Category Soviet Robots in the Solar System

TIMELINE: 1982-1983

The final missions in the Soviet Venera series were launched in June 1983. Having achieved most of their objectives with the Venera landers, these two spacecraft were outfitted with large radar antennas replacing the entry system and sent to Venus as orbital radar mappers. Both were successful, with their radars discerning the surface through the ubiquitous clouds to map from 30"N to the north pole with a resolution of about 2 km.

Launch date

1982

No missions

1983

2 Jun Venera 15 orbiter Successful radar mapper

7 Jun Venera 16 orbiter Successful radar mapper

PIERCING TIIE CLOUDY VEIL OF VENUS: 1983

Campaign objectives:

After six consecutive successes of their heavy Venus landers starting with Venera 9, the Soviets decided to send radar imaging orbiters in the 1983 opportunity instead of more landers. In 1978 the US Pioneer 12 orbiter had obtained radio altimetry data of the entire planet at the very low resolution of 150 km. and operated the altimeter in a side-looking mode to obtain a narrow equatorial strip of topography at a resolution

W. T. Huntress and M. Y. Marov, Soviet Robots in the Solar System: Mission Technologies and Discoveries, Springer Praxis Hooks 1, DOl 10.1007/978-1-4419-7898-1 17,

© Springer Science+Business Media, LLC 2011 of 30 km. This data was used to target the Venera 13 and 14 landers in 1981. The 1983 Venera radar or hi tors were intended to use hi sialic radar techniques ю improve the resolution to 2 km or better, albeit only over about 25% of the planet.

Venus had become more or less a ”Red ‘ planet, left almost exclusively to Soviet exploration. After the Mariner 5 flyby in 1967 it was over a decade before the US revisited the planet, and the two small Pioneers in 1978 were primarily focused on the ionosphere and atmosphere. But at that same time the US was also developing a proposal for a Venus Orbiting Imaging Radar (VOIR) mission. NPO-Lavochkin had been working on a Venus radar mapper since 1976 and, after having pioneered local surface imaging, the Soviets wanted to conduct their radar mapping mission before the Americans. As events transpired, they did not have to compete, since VOIR was canceled in 1981 and replaced by a simpler, less costly mission named Magellan that was noi launched until 1989. In essence all that NPO-Lavochkin had to do was to replace the entry system of its spacecraft with a side-looking radar to obtain imagery and electrical properties of the surface of the planet, and to add a radio altimeter to measure the topography on the ground track. But modifying the spacecraft to carry the radar was not without challenge.

Rumors of a Soviet Venus radar mapping mission began to circulate in the US in 1979, as NASA was trying to obtain funding for its VOIR mission. Familiar with the heavy nuclear-powered RORSAT orbiting radars the Soviets used to track Western navies, most observers in the IJS did not believe they had the technology to build a lightweight low-power synthetic aperture radar. It was indeed a struggle, particularly the data storage and computing requirements, and the launch had to be slipped from 1981 to 1983, but ultimately it performed rather well.

Spacecraft:

Venera 15 and 16 were the first in this series of carrier vehicles to be modified in a significant way since Venera 9. The bus was lengthened by 1 meter to accommodate the 1,300 kg of propellant needed to put such a heavy craft into orbit around Venus. The load of nitrogen for the attitude control system was increased from 36 to 114 kg to permit the large number of attitude changes that the orbital mission would entail. Two more solar panels were added outboard of the standard pair to provide the extra power to operate the radar system. The parabolic antenna was enlarged by 1 meter to a diameter of 2.6 meters to increase the bandwidth from 6 to 108 kbits/s and a new 5 cm band telemetry system was introduced to communicate with the 64 and 70 meter ground stations. The spacecraft were identical, and consisted of a cylinder 5 meters long and 1.1 meters in diameter. A 1.4 x 6.0 meter parabolic panel antenna for the synthetic aperture radar (SAR) was installed at the top, in place of the entry system. The entire SAR system weighed 300 kg. A 1 meter diameter parabolic dish antenna was mounted nearby for the radio altimeter. The electrical axis ol’the radio altimeter antenna was aligned with the long axis of the spacecraft, and the SAR was angled 10 degrees off this axis. During imaging, the radio altimeter would be lined up with the local vertical and the SAR would look off’ to the side by 10 degrees.

