Third Generation Lunars

By Charles S. Sheldon II[1917-1981], was Chief of the Science Policy Research Division of the Library of Congress, Congressional Research Service

1971-1975

THE THIRD GENERATION of LUNAR FLIGHTS

The first generation of lunar flights used the A-l class of vehicle for direct injection into flight toward the Moon. This permitted the sending of about 400 kilograms and limited the variety of missions which could be performed. As explained earlier in this study, the fairly northern location of Tyuratam also limited the Soviet capacity to fly many space missions by the direct injection technique. So they shifted to the more powerful upper stage and to the orbital launch platform technique so that the escape path could be initiated near or over Africa .

This second generation system using the A-2-e raised the capacity of the basic rocket to send as much as 1.600 kilograms to the vicinity of the Moon. Within the limits of this newer basic craft, the Russians were able to accomplish a number of scientific and engineering "firsts". They had already been the first to fly by the Moon, to strike the Moon, to take photographs of the far side. Now they added the first survivable camera landed on the surface, the first orbit of the Moon, and the first pictures from orbit. The first generation flights had included Luna 1 through 3; the second generations were those of Luna 4 through 14, plus some unacknowledged partial failures in Earth orbit.

The weights carried by the second generation were still too small to carry out additional automated missions the Russians had in mind. The creation of the Proton or D class of vehicle with added upper stages provided the opportunity to do more. The new D-l-e class of launch vehicle was first committed to a program to send men around the Moon. These Zond flights, numbered 4 through 8 before the program was abandoned, are treated in a separate area of the web site.

A. LUNA 15

As the summer of 1969 approached, the Americans had already had their previous Christmas flight of Apollo 8 to lunar orbit, and in the spring had practiced rendezvous operations in lunar orbit with Apollo10. The Soviet Union had its full crop of rumors, confident predictions, and contradictory accounts about what the Russians were going to do to offset or even beat the upcoming Apollo 11 flight to the Moon with the goal of landing men for the first time. These rumors and their possible validity are treated in a different section.

By late June or early July there were rumors in Moscow that the Russians were about to do something spectacular within a few days related to the Moon. Several accounts tied these rumors to the big G-l-e vehicle in the Saturn V class. Rumors say it was launched, but failed to reach orbit. It is known that tracking ships which had been on station in various oceans including the Indian Ocean shortly departed their stations for port. But despite this possible setback, a different kind of important launch came on July 13 from Tyuratam. It used the D-l-e vehicle and was named Luna 15. It was put into the usual kind of intermediate orbit from which it was sent toward the Moon. The typical midcourse correction was executed on July 14 and on July 17, it was braked into lunar orbit. Apollo 11 was launched with its human crew toward the Moon on July 16, with the target date of July 20 for landing on the surface. The Soviet flight and its successors of the same series flew a slower course than used previously in order to maximize payload capacity, despite use of a more powerful launch, vehicle.

There was some concern in the United States as to whether this somewhat mysterious flight, whose detailed goal had not been revealed, would interfere with the manned mission. All the Russians had said was that Luna 15 was designed to study the space around the Moon, the gravitational field of the Moon, the chemical composition of lunar rocks, and provide surface photography. American astronaut Frank Borman who had recently been in the Soviet Union made a personal appeal to Soviet officials for the orbital elements which had not been announced at first, and asked for assurances that the flight would not interfere with the Apollo mission. He was given the orbital data of 203 by 55 kilometers, with a period of 120.5 minutes, and was told that there was no intention of endangering the Apollo flight.

On July 19, TASS announced an orbital change to an inclination of 126 degrees, with the orbit ranging between 221 and 95 kilometers, with a period of 123.5 minutes. On July 20, this was modified again to an inclination of 127 degrees, and the range from 110 to 16 kilometers, with a period of 114.0 minutes. This happened just before the landing of Apollo 11. It looked like either a Soviet readiness to take high resolution pictures of future landing sites, or a preparation for an immediate landing by Luna 15 itself. The next Soviet announcement came on July 21, while the Americans were on the lunar surface. Luna 15 had fired a retrorocket and had "reached" the lunar surface in the "preset" area. A total of 86 communications sessions had been held with the craft and it accomplished 52 revolutions of the Moon. The station was described as greatly improved over its predecessors, being able to land in many parts of the Moon through its orbital adjustment abilities. Even at the time there seemed little doubt from the wording of the Soviet statements that Luna 15 was intended to make a soft landing on the Moon to conduct further experiments, and in this it failed. The Jodrell Bank observatory estimated from the Doppler shift of signals that the payload impacted the surface of the Moon with a residual speed of about 480 kilometers an hour, which would seem a good confirmation that the mission was to slow it for a landing, not merely redirect it to impact.

Even with the advantage of hindsight, in the absence of a Soviet explanation, we have no conclusive answer as to the intended mission of Luna 15. On the one hand, there were the Moscow rumors of early July that the Russians would attempt an automated sample return flight, a mission accomplished later by Luna 16. But these rumors require further assessment which will follow in a later section of the web site of this report on manned flight. On the other hand, the flight might have been intended to land a roving vehicle as did Luna 17. Luna 15 and Luna 17 both flew in retrograde orbits while Luna 16 flew a posigrade orbit. Luna 15 and Luna 17 made landings in daylight portions of the Moon, while Luna 16 made a landing in the flights portion. Moreover, the geared electric motors for the Lunokhod drive had already been tested in lunar orbit on board Luna 12 and Luna 14. If the Russians were trying to beat the Americans in returning a lunar sample to Earth, they were cutting it very close by lingering four days in lunar orbit before collecting their sample, so that the sample collection would come after Apollo 11 had gathered samples, even though the Russians with an unmanned vehicle might have made a faster return flight.

B. KOSMOS 300 AND KOSMOS 305

Kosmos 300 was launched on September 23, 1969 to a low Earth orbit. The time of launch and the nature of the debris in Earth orbit both suggested another lunar flight had been attempted which was not successful in leaving Earth orbit. The payload survived separation from the orbital launch platform even though it did not go into deep space, because of the nature of the orbital maneuvers which it was able to make during its four-day life. Because the relation of this flight to phases of the Moon was not like Zond 7, but did resemble Luna 16 and 17, it is a reasonable supposition that this was another in the series begun by Luna 15, and was launched by the D-l-e vehicle.

Kosmos 305 was launched one lunar month after Kosmos 300, coming on October 22, 1969 . It may have been even less successful than its immediate forerunner, because the Russians did not announce an orbital period for the payload. This almost certainly means the payload decayed before the end of the first revolution. Some debris remained in orbit about two days, perhaps residue of the carrier rocket and the orbital launch platform of the D-l-e vehicle.

 

C. LUNA 16

Luna 16 was launched on September 12, 1970 at 1626 Moscow time, and entered a preliminary low Earth orbit from which it was fired- toward the Moon in the second half of its first revolution around the Earth about 67 minutes after launch, using the orbital launch platform technique. Left behind in orbit were the typical 4 meter-diameter by 12 meter-long stage and an irregular launch platform. This stage of about 4,000 kilograms was typical of the D-l-e.

