DESIGNING A LUNAR ROVER

Although the Lunokhod was portrayed by the Soviet Union as a safer, cheaper alternative to the manned Apollo missions, in fact the Lunokhod long pre-dated Apollo. Originally, Lunokhod was an integral part of the manned Russian lunar programme. Moon rovers were to pave the way for manned landings by surveying sites before cosmonauts landed, the L-2 programme. They would leave beacons to guide the LK landing ships in. Later, bigger rovers would be landed and cosmonauts were expected to ride them across the moon (the L-5 programme).

The moon rover was originally designed in Korolev’s OKB-1. The preliminary studies were done by Mikhail Tikhonravov in I960. When the Americans first landed a rover on Mars, the Sojourner (1997), it was tiny. By contrast and in typical Soviet style, the Russians started large. Korolev’s team determined that the rover should be at least 600 kg, the size of a small car. This would require a launcher much larger than the Molniya then in design, so Korolev made it a candidate for an early version of the N-1 rocket. Korolev issued the order for the construction of a moon rover in March 1963, but the project progressed slowly and was set back when later that year the state Institute for Tractor and Agricultural Machinery Building declined to develop it, deeming the project to be ‘impossible’.

So, later in 1963, Sergei Korolev instead turned to VNII-100 Transmash of Leningrad, or the Mobile Vehicle Engineering Unit [3]. In September of that year, Korolev met with VNII Transmash engineers to go through the possibilities.

Alexander Kemurdzhian

Transmash designed tanks for the Red Army – indeed, during the siege of Stalingrad, tanks were sometimes rolled out of the factory straight up to the front line. The important role of Alexander Kemurdzhian in the Soviet lunar programme emerged only in recent years. He was born on 4th October 1921 in Vladikavkaz and entered the Bauman Technological College in Moscow in 1940. When the war broke out, he went to Leningrad Artillery College and participated in some of the epic battles of the war, such as the crossing of the Dniepr. After the war, he worked on truck design, specializing in transmission systems, for which he obtained a doctorate in 1957. Two years later, he moved into the new area of air cushion vehicles (hovercraft). Kemurdzhian had a personal interest in spaceflight (something he made dear to Korolev) and saw the potential for remote-controlled vehicles exploring the planets. The rover project was no sideshow, for in 1964 it won approval – as the L-2 programme – in the 1964 government and party resolution committing the Soviet Union to going to the moon.

The conceptual study was completed in six months, by April 1964. One of the first problems faced by the designers was the load-bearing capacity of the lunar soil, for this would govern chassis, power systems and wheel design. Until such time as soft – landers tested the surface, it would be impossible to know the answer for definite. In an attempt to make the best possible estimate, a conference of lunar and astro­nomical experts were gathered at Kharkov University that year, hosted by Professor Barabashev and also attended by Professor Troitsky of Gorky University and Pro­fessor Sharanov of Leningrad University. In the event, their estimates were broadly

Moon rover on test

correct, being confirmed by Luna 13 two years later. First design sketches were concluded in September 1965.

The rover project was turned over, along with all the other unmanned lunar and interplanetary programmes, to OKB Lavochkin in 1965. Kemurdzhian worked closely with the director of OKB Lavochkin, Georgi Babakin, to finalize what was then called in 1966 the Ye-8. The Ye-8 was originally intended to pave the way for the manned lunar landing. Before the first Ye-8 landed, suitable sites would first be selected by a close-look lunar orbiter. To do this, a version of the rover was adapted for a photography mission in lunar orbit to select a main landing site for the lunar landing, but there was also a reserve one nearby, not more than 5 km distant. Two Ye-8s would then be landed, one at the main site, one at the reserve. These would confirm the suitability of both sites for the manned lunar landing. In an elaboration of the plan, an unmanned LK would be landed near the rover at the reserve site and checked out to see that it was in good working order. If when he landed his LK was disabled, the sole cosmonaut could travel to the reserve LK to return to Earth. In a further version, the cosmonaut could use the rover to travel across the lunar surface from the main site to the reserve site.

A number of designs using different numbers of wheels were considered in the course of 1965-6. The designers considered tractors, walkers and even jumpers, from caterpillar to four-wheel designs. The very first rover design was for a dome carried on four caterpillar wheels, very like a tank. The first rovers were designed to weigh nearly a tonne, about 900 kg. When it was apparent that the N-1 would not become quickly available, the Ye-8 was scaled down so that it could be accommodated within Chelomei’s UR-500K Proton. The final rover design was for an unmanned rover. In a further modification of the original plan, the Ye-8 would be launched before the Ye-8LS lunar orbiter, the opposite of what had been intended.