Launch mass: 5,250 kg (Venera 15) 5,300 kg (Venera 16)

Fuel mass: 2,443 kg (Venera 15) 2,520 kg (Venera 16)

Payload:

1. Polyus-V synthetic aperture radar (SAR) operating at a wavelength of 8 an

2. Omega radiometric altimeter

3. Thermal infrared (6 to 35 microns) Fourier emission spectrometer (IFSE, DDR-USSR)

4. Cosmic ray detectors (6)

5. Solar plasma detectors

6. Magnetometer (Austria)

7. Radio occultation experiment

All of the components of the SAR and radio altimeter were shared except for the antennas. The electronics cycled the 80 W traveling wave tube oscillator between the antennas every 0.3 seconds. An onboard computer controlled their sequencing and operation. The SAR antenna would illuminate the surface over 3.9 milliseconds with 20 cycles of 127 phase shifts for cross-track encoding. Spacecraft motion over that same interval swept out a 70 meter virtual antenna. After each transmission, the antenna was switched to the receiver, which digitized the magnitude and phase of the reflected radar pulses and stored the data as 2,540 complex numbers in a solid-state memory buffer. To keep up with the radar illumination cycle of 0.3 seconds, the data were read out alternately onto two tape recorders to complete a period of 16 minutes

ol mapping during a periapsis pass. Each such pass produced about 3,200 return images to compose a data strip approximately 120 x 7,500 km. Once the data were received on Earth, each individual 3.9 millisecond return was divided by time delay mto 127 ranges across-track and 31 ranges along-track and then processed to correct for atmospheric, geometric, and orbital effects. The individual return images for a pass were then assembled to yield, an image strip representing the slope, roughness, and emissivity of the surface of Venus.

During altimetry, the antenna would transmit a code sequence of 31 pulses, each of 1.54 microseconds duration. After transmission, the antenna was switched to the receiver, which recorded the reflection of the pulses from the surface over a period of 0.67 millisecond. The oval footprint of the altimeter radio beam was 40 km cross-track and 70 km along-track. After onboard processing of the return waveform, the data were stored on the tape recorder for later transmission to Earth, which further processed the data to correct for atmospheric, geometric, and orbital effects to yield altitudes. A low resolution mode was used until the orbital elements were precisely determined, and then it was switched to a high resolution mode. In combination with Doppler analysis, the high resolution mode reduced the footprint to 10 x 40 km with an error of about 1 km. The vertical accuracy was about 50 meters.

It was also decided to include an infrared Fourier-transform spectrometer supplied by East Germany. This weighed 35 kg and was intended to provide a higher spectral resolution than the infrared radiometer operated by the Pioneer 12 orbiter. ft divided the spectrum into a continuous set of 256 channels over the range 6 to 35 microns. It had a field of view of 100 x 100 km, and provided 60 complete spectra along each periapsis pass. The objectives were to obtain atmospheric temperature profiles from the 15 micron carbon dioxide band in the 90 to 65 km altitude range, the temperature of the upper cloud deck, the abundances of aerosols, sulfur dioxide and water vapor in the atmosphere, and data on the thermal structure and dynamics of the clouds and atmosphere.

The cosmic ray and solar wind experiments were similar to those flown on every Venus mission since Venera 1.

Mission description:

Venera 15 was launched on June 2. 1983, and conducted midcourse corrections on June 10 and October 1 before entering orbit around Venus on October 10. Venera 16 was launched on June 7, conducted midcourse corrections on June 15 and October 5. and entered orbit on October 14. Their orbital planes were inclined about 4 degrees relative to one another, so that any area that was missed by one spacecraft should be able to be imaged by the other. Venera 15 made an orbital trim on October 17, and Venera 16 did so on October 22. Each operating orbit was inclined at 87.5 degrees to the equator, with the periapsis at 1,000 km and the apoapsis at — 65,000 km and a period of 24 hours. The periapsis was positioned at about at 62 N and each periapsis passage would image the surface on a 70-degree arc. Both spacecraft began science operations on November 11. Small burns w’ere made from time to time to preserve the periapsis. accommodate high gain antenna position changes as the Sun-vehicle – Earth angle decreased, and maintain the 3 hour interval between the periapses of the two spacecraft.