A midcourse correction was made on September 13, and after 26 radio sessions with the payload, it was braked on September 17 into a low circular orbit of the Moon at 110 kilometers an inclination of 70 degrees, and a period of 119 minutes. Further orbital adjustments on September 18 and 19 brought the orbit to between 106 and 15 kilometers, and the inclination to 71 degrees. On September 20, the retrorocket was fired for final descent. At an altitude of 600 meters this engine was turned on again to begin the controlled landing. It was switched off at 20 meters, and two smaller engines were turned on to burn until the altitude was 2 meters. The descent had been controlled by a combination of pre-programmed instructions and radar altimeter measuring both distance and rate of descent. By this time 68 radio sessions with Earth had been held. At 0818 Moscow time, Luna 16 was safely on the surface of the Moon on the Sea of Fertility at 0° 41' S and 56° 18' E., as planned. To this point the mission of Luna 16 was still un-described, as were its size, appearance, and equipment.

The first pictures to be released after the landing proved to be only generally indicative of the craft—an artist's impression without reference to the real craft. Later drawings were much more detailed and eventually replicas were put on display, starting with Moscow on November 12, 1970 . The craft consisted of a multi-purpose, self-contained landing stage made up of various spherical tanks and cylinders bound together by open trusswork. It had four very short shock-absorber legs. In the lower center was a large bell-shaped nozzle for the main descent and maneuvering engine which was liquid fueled with a multiple burn capability. It was supplemented by two independent lower-thrust braking engines, and various small vernier engines for orientation. The device had chemical batteries and transformers, radios and their antennas to operate in several wave bands, optical and accelerometer sensors for orientation, gyros, computers, timing devices, a heat-regulating system, and a radar altimeter. Some equipment was in the main structure; others were in separate exterior compartments. Specialized to this class of mission, there was an extendable arm which could be controlled from Earth to reach out beyond the immediate blast area of touchdown. At the end of the arm was an elaborate drilling rig which could draw a sample of the lunar soil, and then manipulate it back for insertion into a special container. Telephotometers were placed to guide the Earth-bound remote operator of the drill rig.

Mounted on top of the multi-purpose landing stage was an ascent stage made up of spherical propellant tanks and a liquid-fueled main engine, plus vernier engines for steering. These were all fastened together by exposed trusswork. Atop the propulsion section was an instrument cylinder with its electronic computing equipment, various sensors, gyros, radios, chemical batteries, transformers, and 4 projecting radio antennas. Strapped to it was the actual recoverable portion, a sphere heavily protected by ablation material. Inside was the container to receive the lunar sample in its cylinder, packed parachutes, radio beacon, batteries, and antennas. It is hard to judge the true size of the total assembly of two stages and associated equipment, but it must have been close to the 4 meters diameter of the D-l-e rocket (also estimated as 3.72 meters), and also stood about 4 meters high.

Because the D-l-e vehicle is used for the third generation series of unmanned lunar programs, we can estimate the weight brought to escape speed to be on the order of 5,000 to 6,600 kilograms. After retrofire to slow into lunar orbit, the weight may lie in the range of 4,000 to 4,500 kilograms. Further braking to achieve a landing should give a number in the range of 1,800 to 2,000 kilograms. These are very rough estimates. In the case of Luna 16, the Russians finally announced a landed weight of 1,880 kilograms. (29)

As events of the flight unfolded at the time, no advance warning was given of the specific intended mission, but over the weeks following, more detailed accounts were made public. The first task of the craft, once on the surface of the Moon, was to review its own house-keeping functions to insure that all subsystems were in working order. It had to establish not only its exact location on the lunar surface, but also find the local vertical. Then the arm attached to the landing stage was extended out, generally beyond the immediate blast area of the braking rocket. Its special drilling unit, consisting of a hollow cylinder with cutters at the end went to work, with controllers on Earth sensing remotely how fast to cut in relation to the apparent hardness of the lunar material. The drill was allowed to cut into a depth of about 35 centimeters. The Russians are not certain whether at this point they reached bed rock or an isolated hard stone. But rather than risk damage to the equipment, drilling ceased. The sample in the tube consisting of soil ranging from fine dust to more granular sand was carried on the same sampler arm up to the ascent stage and inserted into the recovery capsule which was then hermetically sealed.

Then pre-programmed information plus instructions from Earth prepared the spacecraft for launch. After 26 hours and 25 minutes on the surface, the ascent stage took off at 1043 Moscow time on September 21, using the descent stage as its launch platform. The lower stage remaining on the Moon continued to broadcast to Earth data on local temperature and radiation conditions.

According to the Bochum radio space observatory in the German Federal Republic , strong and good quality television pictures were returned from the craft Such pictures were not made available in the United States either by Bochum or by any other source, so the report has to be accepted with reservations.

The return flight to Earth was made without midcourse corrections. In contrast to the Zond flights which were to have been precursors to manned flights, and hence made with as low a G-load, and as low heat load; return as possible from the Moon, the Luna 16 payload made a straight ballistic return to Soviet territory. The time and area of recovery was announced in advance by the Soviet Government. As it came closer, the ground complex calculated its point of return with increasing accuracy. On September 24, the recovery capsule with its sealed cylinder of lunar soil was separated by a pyrotechnic device from its lunar launch rocket, while approximately 50.000 kilometers from Earth. The capsule hit the dense atmosphere at 0810 Moscow time.

After aerodynamic braking, which put a 350 G-load on the capsule, and raised its surface temperature to about 10,000° C., it slowed down still more. At 0814 the braking parachute and then the main parachute were deployed, together with the antenna for the radio beacon. As it came down on its parachute at the predicted location, both aircraft and helicopters of the rescue force heard the radio beacon and made a visual sighting of the parachute. It landed at 0826, and soon was retrieved. The total flight has lasted 11 days, 16 hours.

The landing was announced about two hours after the event with the report the capsule had come through in good condition. No weight for the sample was given at that time. Western observers assumed it was fairly small, perhaps only a kilogram or so. Later it was revealed to be only 101 grams. Even so, this afforded an important resource to analysts in the Soviet Union . After the helicopter pickup, the special factory facility in the area removed the hermetically sealed container with the core sample from the capsule without re-pressurizing it. The container was then flown to Moscow to the major lunar receiving laboratory. As an aid to quarantine, the container was placed in a stainless steel chamber with glass portholes. Then pumps lowered the pressure to a high vacuum, following which sterilizing gas was introduced to kill any Earth germs on the exterior of the container. A variety of remote control devices, like those used at Houston, opened the core-containing tube, and passed portions of the lunar material to various sealed sub-laboratories equipped with more manipulators and chambers with built-in rubber gloves. Precision scales, electric heaters, binocular microscopes, vibration mills, and special sealed samples in separate bags for biologists and geochemists were all provided. Thin slices were polished to transparency for further detailed analysis. Any out-gassing from the lunar material was subjected to 800° C. heat to insure sterility.

The early descriptions of the actual material were very similar to those from Houston —some disagreement over the exact color, and clinging external dust on the container. The color had first been described as dark blue, but later was more generally called gray, with the appearance of being green or brown at some lighting angles. The average density was 1.2 grams per cubic centimeter in original condition, but shook down to about 1.8 grams. Analysis was continuing, and small samples were made available to scientists in other countries, including a direct exchange with the United States .

