Category Soviet and Russian Lunar Exploration

The following year, the State University of Leningrad convened a conference of physicists to examine the nature of the moon and the planets. It was held in Leningrad in February 1956. Most of those attending were scientists, astronomers and what would now be called planetologists. Also there was Mikhail Tikhonravov, not repre­senting Pionerskaya Pravda, but this time the Artillery Institute, where NII-4 was located. The conference in Leningrad State University, which reviewed the state of knowledge of our moon at the time, was well publicized and news of its deliberations were again picked up in the West [3].

Following the deliberations in Leningrad State University, Korolev paid a visit to Tikhonravov’s Artillery Institute. There, he asked its designers, engineers and experts to explain their work to him. As was his wont, Korolev said little, preferring to listen and taking a particular interest in their work on trajectories. Being a man more of action than of words, the institute soon found out that it had made its mark. Wielding his authority as chief designer, Korolev transferred the institute to his own, the first experimental design bureau, OKB-1. There, the NII-4 personnel could be under his direct control and enlisted fully in his cause. They now became department #9 of OKB-1, founded 8th March 1957 [4]. We do not know what Mikhail Tikhonravov thought of this. He was a quiet man who preferred to work in the background and who rarely sought the limelight. His unassuming nature concealed great imagination, a steely sense of purpose and, as the situation in the early 1950s required some considerable courage.

This was typical of Korolev. Long before his intercontinental ballistic missile had flown, some time before the first Sputnik had even been approved, he was already thinking ahead to a flight to the moon. Working on several projects at once daunted many lesser men, but it was his forte. Korolev’s drive, imagination, timing and ability to knock heads (and institutes) together do much to explain the early successes of the Soviet space programme [5]. The relationship between Tikhonravov and Korolev has attracted little attention, but it was a key element in the early Soviet lunar programme. One person who has commented is Sergei Khrushchev, son of the Soviet leader Nikita Khrushchev. Sergei Khrushchev says that Korolev was not an originator of technical ideas, but someone able to gather the best engineers and technicians around him. He was able, though, to spot talent, to organize, to manage, to drive ideas and concepts through the political system. Although many of the ideas of his design bureau were attributed externally to him, he made sure that, within the bureau, individual designers were recognized, promoted, praised and rewarded. Khrushchev: ‘Mikhail Tikhonravov was a man ofbrilliant intellect and imaginative scope [but] totally devoid of organizational talents’ [6]. The combination of Korolev the organizer and Tikhon – ravov the designer worked well and between them they built the moon programme.

In early 1964, Russia’s plans were still to fly around the moon using the Soyuz complex. With the construction of Soyuz already under way, the R-7 rocket already available and the first group flights showing remarkable promise, there was a real prospect that this could be achieved over 1966-7 or so.

There was still considerable uncertainty about the future medium – and long-term direction of the Soviet space effort. The death of John Kennedy had now eliminated the prospect of a joint mission. In 1963, Jodrell Bank Observatory director Bernard Lovell had visited the Soviet Union as a guest of Mstislav Keldysh and learned, to his surprise, that the Soviet Union had no plans to race the Americans to the moon (exactly as Khrushchev had told the United Nations). Instead, they would build an Earth-orbiting space platform. Indeed, designs of Soviet cosmonauts spacewalking around such platforms soon found their way to the West. Bernard Lovell’s remarks were disputed by some Soviet scientists, but his visit created some considerable doubt about the nature of Soviet intentions.

Although the Soyuz complex had made considerable progress during 1962-3, this slowed down during 1964. However, it is important to stress that the Soyuz complex was no mere study. Not only did the design progress to an advanced stage, but initial flight models were in construction. The slowdown was not because of an action on the part of government, but due to gross overwork in OKB-1. Concerned with the complexities of the Earth orbit rendezvous manoeuvres required, Korolev now began to revise the concept. The weight of the complex to be assembled in Earth orbit would be about the same, 18 tonnes. Under the new plan:

• Only three spacecraft would be involved.

• The rocket block would use the much more powerful hydrogen fuel.

• The Soyuz spacecraft would, for the lunar journey, be shortened and lightened to five tonnes: the orbital module would not be carried. This would now be called the Soyuz 7K-L-1 (L for Luna, Luniy or moon).

Learning about this, a rival design bureau, OKB-52 of Vladimir Chelomei, came up with a rival proposal. Using the new Proton rocket which he was building, he said that he could send such a spacecraft directly to the moon. Only one rocket would be required and there was no need for orbital rendezvous or the transfer of fuels in Earth orbit. He persuaded the government that the plans for Earth orbital rendezvous were too cumbersome. Korolev was so busy with other projects and Chelomei managed to get government approval before he realized what was going on and could stop him.

