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Currently, electric rocket engines have largely reached the efficiency limits determined by the principle of rocket thrust. Electrodynamic tethers, interacting with an external magnetic field and actually being jet engines, are devoid of such restrictions. However, their thrust is limited by the concentration of the external plasma and depends on its fluctuations. The paper is the first to propose to create a current in the tether by propellant ionization, receiving a large thrust from a relatively short tether and a strong magnetic field deflecting charged cosmic particles. The numerical analysis showed that the length of the tether of hundreds of meters near the Earth provides a specific impulse of up to hundreds of kilometers per second and its proper acceleration of the power plant at a level of 0.01 m / s2, as well as protection of the central region of the tether from particles with an energy of more than 1 MeV. This makes it possible to consider it for maneuvering satellites with practically no restrictions on the delta-V, for performing fast high-energy inter-orbital flights and for radiation protection of a high-latitude orbital station. In the future, such a tether can be used for rapid deceleration of orbital objects, launching into geostationary orbit, interplanetary transfers and protection of objects from charged particles. The study describes possible areas of application and directions for further research of the concept of such a tether.

The paper considers heterogeneous condensed systems which potentially make it possible to use highly efficient oxidizers in their composition, including those liquid. The existing technologies are unable to include them in composition of the solid rocket propellants. Placing oxidizers such as nitrogen dioxide and tetranitromethane in hermetically sealed combustible polymer capsules connected by physical or chemical means allows creating a microhybrid rocket engine. Studies based on analyzing characteristics of similar systems and thermodynamic calculations demonstrate that such systems are potentially able to ensure mechanical strength required for the rocket engine functioning, sufficient speed, combustion static stability and chemical compatibility of components, as well as power at the level of liquid high-boiling fuel vapors, while maintaining advantages of the solid fuel engines. Considering their initial higher safety in production and operation, as well as the ability to be produced by modern technologies, microhybrid rocket engines appear to be promising area of further research.

The paper considers possibility of using propulsion systems based on the flash evaporation effect (steam rockets) as a simple high-thrust engine or a self-supercharged source of hot steam gas. Thermodynamic analysis, on the example of water as a working fluid, made it possible to estimate efficiency indicators of the steam rockets. Analysis results show that steam rockets on water are not inferior to the gas jet propulsion systems being able to achieve specific impulse of about 700 m/s with the mass energy return of up to 600 m/s. At the same time, steam rockets occupy half the number of the gas jet propulsion systems, and they are the only high-thrust engines providing complete safety before the launch preparations. This allows introducing steam rockets in spacecraft maneuvering, transport operations within the manned programs, launch vehicle gas generators, etc.

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