The many articles by Soviet scientists which discussed Luna 16 put heavy stress on the eventual use of the Luna 16 techniques for exploration of Mars, Venus, and the planetoids. While Luna 16 was extolled as cheaper for exploring the Moon than the manned Apollo flights, the Russians also stated that their exploration of the Moon would use several techniques in the future, including both automated devices and manned expeditions.

1. Comparative Cost of Luna 16 and a Typical Apollo Mission

The question of comparative costs has been raised in both Soviet and U.S. discussions, with some very wide-ranging estimates. There is no definitive answer, but perhaps a reasonable perspective can be suggested.

(a) In the first place, neither the U.S. nor the Soviet program has been aimed at purely scientific objectives. To the degree that their respective programs have been designed to build a general capability in space flight, or to create an image of success, or to fulfill non-quantifiable goals of exploration, no comparison of scientific returns in relation to the costs is statistically valid anyway.

(b) If one makes the arbitrary and even invalid assumption that the only goal sought is science, then there are still difficulties in the comparison. If the goal was simply to have brought home a token sample, this Soviet Luna approach is cheaper. But if the ability to bring home 101 grams is compared with many tens of kilograms on each flight, the U.S. unit cost per kilogram is lower. The Soviet sample was not only small, but was selected virtually at random. U.S. samples ideally were carefully selected for variety and interest, and could be

described and documented as to their original location. Our crews were capable of ranging over a fairly wide territory.

(c) No direct cost comparison is possible between Soviet flights and U.S. flights because the Russians do not make available cost data. Even if they did, very careful definitions would have to be drawn up as to whether costs related to total programs including their research and development, and what arbitrary share of joint costs should be allocated to a particular project such as for flight to the Moon. The closest approach one can make is to consider what it would cost us to conduct a Luna 16-type mission, and then perhaps to compare the out-of-pocket costs for this automated mission with an Apollo mission. The full analysis goes beyond the scope of this study, but a conservative estimate is that a manned Apollo round trip with the maximum amount of supporting equipment and doing many things besides bringing home rock sample? costs on the order of $450 million. Using the Saturn I B or Titan III E with Centaur stage, and new lunar landing and return stages would give an out-of-pocket cost of about $100 to $120 million for each Luna 16 type flight if the program contained as many flights as were planned for Apollo. This means an Apollo cost about four times as much as the equivalent of a Luna 16.An Apollo flight brings more than four times the variety and amount of scientific returns as one Luna 16 flight, regardless of the impressiveness of the Soviet automatic system.

(d) As will be developed later in this study, the Soviet Union did not go the Luna 16 route to save money compared with the manned lunar landing route. It also has spent the large sums needed to support a manned lunar landing, but has not produced the visible result in this regard which the United States has achieved. Looking beyond out-of-pocket costs, the United States committed about $35 billion to the Apollo program ($21.35 billion to achieve the first manned landing), and the Russians by spending for both an advanced unmanned and its two manned lunar programs (built around Zond and around the missing G-l-e) probably committed the equivalent of about $49 billon for such programs if these were intended to be of about the same scope and duration as the Apollo program of the United States. This country earlier had program planners who would have been very pleased to have the equivalent of the automated lunar programs undertaken by the Russians (called by the planners. Prospector), but the ultimate, decision was we could not afford as many program elements as the Russians have undertaken, and hence these Prospector plans were not implemented with hardware.

D. LUNA 17 AND LUNOKHOD 1

1. Flight of Luna 17

About two lunar months after the launch of Luna 16, Luna 17 was launched at 1744 Moscow time on November 10, 1970 . It followed the usual Soviet practice of entering an Earth parking orbit from which the usual Zond probe rocket was fired, leaving behind the separated carrier rocket and orbital launch platform. At a distance of about 289,000 kilometers from Earth the payload was observed by the Kazakh Astrophysical Institute using a telescope fitted with an electronic television enhancement system. Midcourse corrections were conducted on November 12 and 14, and 36 radio sessions were held. On November 15, the braking rocket brought Luna 17 to a circular orbit around the Moon at an altitude of 85 kilometers and a retrograde orbit of 141 degrees to the lunar equator. On November 16, an orbit adjustment lowered the perilune to 19 kilometers.

On November 17, the main braking engine was turned on to begin final descent to the surface, which was reached at 0647 Moscow time, with the location of 38° 17' N. and 35° W. in the Sea of Rains. The landing stage was essentially the same as used for Luna 16, except that in place of the drilling arm, it carried a flat platform on top with dual ramps on opposite ends. Instead of the Luna 16 payload of an ascent rocket assembly, it carried a mobile vehicle, Lunokhod 1.

2. Description of Lunokhod 1 Roving Vehicle

The Lunokhod 1 was shaped like an old-fashioned bath tub, equipped with eight wheels, four to a side, and a large convex lid to the tub-like compartment. This lid was hinged at one edge to lift up and over exposing on its underside an array of solar cells. The vehicle carried a cone-shaped antenna, a highly directional helical antenna, four television cameras, and special extendable devices to impact the lunar soil for density and mechanical properties tests. Both the landing stage and the roving vehicle carried Soviet metal pennants and coats of arms.

The Lunokhod 1 is undeniably a remarkable vehicle. It was built of unspecified light-weight materials designed to withstand the stresses of flight from Earth and the great extremes of temperatures on the Moon. It had to avoid the use of plastic materials which deteriorate in the radiation environment of space, and also to minimize the use of moving parts which might weld together in a high vacuum. Its eight wheels were independently powered, and a special suspension system was designed to overcome the unevenness of the terrain (lurain) which it might cross. In order to develop the electric motors for the wheels, these were test flown on both Luna 12 'and Luna 14, and were found to be successful. The device was controlled by a four-man crew on Earth, and it had the ability to move at two speeds, either continually or in short increments. The device could move forward or backward, and by applying power in opposite directions to the wheels on each side, it could turn in its tracks. Automatic sensors 'and safety devices would stop the vehicle if they discovered that through inadvertence the human crew on Earth had directed the vehicle up or down too steep a grade, or if it tilted too much to one side. The two gangways on the Lander platform were to insure that if a boulder blocked descent in one direction, there would be a second chance to move off the platform.

The four television cameras permitted observation in all directions, also they permitted stereo views; and views could be close up or of distant panoramas. The TV cameras weighed under 1.5 kilograms each, used 2.5 watts of electricity each, and could take pictures with 500 elements for each of 6,000 lines. Data could be sent back to Earth for display at various rate—near real time, or slowly for detailed facsimile reproduction. The vehicle contained various radio systems, computer elements, chemical batteries, a thermal regulating system of pipes circulating fluid and adjustable louvers at the heat exchanger. The experimental gear was fairly diversified. Soil properties could be measured both by the impacting devices and by optical studies of the vehicle tracks. An X-ray spectrometer permitted analysis of soil constituents. Cosmic ray detectors permitted analysis of intensity and energy levels of protons, electrons, and alpha particles, measuring also their direction. Solar flares could be studied. An X-ray telescope permitted detailed search of the heavens for sources, recording the data in the memory units for later broadcasts to Earth.

