Russian engineers have created an electrothermal propulsion system for satellites of the CubeSat format, operating on a mixture of distilled water and ethyl alcohol. Addition of alcohol will allow the working mixture not to freeze at low temperatures in orbit. The prototype engine will be installed on the SamSat-M nanosatellite, according to the Samara National Research University named after Korolev.
The new engine is of the electrothermal type. In them, the reactive impulse is created not by the chemical reaction of the fuel with the oxidizer, as in liquid rocket engines, but due to the heating of the working fluid. As a working fluid, water can be used, which, with sufficient heating, turns into steam, emerging through the nozzle and imparting an impulse to the satellite.
Engineers from Samara decided to add ethyl alcohol to the water used as a working fluid. In the mixture obtained, the alcohol content is about 40 percent. Due to the addition of alcohol, the mixture will have a lower freezing point, which will simplify its maintenance in the liquid state in conditions of low temperatures in orbit.
The developers created a prototype engine, its mass with the working body is 1.55 kilograms, of which the working body accounts for approximately 450 grams. The calculated total impulse of the engine speed when used on a CubeSat satellite is 80 meters per second.
In addition to using an unusual mixture as a working fluid, the engineers also created a new heating system. It uses supercapacitors, which make it possible to accelerate the heating of the working fluid.For the first time the engine is planned to be tested on the SamSat-M satellite. It will be executed in the format CubeSat 3U and has a size of 10 × 10 × 30 centimeters. It is assumed that the assembly of the satellite will be completed in 2018. If the tests in orbit are recognized as successful, the engineers plan to deploy a small-scale production of engines.
There are other projects of electric motors using unusual materials as a working fluid. For example, the European Space Agency recently tested astraight-through ion engine using air from the surrounding atmosphere. It is assumed that small satellites with such an engine will be virtually unlimited in orbit with a height of 200 or less kilometers. In addition, there are projects to create engines that use a magnetic fluid and even space debris as a working fluid .