Mapping and altimetry would typically begin at 80"N on the inbound side of the pole and continue over the pole down to 30 N on the retreating side. Radar imaging w as conducted continuously w ith a best resolution of about 1 km. The data collected on each 16 minute periapsis pass was stored on the tape recorders, then replayed to Earth during a daily 100 minute communications window prior to the next periapsis. During each 24 hour interval Venus would rotate on its axis by 1.48 degrees, and so successive mapping passes partially overlapped one another. At that rate. 8 months was required to cover all longitudes. The 24 hour orbit was necessary to enable the spacecraft downloads to be synchronized with the receiving stations in the USSR. Several orbital corrections w ere made during the mission to maintain the period and shape of each orbit. In June 1984. Venus went through superior conjunction and no transmissions were possible while it passed behind the Sun as seen from Earth. This provided an opportunity to conduct radio occultation experiments to study the solar and interplanetary plasma. After conjunction. Venera 16 rotated its orbit backwards 20 degrees relative to its partner to map areas missed prior to superior conjunction, and mapping was concluded shortly thereafter, on July 10.

Between them, the two spacecraft were able to image all of the planet from 30: N to the north pole, or about 25% overall. The resolution of 1 to 2 km w;as similar to w hat could be achieved by the 300 meter Arccibo radio telescope dish operating as a radar, but it w? as limited to equatorial latitudes and could not get the accompanying altimetry.

Venera 15 reportedly exhausted its supply of attitude control gas in March 1985. but Venera 16 continued to transmit data from its other instruments until May 28 of that year. No attempts w ere made to change orbits for higher resolution or increased coverage.

Results:

Together, the two spacecraft imaged from 30°N to the north pole at a resolution of 1 to 2 km. The primary product consisted of 27 radar mosaics at a scale of 1:5,000,000 of the northern 25% of the planet. The results confirmed that the highest elevations, meaning those which stand more than 4 km above the plains, have greatly enhanced radar reflectivity.

The radar experiments produced major discoveries about the surface of the planet, imaging new types of terrain that included:

Coronae large circular or oval features with deep concentric rings

Domes flat, nearly circular raised features some with central calderas

Arachnoids – collapsed domes with radial cracks

Tessera – large regions of linear ridges and valleys

Prior to Venera 15 and 16, the coronae glimpsed by Arecibo had been thought to be impact features filled with lava. About 30 coronae and 80 arachnoids were in the area mapped. As no evidence of plate lectonics was evident, the coronae, domes and arachnoids were all postulated lo be surface expressions of mantle plumes heating an immobile crust. There wjere no direct terrestrial analogs. The tessera appeared to be the oldest crustal regions on the planet, and were often overlapped by lava flows.

Even if large ohjects that penetrate the thick atmosphere are destroyed before they can reach the ground, they can create a shock wave that leaves an impression on the surface. There were about 150 craters in the area surveyed. Analysis of the cratering data led to a very young age of 750 + 250 million years, consistent with the idea of catastrophic resurfacing making the tessera, and large scale ‘blistering’ over mantle plumes between resurfacing events.

The altimeter produced extensive data on topography in the northern hemisphere. In combination with the radar data, scientists w’ere able to produce detailed maps of the surface.

The infrared spectrometer on Venera 16 malfunctioned, but the one on Venera 15 worked in orbit for 2 months before it too failed. The spectra clearly resolved carbon dioxide, water vapor, sulfur dioxide, and sulfuric acid aerosol. This data was strong confirmation that the particles in the upper cloud layer were a 75 to 85% solution of sulfuric acid. The aerosol distribution and mixing ratios for sulfur dioxide and water vapor were determined in the altitude range 105 to 60 km. The thermal structure and optical properties of the atmosphere were also determined in this altitude range. The clouds ranged from 70 to 47 km, but in the polar region the clouds were 5 to 8 km lower and the air above 60 km was warmer than in equatorial regions. The average surface temperature was measured at 500°C. but some warmer spots were detected along with some cooler regions. There were no features in Ihe spectrum to suggest the presence of organic compounds.

The two orbiters produced 176 radio occultation profiles between October 1983 and September 1984.