The lid top to the vehicle during daylight fumed over showing the underside of solar cells to expose them to the Sun for current operations and recharging chemical batteries. At night, the lid closed down to minimize damage to the cells, and a radio isotope heat source maintained an adequate level of internal heat to permit the equipment and chemical batteries to survive the lunar night.

3. Review of Operational Life

On November 17, at 0720 Moscow time, radio links with Lunokhod 1 were checked out, and at 0831 the first television pictures were returned. At 0928, Lunokhod 1 descended the steep ramp to reach the surface of the Moon, and began its travels in low gear. Its separate weight was 756 kilograms.

Designed to operate for three lunar days, it continued to function at least in part for 11 or 12 lunar days, making an impressive record by any standards. During the 'almost year-long period it operated, it occasioned a continuing flood of TASS reports 'and commentary. Rather than repeat in narrative form the highlights of all the activities reported, much of this information has been summarized in a single table, below, and supplementary comments will be added to supply details and interpretations.

The first operating day was short because it was about half over when the landing was made. Fairly detailed accounts reviewed all the activities for the first three lunar days. After that, the accounts were still frequent but more sketchy on precise numbers and details. Sample reports of the early period follow:

On the first lunar day of operation, between November 17 and 22, when it parked for the lunar night, Lunokhod 1 traveled 197 meters, .and in 10 radio sessions with Earth sent back 14 close-up pictures, more than Luna 9 and 13 combined; it also sent back 12 panoramic views.

During the first lunar night, the supplemental French-supplied laser reflector experiment (12 tetrahedral prisms) was tested, and on the first tries, both December 5 and 6, a reflected signal was picked up by the Russians. The French were not successful in their first attempts, and there was speculation in the Western press that the Russians had temporarily withheld precise pointing instructions from the French to enable themselves to be the first to reflect laser signals. During the first lunar night two radio sessions were held with the vehicle to assure that systems were still operating.

On December 9, the solar cell panel was reopened and pointed toward the Sun. On December 10, further travel began, and now at higher speed. On December 14 to 16, no travel was undertaken and the available power was used to operate other experiments. These included generating stereo, pairs of pictures, and the X-ray spectrometer experiment. When travel resumed, Lunokhod 1 descended into a crater 3 meters below the level of the Luna 17 Lander, and then came out again. By the end of the second operating day, total travel amounted to 1,179 meters, and the vehicle was 1,370 meters away from the Lander. Some 33 telepanoramas had been returned to Earth, and additionally some 7 astronomical panoramas had been conducted, to permit a very precise definition of the vehicle's location.

Apparently close to real time television was used to direct the travel, while panoramic studies were conducted for accurate location, topography, and astronomy. Soil chemistry studies took enough power that they were done in periods of no travel. These ceased after the ninth lunar day. Astronomy tests for X-ray measurements and mapping of radio sources were referred to without quantitative counts either after the first three days or in summation. Soil mechanical tests were quantified for the first three days and in total but not mentioned after the ninth day. A few discrepancies between lunar day totals and cumulative totals for travel show up in the announcements. The figure for the eleventh day became a vague "almost 100 meters", which by subtraction can be established as 88. Finally the experiment ceased officially on October 4, 1971 , the anniversary of Sputnik 1. The reason given was that the radio isotope supply used to keep the instrumentation functional despite the rigors of the lunar night had been too reduced in heat output. If so, the complete .absence of reports that the vehicle had been contacted during the eleventh lunar flights, and the absence of any announcement of its reactivation about September 30, and no reference to 'any work during the twelfth lunar day strongly suggest that to all intents and purposes, the final performance of Lunokhod 1 came with its shutdown on September 15. It may be that October 4 was the day the team of operators abandoned any further attempt to revive the payload. This minor evasiveness about the timing of its end should not detract from the outstanding accomplishments of the first 'automated roving vehicle on the Moon.

4. Scientific Findings

By its very nature, the Lunokhod 1 received more continuing coverage in Soviet reports than most other space activities, although as manned stations are put to longer use they reflect some of the same kind of coverage. Many findings were made by Lunokhod 1, only some of which have been published. The data were said to be yielding very detailed topological maps and information on soil structure and composition of the area explored. Features not visible in orbital photographs were found. Instead of the expected basalt plain, the area turned out to be one of complex lava flows with considerable terrace stratification. Also there were folded ridges, with the soil much stronger on top of the ridges.

The instrument named Rifma was used both for measuring the chemical constituents of lunar soil and for interpreting the signals from space received through the telescope. By searching sectors of the sky with this telescope in conjunction with television panoramas of the sky, it was possible to pinpoint X-ray star sources. Measurements were made at levels between 2,000 and 10,000 electron volts in the 1 to 6 angstrom wavelength range. Although normally the Lunokhod 1 cover was closed during lunar nights, there were some special experiments conducted. On February 10, during the lunar day, an eclipse put 'the vehicle in darkness, and the temperature of the environs dropped from plus 138 degrees Celsius to minus 100 degrees Celsius. This three-hour test of rate of heat loss showed it came through undamaged. In another test, the television system was turned on March 7 during darkness and kept operational to watch the arrival of sunrise.

Several methods of navigation were used during the travels of Lunokhod 1. Laser ranging from the Crimea and also from Pic du Midi in France permitted some very precise measurements. A second approach was the use of dead reckoning, keeping a plot on where the vehicle had been. A third approach was to look for landmarks, and to estimate from changes in angles to these points the location of the vehicle. A fourth method was to take pictures of star fields and to measure the position of the Sun with a sextant in order to establish the vehicle's location.

The Russians reported the telemetry coming from Lunokhod 1 was so extensive that just the engineering data on the behavior of the wheels produced a greater data flow than was obtained from all spacecraft combined for the years 1957-1960. The vehicle experienced many vicissitudes as it climbed into and out of craters and occasionally met boulders. Sometimes the list was 30 degrees. But by changes of course and backing when necessary, it managed very well. Some areas of dust were found with depths up to 20 centimeters. Then the ninth wheel, a distance measuring device, would not 'always turn, and other data were required to establish the actual distance covered.

Another interesting phenomenon was measurement of a 1,000-fold increase in the level of low energy protons between April 7 and 10, 1971, after a solar flare had been observed from Earth on April 6.

As the table shows, during the seventh lunar day, little travel was accomplished, and it was feared that deterioration of systems would require restriction of experiments to static ones. But in fact, it came back to good performance the eighth day, with a rapid deterioration thereafter. When the last of its travels were over it was positioned so that the passive laser reflector supplied by the French could continue to be used for many years to come.

5. Relative Merits of Manned Versus Unmanned Roving Lunar Vehicles

The success of Lunokhod 1 inevitably brought back the recurring questions about the relative merits of manned versus 'automated flights to the Moon. This same kind of analysis has been offered on return of lunar samples. No clear cut answer was possible in that instance, but it was hard to escape the conclusion that Apollo flights at costs up to $450 million each, out of pocket, bringing back 90 kilograms of documented samples selected with some care over many kilometers of terrain (lurain) should have greater scientific merit for analysis than a Luna flight at roughly $100 million or so bringing back about 100 grams from a site selected at random.

