NOW TO THE LUNAR HIGHLANDS

Chief designer Georgi Babakin lived long enough to see the triumph of Lunokhod. He died suddenly in August 1971, aged only 57 and at the very height of his powers. His replacement was N-1 rocket engineer Sergei Kryukov. Sergei Kryukov was born 10th August 1918 in Bakhchisarai in the Crimea, his father being a sailor and his mother a nurse. His mother was ill throughout his early years and died when he was eight. Young Sergei spent much of his childhood in an orphanage, but relatives eventually removed him and ensured he got an education. He caught up quickly, entered Stalingrad Mechanical Institute in 1936 and then its artillery facility, continuing to work there even as the city was under German siege. With the war over, he continued his education in the Moscow Higher Technical Institute while getting work in the # 88 artillery plant there. No sooner had he started than he was transferred to Germany, his task being to reverse-engineer the world’s first surface-to-air missile, the Schmetter – ling, which for the Russians was as important as the A-4 surface-to-surface missile. On his return, he transferred to work for Sergei Korolev in OKB-1, where he developed the R-3, R-5 and R-7 rockets, being number four in the design of the R-7 after Korolev, Tikhonravov and Mishin. His contribution was recognized by an Order of Lenin.

His experience with the R-7 was a useful base for working in Lavochkin. After the R-7, Kryukov went on to work on upper stages, principally the Molniya’s block I and block L. Assigned to develop the block D for Proton and the N-1, he fell out with Vasily Mishin in 1970, but then managed to transfer to NPO Lavochkin, never imagining that within a year he would become director. He had two deputies: one was responsible for moon probes (Oleg Ivanovsky), while the other was put in charge of planetary probes (Vladimir Perminov).

By the time the Luna 17/Lunokhod mission ended, another Ye-8-5 mission had been dispatched. Luna 18 was launched on 2nd September 1971. After a perfect journey to the moon, it entered a circular lunar orbit of 101 km, inclination 35°, 1 hr 59 min. This was lowered to a pre-descent orbit of 100 x 18 km and it fired its braking rockets over an area just north of the Sea of Fertility on 11th September. The small thruster rockets tried to guide it into a suitable landing site, but the fuel supplies gave out and it crashed. Not even Radio Moscow felt able or thought it worth its while to invent a cover-up story. Something like ‘testing new landing techniques’ may have been considered, but this time it admitted that the landing had been ‘unlucky’ in a ‘difficult and rugged’ upland area. Although the term ‘failure’ was not explicitly used, it was one of the few early occasions on which the Russians did not pretend that all mission objectives had been attained. Some scientific data were even obtained from the mission, for scientists were able to infer the density of the lunar soil from the altimeter system and the outcomes were published four years later.

The intentions behind Luna 18 became clear when its backup vehicle was sent aloft on 14th February 1972, entered circular lunar orbit of 100 km on the 18th, 65°, 1 hr 58 min. Luna 20 made a pre-descent orbital firing the following day, bringing it into a path of 100 x 21 km, 1 hr 54 min. The sharper inclination of 65° may have given Luna 20 a safer approach route to the landing site. Luna 20 fired its engines for 267 sec to come in for a landing late on 21st February. This was the critical stage and it had gone wrong twice before. Luna 20’s final orbit had a perilune of 21 km. Once this final engine deadstop blast finished, 1.7km/sec had been cut from velocity and Luna 20 made a rapid descent, coming down at 255m/sec, much faster than Luna 16.

Luna 20 was coming down right on the top of uplands. The Sea of Fertility lies on the right of the moon’s visible face and Luna 16 had landed on one of its flattest parts. To the north, hills rise and there are soon mountains 1,500 m high. It was in a small plateau between two peaks where Luna 20 was aimed, less than 1,800 m from where its predecessor had come to grief on a sharp slope. The area is called Apollonius. It was tougher than anything the American Lunar Module would have tried. Because of the much higher descent rate, the propulsion system fired sooner – at 760 m – and Luna 20 made it, whether through luck or skill we do not know.

And so it came to rest, straddled by towering mountain peaks. Signals at once indicated to relieved controllers that it was safe and secure. Within seven hours, aided by a small television camera, its drill was hard at work scooping up lunar soil. Unlike Luna 16, Luna 20 landed in daylight and a picture of the drilling was subsequently published in the Soviet press [8]. Two cameras were installed on the landing stage, with a viewing angle of 30°. The drill rotated at an anti-clockwise 500 r. p.m., cutting away with sharp teeth which put material into a holding tube. It had two engines: one for the main drilling, but a second to take over if it faltered. The drill was kept sealed until the moment of drilling began, for it was important to keep it lubricated right up to the moment of operation. If it were exposed to a vacuum too early, there was the danger that the lubricant would evaporate.

The drilling operation took 40 min and was photographed throughout. The rig encountered stiff resistance at 10 cm and operations had to stop three times, lest it overheat. When it reached 25 cm, the samples were scooped into the return capsule to await the long journey home. The retrieval took 2hr 40 min in the end and was probably the most difficult of all the sample recovery missions. The conditions were undoubtedly tough and the sample probably much smaller than hoped for.

The cameras swivelled around to take an image of the surrounding moonscape, with Earth rising in the distance. The onboard computer fired the engines early on 23rd February and the return vehicle climbed away from the lunar peaks. Once again, the Kazakhstan landing site required a lunar liftoff when the moon was over the Atlantic. So, 2.84 days later it headed into reentry, the small cabin separating 52,000 km out. Amateur trackers picked up signals from Luna 20 growing in strength as it approached the Earth. Both the ascent spacecraft and the cabin came in quite close to one another, signals fading out only 12 min before touchdown [9].

Despite a steep reentry angle of 60°, twice that of Luna 16, only 5 mm of ablative material burned away. An appalling blizzard hit the recovery area that day. Heli­copters spotted the tiny capsule – parachute, antennae and beacon deployed – heading straight into the Karakingir River some 40 km northwest of Dzhezhkazgan at 48°N, 67.6°E. Would the precious samples be lost at this stage? Luckily, the capsule came to rest on an island in the middle of the river and in a snowdrift and trees. But getting it back was easier said than done. The gale was too severe for the helicopters to land. Four cross-country vehicles tried to get across on the ice but it cracked so they called it off for fear of falling in. Their crews eventually retrieved the battered and burnt capsule the next day when the wind abated. Its contents were opened at the Academy of Sciences. They were surprisingly small – between 30 and 50 g. But it was moondust all the same and the light ash-gray dust was 3bn years old. The records state it consisted mainly of anorthosite, with olivine, pyroxene and ilmenite. High-quality non-rusting iron was found, one of the most interesting findings. The colour was lighter and had more particles than the previous sample. Luna 20’s samples had the highest content of aluminium and calcium oxides of all the moon samples. Two grams of Luna 20 samples were exchanged with American Apollo 15 samples. The Amer­icans were able to provide accurate dating of the Soviet sample. Seventy chemical elements were found, with an average density of 1.15g/cm3.