The arrival of a competitor to Korolev was an important development. Until 1964, Korolev had, as chief designer, ruled supreme over the Soviet space programme. Vladimir Chelomei was a slightly younger man than Korolev – he was born in 1914 – and when Korolev had developed the German V-2 after the war, Chelomei had built derivatives of the V-1 flying bomb. Prom 1944 to 1954, Chelomei had developed pulse jet engines, cruise missiles and sea-borne rockets. His style was quite different from Korolev, being smartly dressed, with a polished manner and he was a great com­municator. All who met him paid tribute to his ambition and powers of persuasion. Chelomei was a professor of the Baumann Technical School, a member of the Academy of Sciences from 1958 and full academician from 1962. He was able to offer the Kremlin a viable military space programme: new military rockets (SS-9, Tsyklon, Proton), anti-satellite weapons (Polyot), radar observation satellites and was even working on a manned platform for space surveillance (Almaz). Nikita Khrush­chev’s son Sergei worked for him.

Chelomei was not the only challenger to Korolev’s hitherto undisputed promi­nence. Korolev’s former collaborator, Valentin Glushko, ran a large engine design bureau, OKB-456, and as we saw in 1958 the two had already quarrelled over the upper stage for the R-7 used to fire the first cosmic ship. In Dnepropetrovsk, Ukraine, another large design bureau had grown up under Mikhail Yangel. He built military missiles for the Soviet rocket troops by the hundreds in his sprawling factory there.

Some of the missiles were adapted as satellite launchers and by 1962 his design bureau was building small military satellites.

Tikhonravov’s background in the space programme went as far back as Korolev’s, even though he was much less publicly prominent. But what do we know about Mikhail Tikhonravov? Mikhail Tikhonravov was the architect of the Soviet moon

programme. He was born 16th July 1900 (os)[1] and began his early aeronautical career by studying the flight characteristics of birds and insects. In 1922, his study called Some statistical and aerodynamical data on birds was published in Aircraft magazine. He graduated from the Zhukovsky air force academy in 1925 and worked in aviation. In 1932 he joined Korolev’s group of amateur rocketeers, the GIRD (Group for the study of jet propulsion), moving in and out of rocketry and jet propulsion in the 1930s and 1940s. He wrote Density of air and its change with altitude for a military magazine in 1924. Seven more articles on aeronautics appeared by 1939. In the course of his work he met the ageing theoretician Konstantin Tsiolkovsky and joined the Moscow GIRD. He was closely involved with Korolev in the construction of amateur rockets launched over 1933-5. The Moscow group had fired the first liquid-fuel Russian rocket from a forest near Moscow. The rocket was called the GIRD-09, a needle­like contraption just able to fly higher than the tall trees. Launching on 17th August 1933, it reached the mighty height of400minits 18 sec mission. The GIRD rocket was designed by Mikhail Tikhonravov. The work of these young rocketeers and theore­ticians was later to become extremely significant for the later moon missions. GIRD was supervised by a technical council with four teams, led respectively by Friedrich Tsander, Sergei Korolev, Yuri Pobedonostsev and Mikhail Tikhonravov, with Tikhonravov having responsibility for liquid propellants [7]. The group was really driven by Sergei Korolev (born 30th December 1906 (os)), a graduate of Moscow Higher Technical School who designed, built and flew his own gliders and for which he developed rockets as a means to get them airborne.

Tikhonravov wrote a book on space travel in 1935 and then disappears from the records until the end period of the war. He was one of the few to escape the purges. Tikhonravov was a talented man who painted oils in his spare time and studied insects and beetles. Tikhonravov re-emerged in 1944 designing high-altitude rockets for the Lebedev Institute of the Academy of Sciences and two years later was transferred to Scientific Research Institute NII-4, staffed mainly by artillery officers, to design and build missiles. In the later 1940s, his name reappears on an edited book on the writings of Konstantin Tsiolkovsky and Friedrich Tsander. Tikhonravov designed the first plans for sending humans into space – the VR-190 suborbital rocket, able to send two stratonauts on an up-and-down mission 200 km high, a flight eventually emulated by Alan Shepard and Virgil Grissom in 1961. From 1948 onward, Tikhonravov worked for the Artillery Academy of Sciences and put forward the idea of grouping rockets together in a cluster of packets to achieve new velocities and lifting power. It was at such a presentation attended by Korolev in 1948 that the two men resumed their collaboration that had been broken by the purges [8]. On 15th March 1950, Tikhon­ravov put forward one of the formative papers of the Soviet space programme, with a convoluted but self-explanatory title: On the possibility of achieving first cosmic veloc­ity and creating an Earth satellite with the aid of a multi-stage missile using the current level of technology.

