Category Soviet Robots in the Solar System

Campaign objectives:

After the August 1964 government declaration that divided the work on the Soviet manned lunar program between Chelomey’s Proton-launched cir cum lunar program and Korolev s N-l launched lander program, Korolev continued throughout the year to argue for both to be consolidated under his ОКБ-1. In addition to organizational and economic arguments, he offered the prospect of reaching the Moon much sooner with a spacecraft already in an advanced stage of design, whereas Chelomey would have to start from scratch. For the circumlunar mission Korolev proposed a stripped down form of his Earth orbital Soyuz complex w hich, as it happened, w^as originally conceived wath lunar missions in mind. The anxiety to get a Soviet cosmonaut to the Moon first, and Korolev’s persuasiveness, won him a partial victory in October 1965 when the government approved his 7K-L1 lunar Soyuz for circumlunar flights that would be launched by Chelomey’s Proton using OKB-l’s Block D as an upper stage. The N-l was neither ready nor appropriate for circumlunar missions, it was for the manned lunar landing program. Although rivals, Korolev and Chelomey appeared to work together well in implementing this circumlunar plan. Meanwhile Korolev would continue to develop the hardware for the manned lunar landing program: the N-l launcher, the LOK lunar orbital version of the Soyuz, and the LK lunar lander.

7K-L1 No.4L

Cireumliinar and Return Test Flight

USSR TsKBEM

Proton-K

September 27. 1967 at 22:11:54 UT (Baikonur) Booster destroyed.

7K-L1 No.5L

Circumlunar and Return Test Flight

USSR/TsKBCM

Proton-K

Zond 8 (7K-L1 No.14)

Circumlunar and Return Test Flight

USSR TsKBEM

Proton-K

October 20, 1970 at 19:55:39 UT (Baikonur) October 24. 1970 October 27. 1970 at 13:55 UT Successful recovery in Indian Ocean.

It was decided to make the test flights of the lunar versions of the Soyu/ in the Zond series, beginning with the 7K-L1 circumlunar model launched by the Proton. Approved in December 1966, the plan for the LI program called for four automated tests prior to the first manned circumlunar flight, which was scheduled for launch on June 26, 1967. The follow-on series was intended to test the 7K-LOK lunar orbital model launched by the N-l lunar rocket, the Soviet counterpart to the Saturn V. This extensive flight testing in the manned program was unique to the Soviets. Ironically, Korolev generally eschewed full-up piloted flight tests in the manner of Apollo, but he abhorred the extensive ground testing the US conducted in all its programs. As a result, Soviet spacecraft generally had a much higher degree of automation than US spacecraft, often to the chagrin of the cosmonauts, and the lack of ground testing led to poor performance in test flights and consequent failures and delays.

The success of Zond 5 in circumnavigating the Moon, returning to Earth and then being recovered in September 1968 set of!’ celebrations in the USSR. It was the first mission of either nation to achieve this feat. Shortly afterwards the Soviets revealed that it was an automated flight of a Soyuz manned capsule. This set off alarms in the US, because the way seemed clear for a cosmonaut to Пу the same mission. There were windows in November and mid-December which would enable the Soviets to steal a march on Apollo 8. whose launch window was in late December. (A window Гог the northerly Baikonur site opened slightly earlier than for the lower latitude site in Florida.) The Soviets used the November window for another test, but Zond 6 Tailed catastrophically during landing. Unaware of this setback the US expected a Soviet manned circumlunar mission in December, but there was no such launch. The way was now clear for Apollo 8. The Soviets had insisted on four successful automated flights of Zond prior to a manned mission. There had been an internal debate on whether it would be justified to make an attempt as reckless as the Soviets Гек the Americans were making with a mission to orbit the Moon using the first manned Saturn V. The failure of Zond 6 rendered this debate moot. After Apollo 8 the Soviets doggedly continued to perfect Zond for the circumlunar mission, but switched their focus and rushed tests of the N-l launcher.

Although most Zond test flights were designed to provide information on the techniques and technologies needed to fly cosmonauts to the Moon and back safely, they also provided information of scientific interest. Instrumentation flown on these missions gathered data on micrometeoroid flux, solar and cosmic rays, magnetic

fields, radio emissions, and the solar wind. Biological payloads were also flown and many excellent photographs of the Moon and Earth were taken.

Spacecraft:

The Soyuz 7K-L1 was a version of the 7K-LOK lunar orbital spacecraft modified to perform a circumlunar mission. Lacking an orbital module, it would have carried two rather than three cosmonauts. It had redesigned instrument panels for lunar missions and a thicker heat shield to handle the faster re-entry from a lunar return. There were a number of other design differences for the circumlunar missions.

Zond 4 is notable for being the first Soviet spacecraft to possess a computer. The 34 kg Argon 11 used integrated circuits, drew 75 W, was capable of 15 operations, and was provided with 4K of instruction ROM and 128 words of RAM.

Zond launch mass: ~ 5,375 kg

Payload:

Zonds 5 to 7:

1. Imaging system (color on Zond 7)

2. Cosmic ray detectors

3. Micrometeoroid detectors (Zond 6 only)

4. Biology payload

Zond 8:

1. Imaging system

2. Solar wind collector

The imaging systems on Zond 5, 6 and 8 carried a 400 mm camera for 13 x 18 cm frames of lsopanchromalic film. Zond 7 carried a 300 mm camera using 5.6 x 5.6 an film, both panchromatic and color. The solar wind collector utilized aluminum foil targets similar to the solar wind collectors that xA. pollo astronauts set up on the lunar surface, except that in the case of the Zond missions they were on the exterior of the descent capsule.

Mission description:

The constraints for circumlunar flights with launch and recovery in the high latitudes of the Soviet Union were fairly severe, yielding only 5 or 6 launch opportunities per year and not always spread out evenly over the year. Hence some Zond tests were made out to lunar distance without the Moon being available. Before the automated circumlunar series, there were two Earth orbital test flights. The first, launched on March 10, 1967, was only the fifth flight of the Proton and the first with Korolev’s Block D fourth stage. It successfully placed the Soyuz into an orbit with an apogee far from Earth and telemetry tests were carried out. No recovery was attempted. The mission, designated Cosmos 146, was an auspicious start. The schedule for the first manned circumlunar flight in June 1967 seemed feasible. But then everything went wrong. The second flight test on April 6, 1967, went awry when the Block D failed.

Worse, on April 23 the first manned Earth orbital flight of the Soyuz failed when it crashed upon landing, killing cosmonaut Vladimir Komarov. His brief orbital flight had been plagued with serious problems and in attempting an emergency landing the parachute became entangled. Both the Zond and Soyuz programs stood down while the common issues were addressed. By September the Zond program was ready to resume.

The first two circumlunar mission attempts fell victim to the Proton launcher. In the first on September 27, 1967. one of the six engines on the booster failed to ignite owing to a blocked propellant line and the rocket was destroyed 97 seconds into the flight. Pad engineers had not removed a cover before flight. On the second launch on November 22, 1967. one of the four engines on the second stage failed to ignite at 125 seconds into the flight and the rocket was destroyed at the 130 second mark.

