Category Soviet Robots in the Solar System

Korolev, Sergey Pavlovich 1907-1966

Founder of the Soviet Space Program Chief Designer OKB-1 1946-1966

Chief Designer Sergey Korolev (this common spelling is not phonetically correct, Korolyov is proper) was the behind-the-scenes Soviet equivalent of von Braun in the US. His Experimental Design Bureau No. l (OKB-1) led the development of first military and, shortly thereafter, peaceful applica­tions of rocketry in the USSR. His identity was a state secret known only to an inner circle; to others he was simply the ‘Chief Designer’. While von Braun was openly engaged with the public and served as an enthusiastic communicator on the American civilian space program, Korolev worked under heavy state security. He V”as not even allowed w’as not made public until after his death.

A passionate advocate of space exploration. Korolev began as a young engineer leading a research group, GIRD, that built small rockets in the 1930s at the same time as Robert Goddard was making his rockets in the US. Korolev became a victim of one of Staling purges in the late 1930s. eonfessing to trumped up charges under duress. He was sent initially to a gulag before being transferred to the ‘sharashkas’. slave labor camps for scientists and engineers, where he could continue to work on rockets in exile for the military. As a result of the eonsiderable hardship he endured, he developed health issues that would persist for the rest of his life. He was released near the end of WW-II to evaluate the captured German V-2 missile and build a Soviet rocket capability.

In 1946 Korolev was appointed Chief Designer of a new department in Scientific Research Institute No.88 (N11-88) to develop long-range missiles. The R-l, which was basically a Soviet-built V-2, led to a succession of ever more powerful rockets named R-2, R-3 and R-5. He proved himself to be a very talented technical designer and manager, and in 1950 his department was upgraded to a design bureau, and then in 1956 was separated from N11-88 to become OKB-1. He began work in 1953 on an I CBM to deliver the heavy 5-ton nuclear warhead. This would require a rocket of unprecedented size and power. The resulting massive multi-stage R-7 (which NATO referred to as the SS-6 Sapwood) was first tested in the spring of 1957. long after technology had reduced the size of the warheads. It was overly large and awkward as a weapon, taking 20 hours to prepare for launch, and only a few were deployed before more praetical delivery systems were produced by competing organizations. However, the R-7N lifting power allowed Korolev to adapt it for space exploration purposes, including Sputnik, which proved to a reluctant Kremlin the political value of non-military uses for large missiles. Like von Braun, Korolev’s passion was the exploration of space, but he needed the military business to build his rockets. Thus his designs owed as much to his dreams as to hard military requirements. Korolev s lobbying to use the R-7 for space exploration, and his insistence on the large and militarily impractical cryogenic rockets best suited to this role, drew impatience from the military, which reacted by plaeing contracts with competitors, in particular Mikhail Yangefs OKB-586 and Vladimir ChelomeyN OKB-52.

Korolev was a charismatic man who through sheer perseverance, political savvy, technical expertise, and talent for leadership established the Soviet space exploration program on the backs of the military, with consequent resentment. Nevertheless, he triumphed because his space spectaculars won him the support of the Soviet political hierarchy and in particular Nikita Khrushchev. The R-7 in its various incarnations became the most reliable and most used space exploration launch vehicle in the 20th Century. The Soyuz version continues in use today to launch cosmonauts into low Earth orbit. The Molniya version launched all of the early Soviet lunar and planetary missions until the more powerful Proton developed by Chelomey became available, and later versions are still used for this purpose. His sudden death in January 1966 was a severe shock, and without his leadership the Soviet lunar program devolved into rivalry between factions, impeding progress and dashing any chance the Soviet Union may have had after their late start.

President of the Soviet Academy of Sciences 11

These series were the second generation of simple, single-module lunar spacecraft, designed for a more complex payload and flight mission. Instead of a direct flight to impact the Moon, they were placed into a highly elliptical orbit that would take them beyond the far side of the Moon, which they would photograph, and upon returning to the vicinity of Farth they would scan and transmit the pictures. The Ye-2 was the first three-axis stabilized spacecraft. It flew to the Moon in spin-stabilized mode, and then switched to three-axis stabilization and control for lunar photography. The Ye – 3 had a modified attitude control system and an improved camera. One Ye-2 and two Ye-3 spacecraft were launched in the six-month period between the start of October 1959 and the end of April 1960 using the Luna launcher. Only the Ye-2 spacecraft, Luna 3, was successful. Both Ye-3 spacecraft were lost to launch vehicle failures.

Mankind’s first venture to the planets began in I960, known only to those in the Soviet Union who performed the task and to the elite in the American spy services. The first Mars space flight campaign consisted of two identical spacecraft built for flyby exploration of the planet. They were launched in October 1960 and preceded the first US attempt at Mars by four years. Two similar spacecraft for Venus were launched in February 1961. These four spacecraft were the first designed to directly investigate our neighboring planets.

Chief Designer and Academician S. P. Korolev began work on Mars and Venus missions at OKB-1 in late 1958, during a hectic time in w’hich not only was his R-7 ICBM being developed and tested but also the second silo-based R-9ICBM. Despite flight tests often occurring at a rate of several per month, he worked on adapting the R-7 for the non-military space exploration role that had always been his dream. He created a small third stage to attain Earth escape velocity, and was ready for the first lunar launch attempts in late 1958. With the successful impact of Luna 2 and far side photography of Luna 3 in 1959, the objectives of the initial lunar spacecraft series were satisfied and Korolev was able to move on to Mars and Venus. He had planned to use an upgraded form of the third stage of the R-7F Luna launcher for planetary spacecraft later in 1959 and 1960, but the Institute of Applied Mathematics of the Soviet Academy of Sciences convinced him that a four-stage rocket would be much more efficient and robust. When American plans for a Venus launch w ere postponed to 1962, Korolev decided to skip the 1959 60 planetary window s in order to gain the time to develop a four-stage R-7 that would have a third stage derived from the R-9 second stage and a wholly new’ fourth stage with a restartable engine. The first three stages and the initial burn of the fourth stage w ould insert the fourth stage into a low’ orbit around Earth. At the appropriate time, the fourth stage would restart to gain the desired interplanetary trajectory and release its payload. This 8K78 vehicle became known as the ‘Molniya’ launcher. It was capable of sending 1.5 tons to the Moon or just over 1 ton to either Mars or Venus.

In early January 1960, Khrushchev aired his concern about the growing US space program at a meeting with Korolev and other space leaders. Pushed by his political master to send a spacecraft to Mars, by the end of February Korolev had a schedule for launching to Mars in that fall. His team balked at the 8-month timescale because the four-stage R-7 was still a ‘paper’ vehicle and the spacecraft was not yet designed there were not even any working drawings. By today’s standards the schedule was ludicrous, but Korolev and his team had, as they put it "a fervent desire to beat the Americans…and were in a desperate hurry’7

The 1M (Mars) and IV (Venus) spacecraft originally envisioned in 1958 were far more complex than the Luna missions. They were fully З-axis stabilized spacecraft with attitude control and propulsion systems, solar arrays and battery power, thermal control, and long range communications. Korolev’s plan called for three

launches in the Mars window to dispatch two flyby spacecraft and one lander, with the optimum date being September 27. A lander had to undertake the most difficult of planetary missions – to pass through the atmosphere, survive impact with the surface, and take photographs. But at that time information on the atmospheric properties of the tw o planets w as unreliable, particularly for Mars. Korolev assumed a surface pressure for Mars between 60 and 120 millibars, which was thin but feasible, and that Venus had an atmosphere more like Earth’s. Experiments in the summer of 1960 using the R-l 1A scientific suborbital rocket (a version of the ‘Scud’ military rocket) took test entry vehicles up an altitude of 50 km for drop tests using parachutes. But designing to the uncertainties, in so short a time, forced the engineers to give up on a lander for Mars and to settle for the simpler flyby task, and for Venus it was decided to design a probe to report on conditions in the atmosphere without the need to survive impact with the surface. Nevertheless, even these simpler missions were very challenging, not least owing to the large uncertainties in the ephemerides of the two planets, wiiich for Mars exceeded the diameter of the planet itself.

