RD-858 engine is the main one in a cluster of engines of the Moon Vehicle. The propulsion cluster was to provide soft landing onto the Moon surface with following lift-off and injection of the vehicle into elliptic orbit of the Moon's artificial satellite.

- High reliability confirmed by autonomous development, as well as operation on the Earth's orbit;
- Burn time exceeding 4000 s;
- Broad range of thrust regulation.

Autonomous single-chamber two-mode double-start pump-fed engine of deep thrust throttling operating on hypergolic propellants in accordance with the generator scheme (without generator gas afterburning). During the first run the main mode and mode of deep thrust throttling are real-ized, during the second one - only the main mode. The working medium of the turbine is gas produced by the gas generator at combustion of the main propellants. During startup the TPU's rotor is spinned up by pyrostarter. The inlet valves are being opened during the startup by gas tapped from a mani-fold of pyrostarters. The valves are piloted by fuel pressure delivered from the pump's discharge branch. The shutdown is performed by pyrovalves under commands of the control sys-tem. The engine has systems of thrust regulation and mixture ratio maintenance. It is also provided with transducers that restrict chamber pressure changing in each operating mode.