L3 system

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Lunar program guide:

Program chronology

Chronology of the Moon Race

Soviet plans for lunar base

DALS

The L3 system was a four-element combination of rocket stages and spacecraft designed to land a Soviet cosmonaut on the surface of the Moon, after the L3's delivery into low-Earth orbit by the three-stage N1 rocket.

The L3 system included:

Block G upper stage (the 4th stage of the N1 rocket)
Block D upper stage (the 5th stage of the N1 rocket)
Lunar Lander, LK, with Block E propulsion system
Lunar Orbital Spacecraft, LOK, with Block I propulsion system

The total weight of the L3 system in a 290-kilometer circular Earth orbit was to be around 70 tons. (111)

L3 flight profile

The N1-L3 system was expected to deliver a manned spacecraft on the surface of the Moon during a 11-12-day expedition, which included the following steps:

The N1 rocket delivers the L3 system into the low-Earth orbit, where it can remain up to one day;
Block G accelerates the L3 system to Earth-escape velocity, sending the L3 system toward the Moon;
Block G separates;
Block D completes the acceleration and conducts two trajectory corrections during a 3.5-day flight between the Earth and the Moon;
Block D provides a breaking maneuver, inserting the L3 system into lunar orbit, where it can remain up to four days;
A Block D engine firing trasfers the L3 system from a circular to an elliptical orbit around the Moon;
One cosmonaut transfers from the LOK spacecraft to the LK lander, during an EVA;
A combination of Block D and the LK spacecraft separates from the LOK spacecraft;
A Block D engine firing transfers the LK lander on a descent trajectory toward the lunar surface;
Block D separates from the LK lander
Block E engine firings onboard the LK lander provides for a soft-landing on the Moon surface;
A cosmonaut conducts an EVA, during a stay on the lunar surface lasting from 6 to 24 hours;
A Block E engine firing provides for the liftoff of the LK ascent stage from the lunar surface and reaching lunar orbit;
The LOK spacecraft docks with the LK lander;
The cosmonaut transfers from the LK lander to the LOK spacecraft during a spacewalk;
Block I onboard the LOK spacecraft provides escape velocity, sending the LOK toward Earth;
Block I onboard the LOK spacecraft provides trajectory corrections during a 3.5-day flight toward the Earth;
A reentry capsule of the LOK spacecraft separates from the habitation module and the instrument section, then it reenters the Earth atmosphere and lands;

Development

Basic configuration of the L3 complex, which included LOK spacecraft was formulated by 1963, or roughly two years behind similar concept was adopted in the United States.

Before August 1964, it was already clear that the N1-L3 would not be able to support three people during the lunar expedition, therefore the crew of the complex was reduced to two cosmonauts with only one of them actually landing on the lunar surface onboard the lunar module, LK, while the second would remain in lunar orbit onboard LOK. (78)

In December 1964, Korolev's team completed a preliminary design of the N1-L3 complex. It envisioned the launch of a two-man spacecraft by a single N1 rocket and the landing of one cosmonaut on the surface of the Moon. (36,52) The expert comission led by Mastislav Keldush evaluated the project, and on February 10, 1965, the plan for the development of the L3 system was officially approved. (52)

PICTURE GALLERY

Lunar Lander animation

A virtual copy of the the Soviet LK lander recreates key stages of the Soviet lunar expedition, as it was envisioned by its designers in the 1960s, but never took place. The historic hardware, which served as a model for this animation is shown below.

LK descent