The scientific objectives for the Mars flyby spacecraft were specified by Mstislav Keldysh in a document dated March 15, 1960:

1. Photograph the planet from a range of 5.000 to 30.000 km at a surface resolution of 3 to 6 km with the coverage including of one of the polar regions

2. Coverage of the infrared C-II band in the reflection spectrum, to search for plant or other organic material on the surface

3. Research into the ultraviolet band of the Martian spectrum.

The instruments and spacecraft were rushed through development in order to meet the deadline. There were many problems at the factories. The spacecraft delivered to the launch site at the end of August were a shambles. Korolev s team worked around the clock to solve the numerous technical problems, constantly taking subsystems apart for repair and retesting. The communications system gave the most trouble. In fact, full scale integrated testing did not begin until September 27, which w? as the optimum launch date!

Korolev also raced to assemble his first four-stage R-7. The new third stage was a conversion from another vehicle, so the real task was to rapidly develop the entirely new; fourth stage with its restartable engine. The pressure on the rocket team was not eased by knowing that the first test launch would be a full-fledged attempt at Mars.

Ultimately, the payload had to be slashed in order to make mass available for test instrumentation on the new upper stage combination. The heaviest instruments – the camera, infrared spectrophotometer and ultraviolet spectrometer – were deleted. The two spacecraft did not reach the launch pad until well after the optimum launch date, which meant they would not be able to approach as close to Mars as intended. But in the event this w as of no consequence because they w ere both victims of their launch vehicles.

Had these Mars spacecraft and the Venus spacecraft in February 1961 succeeded, then the world w’ould have been treated to a spectacular planetary exploration coup in May 1961. The Venus probes would have arrived at their destination on May 11

1M No. l [Mars 1960Л. Marsnik 1]

Mars Flyby USSR OKB-1 Molniya

October 10. 1960 at 14:27:49 UT (Baikonur) Launch failure, third stage malfunction.

1M No.2 [Mars 1960B. Marsnik 2]

Mars Flyby USSR OKB-1 Molniya

October 14. 1960 at 13:51:03 UT (Baikonur) Launch failure, third stage did not ignite.

and 19. and the Mars flybys would have occurred on May 13 and 15. Following only one month after Gagarin’s orbital flight in April, the effect of these triumphs on the West would have exceeded even Sputnik.

The fact that the new four-stage R-7 and Mars spacecraft were even launched is a testament to the can-do attitude of Korolev’s team against almost impossible odds. Nevertheless, a typical Russian sense of resignation ran underneath the optimism. In early September, during the scramble to make the launch date, a spacecraft engineer remarked. "‘Forget about that radio unit and all the Mars problems. The first time wc won’t fly any farther than Siberia!” He was right.

Spacecraft:

The spacecraft was essentially a cylindrical container, 2.035 meters long and with a diameter of 1.05 meters, pressurized to 1.2 bar with nitrogen for the avionics and instruments, with a dome on top housing the propulsion system, which was a fixed 1.96 kN К DU-414 res tar table liquid hypergolic rocket engine that burned nitric acid and dimethylhydrazine. The engine was capable of making one or more trajectory correction maneuvers with a total firing time of 40 seconds.

The pow er system consisted of two fixed 1.6 x 1.0 meter solar panels populated by a total of 2 square meters of solar cells, and had silver-zinc batteries for storage. Thermal control was achieved using internal circulation fans in association with shutters on the exterior to stabilize the internal temperature to 30 C.

The avionics included a telemetry tape recorder and a program timer (actually a clockw ork event sequencer) that had to be preset for a specific time of launch. The communication system consisted of three units. Л directional system used a high – gain 2.33 meter diameter fine copper net parabolic dish for 8 cm (3.7 GHz) and 32 an (922 MHz) band transmitters. This antenna was to open automatically when the spacecraft separated from the fourth stage of the launcher. Two cross-shaped semi-

directional medium-gain antennas were mounted on the back of the solar panels for the command receiver and for low bandwidth telemetry at 922.8 МН/. A low-gain omnidirectional antenna was affixed to the end of the 2.2 meter magnetometer boom Гог use near Earth in the 1.6 meier band. Commands were sent at 768.6 MHz at 1.6 bits/s. Before executing an uplinked command sequence, the spacecraft repeated it back and awaited acknowledgement from the ground.

Attitude sensing was achieved using fixed Sun and star sensors in combination with gyroscopes and accelerometers, and a system of nitrogen gas jets adopted from Luna 3 provided attitude control and З-axis stabilization. In cruise mode the solar panels were maintained within 10 degrees of perpendicular to the Sun. For telemetry sessions, the spacecraft used radio bearings to turn and lock onto Earth. For the 1VA Venus spacecraft, this mode was improved by using a separate Earth optical sensor.

Launch mass: 650 kg (dry mass —480 kg)

Payload:

1. Boom mounted triaxial fiuxgaLe magnetometer to search for a Martian magnetic field

2. Ion trap charged panicle detectors to investigate the interplanetary plasma medium

3. Micrometeoroid detector to investigate interplanetary spacecraft hazards

4. Cosmic ray detectors to measure radiation hazards in space

5. Infrared radiometer to measure the Martian surface temperature

6. Facsimile film camera system to image the surface (not down)

7. Infrared 3 to 4 micron C-II band spectrometer to search for organic compounds (not flown)

8. Ultraviolet spectrometer to detenu і ne atmospheric composition (not flown)

Most of the instruments were externally mounted. 1 he camera and spectrometer were inside the pressurized module with their optics observing through a port. The camera was the same facsimile film system as that flown on Luna 3 to photograph the Moon and used the 3.7 GHz channel for transmission. It would be triggered by a Mars sensor.

The interplanetary cruise instruments were derived from balloon and sounding- rocket experiments. Shmaia Dolginov supplied the magnetometer and Konstantin Gringauz the two ion traps. The cosmic ray detectors consisted of two Geiger counters and one sodium iodide scintillator inside the pressurized container, and one cesium iodide scintillator mounted externally, all of which were supplied by Sergey Vernov. Tatiana Nazarova provided the mierometeoroid sensor.

All three key planetary instruments outlined in Keldysh’s memo in March were ultimately deleted. The schedule was set in February and the launch window opened on September 20, leaving very little time to build the instruments. The spacecraft itself had a large number of problems in development and testing. On September 20 the radio was still at the factory and the electrical system was not working. The radio

had further problems after it arrived for integration with the spacecraft. By now the minimum energy launch date on September 27 had passed, and every day thereafter the mass that could be launched diminished. To save mass as the days passed, the camera system was deleted. It had suffered test and integration problems of its own. Finally, as the end of the launch window approached, the infrared spectrometer, which had failed to detect life during a field test in Kazakhstan, and the ultraviolet spectrometer were deleted. Pressure integrity tests of the avionics compartment were never done. After the launch of the first spacecraft failed and the mass constraint tightened, the entire science payload and midcourse engine were removed. As it was too late in the launch window to attempt the desired close flyby of Mars, the goal of the mission was reduced to simply gaining flight experience with the spacecraft.

Payload mass: 10 kg

Mission description:

Spacecraft 1M No. l arrived at the pad on October 8 and was launched on October 10, towards the end of the launch window. It did not achieve Earth orbit. Resonant vibrations in the launcher during the second stage burn caused a gyroscope in the avionics to malfunction. At 309 seconds into the Fight, after third stage ignition, the vehicle pitched over beyond permissible limits and the engine was shut down. The stack crashed in eastern Siberia.