The next launch had been scheduled for a window7 in April 1968, but the Soviets were anxious to finish testing and beat the US to the Moon so it w7as decided to go early, without the Moon, and test the spacecraft to lunar distance with the high speed re-entry. On March 2. 1968, Zond 4 w7as launched into a highly elliptical orbit with an apogee al 354.000 km. ll suffered many in flight system failures. An erratic star tracker in the attitude control system complicated the flight, but engineers managed to navigate the spacecraft back to Earth. The sensor failed again in the automated re-entry sequence, resulting a ballistic rather than the intended guided descent. While descending on its parachute over the Gulf of Guinea the capsule realized that it was off course and self-destructed using a mechanism installed in part to ensure that the Americans could not recover the spacecraft in the event of a badly targeted re-entry.

The next Zond launch attempt w’as to have been a cireumlunar flight, but it failed ignominiously on April 22, 1968, when the spacecraft emergency escape system was erroneously triggered at the 194 second mark, shutting down the second stage of the launcher and carrying the Zond spacecraft clear. It was recovered 520 km from the pad. Another planned Zond launch w? ent awry on July 14, 1968. when the oxygen tank in the fourth stage ruptured on the pad during pre-launch testing, destroying the Block D stage and killing three engineers. Fortunately, the lower stages, all loaded with propellant, did not explode. Although undamaged, spacecraft 7K-L1 No.8 was discarded.

After this frustrating series of failures, Zond 5 became the first fully successful cireumlunar flight. Launched on September 14. 1968, it achieved its mission despite suffering several technical problems. The Earth sensor had been mounted incorrectly owing to an error in the documentation. The star-tracker attitude control system was rendered ineffective when its optical surfaces became contaminated by sublimating thermal protection material. Worse, the backup system was mistakenly turned off. But engineers were able to control the spacecraft’s attitude in an awkward and slow’ process using the Sun sensors. Two midcourse maneuvers were conducted, and the spacecraft flew7 around the Moon on September 18 with a closest point of approach at an altitude of 1,950 km. Jodrell Bank announced the achievement and reported the spacecraft heading back to Earth. Only at this point did the Soviets actually admit to having launched the mission! On the voyage home a second attitude control sensor failed. On September 21 the spacecraft re-entered at 11 km/s at an overly steep angle on a ballistic rather than the planned guided ‘skip’ re-emry. fortunately, after the loss of Zond 4, the self-destruction system had been deleted. After a 6 minuie ride through the atmosphere with peak stresses of 16 G and 13.000 C, the descent capsule parachuted into the Indian Ocean at 16:08 UT near 32.63’S 65.55’E. 105 km from the nearest Soviet tracking ship. This was the first water recovery for the Soviets. The eapsule was offloaded at Mumbai. India, for return lo Moscow by aircraft. This boosted Soviet confidence in their human lunar program, but the flight had suffered serious non-fatal failures.

Zond 6 was successfully launched on November 10. 1968. Attitude control again became a problem when the high gain antenna, with the main star tracker attached. Tailed to deploy. The backup siar tracker system and a lower gain antenna were used instead. As the spacecraft flew around the Moon on November 14 at an altitude of 2,420 km it photographed the near and far sides. On its way home engineers had to reorient the spacecraft to try to control the temperature in a hydrogen peroxide tank by exposing it to direct sunlight and unfortunately this also heated and deformed the hatch seal, causing the cabin to depressurize. The biology payload was killed and the altimeter damaged. In preparation for re-entry on November 17 the service module separated as intended but the high gain antenna remained attached to the front of the capsule. The vehicle entered the atmosphere at 11 km/s and after bleeding off some energy it skipped back into space at 7.6 km/s as intended, at which time the antenna detached. All went well with the ‘second dip’ until at an altitude of 5,300 meters the altimeter failed to function properly and commanded the parachute to be jettisoned. Some film was recovered from the wreckage, including the first color pictures of the Moon, before explosives engineers detonated the 10 kg of I N I that had been carried on board the capsule for the radio-command destruct system.

Of tw o circumlunar missions, Zond 5 had failed to perform the skip’ maneuver during re-entry and had made a ballistic descent and splashed into the Indian Ocean, and Zond 6 had flown the intended trajectory only to fail on its parachute within the Baikonur boundary only 16 km from the launch pad. Undeterred, the Soviets made a valiant effort to prepare a mission for the December opportunity. Cosmonauts in training for a circum lunar flight argued to be allowed to fly. A vehicle was rolled out to the pad on December 1. but the spacecraft suffered so many technical problems that the window closed before approval to launch could be obtained. Even after the successful flight of Apollo 8 later in the month, the Soviets continued with the Zond tests. The hardware was available and the obvious thing was to push for success and realize the benefits of the investment. There was no precedent for actually stopping a Soviet space project with this much visibility. There remained the hope of making a manned circumlunar flight, although this prospect faded as the focus switched to the N-l launcher.

But in the next 8 months, w hile the Americans reveled in the success of Apollo 8, 10 and 11. three more set backs were to plague the Soviet manned lunar program. Anxious to solve the problems with the Zonds, another test flight to lunar distance was planned before the circumlunar window’s opened in summer. The launch of 7K – L1 No. l3L failed in January 1969 due to problems with the second and third stages.

One of four sccond-stagc engines shut down early, and then during its phase of the ascent the third stage suffered a breakdown in its fuel feed system and cut off. Even more significant for the manned program, in February and July of 1969 the first two test launches of the N-l lunar rocket also failed.

Nine months after the Zond 6 disaster, and shortly after Apollo 11 succeeded and the Soviet robotic lander Luna 15 crashed, Zond 7 was launched towards the Moon on August 7, 1969. The next day, it conducted a midcourse maneuver and took color pictures of Earth. On August 11 the spacecraft flew around the Moon at an altitude of 1,985 km and performed two sessions of color photography of both the Moon and Earth. It returned to Earth on August 14, made the intended ‘skipping’ re-entry and landed successfully in a preselected area south of Kustanai in Kazakhstan.

The plan had called for four test flights prior to a manned circumlunar mission, but of the four only Zond 5 and 7 wrere fully successful. This poor success rate led to

a proposal to fly one more test flight and then a manned mission to celebrate Lenin’s birthday in April 1970. The supporters argued that the flight would contribute to the program by demonstrating to the world that the USSR was capable of manned lunar missions. But the government rejected it because it would look second rate. To have sent cosmonauts on a circumlunar mission ahead of Apollo 8 would have been one thing, but to do so after Apollo 11 was something else. At the political level, benefit was now being determined relative to American achievements. Approval was given only for the final automated test flight.

Zond 8 vras launched on October 20, 1970. The next day it took pictures of Earth

from 64,480 km, and the day after that it made a midcourse maneuver at a range of

250.0 km. ft transmitted images of Earth for 3 days during its outbound flight and conducted two imaging sessions as it passed behind the Moon on October 24 at an altitude of 1,110 km. After two midcourse correction maneuvers on the return leg, it made a ballistic re-entry over the northern hemisphere on a southbound trajectory to sustain communication in most of the re-entry sequence. All previous Zonds had re­entered over the southern hemisphere, heading north. The capsule splashed into the Indian Ocean at 13:55 UT on October 27, approximately 24 km from the target point 730 km southeast of the Chagos Islands. It was recovered 15 minutes later by the Soviet oceanographic vessel Taman for return to Moscow by way of Bombay, India.