The USSR’s first missile test range was established after WW-II at Kapustin Yar near Volgograd, formerly Stalingrad. Throughout the 1950s this was used to test the early short and intermediate range Soviet rockets, and later for launching the smaller Cosmos satellites. As Korolev worked on his first ICBM design, the R-7, it became clear that a new launch site would be required to accommodate radio guidance and tracking stations along a much longer range within Soviet territory, and to move the work beyond range of US tracking stations in Turkey. Tyuratam in Kazakhstan was selected for the R-7 launch complex. The site was called Baikonur, after a railhead some 270 km to the northeast, in an attempt to deceive the Americans in targeting their missiles. Construction started in 1955, and over the years the site has become an immense facility some 85 km by 125 km in extent including dozens of assembly and launch complexes, numerous control centers and tracking stations, work areas for tens of thousands of workers, the town of Lcninsk to house them, and a 1,500 km test range.

The first launch complex to be built was the one for the R-7, and it is still in use today. It is part of the ‘Center’ or ‘Korolev’ area that includes the N-l assembly and launch complex that was later converted for Energiya and Buran. The ‘Left Flank’ or ‘Chelomey Arm’ to the northwest has assembly and launch complexes for the Proton, Tsiklon and Rokot. The ‘Right Flank’ or ‘Yangel Arm’ to the northeast has a backup R-7 pad and facilities for Zenit and Cosmos.

As with the first campaign to Mars and Venus in 1960-61, the second campaign to both planets in 1962 failed. Of the ten spacecraft launched, only two survived launch and neither of those completed its cruise in a functioning state. But the long Highi of Mars 1 was very encouraging, and the 2M V design was upgraded with new avionics to make the 3MV spacecraft for the 1964 launch opportunities to Venus and Mars.

Six 3MV launches were planned for the 1964 campaign, three each for Mars and Venus, but only five came off. In view of the high rate of previous failures, the first launch in each set of three was to test the 3MV/launeh vehicle system. However, both the Mars vehicle test flight in November 1963 and the Venus vehicle test flight in February 1964 were lost to launch vehicle failures. Although there was little time left before the launch window to Venus opened in March 1964, it proved possible to launch the two spacecraft in late March and early April. The first mission was lost to a launch vehicle failure, and the second, designated Zond 1, failed 2 months into the cruise when pressurization was lost. A single 3MV was successfully launched to Mars in November 1964. Designated Zond 2, it failed in transit after 1 month, in this case because of avionics problems. Both of these missions were given the designation wZond’ because it was realized shortly after launch that neither would be able reach its target in a functioning state.

The 3MV spacecraft that missed its Mars launch window in November 1964 was launched as a test spacecraft in July 1965. It conducted a successful flyby of the Moon as Zond 3, but failed its planetary test objectives when communications were lost before reaching Mars distance. It was the last 3MV launched to Mars. Later in November 1965 three more were launched to Venus. The first, Venera 2, was lost only 17 days before Venus encounter and the second, Venera 3, was lost just as the spacecraft approached the planet. However, they w7ere both the first Soviet planetary missions to reach the vicinity of their targets. The third spacecraft was lost to a launch vehicle failure.

By March 1966 the Soviet planetary program had no success to show for nineteen launch attempts, eleven to Venus and eight to Mars, since the start of the program in October 1960. Meanwhile, the US had achieved successful flyby missions of Venus in 1962 and Mars in 1965. Also, the builder of all Soviet robotic spacecraft to date, OKB-1, was overloaded with work on the manned space program and so the robotic program was transferred to NPO-Lavochkin. Throughout 1966 Lavochkin modified Korolev’s designs to deal with the problems revealed by previous flights, and began to produce their own versions of the Ye-6 and Ye-8 lunar spacecraft and the 3MV planetary spacecraft for Venus. It was decided not to attempt further ЗМ V missions to Mars, and instead to design a new’ heavier spacecraft w’hich would enter into orbit around the planet and deliver a soft lander. This strategy was intended to upstage the US flyby missions of Venus and Mars scheduled for the 1967-1969 launch window’s with entry probe and lander missions to Venus and with orbiter and lander missions to Mars.

Lavochkin prepared two new’ 3MV spacecraft with entry probes for the Venus 1967 opportunity. The entry probe was designed to make atmospheric measurements while descending by parachute and to survive impact on the surface for an assumed marginal atmospheric pressure. Both were launched in June 1967. The second w as lost to a launch vehicle failure, but on October 18, 1967 the first. Venera 4, became

the first successful planetary entry probe. The Soviets initially believed that it had survived all the way to the surface, but it transpired that it had been overwhelmed by conditions while still high in the atmosphere.