1M No.2 did not achieve Earth orbit either. Its launcher failed after 290 seconds, when the third stage engine failed to ignite. An oxidi/er leak on the pad had frozen the kerosene in the feed pipes. The launch window closed before the planned third spacecraft could be launched. The failure of the third stage on both launches robbed the new fourth stage and the spacecraft of any chance to perform.

The Soviets made no announcement of either launch, since they had not reached orbit. But the IJS was cognizant, having tracked them from its surveillance station in Turkey and from a reconnaissance aircraft flying between Turkey and Iran. Tracking stations along the southern borders of the USSR readily picked up radio traffic prior to launches, and the telemetry from early Soviet launch vehicles was unencrypted. The deployment of tracking ships was a further indication that a launch attempt was imminent, and in any ease planetary launch windows were well known. Only a few lunar and planetary launches escaped detection by the Americans.

Nikita Khrushchev was in New York for a United Nations meeting during the launch period. He had a model of the 1M Mars probe with him as a bragging piece. After the first failure, instead of boasting w ith his model, he made his famous speech with accompanying shoe-banging on October 12. When the second launch failed, he was on his way back to the USSR with his model.

Results:

None.

Campaign objectives:

In 1967 Venera 4 worked as well as could be expected considering the unknown environment to which it was sent. The US had only managed a flyby in this launch window for Venus* while the first successful Soviet planetary mission had achieved the impressive technical challenge of descending through the planetary atmosphere and sending back critical data on its characteristics. Knowing the US had no plans to return to Venus because it desired to focus on Mars, the USSR set out to develop an unassailable lead in the investigation of Venus.

NPO-Lavochkin built two new 3MV spacecraft for the 1969 launch opportunity. Venera 4 w7as high above the surface wlien it fell silent after 93 minutes of descent, either when it was crushed or when the battery ran out. It was decided that the new capsules must fall more rapidly in order to reach a deeper level in the time allowed by the battery. The capsules were similar to that of Venera 4, but modified to endure a higher entry velocity and with a smaller parachute for a faster descent.

Taken together, data from the Venera 4 and Mariner 5 missions in 1967 and from terrestrial measurements of the planet’s radio brightness indicated that the surface pressure on Venus greatly exceeded the design tolerance of the descent capsule. But the debate about whether Venera 4 had reached the surface raged on for 2 years. In 1968 Soviet and American scientists met first in Tucson in March, then again at the COSPAR meeting in Tokyo in May. and for a third time at a symposium in Kiev in October. The result was general agreement that the surface conditions were 427C and 90 bar. But this long debate did not reach consensus soon enough to influence the short construction schedule available for the 1969 probes. Knowing only that the pressure exceeded 18 bar, NPO-Lavochkin increased the tolerance to 25 bar for the new missions. By the time Venera 5 and 6 were launched, however, it was accepted that the surface pressure was much greater. With no time for further improvement, the missions were treated simply as an opportunity to obtain data using more precise instruments while new higher pressure designs were created for the next window .

Both missions were successful in descending through the atmosphere and. just as expected, the capsules imploded at altitude. The Soviet media had played down any expectations of reaching the surface. Venera 5 and 6 firmly set the stage for the next mission, which would attempt to reach the surface. This was the first 100% success rate for multiple launches and the first 100% success rate for multiple spacecraft.

Spacecraft:

The carrier vehicle was essentially the same as Venera 4, but the descent probe was strengthened to handle the higher velocity of approach in 1969, which would impose a higher deceleration load of 450 G, and also to withstand a pressure of 25 bar. This used up the buoyancy mass allocation. A lower velocity of 210 in. s was preset for the deployment of the pilot parachute, wath smaller parachutes employed to descend more quickly and obtain measurements nearer to the surface before either the battery expired or the internal temperatures became lethal. The pilot parachute was reduced in size from 2.2 to 1.9 square meters, and the main chute from 55 to just 12 square meters.

Figure 11.1 (right) shows the Venera 6 spacecraft folded in launch configuration. The entry system is at the bottom covered with its dark ablation material. Most 3MV pictures are taken with the probe painted white and bearing the letters "СССР’. The antenna and solar panels are folded to fit into the launcher shroud and the spiral gas cooling pipes are visible on the back of the high gain antenna dish which, by facing in the opposite direction to the solar panels, acts as a radiator. The Venera 5 and 6 spacecraft w ere identical.

Payload:

Carrier spacecraft:

1. Solar wind charged particle detector

2. Lyman-alpha and atomic oxygen photometers

3. Cosmic ray gas discharge and solid state detectors

These are the same as on Venera 4.

Descent/landing capsule:

1. Temperature, pressure and density sensors

2. Atmospheric chemical gas analyzers

3. Visible airglow photometer

4. Radio altimeter

5. Doppler experiment

Atmospheric density was measured during entry by a combination of Doppler tracking and the probe’s accelerometers. In the parachute descent the atmospheric structure experiment measured temperature, pressure and density. This instrument was improved over Venera 4 with three platinum wire resistance thermometers for more precision, two redundant sets of three aneroid barometers covering the ranges

0. 13 to 6.6 bar, 0.66 to 26 bar and 1 to 39 bar, and a tuning fork densitometer for the

wider range of 0.0005 to 0.040 g/cc. The atmospheric gas analyzers were improved and reconfigured to benefit from the experience of Venera 4. A getter was added to measure the total inert gases including molecular nitrogen, and refinements were introduced to make better measurements of molecular oxygen and water. Accuracies were improved by transmitting a pressure reading at the same time as a composition analysis. Venera 5 would make its composition measurements at higher altitudes and Venera 6 at lower altitudes. A number of improvements were made to the radar altimeter to avoid the problems on Venera 4, and three semaphores were provided for altitudes of 45, 35, and 25 km at an accuracy of about 1.3 km. Even though these were night-lime landings, a visible photometer was included to measure light levels during the descent because the dark hemisphere of the planet was known to exhibit an airglow phenomenon of unknown origin.

Mission description:

Venera 5 was launched on January 5, 1969, performed a course correction maneuver on March 14 when 15.5 million km from Earth, and reached Venus on May 16. The entry capsule was released at a distance of 37,000 km and at 06:01 UT it entered the atmosphere at 11.17 km/s at an approach angle of 65 degrees. During the parachute descent at 3°S 18°E on the night side, it provided a set of instrument readouts every 45 seconds for 53 minutes. The transmission ceased at an altitude of about 18 km when the pressure exceeded 27 bar. At that time the external temperature was 320 :C and internal temperatures had reached 28 C. It was 4:12 Venus solar time and the solar zenith angle was 117 degrees.

Venera 6 was launched on January 10, 1969, conducted a midcourse correction on March 16 at 15.7 million km, and arrived on May 17 (one day after its partner). The entry capsule was released at a distance of 25,000 km and it entered the atmosphere at 06:05 UT. It descended over 5 S 23 E on the night side and transmitted for 51 minutes. Signals ceased at an altitude of about 18 km and a pressure of 27 bar, thereby confirming the results from its partner. It was 4:18 Venus solar time and the solar zenith angle was 115 degrees.

The Venera 5 and 6 carrier spacecraft both provided measurements on the upper atmosphere and ionosphere prior to breaking up in the atmosphere.

Results:

The Venera 5 and 6 entry capsules transmitted in excess of 70 temperature readings and 50 pressure readings during the descent from about 55 km altitude to their crush depth. Atmospheric density was derived from the temperature and pressure data by using the hydrostatic equation and verified against parachute descent characteristics inferred from the radio altimeter. Doppler data provided altitude profiles of wind speed and direction, both horizontal and vertical. While there was initially confusion about the altimetry, these instruments did work properly and the temperatures and pressures measured near the radio altimeter marks were a good match to the current engineering model of the planet’s atmosphere:

Each capsule made two readings of atmospheric composition: at 0.6 and 5 bar for

Venera 5. and at 2 and 10 bar for Venera 6. Their readings were consistent and in good agreement with the Venera 4 data:

Neither photometer registered anything except darkness, although the photo­meter on Venera 5 did report a large reading just before termination. This eould have been a flash of lightning but. given the timing, it may merely have been an electrical transient caused by the imminent breakup.