This paper caused a stir and indeed led to Tikhonravov’s banishment. In the final, paranoid days of Stalin, he fell under suspicion for giving unwarranted attention to non-military affairs and for not concentrating sufficiently on the defence of the motherland. He was demoted, rather than imprisoned or worse, but ironically this gave him all the more time to consider long-term objectives. During this period of reflection, the article for Pionerskaya Pravda was conceived. Following the death of Stalin, he was restored to his old work in the Directorate of the Deputy Commander of Artillery. There, he organized the ‘satellite team’ that paved the way for the Soviet Union to launch the first Sputnik. His memorandum A report on an artificial satellite of the Earth (25th May 1954) included a final section called Problems of reaching the moon which outlined a 1,500 kg spacecraft to land on the moon and return using atmospheric braking. His ideas had now moved from a children’s newspaper to an official Soviet document in the period of three years.

April 1956 saw the Soviet Academy of Sciences organize the all-Union conference

On rocket research into the upper layers of the atmosphere. Here, Sergei Korolev made a lengthy presentation. He told the conference:

It is also a real task to prepare the flight of a rocket to the moon and back to the Earth. The simplest way to solve this problem is to launch a probe from an Earth satellite orbit. At the same time, it is possible to perform such a flight directly from the Earth. These are prospects of the not too distant future.

Department # 9 was later reorganized and subtitled the ‘Planning department for the development of space apparatus’. In April 1957, the planning department produced a detailed technical document, A project research plan for the creation ofpiloted satellites and automatic spacecraft for lunar exploration. The key question, iterated by Tikhon – ravov, was the need to construct an upper stage for the planned intercontinental ballistic missile. Meantime, the Academy of Sciences appointed the Commission on Interplanetary Communications to oversee the planning or ‘the conquest of cosmic space’: vice-chairman was Mikhail Tikhonravov.

There the matter rested for the moment, as OKB-1 focused on the great challenge of launching an artificial Earth satellite that autumn.

Chronology of the idea of a Soviet moon rocket

1951 Flight to the moon by Mikhail Tikhonravov in Pionerskaya Pravda.

1954 Report on an artificial satellite of the Earth by Tikhonravov, Glushko and Keldysh.

1955 On the question of the application of rockets for research into the upper layers of the atmosphere by Sergei Korolev.

1956 Conference on moon in Leningrad State University (February).

Korolev formally announces goal of moon mission (April) at conference On rocket research into the upper layers of the atmosphere.

Artillery institute’s research institute NII-4 transferred to OKB-1 as Department #9 under Tikhonravov.

1957 Department #9’s Project research plan for the creation of piloted satellites and automatic spacecraft for lunar exploration (April).

Academy of Sciences establishes the Commission on Interplanetary Communications, led by Tikhonravov.

The Soviet decision to land on the moon was not made until August 1964, more than three years after Kennedy’s address to Congress. Examination of the Soviet documen­tary record in the 1990s suggests that as 1963 turned to 1964 there was a dawning realization of the scale of the American commitment under Apollo. Soviet intelligence reported on the burgeoning American effort, though there was no need to rely on spies, for the American programme was enthusiastically publicized in the open literature. Soviet designers put it up to their own leadership that they had to respond. Again, the decision was taken as a result of pressure from below, rather than because

of a government diktat from on high. Until spring 1964, the Soviet space programme had largely been shaped by goals set by Korolev, Tikhonravov and others in proposals and memoranda outlining a step-by-step Russian approach to space exploration. Now, a subtle shift occurred, with Soviet goals now determined in respect of American intentions.

The process of reappraisal began in the course of 1963. That autumn, Korolev restated and revised his approach, presenting a fresh set of plans to government in which he outlined how Soviet lunar exploration should progress. This was Proposal for the research and familiarization of the moon, by Sergei Korolev on 23rd September 1963. They were all labelled L – after the Russian word for moon:

L-1 Circumlunar mission using the Soyuz complex.

L-2 Lunar rover to explore landing sites.

L-3 Manned landing.

L-4 Research and map the moon from orbit.

L-5 Manned lunar rover.