This strategy of two Venus probe launches at each opportunity was repeated for the next three Venus launch opportunities in 1969, 1970 and 1972. There were four successes in six launches, Venera 5 and 6 in 1969, Venera 7 in 1970, and Venera 8 in 1972. The probes were strengthened for each opportunity until they were finally able to survive the high pressures and temperatures at the surface of Venus. The first spacecraft to land and survive on the surface of another planet was Venera 7. Venera 8 duplicated the feat in 1972 near the morning terminator on the illuminated side of Venus and with a more versatile set of measurements.

Campaign objectives:

Korolev’s team had failed in their first two campaigns at both Mars and Venus. In 1960-61 only one mission of four. Venera 1, succeeded in reaching interplanetary space but it failed soon thereafter. In 1962 they had a new7 multipurpose spacecraft ready, the 2MV series, and launched three each to Mars and Venus. This time, only one of six. Mars 1, was successfully dispatched and it fell silent before reaching its target. Meanwhile, the Americans had frustrations of their own, suffering fourteen failed lunar missions through 1962. Their only success. Mariner 2 at Venus in 1962. served to further frustrate the Soviets who had worked hard to beat the Americans to our neighboring planets.

By now it was evident that there w ere serious problems w ith the reliability of the 8K78 launcher, in particular its fourth stage, and with the spacecraft. The troubled but lengthy flight of Mars 1 revealed problems serious enough to merit a redesign of the 2MV, and Korolev directed that these lessons be applied to building a new 3MV series for the Venus and Mars windows in 1964. and that test flights be conducted in between planetary opportunities. And, of course, he continued to instrument the fourth stage to diagnose its problems. The test flights were intended to validate the whole system from launcher to spacecraft.

The 3MV spacecraft was similar to the 2MV but with improved avionics. Special versions, designated 3MV-1A and 3MV-4A, were built for test missions simulating flights to Venus and Mars. These were lighter test models and did not carry a full set of science instruments. The first 3MV was launched in November 1963. The intent was to test planetary Hyby operations and the camera system at the Moon, and then perform operations to Mars distance before the Mars launch window opened a year later. The launch failed. It was followed in February 1964 with a launch of a test flight to Venus distance just prior to the opening of the Venus window in late March. This launch also failed. Despite these two losses, the Soviets had little option but to proceed with the 1964 program. Two of 3M V spacecraft were launched in the Venus window in March and April, the first succumbing to its launch vehicle and the second. Zond 1. failing in transit.

Undaunted, the Soviets continued with preparations for Mars. Although two flyby spacecraft and at least one entry probe were built, there were technical problems and only one spacecraft made it to the launch pad. The 3MV-4 No.2 flyby spacecraft was successfully dispatched on November 30, 1964. When it became clear that the spacecraft would not be able to meet its objectives, it was named Zond 2. The other Mars spacecraft prepared for this launch window were scrubbed and stored w hile the problems with the ЗМV were investigated. They w’ould subsequently be used for the Zond 3 mission and for the Venus campaign in 1965.

Following the string of five 3MV mission failures in 1963 1964, it was decided to conduct another test. The 3M V-4 No.3 Mars flyby spacecraft that missed its window in 1964 was launched 8 months later. Its task was the same as the spacecraft lost in November 1963, to test the spacecraft and science instruments in a lunar flyby and then test the deep space capabilities of the spacecraft by flying to Mars distance even though the planet would not be present upon arrival. After a successful launch, the spacecraft was designated Zond 3. (The Zond designation had initially been assigned to spacecraft that were clearly not going to be able to meet their objectives, as in the cases of Zond 1 and 2, and would henceforth be used for spacecraft launched either for deliberate testing purposes or to conduct science.) The lunar flyby was timed to photograph the far side of the Moon using the Mars camera, and Zond 3 successfully achieved its test objectives at the Moon. It failed to reach Mars distance but was able to maintain communications for almost 8 months, finally falling silent at a range of over 150 million km.

The Zond 3 spacecraft was the last of the 3MV Mars series to be launched before the robotic lunar and planetary programs were transferred to NPO-Lavochkin, where it w’as decided to abandon the troublesome 3MV design for Mars and instead design a new, heavier and much more capable spacecraft for launch by the Proton. None of the tw o 1M, three 2MV and three 3MV spacecraft launched to Mars, a total of eight including the two 3MV tests, had reached their targets, although Zond 3 did succeed at the Moon.