The Venera 5 and 6 carrier spacecraft returned measurements on the solar wind in the vicinity of Venus and its interaction with the planet.

By early 1974 the Soviet space program was severely traumatized. Its manned lunar program had failed both to beat the IJS to a circumlunar flight and to introduce into service the N-l, its answer to the Saturn V launcher, meant to dispatch cosmonauts to land on the Moon. It had taken second prize with robotic lunar rovers and sample return missions. The all-out Mars effort of 1973 had been an embarrassing failure. In May, Vasily Mishin. Sergey Korolev’s protege and successor, was replaced as Chief Designer by the avowed rival to both, Valentin Glushko, who canceled the N-l and refocused the manned program on a new Energiya launcher and the Buran reusable spaceplane to compete with the space shuttle the US had recently started to develop.

In the early 1970s a "war of the worlds’* had raged in the community of Soviet scientists and engineers working on planetary exploration. The Venusians’ argued for concentrating on Venus where they felt the USSR had a clear advantage, instead of challenging the US wiiere it had gained the advantage. Of course, the "Martians* argued to focus on Mars as the more interesting of the tw o planets. They could not compete with the sophisticated Viking landers, but studies had been underway for several years for a bold and even more prestigious mission to Mars a sample return that w ould require the N-l lunar rocket. The debate w as between Roald Sagdeev, the Director of IKI, and Alexander Vinogradov, Director of the Vernadsky Institute of Geochemistry. Vice President of the Academy of Sciences and Chair of the Lunar and Planetary Section of the Academy’s Inter-Department Scientific and Technical Council on Space Exploration. The ultimate arbiter w;as Mstislav Keldysh, who was scientifically the most acknowledged and most politically well connected member of the community. Keldysh hesitated over the very ambitious plans of the "Martians* and eventually took the practical route by turning to Venus for the immediate launch opportunities. NPO-Lavochkin was allowed to continue designing Mars rovers and sample return missions that w’ould use the Proton launcher, but by 1975 76 these w ould prove impractical. Instead, Sergey Kryukov, who had taken over from Gcorgi Babakin on the latter’s death in August 1971, proposed to salvage the Mars program with a less ambitious mission to Phobos, the larger of the planet’s two small moons. Keldysh w’as supportive of this concept, but it w ould fade after Kryukov resigned in 1977 and Keldysh died in 1978, and the ‘Martians* had to stand down wiiile Venus look center stage for the next ten years.

Nonetheless, it is interesting to describe in some detail the very ambitious plans of the ‘Martians’ at that time. Soviet engineers had been working on designs for Mars sample return missions in parallel with developing the Mars spacecraft for the 1971 and 1973 campaigns. Bolstered by the success of the Luna 16 sample return and the Luna 17 lunar rover missions in 1970, the “top brass” ordered NPO-Lavochkin to fly a Mars sample return mission by mid-decade. Kryukov assumed that the N-l would be available. The first spacecraft design had a launch mass of 20 tons. The 16 ton entry system used an 11 meter acroshell with folding petals to enable it to fit inside the payload shroud. The lander eschewed parachutes and used large retro – rockets to decelerate. A direct return to Earth was planned with a spacecraft based on the 3MV design of Venera 4 to 6, using a two-stage rocket and an entry capsule which would deliver 200 grams of Martian soil to Earth. The Soviets w’restlcd with the complexity of the spacecraft system and also with the issue of biological contamination of Earth. A test mission was tentatively planned for 1973 that would deliver to the surface of Mars a rover based on the successful Lunokhod.

The failure of the N-l rocket program forced a change to a less massive design. In 1974 NPO-Lavochkin began to consider how to use the Proton to accomplish a Mars sample return mission. Two Protons would be used. The first would place a Block D upper stage and the spacecraft into Earth orbit and the second would orbit a second Block D that would rendezvous and dock. The two propulsive stages would then be fired in succession to send a flyby /lander spacecraft to Mars. Spacecraft mass would be saved by not requiring the sample return vehicle to fly directly back to

Earth but instead to enter Mars orbit, where it would rendezvous with an Earth – return vehicle that had been launched by a third Proton. And in one scenario, instead of entering the atmosphere the return vehicle w ould brake into a low Earth orbit for retrieval by a manned mission. Again a precursor mission for landing a rover on Mars w? as planned.

The project wrestled with continuing issues of complexity and mass. This led to a refinement in 1976 in which the first spacecraft would be launched into Earth orbit with its Block D upper stage dry, so as to allow’ for increased spacecraft mass. The second launch would deliver both a second Block D and fuel for transfer into the dry stage. The flybv/lander spacecraft launch mass was 9,135 kg. The flyby spacecraft w7as 1,680 kg, and the entry system 7,455 kg including 3,910 kg for the two-stage surface-to-orbit vehicle and 7.8 kg for the Earth return capsule, which in this version would pass through the atmosphere without having either a parachute or a telemetry system. The struggle to accommodate the complexity, cost and risk of this mission strained Soviet technology beyond its limits. At the same time, NPO-Lavochkin was continuing to mount complex lunar rover and sample return missions through 1976. The results from the considerable funds that were expended on designing these Mars missions were disappointing. Other programs, including a Lunokhod 3 mission, had to be sacrificed. When it became apparent that the project w? as impractical, it w’as canceled and Kryukov was transferred.

While successful at automated lunar sample return, the Soviet Union never got the chan ее to try a Mars sample return mission. In the mid-1970s the space ambitions of both nations were thwarted by their respective governments. In addition to losing the race to the Moon the Soviets had suffered appalling failures at Mars. Performance and cost became serious issues, and risk was less tolerable. Ironically, the result in the US w7as the same despite the success of the Apollo program and the Vikings at Mars. It would be a long time before either nation sent another mission to Mars but once again it w’as the Soviets who were the first to do so, with the Phobos missions of 1988. In the meantime, having taken the lead in planetary exploration in the 1970s by exploring from Mercury to Neptune, America fell behind again in the 1980s as their planetary launch rate dropped to zero and the Soviets reaped success after success at Venus and opened up their program to international cooperation with complex science-dense missions at Venus, Halley’s comet, and finally Mars.

The Phobos-Grunt spacecraft embraces the latest in space technology and erases the tradition of pressurized planetary spacecraft. The launcher will be the Zenit-Fregat. The Zenit rocket is a legacy of the Energiya-Ruran program, and the Fregat stage is a legacy from the Phobos and Mars-96 missions. For Phobos-Grunt to achieve the desired interplanetary trajectory, a burn of the spacecraft’s engine will be required after the Fregat burns out. The spacecraft will make the mideourse maneuvers, orbit insertion, and orbital maneuvers to rendezvous w ith and ultimately land on Phobos. the larger of the two Martian moons. Tradition also survives in the boldness of Russia’s return to robotic exploration: not just a modest step but an ambitious sample return mission, which seems appropriate for a program amongst whose unanswered legacies is a sample return from the Moon. Phobos-Grunt also continues the legacy of international cooperation, because it wall carry the first Chinese Mars spacecraft, Yinghuo 1, and release it into orbit around the planet.