Results:

These were primarily engineering tesl flights, but they also carried payloads which provided scientific results.

Zond 5: High quality photographs of Earth were taken on the way home at a range of 90,000 km. They were useful because the film would be able to be processed on Earth rather than scanned on board and transmitted by radio. A biological payload of turtles, wine flies, fly eggs, meal worms, plants, seeds, bacteria, and other

living matter was recovered. The turtles had lost significant body mass and exhibited other metabolic anomalies. The fly eggs had not produced the expected number of adults, and the next generations of these showed a large increase in mutations.

Zond 6: The crash broke the film canister, but some film was recovered including images of the lunar limb and far side features taken at ranges of approximately 3,300 to 11,000 km. Some stereo pairs were also obtained. Only a few of its images have been published.

Zond 7: Color photography of both Earth and the Moon. A biological payload of turtles, wine flics, meal worms, plants, seeds, bacteria, and other living matter was successfully recovered.

Zond 8: Obtained photographs of Earth and the Moon from distances of 9,500 and 1,500 km.

To sum up, although the photography was excellent the science results from these

test flights were minimal. Data on solar wind and cosmic rays was obtained but not published. The seed samples on recovered flights all showed chromosomal damage but of the animals only the turtles on Zond 5 showed any ill-effects.

The Venera 7 landing on the surface of Venus was a jubilant success for the Soviets. Once the pressure and temperature at the surface were finally confirmed, the NPO – Lavochkin engineers scaled back the pressure design limit from 180 bar to 105 bar and used the saved mass for a stronger parachute and more scientific instruments. In
anticipation of their next generation of larger more complex Venus landers, a photometer was added to determine the illumination at the surface. All of the previous entry probes had been targeted at the night-time hemisphere, mainly to ensure direct-to-Earth comm uni cations. but day-side light-level measurements were required in order to design imagers for future landers. So the 1972 missions were to land in early morning daylight at sites near the terminator from which it would still be possible to transmit to Earth. A redundant deployable antenna was ineluded as a precaution against poor primary antenna pointing or obscuration of the line of sight by rough terrain.

Two launches were attempted, the first successfully dispatching Venera 8 and the second stranding its spacecraft in parking orbit. Venera 8 was the ultimate success of the 3MV series and. as events transpired, the last of its type. It achieved all that the Soviets had worked so hard for over so many years and so many attempts. It was the final reward for dogged persistence. During its construction, NPO-Lavochkin was working on the new generation of Luna spacecraft to undertake sample return, rover and orbiter missions, and the or biters and landers for Mars, both of which would use the Proton launcher, so this was the final planetary campaign to employ the 8K78M Molniya.

Venera 8 supplied the data needed to design the much more sophisticated landers that would be delivered by the next generation of advanced Venera spacecraft to be launched by the Proton rocket beginning in 1975.

Spacecraft:

The carrier spacecraft for Venera 8 was essentially the same as for all missions since Venera 4, but the entry probe was modified. The pressure design limit was reduced to accommodate additional science instruments and the parachute was strengthened, although the size of the canopy was the same as for Venera 7 in order to make the same rapid descent through the atmosphere. Since the probe was to land further from the center of the planet as viewed from Earth, the antenna transmission pattern was changed from the egg-shape that was appropriate when Earth was at the zenith to a funnel-shape for when Earth was low on the horizon. In case the capsule were to come to rest on its side, a second antenna was provided that was to be ejected onto the surface and this was a flat disk with a spiral antenna on each side to enable it to work irrespective of how it settled.

A new honeycomb composite material was used as the primary insulation of the lander. Further thermal protection was provided by using lithium nitrate trihydrate, a phase-change material that absorbs heat by melting at 30’C. In addition to forming ‘thermal accumulators’ inside the pressure vessel, this jacketed the instruments that projected outside.

Launch mass: 1,184 kg

Entry capsule mass: 495 kg

Payload:

Carrier spacecraft:

1. Solar wind charged particle detector

2. Cosmic ray gas discharge and solid state detectors

3. Ultraviolet spectrometer for Lyman-alpha measurements

Descent I landing capsule:

1. Temperature, pressure and density sensors

2. Atmospheric chemical gas analyzer

3. Broad-band visible photometers (2)

4. Gamma-ray spectrometer

5. Radio altimeter

6. Doppler experiment

An accelerometer was to measure atmospheric density during the descent prior to parachute deployment. The altimeter had been redesigned to provide an accuracy of several hundred, meters for the instruments that would operate during the parachute descent. The atmospheric composition experiment now included an ammonia litmus

test, and the atmospheric structure experiment carried four resistance thermometers, three aneroid barometers, and a capacitance barometer. A pair of single-channel broadband cadmium sulfide photometers were carried to measure the integrated downward flux with a 60 degree field of view in the wavelength range 0.52 to 0.72 microns. The optical unit was outside the capsule, mounted on top inside a separate unit scaled against high pressure and insulated against high temperature. The light reached the electronics by a 1 meter long light guide of fiber optic. The photometers were sensitive over the range 1 to 10,000 lux and encoded logarithmically.

The gamma-ray spectrometer was mounted inside the hermetically sealed probe. It was sensitive to emissions from potassium, thorium and uranium, and had been calibrated for these elements against a suite of Earth rocks.

Mission description:

Venera 8 was launched on March 27, 1972, made its midcourse correction maneuver on April 6, and arrived at Venus on July 22. The solar panels charged the batteries of the capsule and a system in the cruise module pre-cooled the capsule by circulating air through it at -15C’C. After being released 53 minutes prior to entry, the capsule hit the atmosphere at 11.6 km/s at 08:37 UT at an angle of 77 degrees on the sunlit side.

approximately 500 km from the morning terminator. Eighteen seconds later it had slowed to 250 m/s and deployed its pilot parachute. The reefed main parachute opened at 60 km altitude and the canopy was fully opened at 30 km. The instruments were activated at 50 km and transmitted data during the 55 minute descent. There was a clear line of sight to Yevpatoria. The capsule thumped onto the surface at 10.70°S 335.25°E. It was 6:24 Venus solar time and the solar zenith angle was 84.5 degrees. The parachute was jettisoned on impact and the secondary antenna was

deployed onto the surface. The capsule transmitted for another 63 minutes reporting measurements on the surface, starting with a 13 minute stream from the primary antenna, then a 20 minute stream from the secondary antenna, and finally a 30 minute stream from the primary.

The Venera 8 carrier spacecraft returned measurements on the upper atmosphere and ionosphere prior to breaking up in the atmosphere.

The second spacecraft to be launched failed to depart from low Harth orbit due to a fourth-stage misfire when the failure of a timer caused the engine to stop after only 125 seconds. It was stranded in a highly elliptical orbit and designated Cosmos 482. At the end of June a fragment separated. This was probably the entry capsule, and it remained in orbit when the main spacecraft re-entered on May 5, 1981.