Spacecraft:

The ЗМ V spacecraft was similar in appearance and general function to the 2MV. It w? as slightly longer at 3.6 meters and had the same inline modular design consisting of a pressurized avionics or "orbital’ module, a propulsion system, and a pressurized flyby instrument module or entry probe. Minor changes were made to the shape in order to modify the moment of inertia and to account for solar wind torques, but the other dimensions were the same as the 2MV. A black shield was added in order to prevent scattered light from interfering with the optical sensors.

A thermal protection cowl was added to the Isayev KDU-414 propulsion system. This system was used for the 1M, 1VA, and all 2MV and ЗМ V spacecraft through to Venera 8. with variously sized tanks for its unsymmetrical dimethylhydrazine and nitric acid propellants. It w as capable of multiple firings, and on the 2MV and 3MV was gimbaled for thrust vectoring under gyroscopic control. The propulsion system assembly, including its tanks, was about 1 meter in length. For 3MV Venus missions the eompressed nitrogen gas bottles used to pressurize the engine propellants and for cold gas attitude control jets were mounted on the engine cowling. For 3MV Mars missions these bottles were on the collar bctw’een the avionics module and the flyby or entry module. Major improvements were made to the avionics, and redundancy w as added to the attitude control system jets. The high gain antenna w as increased to a diameter of 2.3 meters. Low gain omnidirectional antennas were installed on the

hemispherical radiators that circulated liquid. In addition to the attitude, navigation, thermal and operational control systems, the avionics module held 32 cm and meter band transmitters, 39 cm and meter band receivers, and two tape recorders. The solar panels charged a 112 amp-hour NiCd battery array that supplied the spacecraft with DC power at 14 volts.

In addition to the science instruments and the 5 cm impulse image transmitter, the flyby module contained an 8 cm continuous wave transmitter for backup image or spacecraft data transmission, and backup fonns of the command receiver and other avionics capable of operating the spacecraft in the event of a failure in the avionics module.

Each of these spacecraft, both Mars and Venus versions, had experimental plasma pulse engines on the engine cowl for attitude control in addition to the standard cold gas jets. They were tested successfully on Zond 2. and were later perfected and used regularly on Soviet spacecraft.

Launch mass: 800 kg (Cosmos 21)

950 kg (Zond 2)

960 kg (Zond 3)

Payload:

3MV-1A ISo.2:

1. Facsimile imaging system

2. Radiation detector

3. Charged particle detector

4. Magnetometer

5. Micrometeoroid detector

6. Lyman-alpha atomic hydrogen detector

7. Radio telescope

8. Ultraviolet and x-ray solar radiation experiment Zond 2 and 3:

1. Facsimile imaging system

2. Ultraviolet 285 to 355 nm spectrograph in the camera system

3. Ultraviolet 190 to 275 nm spectrograph for ozone

4. Infrared 3 to 4 micron spectrometer to search for organic compounds

5. Gas discharge and scintillation counters to detect Martian radiation belts

6. Charged particle detector

7. Magnetometer

8. Micrometeoroid detector

After the 1962 campaign, a major improvement was made to the facsimile film imaging system for the flyby missions. The imager mass w7as reduced from 32 to 6.5 kg while using 25.4 mm film capable of storing 40 images. Zond 2 carried two of these cameras equipped with 35 and 750 mm lenses. Zond 3 carried one camera with a 106.4 mm lens. Alternative exposures at 1 100th and 1/300th of a second were used, and an image could be taken and developed every 2.25 minutes. The 25 mm film could be repeatedly rewound for scanning at 550 or 1Л00 lines per frame. Imaging data were stored on the tape recorder that was included in the infrared spectrometer electronics. The 5 cm impulse transmitter and modulation scheme were improved for a factor of four decrease in image transmission times. In the high quality mode, camera images were transmitted at 550 pixels/second. which was 2 seconds per scan line, requiring a total of 34 minutes to send a 1,100 x 1,100 image. If necessary, the images could be sent at much slower rate by the 8 cm continuous wave transmitter. An ultraviolet spectrometer operating in the 285 to 355 nm range was built into the camera and reeorded its data on three frames of the film. These instruments were carried inside the flyby module and observed through three portholes – one for each lens and the spectrometer. Л second ultraviolet spectrometer operating in the 190 to 275 nm range was carried externally and produced digital data. The optical system for the infrared spectrometer was also mounted externally, and w as equipped with a small visible wavelength photometer to provide a reference signal. All of the optical instruments were bore-sighted.