The main goal of the Phobos-Grunt mission is to return a sample from Phobos to Earth for in-depth laboratory studies to help to answer key questions concerning the origin and evolution of the Solar System. The payload also includes instruments for navigation and for studying the Martian environment (television, space plasma and magnetic field detectors, and a dust particle detector) and instruments to study the surface of Phobos following the landing. The latter include a panoramic camera, gas

chromatograph, gamma-ray spectrometer, neutron spectrometer, laser time-of’-llight mass spectrometer, secondary ion mass spectrometer, infrared spectrometer, thermal detector, long-wave subsurface radar and a seismometer. The robotic manipulator to be used for sampling carries a micro-television camera, an alpha, proton and x-ray spectrometer, and a Mossbauer spectrometer.

The Soviet lunar and planetary exploration program in the 20th Century left a legacy of scientific results and new knowledge. Tt is difficult to remember how little we knew about the Moon and planets at the beginning of the space age in 1957, and how much wc have learned as a result of sending out spacecraft. Table 21.1 provides a summary of the exploration milestones achieved by the Soviet program, most of which occurred during the first 15 years of the space age. Soviet scientists also made many scientific discoveries in the course of their missions. The early Luna missions established that whereas ihc near side of the Moon is dominated by the dark maria.

the far side is dominated by the bright highlands, an interesting dichotomy that has yet to he adequately explained. Lunar mass coneentrations were first discovered by Soviet spacecraft. Much of what we know of the atmosphere and surface of Venus eoincs from the Venera missions. And while the Soviets were thwarted at Mars, they were first to successfully land (albeit the lander failed after a few seconds), made the first in-situ measurements in the Martian atmosphere, the early discoveries about its ionosphere, and the lack of an intrinsic magnetic field.

The Phobos-Crunt mission represents a hope that Russia will resume a lunar and planetary exploration enterprise with the same boldness, innovation, and persistence that they demonstrated in the first 40 years of space exploration.

Keldysh, Mstislav Vsevolodovich 1911-1978

President, Soviet Academy of Sciences 1961-75

While Sergey Korolev was the engineering genius behind the Soviet space program, Mstislav Keldysh was its scientific genius and his eager partner. 1’here was no single person equivalent to Keldysh in the US space program. As a brilliant and elegant mathematician, he was particularly adept at apply­ing mathematics to complex practical problems, with a special interest in aerodynamic engineering.

From 1946 to 1961 he was head of the research organization NII-1, which is now the Keldysh Research Center. NII-1 was originally Korolev and Glushko’s rocket research group prior to their arrest in the purges. In 1953 Keldysh was named head of the Division of Steklov’s Mathematical Institute which in 1966 became the Institute of Applied Mathematics and now bears his own name. In 1961 he was elected President of the Soviet Academy of Sciences.

Keldysh’s involvement in space research began in 1954 when he co-chaired with Korolev the committee that designed the scientific spacecraft that ultimately became Sputnik 3. Beginning in 1956 he chaired the Academy’s powerful MNTS committee and was regarded as the ‘Chief Theoretician’ of the space program, in charge of the scientific aspect of space including military applications in computers and nuclear weapons design. He and the Academy’s science institutions provided the theoretical basis for space exploration, rocket design, mission design and navigation in space. Unlike in the US, the Soviet Academy of Sciences was charged with developing the mathematical and scientific tools, including instruments, for space exploration, and as head of the Academy Keldysh was a major force in the development of lunar and planetary exploration in the USSR. The government often had the Academy assess the merits of projects proposed by the various design bureaus. Also, the government presented Keldysh to the international community as the face of the Soviet space exploration program, representing it abroad and to the media. His prominence went hand in glove with Korolev’s obscurity.

The Ye-4 impactor and Ye-5 orbiter designs were made obsolete by the Ye-6. It was a modular spacecraft with a carrier spacecraft on which could be mounted either a soft lander or an orbiter module. The first Ye-6 series were built at OKB-1 for soft landings on the Moon but managed not a single success after eleven straight launch attempts over three years between January 1963 and December 1965.

Luna Ye-6M (Lavochkin) series, 1966-1968

Responsibility for robotic lunar and planetary spacecraft design and construction was transferred from OKB-1 to NPO-Lavochkin in 1965. Lavochkin introduced its own modifications, and was immediately rewarded with Luna 9, which became the first successful lunar lander on February 3, 1966. Lavochkin also produced several orbiter versions, and over the following 14 months achieved a record of six mission successes out of nine Ye-6M launches. Both Ye-6M landers were successful, Luna 9 and Luna 13. After one failed launch the first model of the Ye-6S yielded the first lunar orbiter, Luna 10, which had instruments to measure the particles and fields in the lunar environment. It was then modified to acquire orbital photography. Both of these Yc-6LF missions, Luna 11 and Luna 12, were successful although no useful imagery was acquired in the first case. Finally, after another modification produced the Ye-6LS, two failed launches were followed by the Luna 14 orbiter.

Campaign objectives:

і’he first ever Venus campaign consisted of two spacecraft, each almost identical to the two lost in the failed Mars launches four months earlier. As had been the case for the Mars spacecraft, the Venus spacecraft w;ere also built in a great hurry. Although there was additional time, the schedule did not provide the iterative design process and extensive ground testing employed by later flight programs. Korolev’s engineers had to spend considerable time and effort debugging the systems. There were many disassemble, reassemble and test cycles to fix failed items, and after one fix another failure would occur. Once again the communications system was a major problem. Design issues emerged and workarounds had to be devised.

The IV Venus spacecraft had originally been intended to be a lander w ith camera, but by the time the Mars spacecraft were launched in October 1960 it had become clear that the lander w ould not be ready for the Venus launch window^ that opened in January, and the payload mass had to be significantly reduced to accommodate the instrumentation for the new launcher. The lander was abandoned and the mission

1VA No. l [Sputnik 7]

Venus Impaclor USSR /ОКВ-1 Molniya

February 4, 1961 at 01:18:04 UT (Baikonur) Failed to depart Earth orbit, fourth stage failure.

Venera 1 (1VA Ко.2)

Venus Impaclor USSR OKB-1 Molniya

February 12, 1961 at 00:34:37 UT (Baikonur) February 17, 1961 May 20, 1961

Failed in transit, communicalions lost.

descoped to a simple impactor. The goal was changed to undertaking science during the interplanetary cruise and in the environment of Venus prior to impact. Л small passive entry capsule was carried containing medallions. The 1VA redesign used as much of the 1M spacecraft as possible. Launched in February 1961, these were the second set of spacecraft to be launched to a planet, and the first to Venus, preceding the first US attempt at Venus by 18 months.

Only one 1VA spacecraft, Venera 1, was successfully launched on a trajectory to Venus. It was the first spacecraft ever successfully sent on a trajectory to another planet. Unfortunately it suffered from severe attitude control and thermal problems, and was lost after less than a week’s flight time.

The truncated flight of Venera 1 was offset by the triumph of the orbital flight by Yuri Gagarin on April 12, 1961. These achievements, together with the capability to launch heavy satellites and three successful Luna missions in 1959, established the USSR as pre-eminent in space flight in mid-1961. All that America could claim was eight lunar mission launch failures and one launch which, due to insufficient boost, resulted in a distant lunar flyby, all involving tiny spacecraft that had been created more as an afterthought to rocket development than as deliberate designs for space exploration.

Spacecraft:

The spacecraft were 2.035 meter long canisters. 1.05 meters in diameter, that were pressurized to 1.2 bar. They had 1 square meter solar arrays, medium-gain antennas on each panel, a boom omnidirectional antenna, and a dome-shaped propulsion unit on top. The sequencer, communications, attitude control, navigation, and propulsion systems w ere the same as the 1M spacecraft. The attitude control system had three modes of operations: a З-axis cruise mode for continuous solar pointing, a

back-up system for spinning about the solar axis in the event of some failure in the primary system, and a З-axis Earth pointing system for communication using the 2.33 meter high-gain parabolic mesh antenna. Thermal control was by passive louvers activated by internal temperature. A key difference with the Mars spacecraft was the addition of an Earth sensor, instead of a radio beacon, for more precise orientation during a high gain telemetry session.

