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There are three basically three ways to get a person to the moon and back:

  • Direct. One spacecraft launches from Earth, lands on the moon, takes off again, and lands back on Earth. It may shed parts as it goes, but it never docks with another spacecraft. This means that you must land on the moon all of the mass to get you back to Earth and through the atmosphere. The earliest plans for Apollo assumed this mode would be used, but it was quickly realized that it would require an enormously large launch vehicle.

  • Earth orbit rendezvous. Multiple, smaller launch vehicles put pieces of the final spacecraft into Earth orbit, where it is assembled. The rest of mission is like the direct mode. Many officials in Apollo program argued for this mission mode, until Gemini convinced them that lunar orbit rendezvous was feasible.

  • Lunar orbit rendezvous. One spacecraft launches from Earth and travels to the moon. Once there, a small portion of the spacecraft lands on the moon. The lander ascends back to lunar orbit, rendezvousing with the main spacecraft, which returns the crew back to Earth. This was the ultimate mode that Apollo used.

The Soviet LK lunar lander was designed for the same LOR mode that Apollo used. However, are there records of Soviet planners considering any of the other mission modes?

lunar mission modes

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    $\begingroup$ Chelomei's UR-700 planned on direct launch, didn't it? Is that a serious enough plan to be worth an answer? $\endgroup$ – DylanSp Sep 20 at 22:02
  • $\begingroup$ @DylanSp: Yes, that would fit with the question. $\endgroup$ – DrSheldon Sep 20 at 22:11
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The following journal article appears to describe an Earth-orbit-rendezvous mission. It says "modified version of the direct scheme", but careful reading reveals that it is EOR.

""LUNAR Theme" after N1-L3" Journal "Aviation and Cosmonautics" No. 2 of 1993 http://epizodsspace.airbase.ru/bibl/stati/lunnaytema.html

ЦКБЭМ по предложению В. Мишина в 1972 году разработало улучшенный вариант лунного ракетно-космического комплекса — Н1-Л3М. Предлагалось основательно форсировать носитель Н-1 и создать новый корабль для полета по оригинальной двухпусковой схеме. При этом планировались не кратковременные визиты на поверхность «ночного светила», а подготовка необходимой инфраструктуры для устройства в недалеком будущем лунной базы и проведения экспедиций средней продолжительности (до трех месяцев). Получалось, что при финансировании, не выходящем за рамки бюджетных ассигнований на Н1-Л3, уже к 1978—1980 годам могла появиться реальная возможность выполнения новой программы.

TsKBEM, at the suggestion of V. Mishin, in 1972 developed an improved version of the lunar space-rocket complex - N1-L3M. It was proposed to thoroughly force the N-1 carrier and create a new ship for flight according to the original two-launch scheme. In this case, it was planned not short visits to the surface of the "night luminary", but the preparation of the necessary infrastructure for the construction in the near future of the lunar base and expeditions of medium duration (up to three months). It turned out that with financing that did not go beyond the budgetary allocations for N1-L3, by 1978-1980, a real possibility of implementing the new program could appear.

Возможности постепенного наращивания массы выводимого груза закладывались в проект Н-1 с самого начала, но реальным в ближайшее время могло оказаться только форсирование первой ступени Н-1, что давало прибавку в массе полезного груза только в 10—11 процентов.

Вот почему решили остановиться на модифицированном варианте «прямой схемы», при котором лунный корабль и тормозной ракетный блок выводятся на околоземную орбиту по отдельности своими Н-1. Затем каждый с помощью собственных разгонно-тормозных блоков (РТБ) выходит сначала на траекторию полета к Луне, а затем на селеноцентрическую орбиту, где и происходит их стыковка. При этом, если стыковка сорвалась, космонавты возвращаются на Землю. Тормозной блок используется для схода ЛК с окололунной орбиты и гашения скорости, а на некоторой высоте от поверхности Луны происходит его отделение. Мягкая посадка производится с помощью двигательной установки (ДУ) и посадочных опор корабля. Для возвращения необходимы отделение посадочных приспособлений и взлет с работающим на полной тяге двигателем ЛК. После старта с Луны корабль должен выйти на селеноцентрическую орбиту, с которой взять курс к Земле или сразу же перейти на траекторию возвращения.

Opportunities for a gradual increase in the mass of the displayed cargo were laid in the N-1 project from the very beginning, but in the near future, only the first-stage boost of the N-1 could turn out to be real, which provided an increase in the payload mass of only 10-11 percent. That is why they decided to dwell on a modified version of the “direct scheme”, in which the lunar ship and the braking rocket block are put into low Earth orbit separately with their own N-1. Then, each with the help of its own accelerating-brake blocks (RTB) first goes to the flight path to the moon, and then to the selenocentric orbit, where they are docked. At the same time, if the docking is broken, the astronauts return to Earth. The brake unit is used for the descent of the LC from the lunar orbit and damping, and at a certain height from the surface of the moon, it is separated. Soft landing is done using the propulsion system (DU) and landing supports of the ship. For return, separation of landing gear and take-off with a full-throttle LC engine are required. After starting from the moon, the ship should enter a selenocentric orbit from which to head for the Earth or immediately go on the return trajectory.

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    $\begingroup$ A summary or tl;dr would really help this answer. $\endgroup$ – Organic Marble Sep 19 at 11:47
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    $\begingroup$ Good find! I hope you don't mind if I edit the answer to add a summary and highlighting. $\endgroup$ – DrSheldon Sep 19 at 14:32
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Vladimir Chelomey's plan for a lunar landing used the direct ascent architecture, using the massive UR-700 rocket to launch the LK-700 spacecraft. The UR-700 would have been an immense rocket, with a payload of ~150 tons to LEO or ~50 tons to a translunar trajectory. Chelomey's design bureau, OKB-52, started working on the UR-700 in 1962; it was part of the "Universal Rocket" series, using common, modular parts for simplicity and transportability. Chelomey successfully built the UR-100 ICBM and the UR-500 rocket (the Proton), but the -700 was never built; the N-1 program took priority, and Chelomey didn't retain enough political capital after Khrushchev's fall to present it as a serious alternative.

More Information

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The other answers -- which directly cite Soviet sources -- are the most authoritative answers. However, here is what NASA believed of the Soviet program on 1962 August 1:

A recent Russian article discussed various methods which the Soviet Union had been studying for sending a man to the moon during the decade. The earth orbital rendezvous method was reported the most reliable, but consideration also had been given to the direct ascent method, using the "Mastodon" rocket.

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  • $\begingroup$ as an illustration of this is the Soviet popular science film "Moon" ( 1965) by famous Pavel Klushantsev. youtube.com/watch?v=aT1s5s2LurM Episode in 27:40 - 29:30. $\endgroup$ – A. Rumlin Sep 24 at 5:40

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