Results:

The Venera 8 capsule returned a wealth of data about the atmosphere and surface. It determined atmospheric density from accelerometer data in the altitude range 100 to 65 km and directly measured atmospheric temperature, pressure, composition and down-welling light flux from 55 km down to the surface. Although imprecise, these first profiles of the solar flux versus altitude were sufficient to confirm that the high temperatures were caused by the greenhouse effect. The illumination at the surface was measured and the pattern of change in attenuation attributed to clouds. Profiles of the speed and direction of horizontal winds from 55 km down to the surface were obtained from Doppler data. The wind speed was 100 m/s above 50 km, 40 to 70 m/s in the haze layer near 45 km, surprisingly rapid at 20 to 40 m/s below this down to 20 km, and only about 1 m s from 10 km to the surface. The wind was super-rotating coincident with the motion of the high ultraviolet clouds.

The first report from the radio altimeter was at an altitude of 45.5 km and it gave a total of 35 readings, the last at 900 meters. The capsule drifted 60 km horizontally as it descended. The altimeter produced a ground profile with two mountains 1,000 and 2,000 meters tall, a hollow 2.000 meters deep, and a gentle upward slope toward the landing site. Two echo intensity profiles were obtained from which it w as possible to compute the dielectric constant and a surface density of 1.4 g/ec. The photometers made 27 measurements, and the light level declined steadily from 50 to 35 km as the probe descended through the clouds. Venera 8 was the first to distinguish three main optical regions in the atmosphere: two cloud layers w’ith a thicker upper layer of fog from 65 to 49 km and a lower haze layer from 49 to 32 km. Then the light level was essentially constant to the surface, indicating a relatively clear atmosphere below the clouds. The illumination in this part of the atmosphere was comparable to a cloudy day on Harth at tw ilight. The w eak surface brightness indicated that only 1 % of the incident sunlight reached the surface. On the other hand, the Sun was only 5 degrees above the horizon. The important finding was that the illumination wras sufficient for the next lander to operate a camera.

The gas analyzer returned a composition of 97% carbon dioxide, 2% nitrogen.

0. 9% water vapor, and 0.15% oxygen. Although the ammonia test gave a positive detection at altitudes between 44 and 32 km with readings of 0.1 to 0.01 %. this was compromised by sulfuric acid which also reacts positively. A significant point is that the gas analyzer eon firmed the presence of sulfuric acid in the clouds. This had been offered as an explanation of why the clouds were so arid and yet were able to form cloud droplets. And the fact that such droplets would reflect sunlight so efficiently explained why the planet had such a high albedo.

On the surface, Venera 8 reported a pressure of 93 + 1.5 bar and a temperature of 470 ± 8’C. confirming the measurements by Venera 7 and in good agreement with an extrapolation of the data from the Venera 4, 5 and 6 probes down to the surface using models of the adiabatic temperature lapse rate.

The gamma-ray spectrometer made measurements in the descent, and tw o on the surface. It reported 4% potassium. 6.5 ppm thorium, and 2.2 ppm uranium indicative of a more granitic than basaltic composition. However. this result was contested and all later Venera landers found more common basaltic compositions. Radar mapping many years later showed that Venera 8 landed in an upland volcanic region that was probably older than the lava plains that constitute most of the planet. Alternatively, a potassium-rich basalt that is relatively rare on Earth could account for this particular data.

A HISTORICAL SYNOPSIS

The history of exploring the Solar System by spacecraft is short, spanning less than 42 years at the end of the 20th Century. Prior to January 1,2001, there had been 182 launches. Of these, 89 were successful or partly successful, and three were in transit to their ultimate destinations. The exploration of the planets was dominated in the 20th Century by competition between the USSR and USA. Only five of the total of 182 missions were developed by other parties. It was not until 1985 that Europe and Japan launched their own deep space missions.

In the early years of the space race the USSR was usually first to achieve major feats at the Moon, Venus, and Mars. After the ncck-to-neck race to the Moon in the 1960s, and its culmination with Apollo, the US, which had also had greater success with planetary missions, assumed the leading position in robotic exploration in the 1970s with unopposed successes at Mars, Mercury, and the outer Solar System. The USSR had no answer to the Mariner 9 Mars orbiter, the two Viking orbiters and landers at Mars, the Mariner 10 flybys of Mercury, or the Pioneer 10 and 11 and Voyager 1 and 2 missions to the outer planets – a realm where the Soviets were not technologically prepared to go. The US had conceded only Venus, where the Venera missions reigned supreme. At the beginning of the 1980s the Soviet program could be said to have won the competition at Venus, but lost it everywhere else. This trend changed with the Vega missions in the middle of that decade. The USSR vigorously participated in the International Halley Mission with the European Space Agency and Japan, and contributed two spacecraft as platforms for instruments from any country that wished to provide them. The Europeans and the USSR led this highly successful and precedent-setting enterprise for the Old Continent. The Americans of the New World were a minor player and did not even send a spacecraft to Halley for this first world-wide planetary exploration endeavor.

By the mid-1980s, the Soviets had seized the lead in planetary exploration from the Americans. The USSR gained a great deal of pride and prestige around the world from the Vega missions to Comet Halley, and decided as a matter of policy to open

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 21,

© Springer Science+Business Media, LLC 2011 up future missions to international participation. They would be essentially Russian vehicles and Russian-led missions, but with instruments and scientific participation from around the world. The Americans were at a significant disadvantage in this situation, since they did not have the massive spacecraft to offer valuable instrument real estate to others and to compete with the Russians in this way. In addition, the US planetary program wras suffering from a major decline in the 1980s starting with the administration of Ronald Reagan, who preferred a more direct competition with the Soviet Union.

The Vega campaign had been conceived as an almost entirely Soviet mission with some participation by the French, but was modified with international instruments, many from the Eastern Bloc, being added for the Halley intercept. The next Soviet planetary mission, Phobos. was internationalized earlier in its development, look this to a greater extreme, and had more instruments of Western origin. Mars-96 was the culmination of the international style of Soviet planetary missions, with instruments openly and broadly solicited from around the world and with a larger investment by Western countries including the US. It is supremely ironic that the Americans, who prided themselves on the openness of their space exploration program, remained far more xenophobic in their planetary exploration program than the Soviets, and were obliged to concede the lead in international planetary exploration missions to the Vega, Phobos and Mars-96 missions.

After the fall of the Soviet Union in 1991, attempts to form partnerships between the US and Russian planetary programs failed as the resources for further Russian planetary missions dried up in major national economic problems. The abysmal loss of Mars-96 created an international disaster, demoralized the national program, and embarrassed the post-Soviet Russian national government and its new space agency. Already beset with financial problems, Russia cut its investment in space science missions. At the end of the 20lh Century, the Russian national program of robotic planetary exploration appeared to have been postponed indefinitely.

