Scientists have already invented or are preparing to come up with many new types of engines for space ships. Wildest assumptions even talking about the warp engine to accelerate the ship to speeds far exceeding the speed of light due to the curvature of space in the powerful gravitational field. While this is only a fantasy that may soon become a prospect. But ion engines already exist and are even used. They are already at this stage can develop a speed several times higher than those offered by traditional rocket engines. However, they can’t send a rocket into space. Here are the contradictions. But then the ion engine works and why at this stage it really is the technology of the future?
How does ion engine
The principle of operation of the ion engine is simple and complex at the same time. It lies in the ionization of the gas, which accelerates an electrostatic field to obtain the jet thrust and acceleration of the spaceship according to Newton’s third law.
Fuel or working fluid of the engine is ionized inert gas (helium, argon, neon, xenon, krypton, ohanneson, radon). However, not all inert gases is used as fuel, therefore, as a rule, the choice of scientists and researchers falls on the xenon. Also discusses the use of mercury as the working medium of the ion engine
During engine operation in the chamber a mixture of negative electrons and positive ions. Since electrons are a by-product, they need to filter. For that, the camera is introduced the tube with the cathode mesh in order for it to attract electrons.
Positive ions, on the contrary, are attracted to the extraction system. Then are accelerated between the grids, the difference of electrostatic potentials of approximately 1 200 Volts and discharged as a jet into space.
Electrons that hit the cathode in the trap must be removed from the ship, to retain a neutral charge, and the ejected ions are not attracted back, reducing the efficiency of the installation. Emission of electrons is carried out through a separate nozzle at a small angle to the jet of ions. Thus, what happens in their interactions after leaving the engine, doesn’t matter, because they do not interfere with the movement of the ship.
Advantages of the ion engine for spacecraft
Ions output from the engine accelerated to very high speeds. In the maximum they can reach is 210 km/s. At the same time, chemical rocket engines are not able to achieve 10 km/s, being in the range of 3-5 km/s.
The possibility of achieving high specific impulse allows greatly to reduce the consumption of reaction mass of ionized gas in comparison with the similar indicator for traditional chemical fuel. And yet, the ion engine can operate continuously for more than three years. The energy required for ionization of the fuel is taken from solar panels — in space this is no problem.
Disadvantages of ion thrusters
The possibility of continuous operation of the ion engine is very important, as it is not capable of developing high thrust and instantly accelerate the ship to high speeds. In the current implementations of ion thrust engines barely reaches 100 millinewtons.
Because of this feature, at least until, this engine does not give possibility to start from another planet, even if she has very little gravity.
It turns out that the use of such engines for long-distance travel is not yet possible traction without the traditional installations at a chemical fuel. But their joint use will allow much more flexible use of acceleration. For example, by a conventional engine the machine to disperse more or less high speed, and then accelerate even more due to the ion engine.
In fact, low thrust at the moment is the main disadvantage of these engines, but scientists working in this direction in the future will increase its power, since some progress has been achieved already.
Another, though not such a significant problem is the reliability. In General, ion engines are quite reliable, but you have to understand that their task is to carry the machine very far and very fast. That is to work it needs a long time, so as not to jeopardize the entire mission. Therefore, while the work on increasing power, the developers are trying not to forget and about reliability.
Where are the ion engines
You seem to think that ion engines exist only on paper and in labs, but it’s not. They have already been used at least seven completed missions and use at least four of the existing ones.
Including such engines are used in the framework of the mission BepiColombo, launched on 20 October 2018. In this Mercurian mission uses 4 ion engines with a total capacity of 290 millinewtons. In addition, the device is equipped with a chemical engine. Both of them in conjunction with gravity manoeuvres must ensure that the craft into the orbit of mercury as an artificial satellite.
The use of these engines did not hesitate, and Elon Musk in his program, Starlink, at the expense of these engines, the ship must make small maneuvers to Dodge space debris.
It is now planned to deliver the ISS ion traction setup that will allow you to control the position of the station in automatic mode. Its capacity is chosen on the basis of the available electric capacity of the station. For greater reliability it is also shipping batteries which provide 15 minutes of operation of the engine.
But the most unusual project was ”Prometheus”. The ship in the framework of this project it was planned to send to Jupiter at the speed of 90 km/s. Ion drive ship needs the ball to operate from a nuclear reactor, but due to technical difficulties in 2005 the project was closed.
When invented the ion engine
Considering all the potential of the ion engine, the first time his concept was proposed in 1917 Robert Goddard. But after almost 40 years Ernst Stuhlinger accompanied the concept of necessary calculations.
In 1957 he published an article Alexei Morozov called ”About acceleration of plasma by a magnetic field,” in which he described everything as detailed as possible. This gave impetus to the development of technology and in 1964 the Soviet apparatus ”ZOND-2” were such an engine to maneuver in orbit.
In fact, the ion drive is the first electric space engine, but it had to be refined and improved. Been doing for many years, and in 1970 passed the test designed to demonstrate the effectiveness of long-term mercury electrostatic ion engines in space. Then shows low efficiency and low thrust for a long time discourage the desire of the American space industry to use such engines.