The closest parallel between the Luna 17 with Lunokhod 1 mission would be Apollo 15, which was the first to carry a manned roving vehicle:

TABLE 2-8.—COMPARISON OF LUNOKHOD 1 AND APOLLO 15 ROVER

	Loaded Weight (kg)	Total distance (Km)	Useful life (days) Power source	Control
Name
Lunokhod 1	756	10-5	298 Solar Cels....	Earth
Apollo 15 rover	698	64.4	3 Chemical batteries	Astronaut

SOURCES-Weight of Lunokhod 1:TASS, 8 Feb. 1971 ,1152 GMT. Distance for Lunokhod 1: TASS, 9 Oct. 1971 , 1222GMT. Apollo 15 rover data from NASA press kit and subsequent press releases.

It will be observed this is something of an apples and oranges comparison. Time is of the essence with a manned flight to the Moon, and the greatest mobility and practical speed are important. But if there is time for an unmanned vehicle to recharge its batteries, and for scientists on Earth to study each small advance and discovery so that new tasks can be planned with care, then the extended life of the automated vehicle even with slow speed gives a useful result.

Both roving vehicle types were undoubtedly expensive to develop, although the automated Lunokhod system should cost many times more, including its Earth control units. The mission costs probably were on the order of $450 million for the manned rover and $120 million or more for the one-way trip of the automated rover. The contrast is that men can bring observational powers, deploy certain experiments, collect the most interesting rocks, and make some types of repairs on a scale not yet possible under the Soviet plan. But the Soviet plan permitted improvements in performance and interpretations of experiments which could be used to adjust the further program of the same mission working month after month. Essentially, one expenditure for an Apollo flight would do the tasks of both Luna 16 and Luna17. The American approach brought back better samples and permitted men to have experiences remote study cannot duplicate. The Soviet approach gave more time for intellectual development of surface exploration. It seems reasonable to suggest that the Lunokhod and Apollo approaches are complementary rather than competitive, and in fact even the Russians acknowledge this officially even though they have stressed the comparative cheapness of their automated system.

E. LUNA 18

The next Soviet lunar flight was that of Luna 18, launched on September 2, 1971 at 1641 Moscow time. It was launched with the D-l-e vehicle and carried the same basic third generation bus that had been used since Luna 15. It was observed by Soviet astronomers at a distance of 100,000 kilometers from Earth.

On September 7, Luna 18 was put into lunar orbit at 100 kilometers circular orbit, and an inclination of 35 degrees to the lunar equator, with a period of 119 minutes.

The Russians announced on September 11 that there had been 85 radio sessions with Luna 18, and that it had completed 54 orbits of the Moon. It was then braked to make a landing which occurred at 3° 34' N. and 56° 30' E. in high terrain. They said the topography was unlucky, and signals ceased at touchdown at 1048 Moscow time.

F. LUNA 19

Luna 19 was launched on September 28, 1971 , using the same launch vehicle and bus as its fairly immediate predecessors. The initial emphasis in the press release was on research from lunar orbit. Astronomers were able to spot Luna 19 on the way to the Moon at a distance of 120,000 kilometers. A day later (September 30), the number of fixes obtained on the payload had risen to 60 as more observatories found it.

On October 3, after 26 radio sessions, the Luna 19 payload was braked into lunar orbit, 140 kilometers circular, at an inclination of 40° 35', and with a period of 121.75 minutes.

A minor orbital adjustment on October 7 made the orbit 135 by 127 kilometers, and a period of 121 minutes. After that there were progress reports about monthly, but not many details. Through December 31, 1971 , there had been 316 radio sessions with Luna 19. By January 30, it had completed 1,358 orbits, doing studies of magnetic fields, cosmic radiation, solar data, and meteoroids. By March 10, at 1300 Moscow time, the count was up to 1,810 orbits, and 516 radio sessions. Emphasis in the release now was on gravitational studies, which suggested that more elaborate experiments might have shut down by that time. On March 19, the report was amplified to repeat the list of missions which had been mentioned in January, and to say that selective panoramas of the surface had been taken by camera and facsimile transmission to Earth, covering the region from 30° to 60° S. and from 20° to 80° E.

On October 3, 1972 , Luna 19 had completed over 4,000 revolutions. It had carried 19 experiments. TASS said it was near the end of its mission. Findings from radio wave propagation suggested a plasma around the Moon from the interactions of solar radiation and the lunar surface. The Luna 19 mission had taught more about the energy spectrum, and the charge components of cosmic rays in space. There had been over 1,000 communications with the payload. The study of orbit changes during the mission had helped to map the location of mascons. On ten occasions, surges of solar activity were studied, with the results combined with data from Venera 7 and 8, Mars 2 and 3, and Prognoz 1 and 2.

Later some more details of the findings were published. The plasma found near the Moon appeared on the lighted side with the greatest concentration at 10 kilometers altitude. It was detected by using a dispersion interferometer sending out coherent signals on 32 cm. and 8 cm., with receipt of the signals on Earth. Some 15 sessions had been held in May and June 1972 to gather the data.

G. LUNA 20

1. Flight of Luna 20

Luna 20 was launched on February 14, 1972 at 0628 Moscow time, using the D-l-e vehicle and the usual orbital platform technique for injection into translunar flight. A midcourse correction was made on February 15, and then it was braked into lunar orbit on February 18. The orbit attained was 100 kilometers circular, at an inclination of 65 degrees and a period of 1 hour 58 minutes. A day later, the perilune was lowered to 21 kilometers. On February 21 at 22:19 Moscow time, Luna 20 was braked to a landing at 3° 32' N., 56° 33' E. in mountainous terrain near the Sea of Fertility . It may be observed that the landing site was very close to that selected for the failed soft landing of Luna 18. The braking burn took 267 seconds. Free fall then was permitted to an altitude of 760 meters. Here, there was a second burn that lasted until the payload was 20 meters above the surface where the main engine was turned off, and, small thrust braking took over. The landing site was about 120 kilometers north of the Luna 16 site, but in uplands rather than in a mare.

2. Surface Activity

After landing, the standard platform turned on its television system to take panoramic pictures of the surroundings. Then it activated its extension arm to place its drill on the most promising spot within reach to drill a sample from hard rock, with the work proceeding in stages. The drilling system used a percussion rotary drill designed to preserve the natural strength of the rock sample, and oil vapor lubrication to prevent its parts from sticking. After each brief application of the drill, there would be a pause for a fresh television view. The sample acquired was one with both sand and hard rock The drilling arm had been rigged to emerge vertically from the platform rotate to the desired azimuth, and then was lowered to the ready position for drilling. All this took 7 minutes. After television inspection, there were 2'more minutes spent to adjust the direction of the drilling arm and 3 minutes for final descent to surface contact. The drill operated at 500 rpm, and it took just 7 minutes to extract the sample. After this was completed, the arm lifted up the drilling unit with its intact sample to line it up with the recoverable capsule and insert it. This was hermetically sealed. There followed a 20 hour wait to insure that when launch came for the return flight to Earth it would be carried to the selected area of the Soviet Union.

