Soviet and Russian Lunar Exploration

LK window
burn would be done by block D. It would be jettisoned a mere 1,500 m above the lunar
surface, leaving the LK's main engine to complete the descent to the lunar surface.
This would be the same engine used for take-off.
Hover time was much tighter on the Russian LK than the American LM. The
Russians had about a minute to find the landing site and put the spacecraft down.
The pilot could, of course, use more than 1 min, since it was the same engine used for
the ascent, but this would eat into the thrust required for ascent. The LM had a longer
hover time, about 2 min. By the end of the 2 min, the LM would be out of fuel and the
mission would have to abort. Below a certain altitude, the period of time for firing the
ascent stage would be longer than the time taken to fall to the surface, so the LM
would crash (this was called 'dead man's handle'). All but one of the Apollos were
sufficiently well targeted not to present a problem. The most difficult landing was the
first, Apollo 11, which landed with only 19 sec of fuel to spare. 'Dead man's handle'
did not operate on the LK, since the engine used for the ascent was already firing.
Arguably, it was safer. The LK lunar lander, like Apollo, had four legs. The first
Soviet moon landing would have been shorter than that of Apollo 11, without a sleep
period.
Once on the surface, the sole cosmonaut would carry out a spacewalk. We do not
know how long the first lunar stay was planned. A moonwalk duration of four hours
has been suggested, so the surface stay time would have to be long enough to report
back after landing, prepare for the moonwalk, carry it out, return and prepare for
take-off and rendezvous.
After several hours on the surface, the cosmonaut would lift off from the moon in
the upper stage of the LK, and conduct the type of rendezvous pattern tested by
Cosmos 186-188, 212-3 and Soyuz 2-3 and 4-5 in which the LOK orbiter performed
the active role. A backup two-nozzle engine was also available should the motor fail to
light for the critical liftoff from the moon. On liftoff, the backup engine was actually
fired simultaneously with the main engine, but turned off if the main engine lit up. The
LK had five chemical batteries, three on the descent stage, two on the ascent. Cabin
pressure was oxygen/nitrogen at 560 mm.