The spherical entry device was mounted inside the pressurized canister, and not separable. Having been encased with thermal shielding, it was expected to survive as the rest of the spacecraft burned up on atmospheric entry. It was to free-fall through the atmosphere and impact the surface. Although it was not designed to survive an impact with a solid surface, it was expected to be able to float if it happened to come down on an ocean.

At that time the Venus ephemeris was more poorly known than Mars, the errors being about 15 times its radius, so achieving an impact was not an easy task. Radar ranging of Venus wus obtained for the first time in early April, while the planet was at inferior conjunction, enabling the ephemeris error to be reduced to 500 km. It is possible that if Venera 1 was still functioning, the Soviets would have used this new data to program a trajectory correction maneuver a few weeks prior to its arrival at the planet in May.

Launch mass: 643.5 kg

Payload:

Main spacecraft:

1. Boom-mounted triaxial fluxgate magnetometer to search for a Venus magnetic field

2. Ton trap charged particle detectors to investigate the interplanetary medium

3. Micro meteoroid detector to investigate interplanetary spacecraft hazards

4. Cosmic ray detectors to measure radiation hazards in space

5. Infrared radiometer for Venus temperature

These instruments were identical to those on the 1M Mars spacecraft. It is also reported to have had a pair of parallel magnetometers to measure the interplanetary magnetic field.

Entry probe:

1. Commemorative globe and medallion

The entry probe contained a 70 mm diameter metal globe with a commemorative medallion inside. The terrestrial oceans on the globe were blue-tinted and continents gold-tinted. It was designed to float. The medallion disk was inside the globe, which in turn was contained in a shell composed of pentagonal stainless steel elements on each of which was inscribed (in Russian) ‘Earth-Venus 196Г.

Mission description:

On February 4,1961, the new Molniya planetary rocket managed for the first time to deliver its fourth stage with attached spacecraft into a low ‘parking’ orbit. After 60 minutes of unpowered coast, the engine failed to rcignite, stranding the 1VA No. l spacecraft. The failure was caused by a power supply that used a transformer which not been designed to work in vacuum! The large orbital mass, 6,483 kg including the propulsive stage, prompted speculation in the West that it was a failed manned craft. The Soviets later said that they had been testing an orbiting platform from which an interplanetary probe could be launched. In fact, the ‘platform’ was no more than the new fourth stage of the launcher with the spacecraft attached. The Soviet description was doubtless highlighting the introduction of the parking orbit technique for deep space missions. It was designated Sputnik 7 in the US. On February 26 it re-entered the atmosphere over Siberia. Interestingly, the wreckage was discovered by a young boy and the heat-damaged pennant handed over to the KGB. The recovered articles were returned to the Academy of Sciences, which later sold them at auction in New York in 1996 to raise money for Russia’s impoverished science programs.

The powder supply problem in the first launch was traced to improperly mounting a transformer outside where it would be exposed to vacuum. A quick fix was rigged in time for the second launch by scaling the apparatus inside a vacuum-tight battery box.

On February 12. 1961. an Automatic Interplanetary Station’ that was later named Venera 1 was successfully boosted out of parking orbit. Communications sessions 2 hours and 9 hours after launch confirmed that the spacecraft was on a 96- day type I trajectory that would take it to the vieinity of Venus. Subsequent traeking indicated that a large midcourse correction would be required, but the target was in the cross-hairs! Analysis of the telemetry showed that operation in the Sun-pointing mode was unstable. The spaeeeraft automatically switched to the backup spin – stabilized mode in which most electrical systems except the sequencer and thermal control were shut down. This was a serious design error, since the command receiver was also turned off and denied the ground control of the spacecraft. In this safe mode, the spacecraft would re-activate the communication system every 5 days for a session with Earth. The high gain antenna could not be used because the spaeeeraft could not point at Earth. After an agonizing 5 days, the spacecraft contacted Earth on February 17 at a distance of 1.9 million km. The session was used to check the primary Sun-pointing operation, which failed again. On February 22 the spacecraft failed to respond, and no signal was received. The Soviets asked Jodrell Bank to listen for telemetry, and sent a team to England to assist, but nothing was heard. Attempts by Yevpatoria on March 4 and 5 also failed to receive any signal. Due to the inability to conduct a midcourse maneuver. Venera 1 flew silently past the planet at 100,000 km distance. In case it was silently continuing its mission, commands were sent on May 20. 1961. the day of the encounter, without result.

It was later determined that the altitude control system failure was due to the Sun sensor overheating. The thermal control design had only considered the average temperature for the instrument, and not the localized temperature at an unpressuri/ed sensitive clement. The lack of response after February 17 was attributed to a failure of the sequencer for the communications system. There was also evidence that the motorized thermal control shutters were not operating properly.

The flight of Venera 1 was followed worldwide as the first mission to another planet – another coup for the Soviet Union. But failure followed quickly. Radio Moscow announced the loss on March 2, noting that an investigation was underway and that sabotage was not excluded. The window closed on February 1 5, before the third 1VA could be launched.

Results:

None for Venus. Results were obtained from the Venera 1 instruments during its short cruise period. A faint interplanetary magnetic field on the order of 3.5 nT was reported and the solar wind plasma flow discovered by Luna 1 to 3 was found to be present beyond the Earth’s magnetopause in deep space. Venera 1 marked the first flight of a true interplanetary spacecraft with all the capabilities necessary for such a mission, including flexible attitude stabilization modes and midcourse maneuvering.

Campaign objectives:

The Ye-8 series was developed to support the Soviet lunar cosmonaut program. By the time that the Soviets entered the Moon race in mid-1964 Russian engineers at OKB-1 had already developed plans for a lunar rover. This, along with all the other lunar robotic programs, was transferred to NPO-Lavoehkin in 1965. In early 1966 an automated lunar surface rover entered the mission plan for supporting a cosmonaut on the lunar surface. The function of the rover was to precede the cosmonaut to the landing site, to survey and certify the site as safe for landing, to act as a radio beacon to guide the manned lander in, to inspect this lander after touchdown and certify it as safe for ascent, and, if it were not so, to transport the cosmonaut to a backup ascent vehicle that was already in place.

When the robotic lunar exploration program was transferred to NPO-Lavoehkin. Georgi Babakin set to work on a design for a spacecraft to meet these requirements. The availability of the powerful four-stage Proton launch vehicle using the Block D translunar injection stage enabled the resulting Ye-8 to be much heavier and more complex than its Ye-6 predecessor. The multi-purpose, in-line module design of the Ye-6 series was abandoned for a spacecraft design suited principally for soft landing a rover, and eventually other types of payload.

Spacecraft:

The spacecraft comprised three main components; a lander stage on the bottom, the rover that was carried on top, and a pair of side-mounted backpacks’, each of which had avionics and two cylindrical propellant tanks.

Cruise and lander stages:

The lander stage was based on a quartet of 88 an diameter spherical propellant tanks arranged in a square 4 meters on a side and connected using cylindrical inter-tank sections. These tanks fed a single engine whose thrust could be varied over the range 7.4 to 18.8 kN and a set of six vernier engines, two of which were mounted next to the main engine and were for use during the final descent to the surface. The other verniers were positioned around the periphery to provide stabilization. The landing system, engine, and radar altimeter were located between the tanks on the underside of the square tank assembly. Hach of the tanks supported a shock absorbing landing leg. Attitude control thrusters were located at various places around the lander. The avionics and attitude control sensors to control the translunar trajectory, lunar orbit insertion, orbital maneuvers, and landing, were housed in the inter-tank cylindrical sections. Water cooling was used for thermal control. Communications at 922 MHz and 768 MHz were by way of a cone-shaped antenna mounted on a boom. Uplink was at 115 MHz.