Unfortunate fate has been a bedfellow to Russian history for a millennium, and so it was for the Russian planetary exploration program just as it reached its peak in the late 1980s while that of the US was declining. A decade later there w? as no Russian planetary exploration program, the IJS program was revitalized, and the French, a bell-weather for international involvement in space science and a participant on Soviet missions since the early 1970s. were now making trips to Washington instead of to Moscow. But the hopes and dreams remained alive in Russia. After watching from the sidelines since 1996. and contributing primarily by offering launch services for cash, the Russians are just now emerging after a 15 year absence with the launch of a Phobos sample return mission scheduled for 2011 and with plans for a lunar orbiteriander missions for later in the decade.

Afanasyev, Sergey Aleksandrovich 1918-2001 ‘

First Minister of General Machine Building 1965-1983

Sergey Afanasyev’s organization managed the institutions and workforce that built ballistic missiles and satellites vital to the defense of the Soviet Union, as well as the spacecraft and launch vehicles for their politically important space ex­ploration program. Leonid Brezhnev once told him,

“We believe in you, but if you fail w;e will put you against a brick wall and shoot you.” Known as “the big hammer”, he could be a very rude and intimidating man but he had a talent for orches­trating immense projects. He was among the most powerful people involved in the USSR’s space program, which included Korolev and his rival Glushko. His criticism of Korolev’s management of the manned space program resulted in the separation of the robotic program from Korolev’s bailiwick to that of Georgi Babakin in 1965. He oversaw the Soviet Union’s response to the Apollo project and was ultimately responsible for canceling it after many setbacks.

LUNAR SPACECRAFT

Russian lunar spacecraft can be divided into families according to their evolution from the very first simple flyby and impactor spacecraft in 1958-1960, exemplified by Luna 1 to 3, to the first modular designs built for soft-landing culminating with Luna 9 and 13, to the final series of complex sample return and lunar rover missions beginning with Luna 15 and continuing through to Luna 24. After the first success at soft-landing, some of these spacecraft were modified to carry lunar orbital payloads, in particular to perform tasks in support of an eventual manned lunar landing. These modifications were easily and quickly accomplished because of the modular design. The final series were essentially large soft-landcrs with interchangeable payloads. Although they were complex, they achieved the first robotic sample return missions and first lunar rovers in addition to a pair of orbiters.

Luna Ye-1 series, І958-1959

in the summer of 1958, the Americans and the Russians were racing to launch the first spacecraft to the Moon as a major signal of strength in rocket technology. The spacecraft were small and lightly instrumented and were flown opportunistically on what were mainly test flights of military rockets. The goals were more technological and political than scientific.

The Americans tried eight times to reach the Moon without success in 1958 1960. Only one spacecraft, Pioneer 4, was launched successfully to Earth escape velocity, but it missed the Moon by a wide margin.

To counter the American lunar campaign, the Soviet Union built the Ye-1 lunar impactor spacecraft for launch on a new’ three-stage Luna rocket derived from the R-7 that launched Sputnik. The Yc-1 wras a very simple spherical payload similar to Sputnik, spin-stabilized, with several protruding antennas. Six such spacecraft w’crc launched during the 12 months between September 1958 and 1959. All but two were

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lost to launch vehicle mishaps, but owing to the Soviet way of not naming a mission until it was successfully underway, these were Luna 1 and Luna 2. Although Luna 1 missed the Moon on January 4, 1959, it was the first spacecraft to achieve escape velocity – two months before Pioneer 4. The final spacecraft to be launched in this series, Luna 2, became the first spacecraft to impact the Moon on September 14, 1959. Tn effect, the Soviets had kept launching until their goal was achieved, and then they moved on.

TIMELINE: OCT 1960-FEB 1961

The Moon had been the principal target for the USSR in 1958 and 1959, and for the US as well through 1960, hut both had ambitions to send spacecraft to the planets. Venus was the closest and most accessible, but Mars, slightly farther away, was the most fascinating. Having been successful at the Moon, the Soviet Union was ready to start launching planetary missions in 1960. The US, struggling to achieve success at the Moon, decided to put off attempting planetary missions.

Korolev developed a four-stage version of the R-7 rocket to launch missions to the planets, and a spacecraft quite different from the initial Luna series to meet the challenges of interplanetary flight. The new rocket and spacecraft were ready for the launch opportunities for Mars in late 1960 and for Venus in early 1961. The first attempts to send a spacecraft to Mars were on October 10 and 14, 1960. and in both cases the third stage failed, giving the new fourth stage and spacecraft no chance to perform. Later on February 4, 1961, the first attempt to send a spacecraft to Venus was foiled when the engine of the new fourth stage failed to ignite. Finally, on its fourth launch on February 12, 1961, the new rocket succeeded in sending its payload on a trajectory towards the planet Venus. Unfortunately, the Venera 1 spacecraft had a number of problems and failed early in its flight.

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THE FIRST LAUNCH TO MARS: 1960

TIMELINE: DEC 1968-APR 1970

The flight of Apollo 8 in December 1968 marked the beginning of the end for the Soviet Union’s campaign to put cosmonauts on the Moon. The Zond circumlunar flight test series had been plagued by problems. Even the successful flight of Zond 5 suffered so many subsystem anomalies that engineers were very reluctant to trust a spacecraft to a manned mission. The crash of Zond 6 made beating Apollo 8 to the Moon almost impossible, and the circumlunar program endured a further setback on January 20, 1969, when the next Zond test flight fell victim to yet another launcher failure. Any chance that cosmonauts could reach the Moon in competition with the Americans was dealt a severe blow on February 21, 1969, when the counterpart of the Saturn V, the N-l, failed spectacularly on its maiden flight. It had been intended to deliver a modified Zond into lunar orbit. The second attempt to qualify the N-l on July 3, 1969, less than a fortnight ahead of the launch of Apollo 11, resulted in the biggest explosion in the history of rocketry and destroyed the pad facilities. The last of the scheduled Zond flight tests, Zond 7, was a success in August, 1969, but by then the race was over. Instead of following up with a manned circumlunar mission the Soviets added another automated flight, which flew successfully in October 1970 as Zond 8. After two further attempts to qualify the N-l in June 1971 and November 1972 also failed, the manned lunar program vras canceled.

However, the Soviets countered the Apollo program with a series of robotic lunar missions using a new, large spacecraft that was originally designed to land a rover for a cosmonaut to employ on the lunar surface. When in late 1968 and early 1969 it became clear that the Americans were likely to beat them to the Moon, the Soviets opted to use this robotic landing system to try and upstage Apollo by being the first to return a lunar sample to Earth.

While the sample return system was being developed for use with the lander, the first launch of the new’ lander with a rover was attempted on February 19, 1969, but it was lost when the payload shroud failed shortly after the Proton launcher lifted off’. The first sample return spacecraft was launched on June 14, but lost when the

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fourth stage failed. Rushing to beat Apollo 11 to the Moon, another sample return mission was launched on July 13, 1969, ten days after the devastating N’-l explosion and 3 days before Apollo 11 was launched. This spacecraft, Luna 15, successfully reached lunar orbit 2 days ahead of Apollo 11 and Westerners, uninformed of its intentions, viewed it with suspicion. Shortly after the lunar module of Apollo 11 set down on the Moon on July 20 and its astronauts made their historic moonwalk, the Soviet spacecraft crashed attempting to land in the Sea of Crises, some distance cast of the Apollo 11 site in the Sea of Tranquility. The next three attempts through the middle of 1970 to return samples from the Moon with this type of spacecraft were all lost to launch vehicle failures.

