L1 No. 9 (Zond-5)



L1 No. 12L (Zond-6)


L1 No. 13L




Soviet lunar program

Practically immediately after the Soviet Union sent the first cosmonaut into orbit, the Moon became the destination for human space flight. In May 1961, President Kennedy proclaimed the lunar landing on the surface of the Moon before 1970, as the main goal for NASA. However, the Soviet government was slow to respond to the US challenge.

Previous chapter: Early piloted spacecraft


In 1962, four departments within Sergei Korolev's OKB-1 design bureau began studies of possible scenarios of lunar expeditions. Among multiple concepts, engineers investigated possible lunar flyby missions, which would require less rocket power than actual landing expeditions. Two such scenarios were under consideration. The first plan involved a pair of launch vehicles based on the R-7 rocket and carrying the 7K (Soyuz) spacecraft and the separate Earth-orbit escape stage propelled by liquid hydrogen.

The second option also involved two launches of R-7-based rockets: one carrying a modified Vostok spacecraft along with an additional fuel tank and the second rocket was delivering a liquid oxygen tank along with an engine derived from Block L on the Molniya rocket. In parallel, Vladimir Chelomei's OKB-52 design bureau started its own work on the circumlunar mission, which had an advantage over Korolev's plans thanks to its reliance on a more powerful UR-500 rocket, which could accomplish the task in a single launch. (52)

At the end of 1962, OKB-1 was reviewing various scenarios of lunar and martian expeditions, which could take advantage of the prospective N1 rocket with the expected payload of 75 tons to the low Earth's orbit. Four architectures were chosen out of 26 possible schemes to put cosmonauts on the lunar surface. The favored scenario required three N1 rockets launching the 19K lunar expeditionary system and a pair of 21K tankers for in-orbit fueling of the 19K ship. The crew would be delivered later on the vehicle derived from the 7K spacecraft. The expedition would use a direct descent to the lunar surface, skipping complex and dangerous rendezvous in the lunar orbit.

By 1963, OKB-1 formulated the whole array of lunar exploration projects. The L1 circumlunar mission concept was at the root of the 7K (Soyuz) spacecraft development, which would be a part of the three-component mission, all of which would be launched by boosters derived from the R-7 ballistic missile. The same strategy also proposed the L2 unmanned lunar rover, the L3 complex for an expedition to the Moon and the L4 lunar orbital station and the L5 crew-carrying lunar rover. For the time being, the L3 lunar landing project became a focus for OKB-1 during most of 1964.

It took more than three years after Kennedy's speech in 1961 for the cash-strapped Soviet government to commit needed resources for the manned expedition on the surface of the Moon. "Do not leave the Moon to the Americans," Nikita Khrushchev reportedly told leaders of the Soviet rocket industry, "...Anything you need in order to do it, will be provided." On Aug. 3, 1964, the Soviet government finally gave full go ahead to the lunar landing effort with Decree No. 655-268. The now secondary task of the lunar flyby was delegated to Vladimir Chelomei's own spacecraft launched by the newly developed UR-500 (Proton) rocket. At the same time Korolev could now focus on the much more difficult but prestigious task of beating the Americans to the Moon with his L3 lunar landing system.

However, the development of a heavy-lifting launcher, needed for the lunar expedition, was plagued with political and technical problems. Powerful captains of the Soviet rocket industry fought for the leadership and influence in the program, stretching the project's already limited resources, while the Soviet military, which financed rocket development, had always remained skeptical about the prospects of giant space launchers.

At the end of 1964, Korolev also approved the idea to dock a pair of the 7K spacecraft in the Earth's orbit as a rehearsal of future operations during lunar expeditions. The Soyuz variant proposed for this purpose was designated 7K-OK, where the "7K" designation was inherited from the original manned vehicle in the lunar fly-by project, while "OK" stood for "okolozemny korabl" or "near-Earth-orbital spacecraft."

The fall of Khrushchev in October 1964, further delayed the program, which continued suffering from the lack of funds and resources.

The Oct. 25, 1965, a government decree formally approved the development of the 7K-OK Earth-orbiting spacecraft, in parallel with the work on the 7K-L1 variant, which aimed to fly behind the Moon before the Apollo.