Mission description:

The 3MV-1A No.2 mission ended in failure when the spacecraft was stranded in low Earth orbit. The third and fourth stages apparently separated abnormally. The fourth stage diverged in attitude during coast, and was incorrectly aligned when the engine ignited. Telemetry w’as lost at 1,330 seconds into the flight and the fourth stage with its payload remained in Earth orbit. With this mission, the Soviets initiated a policy of designating lunar and planetary missions stranded in parking orbit as ‘Kosmos a designation that was previously used for scientific satellites, in an effort to obscure their intended purpose. Today. Cosmos is used to designate military missions. 4 he failed 3MV-1A became Cosmos 21 and it re-entered 3 days later.

One year later, after another failed test launch of a 3MV Venus spacecraft and two launches to Venus, including Zond 1. the 3MV-4 No.2 spacecraft was launched on November 30. 1964, for what was intended to be a flyby of Mars at a distance of 1.500 km. However, one of the solar panels did not open due to a broken pull cord. The second panel was finally deployed on December 15 after several engine firings shook it loose, but by then it was too late to perform the first trajectory correction. It suffered other problems, including a timer that failed to activate the thermal control system properly. Unlike Zond 1 earlier in the year, the Soviets revealed Mars as an objective but. knowing that the flyby would not occur in the planned manner, they named the spacecraft Zond 2 and said its objectives were to carry out experiments ‘"in the vicinity of Mars”.

During the last authenticated communications session on December 18, 1964, the plasma engines were successfully tested. After that, communications became erratic. Jodrell Bank monitored transmissions from Zond 2 in Ianuarу and on February 3. 10 and 17. but it is unclear if any further operations were conducted. The Soviets finally announced on May 5 that contact had been lost. The USSR lost the opportunity to be the first to fly past Mars. This honor went to Mariner 4 on July 15. 1965, which the US had launched 2 days before Zond 2. On August 6 the silent Zond 2 flew by Mars at a range of 650.000 km.

Zond 3 was launched successfully on July 18, 1965. Approximately 33 hours later the imaging sequence began at a range of 11,570 km from the lunar near side, and continued through the lunar far side passage over a period of 68 minutes as the range closed to 9.960 km. The closest point of approach had been 9,219 km on the far side. A total of 28 linages were developed on board and transmitted on July 29, by which time the spacecraft was 1.25 million km from Earth. The spacecraft continued on its deep space test flight. A midcourse correction of 50 m/s was made on September 16 at a range of 12.5 million km. The images were rebroadcast from 2.2 million km and again at 31.5 million km to test the capabilities of the communications system. The last communication was on March 3, 1966, at a range of 153.5 million km, well on the way to the orbital distance of Mars.

Results:

There were no results for Mars. Zond 2 made a successful technology demonstration that was important for later deep space missions by operating its six plasma engines prior to the loss of communications, but they were found insufficient to control the attitude of the spacecraft. Zond 3 photographed 19 million square kilometers of the lunar surface including the.30% of the lunar far side that had been in darkness for Tuna 3. The twenty-five visible-band images and three ultraviolet-band images were of much better quality than the Luna 3 pictures. The Soviets achieved an engineering success with their first course correction to be performed using both solar and stellar references.

TIMELINE: AUG 1970-FEB 1972

The Soviets reached the zenith of their success at the Moon with robotic missions in 1970 and 1971. In September 1970 the Luna 16 mission successfully returned a sample of the Moon to Earth; an impressive achievement still unmatched by the US. In November the Luna 17 mission successfully deployed the first robotic rover on the Moon, Lunokhod 1; another achievement unmatched by the US. An attempt at sample return in September 1971 failed when communications were lost as Luna 18 was landing. It was followed immediately by Luna 19, a successful orbiter version of the spacecraft. Luna 20 became the second successful sample return mission in February 1972.