The two detachable backpacks’ were mounted vertically on opposite sides of the square tank assembly and were for cruise and orbital operations, bach consisted of a pair of 88 cm diameter cylindrical tanks, between which were avionics and battery modules. The tanks contained propellants to feed the main engine. On top of each of these tanks was a smaller spherical tank of nitrogen for the cold gas attitude control system.

The Isayev design bureau built the new throttleable KTDIJ-417 main engine. Its purpose was to conduct midcourse maneuvers during the translunar coast, lunar orbit insertion, orbital maneuvers, and key portions of the descent. Once the operational orbit at about 100 km altitude had been achieved, descent to the surface began with a burn of about 20 m/s to lower the perilune to about 15 km directly over the landing site. The backpacks were jettisoned and. with perilune looming, the main engine was ignited for a 1.700 m s ‘dead stop’ burn lasting 270 seconds designed to completely eliminate its horizontal velocity. After the spacecraft had free fallen to an altitude of about 600 meters and accelerated in the weak lunar gravity to a descent rate of about 250 m/s the main engine was reignited. This was shut down at 20 meters and the landing verniers ignited until a contact switch cut them off at a height of 2 meters. If all had gone to plan, the vehicle would then touch down at a velocity not exceeding 2.5 m/s. Unlike the Ye-6 soft landers, whose targets were constrained by the need to make a vertical descent from the translunar coast, the new spacecraft, by first going into orbit, could land anywhere.

f or a rover mission, two sets of folding ramps were mounted on top of the upper side of the lander fore and aft of the rover, whose wheels were on the middle of the ramps. The ends of the ramps were carried folded up against the rover, and once on the Moon they were unfolded and lowered to provide the rover with two options for driving off the lander down onto the surface.

Lunokhod rover:

The body of the Lunokhod rover was a tub-like pressurized magnesium alloy shell for avionics, instruments and environmental controls covered by a large hinged lid. In daylight on the lunar surface the convex lid would be opened over the rear of the rover to expose solar cells on the inside surface of the lid to generate pow er and also to expose radiators in the top of the ‘tub’ for thermal control. In darkness the lid was closed. It was a very simple and effective design. The solar cells (Si on Lunokhod 1 and GaAs on Lunokhod 2) gave 1 kW of power to recharge the internal batteries. The body was mounted on a carriage of eight wheels, 51 cm in diameter and made of ware mesh with titanium blade treads. This design was in response to the data on lunar soil provided by Luna 9; the thin dust layer and firm soil that this found led to the abandonment of a caterpillar track design. Each wheel had its own suspension system using a special fluoride based lubricant to operate in vacuum, a pressurized independent DC motor and an independent brake.

The rover was controlled entirely from Earth by a five-person team, there was no automated mode, and steering required independently changing the speed settings on the wheels. It could move with only two operational wheels on each side, and any of

the axles could be severed to shed a wheel if it became locked. The smallest turning radius was 80 cm. Internal gyroscopes indicated its orientation. It was designed to drive over obstacles 40 cm high or 60 cm wide, to climb slopes of 20 degrees, and to maneuver on slopes as steep as 45 degrees. There were fail-safe devices to prevent movement over excessive slopes. Lunokhod 1 had only one driving speed, 800 m/hr, traveling either forward or in reverse, but Lunokhod 2 was capable of 800 and 2,000 m/hr in either direction.

The control team operated and navigated the vehicle by viewing through a pair of television cameras mounted on the front of the rover. These returned low resolution images at a rate of 20 seconds/frame for Lunokhod 1 and at the much improved rate of up to 3.2 seconds/frame for Lunokhod 2. The signal time delay to the Moon and back to Earth was 5 seconds, which had an effect on operations. Pour other scanning photometer imagers of the type used on Luna 9 were mounted on the chassis. A pod on each side held a vertically mounted imager to give a 180 degree view at a 15 degree down angle, jointly providing a full panoramic view around the rover. A second imager was set above the first, nearer the top of the ‘tub’, and was mounted horizontally. These would jointly provide a full vertical panorama that included the sky and stars for navigation at the zenith and a vehicle level indicator at the nadir.

The rover was designed to survive three lunar nights, each lasting a fortnight over a period of 3 months. In darkness it was the kept alive by a small radioisotope heater with 11 kg of polonium-210 and by a radiator on top of the closed lid. Thermal control was by circulating internal air and by open-cycle water cooling. The rover was equipped with a conical low gain antenna, a steerable directional helical high gain antenna, television cameras, and extendable devices to impact the surface for soil density and mechanical property tests. Lunokhod 1 was 135 cm high, 170 cm long, 215 cm wide at the top, 160 cm wide at the wheels, had a wheelbase of 2.22 x

1.6 meters, and a mass of 756 kg.

Lunokhod 2 was an improvement based on experience with Lunokhod L It had an additional camera on the front at adult height for easier navigation. Its images could be transmitted at rates of 3.2, 5.7, 10.9 or 21.1 seconds‘frame, with the fastest rate being instrumental in improving driving operations. The 8-wiiecl drive system was improved, and Lunokhod 2 was twice as fast for twice the range. Additional science instruments were carried.

Luna 17 launch mass: 5,660 kg (landed mass 1,900 kg; rover 756 kg)

Luna 21 launch mass: 5,700 kg (landed mass 1,836 kg; rover 836 kg)

Payload:

Lunokhod 1:

1. Two television cameras for stereo images in the direction of travel

2. Four panoramic imagers

3. PrOP odometer/speedometer and soil mechanics penetrometer

4. Soil x-ray fluorescence spectrometer

5. Cosmic ray detectors

6. X-ray telescope for solar and extragalactic observations

7. Laser retro-reflector (France)

8.

Radiometer

four imagers were facsimile cameras of the type flown on Luna 9, with improved sensitivity and gain control and mounted two to a side. One camera in each pair was mounted for 180 degree horizontal scanning and the other for vertical scanning from surface to sky. bach 180 degree panorama consisted of 500 x 3,000 pixels. Between them, each pair of cameras provided a 360 degree panorama. The horizontal ones provided context for the forward cameras and the vertical ones assisted navigation in the driving process.

A ninth spiked wheel trailed behind the rover with an odometer to measure distance and speed. The surface penetrometer was mounted on a pantograph. The French laser retro-reflector weighed 3.5 kg and consisted of fourteen 10 cm silica glass prisms. It was designed for 25 cm accuracy. Due to Soviet secrecy, the French were given only a drawing for how the device would be mounted and were not told in advance what kind of lunar vehicle would carry it.

Lunokhod 2:

1. Three front television cameras for stereo images in the direction of travel

2. Four panoramic imagers

3. PrOF odometer/speedometer and soil mechanics penetrometer

4. Soil x-ray fluorescence spectrometer (Rifma-M)

5. Cosmic ray detectors

6. X-ray telescope for solar and extragalactic observations

7. Laser retro-reflector (France)

8. Radiometer

9. Visible-ultraviolet photometer

10. Boom magnetometer

Based on experience with Lunokhod 1, a third forward viewing television camera was mounted higher on Lunokhod 2 to provide a better driving perspective while the lower pair of television cameras provided stereo images of potential obstacles. The visible-ultraviolet photometer was to detect Larth airglow and galactic ultraviolet sources. The magnetometer was mounted on a 1.5 meter long boom in front of the rover. A Soviet-made photocell was added to the French retro-reflector to register laser strikes and the x-ray fluorescence spectrometer was improved.

Mission description:

First attempt falls do war aitge

The first attempt to launch a Ye-8 with a rover failed spectacularly on February 19. 1969, when the payload stack on top of the vehicle disintegrated 51 seconds into the flight. The launcher then exploded and scattered wreckage 15 miles downrange. The investigation discovered that at the point of maximum dynamic pressure, when the loads on the vehicle were greatest, the newly designed payload shroud for the Proton failed. The radioisotope heater that was to have kept the rover warm during the lunar night was never recovered from the debris, and rumors persist that the soldiers who actually found it decided to use it to heat their barracks during that year’s very cold winter.