In January 1966, the Soviet lunar program recieved another blow with the death of Sergei Korolev. After many delays, the first unmanned Soyuz 7K-OK spacecraft was finally launched in November 1966.

On Feb. 4, 1967, the Soviet government issued another decree, which proclaimed the flight around the Moon and the human landing on its surface a task of "state importance." The document required the circumlunar mission to be accomplished between June and October 1967. The flight testing of the 7K-L1 system began in March 1967, with the largely successful launch of the UR-500K rocket variant delivering the 7K-L1 No. 2P unmanned spacecraft prototype.

The N1 moon rocket had not reached the launch pad until 1969, and its first and three subsequent test missions ended in catastrophic failures, revealing serious technical flaws in the design of the booster. The program was finally abandoned in 1974 and its leader Vasily Mishin was ousted as a head of the industrial conglomerate responsible for the project.


Manned lunar exploration projects in the 20th century:

Official name
USA (Department of Defense)
7K, 9K, 11K
Lander with the L2 rover launched by 9K/11K system
as an alternative to 7K payload
Robotic lunar
surface rover
for lunar expedition
Lunar orbital station
with a crew of 2 or 3
Manned lunar
surface rover


Soviet deep-space spacecraft (proposed and developed):

Official name
7K (Soyuz, LOK)
Manned vehicle for lunar flyby,
circumlunar mission
Developed as part of N1-L3 and 7K-OK projects


Space tug for circumlunar mission
launched by R-7-based rockets
Not built
Space tanker for
the 9K spacecraft
Not built
Lunar lander for the L2 rover
launched with 9K/11K booster tanker
Evolved into a Luna lander
Heavy space tug
based on the N1 rocket
Not built
Heavy tanker
based on the N1 rocket
Not built
TMK-1/2 (M/V)
Manned vehicle for Mars and Venus flyby
based on liquid propulsion
Not built
Manned vehicle for Mars and Venus flyby
based on electric propulsion
Not built
SMTK (M1/M2)
Assembled spacecraft
for Mars mission
Not built


Soviet missions preparing human expedition to the Moon:

Official name
Industry name
Launch date
Landing date
Mission summary
1 Kosmos-133
7K-OK No. 2
Nov. 28, 1966
Nov. 30, 1966
Destroyed on reentry
2 Unannounced
Dec. 14, 1966
Destroyed on Pad 31 due to an accidental ignition of the emergency escape system, resulting in three fatalities.
3 Kosmos-140
7K-OK No. 3
Feb. 7, 1967
Feb. 9, 1967
Lost pressure and sunk in the Aral Sea during botched landing
4 Kosmos-146
7K-L1 No. 2P
March 10, 1967
Tested systems of the Block D upper stage
5 Kosmos-154
7K-L1 No. 3P
April 8, 1967
A second firing of the Block D failed in orbit
6 Soyuz-1
7K-OK No. 4
April 23, 1967
April 24, 1967
Vladimir Komarov
Planned for docking with a second Soyuz. Developed problems in orbit. Crashed on landing killing Komarov
7 Unannounced
7K-L1 No. 4
Sept. 28, 1967
Proton's 1st stage failed; escape system saved the reentry craft
8 Kosmos-186
7K-OK No. 6
Docked with Kosmos-188. Made ballistic return
9 Kosmos-188
7K-OK No. 5
Docked with Kosmos-186. Self-destructs on landing
10 Unannounced
7K-L1 No. 5
Nov. 22, 1967
Proton's 2nd stage failed. The escape system saved a reentry craft
11 Zond-4
7K-L1 No. 6
March 2, 1968
The descent module self-destructed during reentry
12 Kosmos-212
7K-OK No. 8
April 14, 1968
April 19, 1968
Docked with Kosmos-213
13 Kosmos-213
7K-OK No. 7
April 15, 1968
April 20, 1968
Docked with Kosmos-212
14 Unannounced
7K-L1 No. 7
April 23, 1968
Escape system self-initiated during launch
15 Unannounced
7K-L1 No. 8
July 14, 1968
An on-pad explosion of the upper stage killed one person; craft damaged
16 Kosmos-238
7K-OK No. 9
Aug. 28, 1968
Sept. 1
Test flight
17 Zond-5
7K-L1 No. 9
Sept. 15, 1968
Sept. 21, 1968
Flew around the Moon; splashed down in the Indian Ocean
18 Soyuz-2
7K-OK No. 11
Rendezvous with Soyuz-3
19 Soyuz-3
7K-OK No. 10
Attempted to dock with Soyuz-2 but failed due to wrong orientation
20 Zond-6
7K-L1 No. 12
Nov. 10, 1968
Nov. 17, 1968
Flew around the Moon; reentry craft depressurized during landing and crashed
21 Soyuz-4
7K-OK No. 12
Vladimir Shatalov
Docked with Soyuz-5
22 Soyuz-5
7K-OK No. 13
Boris Volynov, Yevgeny Khrunov, Aleksei Yeliseev
Docked with Soyuz-4; Khrunov and Yeliseyev transferred to and landed onboard the Soyuz-4
23 Unannounced
7K-L1 No. 13
Jan. 20, 1969
Proton's 2nd stage failed; the escape system saved a reentry craft
24 Unannounced
7K-L1A (7K-L1S)
Feb. 21, 1969
The N1-L3 launch (No. 3L) failed at T+68.7 seconds
25 Unannounced
7K-L1A (7K-L1S)
July 3, 1969
N1-L3 launch (No. 5L) failed at launch
26 Zond-7
7K-L1 No. 11
Aug. 8, 1969
Aug. 14, 1969
Flew around the Moon
27 Soyuz-6
7K-OK No. 14
Georgy Shonin, Viktor Kubasov
28 Soyuz-7
7K-OK No. 15
Anatoly Filipchenko, Viktor Gorbatko, Vladislav Volkov
Planned to dock with the Soyuz-8
29 Soyuz-8
7K-OK No. 16
Vladimir Shatalov, Aleksei Yeliseev
Failed to dock with Soyuz-7 due to Igla rendezvous system failure
30 Unannounced
7K-L1E No. 1
Nov 28, 1969
Test of the Block D upper stage version for the N1 launcher; Proton failed during launch
31 Soyuz-9
7K-OK No. 17
June 1, 1970
June 19, 1970
Andriyan Nikolaev, Vitaly Sevastyanov
Set flight-duration record
32 Zond-8
7K-L1 No. 14
Oct. 20, 1970
Oct. 27, 1970
Flew around the Moon; landed in the Indian Ocean
33 Kosmos-379
Nov. 24, 1970
A lunar lander test in the Earth orbit
34 Kosmos-382
7K-L1E No. 2
Dec. 2, 1970
A flight test of the Block D upper stage version developed for the N-1 launcher; fired seven times in orbit
35 Kosmos-398
Feb. 26, 1971
A lunar lander test in the Earth orbit.
36 Unannounced
June 27, 1971
The N1-L3 launch (No. 6L) failed at T+50.1 seconds
37 Kosmos-434
Aug. 12, 1971
A lunar lander test in the Earth orbit
38 Unannounced
Nov. 23, 1972
The N1-L3 launch (No. 7L) failed at T+107 seconds


Next chapter: First space stations


Compiled by Anatoly Zak

Last update: May 18, 2021

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insider content


Scale model of the launch complex for the Proton rocket with the L1 spacecraft in Baikonur. Copyright © 2002 Anatoly Zak

The Proton rocket with the 7K-L1 spacecraft for the circumlunar mission is poised for launch in Baikonur on Nov. 22, 1967.


The L1 spacecraft separates from the third stage of the UR-500K rocket during ascent to orbit. This version of the flight scenario illustrates immediate separation of the lower and middle sections of the payload fairing. Copyright © 2017 Anatoly Zak


Block D fires its SOZ thrusters before igniting its main engine. Copyright © 2017 Anatoly Zak

Scale model of the UR-700 launcher, which Vladimir Chelomei proposed as an alternative to Korolev's N1 rocket. Copyright © 2001 Anatoly Zak


Soyuz-4 photographed from Soyuz-5 during undocking on Jan. 16, 1969.

The N1-L3 complex during its assembly at Site 112 in Tyuratam.

The N1 moon rocket leaves the assembly building at Site 112 in Baikonur.


An N1 rocket on the pad, probably before its third launch in 1971. Click to enlarge. Credit: Roskosmos