In early January 1969 the Soviets followed up their 1967 success at Venus with two launches of spacecraft similar to Venera 4 but modified to descend through the atmosphere more rapidly, and thereby provide data from deeper levels than before. Although Venera 5 and Venera 6 worked well, they imploded far above the surface.

The Soviets were ready with a new spacecraft designed for Mars in March 1969. Like the new Luna for delivering rovers and sample return spacecraft, these were heavy spacecraft that needed the Proton launcher. They had been designed Lo be able
to enter orbit around Mars and dispatch a lander, but for the 1969 window they were to release a probe to get the data on the atmosphere that was required to design that lander. When the probe was deleted owing to development and test problems it was decided to equip the two spacecraft for this window as orbiters. Neither survived its launcher. These spacecraft and their launch attempts were virtually unknown in the West until after the Cold War. Blissfully unaware of this potentially overwhelming competition, the IJS dispatched two more flyby missions to Mars in 1969, Mariners 6 and 7, both of which were successful.

Campaign objectives:

In planning of their 1973 campaign for Mars the Soviets were aware of the IJS plan to send orbiter/landers to the planet in 1975. They also knew that these Vikings were considerably more capable than their own 1971 lander. Adding to this problem, the 1973 opportunity required more energy than that of 1971 and they could not repeat the M-71 orbiter /lander strategy. If they were to send landers to Mars in 1973. then the carrier spacecraft would have to fly past the planet. Their spacecraft were too massive and the Proton-K launcher did not have enough capability to combine an orbiter and a lander in 1973. Chagrined by the poor performance of their spacecraft in 1971 in comparison to the success of the Mariner 9 orbiter, yet encouraged by the near-success of the Mars 3 lander, the Soviets w ere determined to score a success at Mars ahead of the Viking missions. In fact the US had hoped to launch these in 1973 but financial problems forced a postponement to 1975. Knowing there would be no American competition in 1973, the Soviets decided upon four launches to send an armada consisting of two or biters and two flyby landers. The or biters would be sent first so that they could act as communications relays for the landers on the surface. After releasing its lander, a carrier spacecraft would relay telemetry from the entry system to Earth in real-time during the entry and descent, and then perform its own remote-sensing observations of the planet in making its flyby.

By 1973 the US and USSR were in a period of detente, and cooperation between the two space programs had increased with a number of joint working groups and a joint Apollo-Sovuz mission scheduled for 1975. The Soviets gave the US the data from Mars 2 and 3 and from Venera 8 in return for an accurate ephemeris for Mars, models of its atmosphere, and Mariner 9 orbital imagery of the zones chosen for the Mars 6 and 7 landers.

In order to save cost and reduce risk, Soviet engineers used the same spacecraft as in 1971 with minimum changes. But they were plagued with electronics problems in test and in flight. One crucial difference between the 1971 electronics packages and those built for 1973 were that gold leads had been replaced with aluminum on a key transistor used throughout the spacecraft. This difference was discovered very late in the integration and test program, wiien some of the new 2T-312 transistors suffered failures. The difficulties with the 2T-312 transistor were to be the Achilles’ heel of the 1973 campaign. They were in almost every engineering subsystem and science instrument on the spacecraft. Tests showed that these transistors generally failed 1.5 to 2 years after production. This would correspond to Mars arrival, and they could not all be replaced in time to meet the launch window. An analysis estimated a 50% likelihood of a complete mission failure owing to these transistors. In a US program this would have mandated postponing the mission, but the Soviet decision makers, in their rush to beat the Amerieans to the surface of Mars, dismissed the concerns of the engineers and opted to take the risk and launch with the suspect transistors.

The problem of the transistors became manifest almost immediately after launch, and plagued the entire campaign. All four spacecraft reached Mars but with three in a seriously crippled state. One orbiter flew past the planet, one lander missed and the other lander was lost just before touchdown after returning a degraded set of descent data. Mars 5 was able to achieve orbit, but then failed after less than a month.

The paucity of data from this flotilla compared to the mass of data returned from the single long-lived Mariner 9 orbiter, considered together with the lack of a viable competitor to the forthcoming Viking missions, led the Soviets to abandon Mars in favor of Venus for the foreseeable future – and it would be 15 years before they tried again.

Spacecraft:

The overall design and subsystems of the spacecraft for the 1973 Mars campaign were the same as before, although the scientific instruments were slightly different. The most signifieam engineering difference was the installation of a new telemetry system solely to enable the flyby carrier to relay data from its entry system to Earth in real-time; this would prove crucial in the ease of Mars 6. The landers telemetry system remained the same and communications from the surface would be through the or biters.

The M-73 orbiters were almost identical to the M-71S spacecraft. Their function was to enter into orbit around Mars, communicate with the landers, and obtain their own information on the composition, structure, and properties of the atmosphere and surface of the planet. The science payload was mounted on top of the spacecraft, in the same place as the entry systems of the flyby spacecraft. The principal function of the flyby carrier was to release the entry system on a proper entry trajectory and provide a real-time telemetry relay during the descent. It had science instruments for cruise and Mars flyby observations. Because the Mars 3 lander had made it to the surface, the entry systems were the same. However, the science payload of the landers was upgraded.

Mars 4 and 5 launch mass: 3,440 kg (orbiter; dry mass 2,270 kg)

Mars 6 and 7 launch mass: 3,260 kg (flyby vehicle)

1,210 kg (entry vehicle)

635 kg (lander system on descent)

358 kg (lander)

4,470 kg (total)

Payloads:

Some of the M-73 scientific instruments were redesigned forms of those carried by Mars 2 and 3, but others were new. The Mars 4 and 5 orbiters and the Mars 6 and 7 flyby spacecraft were equipped as follows:

1. FTU facsimile imaging system

2. Optical-mechanical panoramic imaging system

3. Infrared radiometer (8 to 40 microns) for measurement of surface temperature (Mars 5 only)

4. Infrared photometer in five carbon dioxide bands around 2 microns to obtain surface altitude profiles

5. Microwave polarimeter (3.5 cm) for measurement of dielectric constant and subsurface temperatures

6. Two polarimeters in ten bands from 0.32 to 0.70 microns to characterize surface texture (French-Soviet)

7. Four band visible photometer in range 0.37 to 0.6 microns for measurement of color and albedo of the surface and atmosphere (Mars 5 only)

8. Infrared narrow-band 1.38 micron photometer for measurement of water vapor content in the atmosphere

9. Ultraviolet photometer (0.260 and 0.280 microns) for measurement of ozone

10. Scanning photometer (0.3 to 0.9 microns) to study emissions in the upper atmosphere (Mars 5 only)

11. Gamma-ray spectrometer for surface elemental composition

12. Micrometeoroid sensors (Mars 6 and 7 only)

13. Lyman-alpha photometer for measurement of upper atmosphere hydrogen (French-Soviet)

14. Solar wind plasma sensors (8) for measurement of speed, temperature and composition in the 30 eV to 10 keV energy range (Mars 4 and 7 only)

15. Boom mounted three-axis lluxgate magnetometer (Mars 4 and 7 only)

16. STHRHO-2 to study solar radio emissions (French-Soviet. Mars 7 only)

17. ZIIEMO to study solar protons and electrons (French-Soviet, Mars 6 and 7 only)

18. Multichannel electrostatic analy/cr (Mars 4 and 5 only)

19. Dual-frequency radio occultation experiment to profile ionospheric electrons and tropospheric density.

Two types of imaging system were employed. The first was a version of the M-71 FTU camera with various technical improvements and more film and faster scanning rates. The second was a single line push-broom panoramic imager that was to scan a 30 degree field of view from horizon to horizon and was sensitive in both the visible and near-infra red. It stored its data on a 90 minute analog tape recorder for replay to Earth.