3 Return, Flight and Recovery

Launch occurred at 0158 Moscow time on February 23. The sample was well shielded by ablative material on the recovery capsule. After separation of the capsule from the launch rocket, it made a ballistic entry with aerodynamic braking, and then further slowing by parachute. Its radio beacon was picked up by aircraft The landing took place on an island in the Karakingir river at 67° 34' E 48° N. Three tracked rescue vehicles trying to reach it broke through river ice, and pickup had to await the availability of a helicopter and daylight. The bright orange parachute was then spotted. About 5 mm of material had been ablated from the capsule surface. The sealed container with the lunar sample was taken out and transported to the lunar receiving laboratory where 14 hours after the return the contents were put into a steel tray. The landing had occurred at 2212 Moscow time on February 25, 40 kilometers northwest of Dzezkazgan in Kazakhstan , the landing conditions were ones of blizzard and low clouds. The search area had measured 80 by 100 kilometers This time the entry was at an angle of 60 degrees, providing a lower G load than that experienced by the" return of Luna 16. However, temperatures ran higher.

The sample container was opened in a helium atmosphere. The sample itself proved to be lighter in color than that returned by Luna 20. It was described as light to dark brown, and also as light gray again demonstrating the difficulties associated with describing the colors of most lunar samples.

Later, the Luna 20 return vehicle was referred to as a VLAS (returnable lunar automatic station), said to have considerable micro-miniaturized equipment to make it function. Luna 16 and 20 were described as essentially the same except for minor regrouping of components to improve conditions. It was noted that this time the landing had been made in daylight in order to gain better quality stereo telephotos of the landing site.

4. Scientific Results

This flight provided an opportunity for further scientific exchanges. The United States was given 2 grams plus photographs, in exchange for 1 gram from Apollo 15. Earlier the United States had supplied material from Apollo 11 and 12 for material from Luna 16. The French had been given material from Luna 16, also, and now received a sample from Luna 20.

Soviet analysis of the sample found traces of 70 chemical elements. The highlands sample, as indicated, was lighter and had more large particles. Their density was described at 1.1 to 1.2 grams/cm3 compactable to 1.7 to 1.8 grams/cm3. The rock was called anorthosite.

For the future, the Russians saw opportunities to bring home samples from the far side of the Moon. But this will require a trans-Earth injection burn from lunar orbit on the far-side of the Moon, and may require a lunar orbiting communications satellite correctly positioned as well, to maintain links with Earth.

H. LUNA 21 AND LUNOKHOD 2

1. Flight of Luna 21

Luna 21 was launched on January 1973 at 0955 Moscow time using the D-l-e vehicle and translunar injection from an Earth orbital platform in the regular manner. An orbital correction was made on January 9. The Tadzik observatory tracked the flight from 86,000 kilometers to 224,000 kilometers, using an electronic optical enhancer.

On January 12, Luna 12 was braked into an orbit around the Moon with parameters of 100 to 90 kilometers, an inclination of 60 degrees, and a period of 1 hour, 58 minutes. On January 13 and 14, the perilune was lowered to 16 kilometers, and then on January 16 at 0135 Moscow time, it was braked to a soft landing at the eastern edge of the Sea of Serenity in Le Monnier crater.

Luna 21 circled the Moon 40 times before preparing to land. The braking rocket was fired at 16 kilometers altitude, then going into tree fall to an altitude of 750 meters. The second firing lasted to 22 meters altitude when the main engine was cut off and smaller thrusters operated to a height of 1.5 meters where at cut off it was allowed to drop the remaining distance. This would be equivalent to a 40 centimeter drop on Earth.

Pyrotechnics were fired to separate the transported lunar rover from the landing stage. The landing stage was one of the standard platforms now in regular use. It carried a bas relief of Lenin and the Soviet coat-of-arms.

2. Operations of Lunokhod 2

Lunokhod 2 was an improved roving vehicle of 840 kilograms (compared with 756 for its predecessor). After television inspection of the surroundings and lowering of the landing ramp, Lunokhod 2 rolled down the landing ramp at 0414 to the surface of the Moon. Gear was checked and more television pictures were taken. It also carried a bas relief of Lenin and the Soviet coat of arms. Again, a French-supplied radar reflector was incorporated to aid in laser tracking and distance measuring. It remained stationary 30 meters away from the Lander until January 18 to charge batteries after opening its solar panel lid.

On January 18, Lunokhod 2 sent TV panoramas and began to move. It also studied the X-radiation of the Sun and studied soil mechanical properties. More battery charging followed. This time, the rover also had kept its solar panel open during most of the flight from Earth in order to save time in battery charging, folding the lid to closed position only during dynamic operations.

Lunokhod 2 re approached the Lander to within 4 meters to take pictures of it, and then from a distance of 6 meters took a panorama of the surroundings. It was then moved several meters, going through a narrow passage and turning sharply to get into a good viewing position As with Lunokhod 1, a complete review of daily Soviet accounts over several months would become tedious, so a summary table will be presented with general comments and interpretations on these data.

SOURCES: Mostly from many individual Soviet TASS bulletins. The summary figures on total performance were carried as a TASS announcement in Pravda, Moscow , June 4, 1973 , p. l.

It was not possible to build quite as specific a table this time as with the previous surface rover. But in general, the distance was three to four times as great; television pictures were four times as numerous; television panoramas were perhaps 40 percent as numerous, soil mechanical tests half again as many, and no counts were provided on other activities although all were carried on and with improved equipment.

It was noted by the Russians that Lunokhod 2 was at work in an area only 180 kilometers north of the landing site of Apollo 17. The region was one of transition from the Sea of Serenity to the Taurus Mountains .

A more detailed description was provided of the functions of the human controllers on Earth. A five-man crew was now used. Commander, driver, navigator, radioman, and engineer. Their task was made more demanding by giving the Lunokhod 2 double the speed of its predecessor. Physiological monitoring was done of the ground crew and they were found to work under heavy stress, yet with their high competence, they remained fairly "cool".

The vehicle had been modified for this mission to add in a higher position an extra television camera so that the Earth driver could see farther ahead and direct the vehicle with more confidence, The pictures formed on the Earth screen once every three seconds.

Another new instrument was an astrophotometer. It was used to determine the night sky glow on the Moon (important to guide planning of future observatories on the Moon which might be discouraged it there developed the news that a dust ring circled the Moon). It also looked for Zodiacal light in the plane of the ecliptic. It also was seeking clarification on the spectral composition of the Milky Way. This instrument previously had been tested on Kosmos 51 and Kosmos 213 in Earth orbit.

The laser reflector work went even better with this flight, being used successfully both from the Crimea and the French Pic du Midi Observatory. It proved possible to gauge distances from Earth to Moon with an accuracy of 20 to 30 centimeters, and to measure shifts of the Earth's pole of as little as 10 centimeters. .

The Lunokhod 2 "9th wheel" soil tester was a conical punch with cruciform blades. As it turned, sinking its blades in the soil, the resistance to displacement and compression could be measured.

Another new device was a magnetometer mounted on a pole projected ahead of the vehicle 2.5 meters. It was applied typically in one crater study in which it moved away from the crater four times at 90 degree angles to measure any associated magnetism.