What is interesting here is the prominence given to a manned landing, which had hitherto not featured at all in Soviet planning. Khrushchev received representations from Chelomei, Yangel and Korolev that each one of them had the project that could respond to Apollo:

• Korolev offered the latest version of the Soyuz complex for a round-the-moon mission. He also had a powerful, heavy-lift N-1 booster under development, which could put a man on the moon. The project had developed only slowly since 1956 and was now languishing.

• Chelomei proposed his UR-500 Proton rocket for a direct around-the-moon mission and a much larger derivative, the UR-700 for a direct ascent lunar landing.

• Mikhail Yangel’s bureau offered a third rocket, the R-56.

Siddiqi has chronicled how the Soviet approach changed in the course of 1964 [4]. The first American hardware had begun to appear and the Saturn I had begun to make its first flights. The various design bureaux saw the moon programme as a means of keeping themselves in business – and making sure that rivals did not rise to promi­nence at their expense. Korolev even made a blatant appeal to Khrushchev to the effect that it would be unpatriotic and unsocialist to let the Americans pass out Soviet achievements. Khrushchev eventually gave in and by this time the leading members of government, the party, the military and the scientific establishment had come round to the view that it would be wrong not to beat the Americans to the moon. A final contributory factor was that the Soviet Union had coasted through the successes of Gagarin, Titov and the two successful group flights. At some stage, the political leadership realized that complacency was no match for some serious forward planning.

Whatever the mixed circumstances, the government and party issued a resolution on 3rd August 1964, called On work involving the study of the moon and outer space. This resolution:

• Formally committed the Soviet Union to a moon-landing programme.

• Charged the task to Korolev’s OKB-1, with the objective of landing a man on the

moon in 1968. The N-1 heavy lift rocket, now eight years in design would be used.

• Committed the Soviet Union to continue to pursue the around-the-moon project.

This would be done by Chelomei’s OKB-52, with the objective of sending a man

around the moon in 1967. This plan replaced the Soyuz complex.

This is one of the most important government decisions in our story. It was a joint party and government resolution, # 655-268 to be precise. It gave the two bureaux the authority to requisition resources to bring these programmes to fulfilment. A word of caution though: although the party and government issued the decree, it was a secret one. Whilst known to the senior ranks of party, government and industry, it was not on the evening television news and indeed it was not uncovered until the Soviet Union had ceased to be.

The resolution was problematical for a number of other reasons. First, it came more than three years after the American decision to go to the moon, so the Russians were starting from far behind and also committed themselves to the finishing line sooner. Second, they divided the project into two distinct tasks, unlike the Americans who aimed to circle the moon on the way to a landing. The two tasks were given to two different design bureaux, meaning two different sets of hardware. The decision was a political compromise, giving one project to Korolev (at the expense of Yangel) and one to Chelomei (at the expense of Korolev). This might have been acceptable if the USSR had considerably more resources than the United States, but the very opposite was the case. Third, as we shall see, the Russians had a lot of difficulty in even keeping to the plans that were formally agreed. Fourth, it meant that Soviet methods of space exploration were determined less by the setting of objective goals and methods, but by reference to American intentions and the need to reach acceptable compromises between the ambitious design bureaux within the Soviet Union itself. Indeed, under Leonid Brezhnev, the Soviet system became less and less able to take hard choices, less able to say ‘no’, permitting and funding the many rival projects of the competing military-industrial elites simultaneously [5]. So the 1964 resolution was a pivotal, but problematic decision.

The original Soyuz complex was now gone from the moon plans, with the danger that four years’ design work would now go to waste. Korolev saved the 7K spacecraft and made the case to the government that it should be adapted for Earth orbital missions and to test out rendezvous and other techniques that would be required for the moon landing. The 7K was now renamed the 7K-OK (OK standing for orbital craft, Orbitalny Korabl). The spacecraft was now called Soyuz, even though it had been one part of a much bigger project called the Soyuz complex. As such, it became the basis for the spacecraft still operating today. The intention was that the 7K-OK follow as soon as possible from the Vostok programme. In the event, Soyuz was delayed, had a difficult design history and did not make its first unmanned flight until 1966.

Thus in August 1964, the Soviet Union:

• Abandoned Earth orbit rendezvous as a means of flying a cosmonaut to the moon, scrapping the Soyuz complex.

• Matched President Kennedy’s challenge to land an American on the moon by a commitment to land a Soviet cosmonaut there in 1968.

