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.