In a number of tests, the vehicle was repositioned to correct for any solar influences in the soil measurements. In mid-February one day, as it moved, it crossed a one meter long plate with a surface so smooth that no tracks were left—highly unusual in the experience of these operations.

Sky glow tests after sunset showed from 10 to 15 times Earth level suggesting a dust atmosphere.

When Lunokhod 2 went up 25 degree slopes, there was 80 percent slippage in the wheels. On another occasion, the vehicle traveled 800 meters" in a single hour. After climbing an 18 degree slope to the run of a crater, it went down to a depth of 100 meters in the crater to study it: then half way out, the wheels sank to a depth of their hubs, and it had to back off, and find another way out.

In March, the Russians revealed the radioactive heat source used to keep Lunokhod alive during the lunar night. It was Polonium 210, converted from Bismuth, with a half life of 20 weeks. This isotope has a low neutron and gamma ray output and mostly emits alpha particles, minimizing shielding problems.

As the Lunokhod 2 left the seabed and climbed into continental areas, it was at an elevation about 400 meters higher than the Luna 2l Lander. A clue to the level of activity was provided by the record of the second lunar day. There had been 6,490 radio commands, 65 hours of communication, including one that lasted 12 hours, with more than 120 turns. The average session had been about 6 hours. For each 10 kilometers traveled, there were over 200 mechanical tests with the rotating penetrometer, as well as continuing magnetic surveys with corrections for solar wind effects. The daytime lunar sky was found to exceed Earth sky luminosity by 13 to 15 fold, giving a poor prognosis for lunar observatories in the future, if the finding was confirmed.

A tectonic fracture 300 meters wide and 16 kilometers long was approached. An explanation of Soviet picture taking systems was supplied in connection with

Lunokhod 2 which helped to explain the not always clear descriptions given in connection with Soviet space flights. There are three kinds. (1) An optical mechanical system for direct images, as used on Luna 9 and later missions for preparing panoramas. They make possible high resolution pictures at low power levels using simple antennas, by scanning only one line at time from a stationary position.

(2) Photo television, as used for Luna 3, Zond 3, Luna 12, and Mars 2 and 3. These record pictures on film, which is developed on board and later scanned for facsimile transmission to Earth. (3) Electronic for slow frame television and photo television. While not as fast as television on Earth because of technical complications, it served the purposes of steering Lunokhod 1 and 2 and for making other studies.

In general, the Russians praised their design approach as preferred for some years over the more hasty work that astronauts must perform. They saw coming not only use of roving automated vehicles on Mars or Venus, but also coupling a rover with a sample gatherer to load an Earth return rocket.

On the fourth day, Lunokhod 2 made further studies of the rille it had discovered, with stereo pictures of its walls, physical and chemical studies of the soil and by making a .5 kilometer perpendicular excursion from the rim, and back by the same route to make more precise magnetic measurements. It found one to two-meter sized rocks near the edge of the rille, making this difficult to approach. It did find that magnetism changed significantly in approaching the rille. The conclusion of magnetic studies was that the Moon has a weak global field, which is stronger locally, and that meteorites tend to demagnetize areas they strike. It discovered there was a definite magnetic anomaly associated with the rille up to 150 to 200 meters from it.

While it was announced as resuming travel on May 9, as it left its long study of the rille to move toward the Taurus Mountains, there were no more daily accounts of activity and by subtraction from the total travel the known travel on previous days, it looks as if it moved possibly 800 meters on the ninth, and then traveled no more. The announcement that its mission was complete came on June 3 which should have been some time in the lunar flights. Without any progress reports during the intervening 25 days, one suspects the mission terminated without immediate announcement, and the next several weeks of diagnostic work and improvisation failed to revive the vehicle. Even so, it exceeded its designed life of three lunar days and was a more comprehensive mobile laboratory than its predecessor. Apparently, premature failure prevented parking the vehicle to permit continuing use of the French-supplied reflectors for laser experiments.

A more complete review of its equipment and operations did not come until November 1973. The landing site was finally pinpointed sit 30° 27' E. and 25° 51' N. The principal equipment, listed included its magnetometer, Rifma-M X-r»v spectral analyzer, its phvsical-mechanical impact wheel, a special reference plate with 39 shades for comparison by the television cameras, and the Rubin 1 radiometer, an astrophotometer, and the French laser corner reflector. Those devices which were new or additional compared will Lunokhod 1 were the magnetometer, astrophotometer, the Rubin 1, and the improved Rifma. The television equipment was enhanced in capacity and helped by having the cameras placed higher on the vehicle.

The same article reviewed the topography,. Craters, and rille which were explored and mapped. At the lauding site, the soil was found to be 24 +/- percent silicon. 8+/- 1 percent calcium, 6± .6 percent iron, and 9±1 percent aluminum. This contrasts with the 10-12 percent iron found by Lunokhod 1. As Lunokhod roved up into the hills, it found that iron dropped to 4+/- .4 percent and aluminum rose to 11.5:±1 percent. Laser ranging proved accurate to 40 centimeters. The Rubin 1 laser emission photodetector returned a radio signal to Earth whenever a beam from Earth hit it. There were more than 4,000 hits, and there were 1,500 photos of the Moon to show the vehicle's location. Sky brightness was measured 14 times. (30)

The Rifma-M fluorescent spectrometer used on Lunokhod 2 was described in greater detail together with its findings on chemical composition of the Moon in 1974? (31)

I. LUNA 22

Luna 22 was launched on May 29, 1974 at 1157 Moscow time using the D-l-e class of vehicle and making use of the standard Earth orbital launch platform technique. It. was described as designed to study the Moon and space near the Moon. The Georgia Astrophysical Observatory was able to observe the payload at a distance of 250,000 kilometers from Earth. A path correction was made on May 20. After 23 radio sessions, it was braked into lunar orbit on June 2. The orbit was 220 kilometers circular at an inclination of 19° 35' to the equator of the Moon, and a period of 2 hours 10 minutes.

The mission was described a few days later as that of continuing the work done by Luna 19, the big orbiter which had preceded it. Its geophysical studies were to include taking pictures of large areas, studying magnetic fields, cosmic radiation, and gravitational data. It was known it, would speed up slightly and dip over lunar seas. It was also believed the far side would show a distention of 2 to 4 kilometers.

On June 9, the orbit was modified to 244 by 25 kilometers to permit the taking of

high resolution pictures at perilune, and to couple these with altimeter readings and gamma ray analysis of lunar rock composition.

Other orbital activities included measuring meteoritic density and the spectrum of solar cosmic rays and concentration of circumlunar plasma and magnetic fields.

After the picture taking was over, on June 13, the orbit was raised to 299 by 181 kilometers to continue gravitational studies.

The next major announcement came on November 11, 1974 indicating that by 1800 Moscow time on November 11, Luna 22 had completed 1,788 orbits of the Moon and now the orbit had been adjusted to 3,437 by 171 kilometers, at an inclination of 19° 33' and with an orbital period of 3 hours 12 minutes.

By 1100 Moscow time on April 2, 1975, Luna 22 had completed 2,824 orbits of the Moon, and its orbit was 1,409 by 200 kilometers at a 21° inclination, and still a period of 3 hours 12 minutes. It continued to supply data related to lunar gravity, magnetic fields, and surface relief.

