have for at least 10 years been extensively using an electric propulsion technique called a "plasma thruster" which they have begun to market overseas.
This thruster has been used on close to a hundred Russian military satellites, but is relatively unknown in the West. The main advantages of electric propulsion are: It requires an electric power plant It offers only low thrust propulsion, which means a longer time to deliver the cargo For an analogy, chemical rockets are like express delivery via powerful and fast airplanes, whereas ion drive vehicles in interorbital space are like the big tankers on the oceans which deliver their cargo slowly but cheaply and safely via surface transport and more mundane technology.
For missions to asteroids, it is actually advantageous to use a continuous, low thrust vehicle as this greatly expands the "launch window" period in which it is economically feasible to go to these objects, Ion drive propulsion an overview compared to chemical rockets which impart short blasts of acceleration and deceleration.
This is also called a "thrust profile". Whereas chemical rocketry uses a chemical reaction and controlled explosion for thrust, electric propulsion uses electricity to accelerate the propellant out of the thrust chamber.
Unlike chemical rocketry, there is no chance for an explosion with ion drive. Ion drive is much safer and a simpler technology, and has no relation to chemical rocketry at all. Since electric propulsion vehicles use electricity, the vehicle must produce that electricity, typically by solar cell panels.
In other words, ion drive vehicles are solar powered vehicles. The DS1 ion drive thruster is a 2. Many studies into future large scale space industrialization base all interorbital propulsion on reusable electric propulsion vehicles, with chemical rockets being used only to launch material from Earth's surface to low Earth orbit, and from the lunar surface to lunar orbit, where the cargo is transferred to an electric propulsion vehicle for interorbital transport.
However, some very conservative "immediate term" studies assume all interorbital propulsion is based on today's chemical rockets, e.
That's because lunar and asteroidal materials can be used to refuel today's hydrogen-oxygen chemical rockets with no design modifications at all, whereas large scale electric propulsion vehicles would need development of vehicle designs.
For a comparison between electric propulsion and chemical rocketry in the mainstream studies: Chemical rockets consume 8 TIMES as much fuel propellant than electric propulsion for the same service.
The cargo-to-propellant ratio from low Earth orbit to high Earth orbit is around 4: In comparison, for today's chemical rocketry used for transporting satellites from low to high orbit, it's a 1: Ion drive ejects its propellant at a speed about 15 times that of chemical rockets, hence imparting 15 times more momentum per unit mass of propellant.
Notably, in a few studies, the propellant for ion drive vehicles is stated to be pure oxygen from the Moon or asteroidal material. This is a highly questionable assumption.
Oxygen presents several problems for ion drive, as discussed later.
However, other lunar and asteroid derived propellants should work fine. Also, oxygen should work in the Russian plasma thruster. One reason why only chemical rockets have been used in space for propulsion to date except by the Russian military, addressed later instead of ion drive is the continued lack of basic infrastructure in Earth orbit -- there is no reusable interorbital vehicle service in space at all.
To date, the interorbital vehicle has always been launched with the payload and thrown away after it delivers its payload. To date, ion drive has been used only for stationkeeping propulsion once the satellite is delivered and its solar panels deployed.
Hughes Space and Communications Company is starting to market an ion drive system as an interorbital upper stage, as covered at the end of this article. Nobody is yet marketing a reusable interorbital vehicle, whereby we just launch up fuel tanks and dock for fuel and payload transfer.
It is hoped that the DS1 mission will stimulate more interest in ion drive and electric propulsion in general, perhaps leading to a commercial venture to offer interorbital services via a reusable interorbital vehicle. These services could include hauling satellites from low orbit to geosynchronous orbit, moving old satellites to new orbits, and refueling and maintenance of satellites in orbit.
Future satellites could be designed for interaction with such interorbital infrastructure, though this is a chicken-and-egg situation that must be overcome by broad industry recognition.
The Russian plasma thruster is used primarily on military satellites e. The Russian plasma thruster is a well developed and very efficient engine, and is seen as one of the potentially most valuable exports in their space program.DS1 is a step in the right direction to gaining acceptance of electric propulsion in the west, by using ion drive to get from Earth to an asteroid.
A big part of the DS1 mission is simply to demonstrate and analyze the ion drive propulsion system in space. The ion drive was a type of engine used to propel most starships at sublight velocities.
Ion engines were fueled by power cells, liquid chemical reactants, onboard generators, or virtually any other device capable of providing sufficient power. The engine utilized internal fusion reactions to. DS1 is a step in the right direction to gaining acceptance of electric propulsion in the west, by using ion drive to get from Earth to an asteroid.
A big part of the DS1 mission is simply to demonstrate and analyze the ion drive propulsion system in space. Overview. Welcome to the Ion Propulsion module. Learners of all ages explore the propulsion technology that that made the Dawn mission possible.
Electric Propulsion An Overview. AAE Ch8 –2 OVERVIEW At the beginning of last century, Goddard experimented with electric gas discharge tubes recognizing basic concepts for Electric Propulsion. Direct-drive schemes are feasible without the need of exotic voltage.
The Dawn spacecraft uses ion propulsion to get the additional velocity needed to reach Vesta once it leaves the Delta rocket. It also uses ion propulsion to spiral to lower altitudes on Vesta, to leave Vesta and cruise to Ceres and to spiral to a low altitude orbit at Ceres.
Ion propulsion makes.