• Set the objective of sending a cosmonaut around the moon first, using the new Proton rocket and the skills of the Chelomei design bureau, in 1967.

With an economy half the size of the United States, the Soviet Union had set itself some daunting goals. Not only was it beginning the race three years after the United States, but it set itself an extra circuit to run – and still win both races a year earlier than its rival.

As part of the shake-out of 3rd August 1964, Tikhonravov’s Department #9 in OKB-1 was disbanded. All the work it had done on orbital stations was transferred to the Chelomei OKB-52 for his programme for space stations, called Almaz. Little more was heard of Mikhail Tikhonravov, the father of the Soviet lunar programme, from there on. He was 64 years old then and appears to have retired at this point. Mikhail Tikhonravov eventually passed away aged 74 on 4th March 1974. His prominent role had been obscured by Korolev. It probably should not have been, for the Soviet state did honour this shy man with the Lenin Prize, two Orders of Lenin, ‘honoured scientist of the Russian Federation’ and the title ‘Hero of socialist labour’. In a space programme dominated by giant egos, Mikhail Tikhonravov had been content to labour in the background, though he was never afraid to put forward proposals if that would advance the concepts and ideas he believed in so greatly. He never attracted or sought attention the way others did, but his influence on the Soviet lunar programme can only be considered profound, shaping all its early stages.

The Soviet space programme before Sputnik was the coming together of a number of diverse bodies, people, institutes and traditions. Going to the moon, Earth’s nearest celestial neighbour, had always been a part of this idea.

The Soviet space programme actually stretched back into Tsarist times. Its chief visionary was a deaf schoolteacher, Konstantin Tsiolkovsky (1857-1935). He was a remarkable man who carried out space experiments in his home, drew designs for interstellar spacecraft, calculated rocket trajectories (Tsiolkovsky’s formula is still taught in mathematics) and wrote science fiction about the exploration of the solar system. Rocketry was little encouraged under the tsars – indeed, another early de­signer, Nikolai Kibalchich, was executed in 1881 for turning his knowledge of explosives to use in an assassination plot.

The 1920s became the golden age of theoretical Soviet cosmonautics. Popular societies blossomed, exhibitions were held, science fiction was published, an encyclo­paedia of space travel issued. It was rich in theoretical, practical and popular work. Friedrich Tsander and Alexander Shargei (AKA Yuri Kondratyuk) outlined how spacecraft could fly to the moon and Mars. Popular societies were set up to popularize space travel and exhibitions were held. In St Petersburg, the Gas Dynamics Labora­tory (GDL) was set up in the old St Peter and Paul Fortress. It attracted the brightest Russian chemical engineer of the century, Valentin Glushko and here the first static Russian rocket engines were developed. Glushko, born 20th August 1908 (os), was a precocious young engineer who had built a toy rocket at age 13, corresponded with Tsiolkovsky in 1923 and wrote his own first contributions on spaceflight in 1924. He joined the original rocket engine design bureau in Russia, the Gas Dynamics Labora­tory, in 1925 and was given his own subdivision in 1929, when he was just over 20 years old. The following year, Glushko began his first experiments with nitric acid fuels and developed new ways of insulating rocket engines through exotic materials like zirco­nium. 1931 found him working on self-igniting fuels, swivelling (gimballing) engines and high-speed turbine pumps.

Alexander Shargei addressed some of the key questions of lunar missions in The conquest of interplanetary space (1929). He put forward the notion that, in landing on the moon or planets, the landing stage should be left behind and used as a launching

pad for the returning spacecraft. He suggested that it would be more economical to land on a moon or planet from an orbit, rather than by a direct descent. He outlined how explorers from the moon and planets could return by using the Earth’s atmo­sphere to break their speed through reentry. In 1930, the elderly Konstantin Tsiol – kovsky was advisor to a film called Kosmicheskoye putechestviye (Space journey), a Mosfilm spectacular in which spacesuited Soviet cosmonauts travelled weightless to the moon (the actors were suspended on wires to simulate zero gravity) and then walked its surface.

This flourishing of theory, practice and literature came to an abrupt and gro­tesque end in 1936 with the start of the great purges. The head of the army’s rocket programme, Marshal Tukhachevsky, was seized, charged with treason and shot, all within a matter of hours. Sergei Korolev was sent off to the gulag and Glushko was put under arrest for six years. The leaders of GDL, Langemaak and Kleimenov, were shot. Most other engineers were put under house arrest and very few escaped the wrath of Stalin in some shape or form (lucky Tikhonravov was one of them). The amateur societies were closed down. Fortunate was Tsiolkovsky not to see all this, for he died in old age in 1935.