By 1900 Moscow time, June 2, it had completed 3,296 orbits and the Deep Space Communications Center had held 2,175 radio sessions with Luna 22, The full one-year program was completed, but it still functioned.

There was a surprise announcement on September 3, 1975 . On August 24, the orbit of Luna 22 had been adjusted to lower the perilune to 30 kilometers. Here, the camera system was activated to take another photograph for development on board and facsimile transmission to Earth. A good quality image was obtained. Afterwards, the orbit was changed to 1,286 by 100 kilometers, at 21 degrees inclination, and a period of 3 hours. It was unusual in Soviet practice to be able to activate a camera system after a one-year lapse and to carry out all the steps to return a picture to Earth. .Regular operations were reported as continuing.

In mid-October, the Luna 22 flight was reviewed, to cover its 15 months of operation. It had observed several hundreds of thousands of square kilometers. Because of the lack of atmosphere, it was able to fly much closer to the surface of the Moon than Earth satellites can approach Earth, hence taking high resolution pictures. These low orbits it intermixed with high orbits for picture taking over larger regions. The satellite studied the composition of lunar rocks based on their gamma radiation, circumlunar plasmas, and solar cosmic rays. It also studied meteoritic density, solar long wave emissions, and Jupiter emissions. It studied mascons. There were 1,500 trajectory measurements made during 2,400 radio sessions with Earth. The controllers sent 30,000 radio commands to Luna 22. It was able to measure meteoritic material down to one one-hundred-trillionth of a gram. Its maneuvering fuel was exhausted on September 2. (32)

The Western press reported mission completion in early November 1975. (33) One radio broadcast from Moscow apparently included a statement to the effect that the mission would prove of great help to future manned flights to the Moon, but it has not been possible to pinpoint the time this statement was made. (34)

J. LUNA 23

Luna 23 was launched on October 28, 1974 at 1730 Moscow time using the D-l-e launch vehicle and the orbital launch platform technique. It was described as intended to do further research into the Moon and of space around the Moon. A telescope equipped with television enhancement at the Zayliskiy Alatav Mountains was able to track the flight. Alma Ata Observatory was able to track it two flights, at 30,000 kilometers and at 200,000 kilometers.

An orbit correction was made on October 31. Then on November 2, the braking rocket was fired to put it into a lunar orbit of 104 by 94 kilometers, at an inclination of 138° to the lunar equator (retrograde). The orbital period was 1 hour 57 minutes.

November 4 and 5 the orbit was adjusted to 105 by 17 kilometers. On November 6, it was further braked to land at 0837 Moscow time in the south part of the Mare Grisium. The landing was achieved and signals returned, but the terrain was unfavorable. The attached drill

on the platform was damaged and not able to function. It had been intended to drill a sample to a depth of 2.5 meters, and to test other equipment. As a consequence, communications with Luna 28 were terminated on November 9, after operation of a reduced research program.

 

1976 LUNAR FLIGHT—LUNA 24: THIRD SAMPLE RETURN

Luna 24 was launched on August 9, 1976, almost 2 years after the Luna 23 failure. As of the end of 1980, no further Soviet lunar flights have been made.

On August 18, 1976, Luna 24 landed on the Moon in the south-eastern part of the Sea of Crises at 12°45' N., 62°12' E., a position very close to the unsuccessful Luna 23. (41) The drill was designed to take a sample at a depth of approximately 2 meters. Previous samples taken by Luna 16 and 20 had reached only 30 centimeters. This time, a special drill rig was designed. The walls of the drill pipe were lined with flexible ribbons that were drawn from the outside of the pipe, into the pipe, and around the sample column, as the drill rotated deeper. More ribbon was rolled up around each portion of the lunar sample to keep the pipe from clogging, and to prevent fine sand from falling through. An impact-rotating mechanism was used to penetrate any rock that might be encountered; the motion of the drill changed depending on the resistance. A drum rotated to pull in the ribbon and to move the sample into the return vehicle ampule. A lock was then triggered and the drum moved inside the return vehicle. The beam and drill folded away from the rocket to prepare for launch. (42)

On August 19, the Luna 24 return vehicle was launched from the Moon. The capsule made a ballistic return to Earth, landing 200 kilometers southeast of the city of Surgut. A total of 170 grams of material was returned, and the color was described as brownish or dark grey, depending on illumination. The layers were found to contain different size and color particles. Sixty elements were found using x ray microanalysis and mass spectroscopy. (43)

 

References

1. SOVIET SPACE PROGRAMS, 1971-75, OVERVIEW, FACILITIES AND HARDWARE MANNED AND UNMANNED FLIGHT PROGRAMS, BIOASTRONAUTICS CIVIL AND MILITARY APPLICATIONS PROJECTIONS OF FUTURE PLANS, STAFF REPORT , THE COMMITTEE ON AERONAUTICAL AND SPACE .SCIENCES, UNITED STATES SENATE, BY THE SCIENCE POLICY RESEARCH DIVISION CONGRESSIONAL RESEARCH SERVICE, THE LIBRARY OF CONGRESS, VOLUME – I, AUGUST 30, 1976, GOVERNMENT PRINTING OFFICE, WASHINGTON : 1976,

29. TASS, October 3, 1970 , 1035 GMT.

30. Pravda, Moscow , November 20, 1973 , P. 3 interview with Vinogradov.

31. Doklady Akademii Nauk SSSR, Vol. 214, No. 1, PP. 71-74.

32. Sotsiallsticheskaya Indnstriya. Moscow . October 15, 1975 , p. 8.

33. Flight International, London , November 6, 1975 , p. 705.

34. Perry, G. E., private communication.

A. SOVIET SPACE PROGRAMS: 1976-80 (WITH SUPPLEMENTARY DATA THROUGH 1983), UNMANNED SPACE ACTIVITIES, PREPARED AT THE REQUEST OF Hon. JOHN C. DANFORTH, Chairman, COMMITTEE ON COMMERCE, SCIENCE, AND TRANSPORTATION, UNITED STATES SENATE, Part 3, MAY 1985, Printed for the use of the Committee on Commerce, Science, and Transportation, 99th Congress, 1 st. session, COMMITTEE PRINT, S. Prt. 98-235, U.S. GOVERNMENT PRINTING OFFICE WASHINGTON: 1985

35. Reuter, Moscow, July 29, 1961, quoting his letter to the magazine. Soviet Lithuania.

36. Letter of June 6, 1963; from Ambassador Adiai E. Stevenson to the Secretary General of the United Nations firmed this in 1966, after they had achieved successes with this type of mission. (37)

37. Tass, Apr. 4, 1966. 0756 GMT.

38. Reuters, Moscow, Aug. 30, 1966, reported in the New York Times, Aug. 31, 1966.

39. Tass, Oct. 3, 1970. 1035 GMT

40. Sotsialisticheskaya Industriya, Moscow, Oct. 15, 1975, p. 3.

41. Izvestiya, Aug. 20, 1976, p.2.

42. Izvestiya, Aug. 20,1976, p.2.

43. Pravda, Sept. 5, 1976, p. 3.