REDIRECTION: THE N1-L3M PLAN

The Soviet plan for lunar exploration was now decisively redirected. Vasili Mishin now devised a moon plan even more ambitious than that of Apollo. He decided to match the three days of two Apollo astronauts on the moon with a Soviet plan to put three cosmonauts there for a month. The new Mishin plan, called the L-3M (‘M’ for modified) envisaged a manned lunar mission with two N-l rockets. The N-l would be upgraded with a more powerful hydrogen-powered upper stage. The exact date on which the L-3M plan was adopted is uncertain. The programme was first mooted in September 1969, clearly a first response to the American moon landing two months earlier, and the title ‘L-3M’ first appeared in print in documents in January 1970. The project was scrutinized by an expert commission under Mstislav Keldysh in spring 1971, and a resolution of the chief designers Technical proposals for the creation of the N1-L3M complex was signed off on 15th May 1972.

The first N-1 would place a large 24-tonne lunar lander descent stage, the GB-1, based on block D, in lunar orbit. Independently, a second N-1 would deliver a three – man lunar lander and return spacecraft, GB-2, to link up with the descent stage. Together they would descend to the lunar surface. Initially, three cosmonauts would work on the moon for a full lunar day (14 Earth days) but this would be later extended to be a month or longer. Eventually, four cosmonauts would live on the moon for a year at a time. The ascent stage would have a mass of 19.5 tonnes on launch from the moon and 8.4 tonnes during trans-Earth coast. Launch would be direct back to Earth, like Luna 16, without any manoeuvres in lunar orbit. The lander would incorporate Soyuz within what was called a cocooned habitation block, or OB, a sort of hangar. The crew could climb out of Soyuz into the hangar, put on their spacesuits there and use the hangar as a pressurization chamber before their descent to the lunar surface. The Americans might be first to the moon, but the Soviet Union would build the first moon base. Mishin envisaged the dual N-1 mission taking place in the late 1970s. Mishin’s new plan even won the approval of long-time N-1 opponent, Valentin Glushko. At one stage, the Soviet military considered turning the moon base into their first military headquarters off the planet [16].

An important feature of the N1-L3M was the redesign of the N-1 launcher, given the tentative name of the N1-F (industry code 11A52F). The airframe was much improved and there was a hydrogen-powered upper stage. The top part of the rocket, needle-shaped for the early N-1, was now bulkier and broader. The fact that Russia successfully developed a hydrogen-powered upper stage during the 1960s was one of the last, well-kept secrets of the moon race. The West had not believed the Russians capable of such a development, and it did not come to light until India bought a hydrogen-powered upper stage from the Russians in the 1990s. In fact, we now know that Russia had worked on hydrogen propulsion from 1960 onward and that hydrogen-powered stages had been part of the 1964 revision of the Soyuz complex in OKB-1. This research had continued to progress and by the late 1960s was reaching maturity. Linking this research to the new, improved N-1 made a lot of sense.

The hydrogen motor was the KVD-1, built by the Isayev design bureau (KVD stands for Kislorodno Vodorodni Dvigatel, or oxygen hydrogen engine). The role of the KVD-1 was to brake the assembly into lunar orbit and make the descent to the lunar surface. The KVD-1 engine had a burn time of 800 sec and a combustion chamber pressure of 54.6 atmospheres. The KVD-1 had a turbopump-operated engine with a single fixed-thrust chamber, two gimballed thrust engines, an operating period of up

to 7.5 hours and a five times restart capability. It weighed 3.4 tonnes empty and 19 tonnes fuelled. Its thrust was 7,300 kg and the specific impulse was 461 sec, still the highest in the world at the end of the century. It was 2.146 m tall, 1.28 m diameter and weighed 292 kg. It was sometimes called block R and had the industry code of 11D56.

The Isayev bureau was one of the least well-known of all the Soviet design bureaux and featured little in the early glasnost revelations about the Soviet space programme, its design bureaux and rocket engines. The bureau started life as Plant #293 in Podlipki in 1943, directed by one of the early Soviet rocket engineers, Alexei Isayev. Born 11th October 1908 (os) in St Petersburg, he was a mining engineer and had been given his own design bureau in 1944. This was renamed OKB-2 in 1952, being given its current name, KM KhimMach, in 1974. Besides spacecraft, its work has concentrated on long-range naval, cruise and surface ballistic missiles and nuclear rockets, and by the early 1990s had built over a hundred rocket engines, mainly small ones for upper stages, mid-course corrections and attitude control.

The KVD-1 prototype was first fired in June 1967. The engine was later tested for 24,000 sec in six starts. Five block R stages were built and tested over the years 1974-6 and the engine was declared fully operational. In fact, the KVD-1 was not the only Soviet hydrogen-powered upper stage. Nikolai Kuznetsov also struggled with a hydrogen-powered upper stage engine called the NK-15V, with a thrust of 200 tonnes, which would replace block B. OKB-165 of Arkhip Lyulka also developed engines for the third stage and fifth stage, respectively, 11D54 and 11D57 or block S. A scale model was built of a revised N-1 with hydrogen upper stages [17]. Approval was given for these developments in June 1970.

A new engine and new fuel were developed for the N1-L3M lunar module. Here, under Vasili Mishin, Valentin Glushko’s OKB-486 design bureau made a belated appearance in the N-1 programme. Valentin Glushko designed the new RD-510 engine, with 12 tonnes thrust [18]. The fuel was hydrogen peroxide, also called High

Test Peroxide (HTP). Only one other country in the world used hydrogen peroxide for its space programme: Britain, for its Black Arrow rocket. Hydrogen peroxide actually went back to wartime Germany where it had been developed by Dr Hellmuth Walter for high-speed U-boats.

Like Glushko’s favourite fuel, nitric acid, hydrogen peroxide could be kept at room temperatures for long periods. Hydrogen peroxide had one advantage over nitrogen-based fuels: it did not require the mixing of a fuel with a oxidizer. It was a monopropellant, requiring one tank and a means of igniting the rocket (metallic filings were inserted). There was no need to mix in the product of two tanks in a very precise ratio to get the desired thrust. Nor was HTP toxic, but it could be equally dangerous in another way. HTP must be kept in absolutely pure tanks and fuel lines, otherwise it will decompose or, if mixed with particular impurities, would explode. HTP was later used to fuel the torpedoes on the Russian submarine Kursk, with disastrous results when they exploded in August 2000.