FlightGlobal.com
Home
Premium
Archive
Video
Images
Forum
Blogs
Jobs
Shop
RSS
Email Newsletters
You are in:
Home
Aviation History
1972
1972 - 0553.PDF
FLIGHT International. 9 March 1972 Luna 20 LCNA 20 has successfully returned to Earth with a sample of lunar soil which may prove to be pure bedrock • material. The mountainous terrain on which the spacecraft landed, more difficult than any attempted or planned under the Apollo programme, is thought by Soviet scientists to be unadulterated by the lunar ejecta which litters the sites of previous visits. Soviet reports of the flight paid some attention to the drilling equipment, indicating substantial improvement on that of the earlier mission. The drill was described as a rotary-percussion device able to collect both soft and hard rock. The designers evidently found the Luna 16 drill too weak. They also admit problems with thermal control, saying that the Luna 16 operation was affected by the temperature of the drilling rig itself, which was therefore thermally isolated on the latest model. The rig was hermetically sealed, to prevent vacuum welding, and depressurised immediately before operation. The drill and moving parts were lubricated and cooled with an oil which evaporates in vacuum. The length of the drill was not specified, but that on Luna 16 measured 35cm. In spite of all this, the operators still experienced some difficulty. The rock was evidently harder than anticipated, causing the drill to slow down at 10cm depth. It was halted for a while, probably to cool, and then taken on to a depth of 15cm. It was not clear whether the drill reached its full depth. The sample was then transferred to the recovery capsule on top of the spacecraft assembly where it was hermetically sealed. The drilling spot was selected by means of a television camera. The drill arm was moved to a vertical position and then turned outwards before being lowered to the surface. The return vehicle did not, however, lift off for 20hr after drilling was completed, presumably while further experiments were carried out. Academician G. Petrov confirmed in a Pravda report that the lander section was designed as a standardised delivery platform. It was first used for Luna 16 in Septem ber 1970. The Earth weight after lunar landing, including the return vehicle and its fuel load, was 4,1501b, 1,880kg. No weight or exact dimensions have been given for the separate vehicles but the lander's second payload, that of the Lunokhod rover, weighed 1,5401b, 700kg. The weight of Luna 20 has not been announced. The mission began on February 14. Following standard Soviet procedure, the spacecraft was placed into Earth orbit with an orbital platform from which it was launched into its trajectory. A single mid-course correction was carried out the following day 18,600 miles, 30,000km out. The spacecraft went into lunar orbit on February 18. Landing procedures were detailed considerably more than usual. Initial orbit was circular at 62 miles, 100km altitude, inclined at 65° with a lhr 58min period. On February 19, this was lowered to a descent orbit of 62 miles X 13 miles, 21km, where the spacecraft continued for a further two days of site-selection photography and orbital experiments. At 1913 GMT on February 21 the main engine was fired for 4min 27sec, after which the spacecraft was allowed to fall to an altitude of 2,500ft, 760m. The main engine was then turned on again and guided the spacecraft down to a height of 66ft, 20m. At this point a small land ing engine cut in to lower Luna 20 on to the surface at 1919 GMT. The entire descent from 13 miles took six minutes. The final rate of descent of Luna 16 was 8ft/sec but no comparable figure was given for Luna 20. The landing site lies to the north-east of the Sea of Fertility and some 75 miles, 120km north of where Luna 16 landed. Lunar co-ordinates of the landing site are 3° 32'N, 56°33'E, a point near the edge of the Apollonius mountains. The spacecraft stood on a plateau rising steeply from the edge of the mare about 3,300ft, 1,000m below. Difficulties of the terrain included craters several hundred metres in diameter. It was in similar terrain that Luna 18, thought to have also been a soil collector, was lost on landing when it was believed to have toppled over. Their positions differ only by 2' latitude and 3' longitude. Lift-off of the return vehicle occurred at 1058 GMT on February 22, the spacecraft accelerating to 2,700m/see or 16,106 m.p.h., 25,919km/hr, and, following a high- velocity return, it approached the Earth on February 25 at a speed close to Earth escape velocity. The capsule then separated and entered the atmosphere at a 30° angle, very much shallower than the 60° re-entry angle of the Luna 16 capsule. It touched down at 1912 GMT on February 25. An unprecedented amount of information on recovery operations included the exact location of the landing site on an island in the Karakingir river about 40km north-west of Dzhezkazgan in Kazakhstan. The landing was made at night during a blizzard but the descending capsule was spotted from a tracking aircraft. Helicopters then guided An Apollo-style pennant was carried by Luna 20 (above). The drawing of Luna 20, below, shows it to be very similar in design and operation to Luna 16. The shading indicates the arc of movement for the drill arm. Key: I landing-stage instrument bay; 1 attitude-control thrusters; 3 return-vehicle fuel tanks; 4 VHF antenna; 5 return-vehicle instrument bay; 6 recoverable capsule; 7 drill container; 8 drill arm; 9 television camera; 10 landing-stage fuel tanks; 11 landing-stage main engine nozzle
Sign up to
Flight Digital Magazine
Flight Print Magazine
Airline Business Magazine
E-newsletters
RSS
Events