Luna 17

A second attempt to launch a lunar rover was not made until 20 months later. After the loss of the first mission, the Ye-8 program had focused on attempts at automated lunar sample return in an effort to upstage Apollo. After Luna 16 succeeded with a returned sample in October 1970 it was decided, to launch a rover next. The back to back successes of an automated sample return mission and. a rover one month apart were impressive milestone achievements for the Soviet robotic lunar program.

Luna 17 was launched on November 10, 1970. After midcourse corrections on the 12th and 14th, it entered an 85 x 141 km lunar orbit on the 15th inclined at 141 degrees with a period of 115 minutes. It lowered its perilune to 19 km on the 16th and then at 03:46:50 UT on the 17th successfully touched down at a speed of about 2 m/s in the Sea of Rains at 38.25°N 325.00°E.

The Soviets announced their fourth lunar soft landing, and Westerners expected another sample return like Luna 16. However, about 3 hours after landing, at 06:28 UT, the ramps were lowered, the camera covers released, pictures of the ends of the

ramps were taken to ensure that there were no obstructions, and Lunokhod 1 rolled down the front ramp and 20 meters across the surface. The next day it remained in place and recharged its batteries, then it traveled 90 and 100 meters on the next two days. On the fifth day, 197 meters from its lander, it closed its lid and shut down for the forthcoming lunar night.

The public reaction across the world was astonishing. Somehow, people resonated strongly with the idea of a robotic rover driving around on another world, even if the experience was only a virtual one. The Luna 17 rover was a triumph heralded by the Soviet and Western press alike, whereas the Luna 16 sample return had only gained fleeting admiration. The appeal of the Lunokhod may have been partly derived from its physical form. Its antics were followed ardently in the press for the first few’ days, and the coverage would probably have continued were it not for the requirement to

shut it down for the long lunar night. It would be more than a quarter of a century before the US would recreate the excitement of a robotic rover on another world.

Lunokhod 1 survived its first lunar night and continued its activities. The drivers had some difficulty coming to terms with the frame rate of 20 seconds, and it was realized that the driving cameras had been set too low on the vehicle because their perspective was more like sitting on a chair than standing upright. And their images were so overexposed that the contrast in the scene was poor, especially near lunar noon. Initially excluded from the control room, the scientists had difficulty m having the rover pause at interesting rocks. This was because the engineers’ measure of success was distance covered. However, as the mission wore on it became easier for the scientists to achieve their objectives.

The operators drove the rover over 197 meters on the first lunar day, and as far as 2 km on the fifth lunar day. To test its navigational system, on one early excursion it returned to the lander stage. Over a period of 10 months it traversed rough hills and valleys and crossed many craters. It survived the -150°C cold of the lunar night and 100 C heat of lunar noon. It twice became stuck in craters, but after some effort was able to extract itself. The drivers had difficulty navigating because of the low mount of the cameras which meant they often did not spot a crater until the last moment. At noon the lack of shadows reduced the contrast to /его, making steering impossible. The rover survived a solar flare that might have been fatal for cosmonauts and an eclipse during which it was temporarily plunged into darkness. On the tenth lunar day it was spotted from orbit by the Apollo 15 astronauts.

The last successful communications session with Lunokhod 1 ended at 13:05 UT on September 14. 1971, after the internal pressure suddenly dropped. Officially, the mission concluded on October 4, 1971, the 14th anniversary of Sputnik. Fortunately, during its last communication cycle it had been parked with the laser retro-reflector in a position where it could continue to be used. Lunokhod 1 exceeded its expected lifetime of three lunar days by functioning for eleven lunar days. It traveled a total of 10,540 meters and transmitted more than 20.000 individual pietures, 206 panoramas. 25 x-ray elemental soil analyses, and more than 500 soil penetrometer tests. It was a spectacular success.

Luna 21

The next rover was modified to take account of the lessons from Lunokhod 1. and on January 8, 1973. Luna 21 was launched carrying Lunokhod 2. It performed a midcourse maneuver the next day, and on January 12 entered a 90 x 110 km lunar orbit inclined at 62 degrees with a period of 118 minutes. It lowered its perilune to 16 km the following day and then on January 15 fired its main engine at perilune to de­orbit itself. At an altitude of 750 meters the main engine ignited again to slow7 the rate of descent. At 22 meters this engine was shut down. The verniers took over to a height of 1.5 meters and were cut off. After falling the remaining distance the 7 m/s shock was absorbed by the legs. Luna 21 landed at 23:35 IJT at 26.92 N 30.45 E in Le Monnier bay. an eroded and lava flooded crater cut into the Taurus Mountains on the eastern shore of the Sea of Serenity.

The Lunokhod 2 rover immediately took TV images of the surrounding area from its perch atop the lander. After rolling down onto the surface at 01:14 UT on January 16 it took pictures of the lander and the landing site. It remained in place for 2 days until its batteries were charged, then took some more pictures and began its traverse. During its first full lunar day it covered a greater distance than its predecessor had in eleven lunar days. In one day. it traveled as much as 1.148 meters. It climbed a hill 400 meters high and photographed the peaks of the Taurus mountains poking over the horizon with Earth in the sky above. In late January 1973 an American scientist attending an international conference on planetary exploration in Moscow^ gave a set of Apollo 17 photos of the area w’here Luna 21 landed to Russian scientists at the meeting. These highly detailed photographs were used to navigate Lunokhod 2 to a rille some distance east of its landing site.

Rover operations were conducted during the lunar day, stopping occasionally to recharge the battery using its solar panels. It would hibernate during the lunar night, using the radioisotope heater to maintain thermal control.

Lunokhod 2 operated lor about 4 months, drove 37 km over terrain including hilly upland areas and rilles, more than four times the area of its predecessor, and returned over 80,000 individual images and 86 panoramas. It made hundreds of elemental analyses and mechanical tests of the soil, as well as being used for laser

ranging and other experiments. On May 9, 1973, it accidentally rolled into a small 5 meter crater whose depth had been concealed by a shadow. As the rover was backing itself out, it scraped its lid on the crater wall, causing a spray of dust to cover the solar panel. When the lid was closed for the lunar night, this soil was dumped onto the radiators. On opening the lid for the next lunar day, the resulting thermal and power problems led to the vehicle’s demise, which was announced on June 3.

Results:

Significant scientific results derived from analyzing the pictures of rocks and soil, wheel tracks, craters and other geological features observed by the twjo Lunokhods in more than 20,000 single frame images and 200 panoramas. There were many soil mechanics measurements by the penetrometer and chemical analysis results from the x-ray fluorescence spectrometer. The Sea of Rains and floor of Le Monnier proved to be a typical mare basalt, but the uplands around Le Monnier (the surviving part of the rim of the eroded crater) turned out to have higher concentrations of iron, silicon, aluminum and potassium.

Lasers fired by the French from the Pic du Midi observatory and by the Russians from the Semeis observatory in the Crimea used the retro-reflectors to determine the distance to the Moon to within 3 meters for Lunokhod 1, and 40 cm for Lunokhod 2. In the long term, such observations established the periodic and secular dynamics of the Moon. The cosmic ray instruments recorded the radiation on the Moon, and the x – ray telescope observed the Sun and the galaxy. The magnetometer on Lunokhod 2 measured a very weak magnetic field with variations due to currents induced by the interplanetary magnetic field. The photometer made some surprising observations of the brightness of the lunar sky. In particular, it determined that the day-time lunar sky was contaminated with some dust, and in Earthlight the night-time lunar sky was 15 times brighter than the sky on Earth at full Moon; findings which did not bode well for one day establishing astronomical observatories on the lunar surface.