The FTLT optics were as before: two bore-sighted cameras, one an f/2.8 lens with a focal length of 52 mm and a 35.7 degree field of view, and the other an 174.5 lens with a 350 mm focal length and a 5.67 degree field of view. They each weighed about 9 kg. The wide angle camera was equipped with red. green, blue and orange filters, and the narrow angle one used an orange long-pass filter. Twenty meters of 25.4 mm film was contained in a radiation-shielded magazine. This was sufficient for at most 480 frames. Exposure times alternated between 1 50th and 1/150th of a second. Each camera produced a 23 x 22.5 mm frame and the film could be scanned at up to ten resolutions, only three of which were used actually: 235 x 220,940 x 800, and 1.880 x 1,760 pixels. The scanned images were transmitted at either 512 or 1.024 pixels per second by the dedicated impulse transmitter. At the intended operating altitude these cameras would provide resolutions of between 100 and 1,000 meters.

The push-broom panoramic camera system was first used by Luna 19 in 1971. It comprised two optical-mechanical cameras, each with a single photomultiplier tube and a rotating prism to scan a 30 degree field of view aeross the spacecraft’s track. One camera had red and orange filters and was sensitive across the visible spectrum and the other used a red long-pass filter with a photomultiplier that was sensitive in the infrared. They scanned at 4 lines/seeond and produced 250 cycles line for video recording on magnetic tape at 1,000 IIz. The readout rate was 1 line/second and the transmission was commanded at 256 or 512 pixels line resolution.

The payload of the entry system and lander w as essentially the same as flown on Mars 2 and 3, but with upgraded imagers, mass spectrometer, and temperature and pressure sensors. The Doppler experimeni to measure winds during the descent was new. Most significantly, it was nowr possible to transmit the descent data in real-time rather than storing it for transmission after landing. They were equipped as follow s:

1. Accelerometer for atmospheric density during entry

2. Doppler experiment for winds and turbulence on descent

3. Temperature and pressure sensors on descent and landing

4. Radio altimeter for providing altitudes on descent

5. Mass spectrometer for atmospheric composition on descent and landing

6. Atmospheric density and wind velocity on the surface

7. Two panoramic television cameras for stereo viewing of the surface

8. Gamma-ray spectrometer for soil composition mounted in a petal

9. X-ray spectrometer for soil composition deployed to the surface from a petal

10. PrOP-M walking robot deployed to the surface from this same petal with

onboard gamma-ray densitometer and conical penetrometer.

Doppler measurements and the radio altimeter, accelerometer, temperature, and pressure sensors operated from the beginning of parachute deployment right down to the surface.

Mission descriptions:

All four spacecraft were dispatched successfully but predictably and inevitably first Mars 6, then Mars 7, then Mars 4 suffered system-wide failures within a matter of weeks owing to the faulty transistor. Only Mars 5 arrived relatively trouble free and was able to enter orbit around Mars, but it suffered a pressure leak and shortly thereafter fell silent.

Mars 4:

Mars 4 was launched on July 21, 1973. It made a midcourse correction on July 30, but the computer developed problems that prevented a second midcourse correction. It reached the planet on February 10, 1974, but the engine failed to ignite for the orbit insertion maneuver and the spacecraft flew? past the planet at a range of 1,844 km.

Mars 5:

Mars 5 was launched on July 25, 1973. It made midcoursc corrections on August 3 and on February 2, 1974, and followed through with the orbit insertion maneuver at 15:44:25 UT on February 12 to achieve a 1,760 km x 32,585 km orbit with a period of 24.88 hours inclined at 35.3 degrees to the equator. Some unknown event during orbit insertion triggered a slow leak in the instrument compartment. An accelerated plan of observations w as prepared that focused on obtaining high resolution imagery of the surface. But when the pressure fell below operating levels in the transmitter housing on February 28 after only 22 orbits, this prematurely ended the mission and ruled out the use of this spacecraft as a relay for the landers that were scheduled to arrive in early March.

Mars 6:

Mars 6 was launched on August 4, 1973, and conducted a midcourse correction on August 13. At the end of September the science and operations dow nlink was lost, almost certainly due to the failure of a 21-312 transistor. Only two channels in the telemetry system remained operational, neither of which provided any information on spacecraft status. Refusing to give up, the engineers continued to send commands to the spacecraft in the hope that the receivers might still be functioning. As it turned out the command uplink was unaffected, and Mars 6 dutifully obeyed the commands and executed its autonomous functions. Unable to report to Earth, in February 1974 it autonomously determined its position, calculated the second midcourse correction and carried this out. Upon approaching the planet on March 12, it properly executed the optical navigation and targeting, and then released its entry system at a range of

48,0 km from the planet with just 3 hours remaining to atmospheric entry.

Ground controllers first realized that Mars 6 had done its job shortly thereafter, at 08:39.07 UT, when data began to arrive through the dedicated relay channel. At that time the entry system was 4.800 km from its target. The spacecraft was able to relay data throughout entry and descent, and then continued past the planet, passing within 1,600 km of the surface. This performance was a monumental achievement in spacecraft autonomy for the Soviet program so early in the history of planetary exploration.

The entry system penetrated the atmosphere at 09:05:53 UT at a speed of 5.6 km/s and an 11.7 degree angle of attack. Loss of signal due to plasma effects occurred at 09:06:20 at an altitude of 75 km. The signal was regained at 09:07:20 at 29 km. with the start of the data transmission. The main parachute was deployed at 09:08:32 after the entry system had slowed to 600 m/s at an altitude of 20 km. The canopy opened fully at 09:08:44. and the capsule started to transmit data on altitudes, temperatures and pressures. The mass spectrometry was stored for transmission after the landing. The Doppler shifts on the signal were noted. The capsule appeared to be swaying under the parachute more than expected, impairing the transmission quality. Ignition of the rocket engines was confirmed but the transmission cut off at 09:11:05 when the lander was "in direct proximity to the surface’*, probably when it hit the surface. The velocity at the time of signal loss was 61 m/s, which was excessive for a safe touchdown. The transmitter was programmed to turn off after the lander had been released in order to switch over to a different set of VHF antennas on the lander. No further signals were received. The fate of the lander is unknown. It lies at 23.90 S 19.42 W in the Margaritifer Sinus region, in the vicinity of Samara Valley, where the landscape is characterized by steep slopes.