The survivors of the Gulags were let out – or kept under a relaxed form of arrest – to contribute to the war effort. Rocketeers now put their talents to work in aircraft design to win the war against Germany. Their real shock came in 1944 when they learned of the progress made by Germany in rocket design. Mikhail Tikhonravov was one of a team of Russian scientists to visit Poland in August 1944 behind then rapidly retreating German lines. They went there on foot of intelligence reports sent to Britain which indicated that Germany was developing a rocket weapon. Following the RAF attack on the main German launch site at Peenemunde, Germany had moved testing to an experimental station in Debica, Poland, near the city of Krakow. Polish agents had found the launch and impact sites there and had managed to salvage the remains of the rocket, including, crucially, the engine. British prime minister Winston Church­ill asked Stalin to facilitate access by British experts to the site, though this meant of course that Stalin’s experts would benefit equally from what they found. They found that Germany had stolen a march on them all and under the guidance of their chief designer, Wernher von Braun, had launched the world’s first real ballistic rocket, the A-4, on 3rd October 1942. A month after Tikhonravov’s visit to Poland, the first A-4s were fired as a military weapon. Over 1944-5, the A-4, renamed the V-2, was used to bombard London and Antwerp. The Germans had also moved ahead with sophis­ticated guided missiles (like the Schmetterling) and anti-aircraft missiles (like the Wasserfall) and were far advanced in a range of related technologies. In early 1945, the Red Army swept into the development centre of the A-4, the Baltic launch site of Peenemunde.

The 3rd August 1964 resolution On work involving the study of the moon and outer space should have settled the Soviet moon plan. On the surface of things, it not only set the key decisions (lunar landing, around the moon) but the method all in one go. By contrast, the Americans had decided how to go to the moon in two stages, taking the decision in May 1961 and settling on the method, LOR, in autumn 1962.

In reality, the decision of August 1964 settled much less than it appeared. Many of the parties involved continued to fight for the decisions of August 1964 to be remade. Korolev would not accept the allocation of the around-the-moon project to Chelomei and spent much of 1965 trying to win it back to his own design bureau, with some success. For his part, Chelomei began to present the UR-700 as an alternative to the rocket designated for the moon landing, Korolev’s N-1.

Whereas the Americans had debated between Earth orbit rendezvous, lunar orbit rendezvous and direct ascent, the debate in Russia was over which rocket to use: Korolev’s N-l; Chelomei’s UR-700; or Mikhail Yangel’s R-56. Despite the govern­ment decision of August 1964, these were still in contention.

Russia’s three ways to go

Korolev design bureau (OKB-1) N-l

Chelomei design bureau (OKB-52) UR-700

Yangel design bureau (OKB-586) R-56

Korolev’s N-l

Korolev had originally planned the N-l as a rocket which would send large spaceships unmanned, then manned, on a flyby of Mars. The concept of the N-l dated to the period 1956-7 and was refined over the next number of years by Mikhail Tikhon­ravov, Gleb Yuri Maksimov and Konstantin Feoktistov. Whereas the R-7 could lift four tonnes into Earth orbit and was a huge advance in its day, the N-l was designed as a great leap forward to put 50 tonnes into orbit. Early designs assumed that the N-l would be used for the assembly of a manned Mars expedition in Earth orbit. This would be for a Mars flyby, rather than a landing, much like Korolev’s early designs for the moon. The 50 tonnes were gradually revised upward to 75 tonnes. Several such Mars proposals were developed in OKB-1 over 1959-67, based first around the assembly of 75-tonne interplanetary spaceships in Earth orbit [6].

N-1 was now adapted for a manned flight to the moon, though designers kept, in their bottom drawer, plans to redevelop the N-1 for a Mars mission, the N-1M. Korolev completed his design for the lunar N-1 on 25th December 1964.

The N-1 concept was reshaped around lunar orbit rendezvous, the same tech­nique as that used by the Americans, although there were some differences in the precise detail. In the early stages, a double N-1 launch was considered necessary, with Earth orbit rendezvous preceding the flight to the moon, but this was seen as too complex, not essential and was eventually dropped. The tall N-1 was similar in dimensions to the American Saturn V, being almost exactly the same height. Unlike the Saturn V, the N-1 used conventional fuels (liquid oxygen and kerosene), which required a large number of engines of modest thrust, 30 altogether. The performance of the N-1 was inferior, able to send only two men to the moon and put only one on its surface.