The rover design was settled in 1967 and a 150 kg scaled prototype was constructed in Leningrad that year. A version was tested in the volcanic region of Kamchatka in the Soviet far east, which was the Earth’s surface closest in character to the moon. Models were tested in the Crimea and early versions of the transmission gears and wheels were flown out to the moon on Luna 11 and 12 in 1966 and Luna 14 in 1968. Even though it had been scaled back, the final rover was still a substantial piece of engineering. The vehicle, to be called ‘Lunokhod’ or ‘moon walker’ in Russian, weighed 756 kg and was 4.42 m long (lid open), 2.15 m in diameter and 1.92m high. Its wheel base was 2.22 m by 1.6 m. The main container was a pressurized vehicle, looking like an upside down bathtub, carrying cameras, transmitters and scientific instruments. It was kept warm by a small decaying radioisotope of 11 kg of polonium-210. The eight 51 cm diameter wheels were made by the Kharkhov State Bicycle Plant, made of metal with a mesh covering. There was a ninth wheel behind the vehicle to measure distance. Each wheel had its own electric motor. In the event of one wheel becoming completely stuck, a small explosive charge could be fired to sever it. The vehicle was designed to climb slopes of 20° and manage side slopes of 40 to 45°. The main designers were, aside from Kermurdzhian himself, Gary Rogovsky, Pavel Sologub, Valery Gromov, Anatoli Mitskevich and Slava Mishkinjuk.

To guide the route chosen, Lunokhod had four 1.3 kg panoramic cameras similar to those on Luna 16 to scan 360° around the rover and two television cameras to scan forward, with a 50° field of view and 1/25 sec speed. The scan of the panoramic cameras was designed in such a way as to cover the horizon right around to parts of the rover and its wheel base. They provided high-resolution images, 6,000 x 500 pixels. Signals were sent back by both an omnidirectional and narrow-beam antenna. The driving camera relayed pictures back to Earth every 20 sec and these enabled a five-person ground crew to drive the Lunokhod: commander, driver, navigator, engineer and radio operator. The rover could go forwards or backwards. Gyroscopes would stop the rover if it appeared to tilt too much forward or backward or to one side.

The selection of the ground crew was an important part of the programme. Two five-man crews were selected from the Missile Defence Corps in 1968 [4]. Volunteers were sent for tests for speed-of-reaction times, short and long-term memory, vision, hearing and capacity for prolonged mental focus and attention. At one stage of their recruitment, they thought they were being trained as cosmonauts. They were under strict instructions not to talk about their work to outsiders. Years later, their names became known. They had been recruited by the Strategic Rocket Forces in the late 1960s when the call had gone out for ‘top class military engineers. Young but experienced. Sporting and in a good state of health.’ Twenty-five were chosen and sent to Moscow for a special mission, they did not know what. They were put through a series of tests in the Institute for Medical and Biological Problems, where the group was reduced by eight. Then, the seventeen remaining were told that they would be driving machines across the surface of the moon, whereupon three resigned, saying that the responsibility and stress would be too much for them. The fourteen remaining were divided: half were sent off to Leningrad to the VNII-100 design bureau where the Lunokhod was built and the other half were assigned to work on the design with the Lavochkin design bureau. In 1968, construction began of a ‘lunardrome’ in Simfer­opol in the Crimea, and the driving teams spent the rest of the year there learning how to drive a Lunokhod model.

Table 7.1. The Lunokhod operators First crew Second crew Commander Nikolai Yeremenko Igor Fyodorov Driver Gabdulkay Latypov Vyacheslav Dovgan Navigator Konstantin Davidovsky Vikentiy Samal Engineer Leonid Mosenzov Albert Kozhevnikov Radio, antenna Valeri Sapranov Nikolai Kozlitin Reserve Vasili Chubukin

Luna 17 descent stage

Lunokhod carried a number of scientific instruments: a French-built 3.7 kg laser reflector, designed to measure the precise distance between Earth and the moon; a RIFMA X-ray fluorescent spectrometer to determine the composition of moonrock; an X-ray telescope; a cosmic ray telescope; and a penetrometer. An energetic particle detector was built by Dr Yevgeni Chuchkov of the Theoretical and Applied Physics Divison of the Skobeltsyn Institute of Nuclear Physics of the Moscow State Univer­sity, calibrated against similar instruments flown on Zond 1 and 3 and the early Mars and Venera probes.

To get Lunokhod onto the lunar surface, the KT stage was used, of the same type as Luna 15 and 16. This was a frame-shaped spacecraft with a toroidal fuel tank; radar; attitude thrusters; 11D417 engine of between 0.75 and 1.92 tonnes of thrust for mid-course correction, lunar orbit insertion and landing; batteries; and communica­tions. The Lunokhod rested atop the descent stage, and – when the moment came – landing ramps would deploy at either side so the rover could descend to the moon at an angle of up to 45°.

Lunokhod instruments

Laser reflector.

RIFMA (Roentgen Isotopic Fluorescent Method of Analysis) X-ray fluorescent spectrometer. Extra-galactic X-ray telescope.

Cosmic ray background radiation detector.

PrOP (Pribori Ochenki Prokhodimosti) penetrometer.

Ultraviolet photometer (Lunokhod 2 only)

Any benefit that was gained by the success of Luna 16 was turned to double advantage just two months later by Luna 17. The sample return, pushed to the back page by the eruption of political violence in the Middle East, had made little public impact. The same could not be said of its successor, put up on 10th November 1970. The spaceship weighed about 5,750 kg.