Lunar Module (LK)

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Above: Virtual model of the Soviet lunar lander (shown without thermal insulation). (requires Flash plugin to view)

During the 1960s, the Lunar Spacecraft, from Russian "Lunnyi Korabl" or LK, was conceived as a part of the L3 lunar expeditionary complex carried aloft by the N1 rocket. From the outset, Soviet designers understood that despite being the largest launch vehicle developed by the USSR, it could only carry two-person crew on a lunar mission and only one to the surface of the Moon.

Similar to the American Apollo missions, LK was designed to separate from the lunar orbital spacecraft, in the orbit around the Moon. After a descent on the lunar surface and, hopefully, a successful "moonwalk," the cosmonaut would blast off from the Moon onboard the LK and link up with the LOK. Following moonwalker's transfer back from the LK to LOK, both cosmonauts would jettison the LK and depart toward Earth onboard the LOK.

However, unlike the Apollo, no internal tunnels between LOK and LK existed, therefore back-and-forth movement of a crew member between two ships would have to be done in spacesuit, via the same hatch in LK, which would be used to walk on the lunar surface. Also unlike the Apollo, the same propulsion unit of the Block E would be used for the final phase of the descent on the lunar surface and for a takeoff. The initial descent to the Moon would be propelled by the Block D stage attached to LK. Block D would jettison and crash onto the lunar surface, after which Block E's engine would take over.

Technical description

As a system, the LK spacecraft consists of a lunar module itself and the Block E propulsion system. However, structurally, the spacecraft would be subdivided into Lunar Landing Aggregate, (Lunnyi Posadochnyi Agregat, LPA) and Lunar Ascent Vehicle, (Lunnyi Vzletnyi Apparat, LVA). In turn, LPA consisted of a lattice-structured main body with a diameter of 2.27 meters and a four-legged lunar landing device, (Lunnoe Posadochnoe Ustroistvo, LPU) In its launch configuration, stowed landing gear would have a span of 2.26 meters. (231) It would be likely deployed immediately after the jettisoning of the protective shroud in preparation for landing in the lunar orbit.

The lunar module consisted off following major elements:

Pressurized cosmonaut compartment;
Flight control avionics;
Life-support system;
Attitude control systems;
Lunar landing device, or LPU, with four landing legs;
Power supply system, consisting of chemical batteries attached to LPU;

Block E was permanently attached to the bottom of the cosmonaut compartment, while the LPA/LPU landing device was connected to Block E with a set of (four?) pyrotechnic devices, which would be severed at the takeoff from the Moon. In addition, a special retractable umbilical mast linked various systems in the LPA/LPU landing device to a cosmonaut compartment. The mast would be retracted prior to the ascent vehicle's blastoff from the Moon. On all its sides, LPA was heavily loaded with various sub-systems and scientific gear including:

a Planeta landing radar;
a pressurized avionics container;
two deployable communications antennas;
three batteries;
four containers with water for a vaporization unit;

The 105-kilogram scientific package would reportedly include a 59-kilogram robotic arm and a drill with an operational life span of 60 minutes. (231)

The LVA ascent vehicle consisted of the cosmonaut compartment, another avionics compartment, the attitude control section and a Block E propulsion unit. Like the Apollo's lunar module, the 2.3 by 3.0 meter's cabin had a complex geometrical shape dictated by its dual function as a landing and docking command center. However where Apollo featured an angular multiplying shape, the LK crew module sported a complex combination of semi-spherical structures. In its architecture, it clearly borrowed from the original design of the Soyuz spacecraft.

A circular cutaway in the front of the cabin enabled to place a window, which afforded good view of the surface below the ship during landing. The pilot could steer the spacecraft to a touchdown while standing at the controls, in case of problems with nominal automated descent mode. To save space and room, the cabin had famously no seat. However, like all Russian spacecraft and unlike Apollo, LK's cabin featured a normal nitrogen-oxygen atmosphere, rather than oxygen-only life-support system in early NASA spacecraft.

The flight control system, featured an onboard computer and enabled the cosmonaut to select final landing site and conduct approach and touchdown manually. (202)

Known specifications of the LK spacecraft:

Height	5.2 meters
Maximum landing gear span	5.4 meters
Total mass of LK spacecraft before descent on the lunar surface including Block E propulsion system	5,560 kilograms 2,950 kilograms
LK liftoff mass on the surface of the Moon	3,800 kilograms

Block E technical description

Block E, developed by the collective of I.I. Ivanov from OKB-586 in Dnepropetrovsk, was one of the most critical systems onboard the N1-L3 complex. Unlike any other phase of the lunar expedition, a failure of Block E during the takeoff from the surface of the Moon would inevitably result in the loss of a cosmonaut.

To improve the reliability of Block E, a one-chamber 11D411 engine had a backup 11D412 engine with two combustion chambers. Combined, two engines would create a propulsion system designated 11D410. Both were burning a mix of unsymmetrical dimethyl hydrazine and nitrogen tetroxide.

Four vernier engines were also clustered around main and backup nozzles of the LK, as evident from published Russian drawings and surviving hardware.

The main engine was designed for two firings - one during the final phase of the landing on the Moon and the second for the takeoff from the surface. The backup engine was designed for a single ignition, however it could be fired during either a descent or an ascent phase of the flight. (98)

Live test firings of the 11D410 engine were conducted at Facility No. 5 in NII-229 (NIIKhIMMash) in Zagorsk (today Sergeiv Posad). By 1972, a total of 250 firings had been conducted. (129)

During its development, the LK lander went through several reincarnations, which becomes apparent when one compares different versions of the spacecraft preserved at various locations in Russia.

Thermal control system

In addition to the extra-reliable propulsion, the lunar lander needed a very effective system to remove heat, while it was constantly baking in sunlight on the surface of the Moon. Korolev's design bureau (known as TsKBEM at the time) subcontracted the development of the thermal control system for the LK spacecraft to NPO Nauka. This organization had extensive experience in development of life-support systems for Soviet aviation and space industry. Within NPO Nauka, Department No. 59 took the responsibility for the development of the first Soviet vaporization device for use in space.

A special vaporizer was developed to remove extra heat from the spacecraft using boiling alcohol as a coolant. The coolant was contained in a special tank divided by a flexible membrane onto a coolant storage and an air-pressurization chamber. The unit had a capability to maintain the temperature of the coolant at a predetermined level. The vaporizer consisted of four elements: the unit itself; four coolant tanks; valves controlling the coolant supply; dosage controllers; pressure sensors, to monitor minimum pressure in coolant supply, which would indicate either depressurization in the supply system or out-of-coolant state.

On the vapor half of the system, it had a valve for the boiling pressure of the coolant, dosage device for the supply of the coolant into the vaporizer, the temperature regulator on the exit from the vaporizing chamber, including a control unit and temperature sensors. (346)

Writing, illustration, photography and page design by Anatoly Zak

Last update: July 30, 2009

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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.

Attention editors: To order full-length high-resolution versions of this animation or other 3D renderings contact Anatoly Zak.

LK descent