The Soviets also finally achieved a landing on Venus after eleven attempts since February 1961. Venera 7 was launched on August 17, 1970. with a descent capsule modified to withstand the massive surface pressure on Venus, and this succeeded in descending through the entire atmosphere and gently impacting the surface where it continued to operate for 23 minutes before succumbing to the high temperature. The Soviets finally had some success at Mars in 1971 after eight attempts since October 1960. The 1971 opportunity was not as energetically favorable as in 1969. requiring the landers to be released in the approach rather than after entering orbit around the planet. This and several engineering problems with the Mars-69 spacecraft forced a complete redesign. The 1971 Mars spacecraft became the basic design reference for all Soviet Proton-launched planetary spacecraft thereafter.

The Soviet plan in 1971 was to start with an orbiter to Mars which would provide precise information on the position of the planet to the spacecraft that followed, to enable these to deploy their landers on the necessarily very precise entry trajectories before themselves entering into orbit. This plan tvas foiled when the launch of the leading orbiter failed on May 10. Fortunately, the Soviets had a backup plan in which the approaching carrier spacecraft would use on board optical navigation to determine the position of Mars and autonomously update their navigation system so that they could properly deploy their landers. This complex and sophisticated system was far in advance of its lime, but very risky. The Mars 2 syslem rvorked, but due to a software error it dispatched its lander on an entry angle which was too steep and

W. T. Huntress and M. Y. Marov, Soviet Robots in the Solar System: Mission Technologies and Discoveries, Springer Praxis Books 1, DOl 10.1007/978-1-4419-7898-1 12,

© Springer Science 4-Business Media, LLC 2011

Launch date

1971

1972

14 Feb Luna 20 sample return

resulted in a crash. It worked perfectly for Mars 3 whose entry system placed the first successful lander on Mars, but after sending 20 seconds of uninterpretable data it fell silent. Both spacecraft entered orbit around the planet and transmitted images of its surface and data on its atmosphere, surface and plasma environment.

The US also had a major success at Mars in 1971. Mariner 9 was the lirst mission from this launch opportunity to arrive and became the first spacecraft to enter orbit. With more sophisticated cameras and systems, and an excellent instrument suite, its accomplishments completely eclipsed those of the much heavier Soviet orbiters.

TIMELINE: 1984-1985

During the 1970s there was mounting interest in the coming apparition in 1986 of the famous Comet Halley. The US was developing various plans for intercepting the comet at close range. The fledgling European Space Agency was considering doing the same. And the very small and academically oriented Japanese Institute for Space and AstronauLical Science had decided to send two small spacecraft equipped with plasma instrumentation.

At the start of the 1980s the USSR began to develop a large balloon mission for Venus with the French. But with the development of the mission advancing well the Soviets became interested in Comet Halley when they realized it would be possible for a spacecraft to use a Venus flyby to redirect itself towards the comet. The two missions were partially combined, and in an unprecedented move the Soviets issued an international call for instruments to fly on their spacecraft to Halley. As a result, their planetary exploration program suddenly became international outside the Iron Curtain. Not even the US had opened its more public space exploration program to such extensive international cooperation.

The spacecraft for this Venus-Halley (Vega) mission was very similar to a flyby Venera, but with an instrument scan platform added to track Halley. But instead of a large balloon consuming essentially the entire mass limit for the entry system, it was decided to carry a lander and augment this with a smaller balloon package. The balloon package would be released from the Lop portion of the entry sphere and the lander from the bottom portion. The balloon was to be inflated after release and then float at an altitude of about 50 km with a battery life of about 50 hours. The lander would be of the standard configuration.

Launched in December 1984, both of the Vega spacecraft performed well. Their landers and balloons were successful, the balloons drifting thousands of kilometers from the night-side to the day-side after more than 40 hours of flight. The spacecraft proceeded to encounter Halley, imaging the nucleus, taking data on the surrounding

W. T. Huntress and M. Y. Marov, Soviet Robots in the Solar System: Mission Technologies and Discoveries, Springer Praxis Hooks 1, DOl 10.1007/978-1-4419-7898-1 18,

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environment, and supporting the rest of the Halley ‘armada5 that comprised the two Soviet spacecraft, two Japanese spacecraft at far encounter, and the European Giotto spacecraft which, with navigational assistance from the Vega missions, was able to refine its trajectory to achieve a very close approach to the nucleus of the comet. The US was notably absent from the armada having failed, in a major embarrassment, to fund a mission to the comet.