Mars 7:

Mars 7 was launched 4 days after Mars 6 but flew a faster trajectory which arrived at the planet 3 days earlier. It made only one course correction on August 16, 1973. An early failure in the communications system cost it one transmitter, but it was able to remain in contact. At Mars the targeting maneuvers to set up the entry system were executed properly and the entry system was released on March 9. 1974. However, most likely owing to a failed 2T-312 transistor, the entry system computer did not issue the command to fire the retro-rocket, with the result that it missed the planet by 1,300 km. The intended target was in the crater Galle at 51.2 S 30.9 W. The carrier spacecraft provided some data during its flyby.

Results:

Orbiters:

Imagery

After Mars 4 failed to execute its orbit insertion maneuver it flew past the planet and continued to return interplanetary data from solar orbit. During the flyby it returned one swath of twelve pictures and two panoramas in a 6 minute imaging cycle from a range of 1,900 to 2Л 00 km. Two dual-frequency radio occultation profiles were also obtained, one on passing behind the planet as viewed from Earth and the other upon exiting and these supplied the first indication of a night-side ionosphere.

The Mars 5 orbiter operated for only 25 days after orbit insertion, and returned atmospheric data and images of a small portion of the southern hemisphere of Mars. In all it returned 108 pictures, but the narrow angle ones were motion blurred. The useful data included 43 wide angle images and five panoramas which were returned in five imaging sessions over a 9 day period, all of roughly the same area, which was near the imaging track of Mariner 6 and showed swaths of the area south of Valles Marineris from 5 N 330 W to 20 S 130"W. Measurements by other remote sensing instruments were also made near periapsis along seven adjacent arcs in this region. High cirrus clouds and yellow clouds of fine dust w ere identified.

Surface properties

Data returned from orbit by the infrared radiometer on Mars 5 showed a maximum surface temperature of-Г C, -43 C near the terminator, and -73°C at night. It gave a thermal inertia for the soil that was consistent with grains 0.1 to 0.5 mm in size, and polarization data in the visible spectrum implied grain sizes smaller than 0.04 mm in aeolian deposits of variable cover. The polarization at 3.5 cm suggested a dielectric constant of 2.5 to 4 at depths of several tens of cm. The oxygen, silicon, aluminum, iron, uranium, thorium, and potassium sensed by the gamma-ray spectrometer from orbit suggested a surface similar to terrestrial mafic rocks.

Lo wer atmosphere

Six altitude profiles were measured by the carbon dioxide photometer along a path between 20 and 120 :W in longitude and spanning 20 to 40r’S in latitude, and these were in general agreement with the Mariner 9 ultraviolet spectrometer data. Surface pressures as high as 6.7 millibars were determined. Mars 3 had found only 10 to 20 precipitable microns of water vapor while the dust storm was raging in 1971. Two years later. M ars 5 found abundances as high as 100 precipitable microns south of the Tharsis region. The water vapor content was variable by a factor of 4 to 5 across the planet. An ozone layer about 7 km thick was detected at 40 km altitude in the equatorial region, not near the surface as anticipated, with a concentration of about 1/1,000th that of Earth’s ozone layer. The Mariners were able to detect ozone only at the poles where it is more abundant. The existence of argon in the atmosphere was confirmed.

Upper atmosphere and ionosphere

The Lyman-alpha instrument found the exosphere temperature to be 295 to 355K. with the temperatures in the altitude range 87 to 200 km being 10 degrees lower. No upper atmosphere emissions were noted by the visible spectrometer in the range 0.3 to 0.8 microns. Mars 5 also performed a radio occulta lion experiment on one orbit and its results, with those from the flyby occupation measurements for Mars 4 and 6. showed the existence of a night-side ionosphere with a maximum electron density of 4,600/cc at an altitude of 110 km, and an atmospheric pressure near the surface of 6.7 millibars.

The fields and particles instruments returned a significant data set to complement the M-71 orbiter data. Two distinct plasma zones were found inside the bow shock between the undisturbed solar wind and the planetary magnetosphere: a thermalized plasma behind the bow shock, and a small electrical current carried by protons in the magnetotail. The bow shock was held at an altitude of 350 km. The plasma results and magnetometer measurements were consistent with the planet having an intrinsic magnetic field of about 0.0003 times the strength of Earth’s field, and inclined 15 or 20 degrees from the rotational axis which, as in the case of Earth, is tilted 23 degrees from the perpendicular to the plane of its orbit.

Flyby spacecraft:

The radio occupation made by the Mars 6 carrier spacecraft verified the detection by Mars 4 and 5 of a night-side ionosphere. The French STEREO instrument on Mars 7 w orked satisfactorily throughout the cruise to Mars but the spacecraft did not return any useful science during the flyby. It was the last of the armada to fall silent, wiiieh it did in September 1974.

Entry systems:

The Mars 6 entry system transmitted for 224 seconds during its descent before it fell silent, providing the first in-situ measurements of this atmosphere. Although a lot of it was unreadable due to the degradation of another 2T-312 transistor, enough data w’as obtained to profile the temperature and pressure from an altitude of about 29 km down to the surface. The density of the atmosphere from 82 km down to this level was inferred from accelerometer data. Winds of 12 to 15 m s were measured from an altitude of 7 km dowm to near the surface. A surface pressure of 6.1 millibars and a temperature of -28 C were derived from temperature, pressure, accelerometer and Doppler data. The surface winds were 8 to 12m/s. Other parameters included a lapse rate of 2.5K/km, the presence of the tropopause at an altitude of 25 to 30 km. and an almost isothermal stratosphere at a temperature of 150 to 160K. These values were consistent with measurements by the Mars 5 orbiter, and were later confirmed by the Viking missions. Instruments also indicated "several times" more atmospheric water vapor than previously reported. The mass spectrometer data were stored during the descent for transmission after landing, and so were lost. However, the current to the vacuum pump was transmitted during the descent as an engineering parameter, and a sleep increase in current was interpreted as an indication of argon at an abundance of 25 to 45%. which was implausibly large; the actual value was found by the Vikings to be a more reasonable 1.6%.

Landers:

Ко transmissions were ever received from the Mars 6 lander and no results w’ere obtained from the surface. The Mars 7 entry system missed the planet entirely.

The Soviet and American enterprises to explore space were created as a by-product of the Cold War, specifically the development of intercontinental ballistic missiles and their modification to put spacecraft on interplanetary trajectories. While aiming their nuclear-tipped missiles at each other, the iwo opposed societies competed for the minds of the rest of the world by demonstrating their technological prowess by exploits in civilian space exploration. The Soviet space exploration program was noi entirely divorced from the military, as it was in the US. As a result. Soviet robotic missions to the Moon and planets were cloaked in secrecy until the early 1980s, and only after the collapse of the USSR has reliable information become available on the full history of the Soviet lunar and planetary exploration program. The key leaders and institutions involved, and almost all decisions and events, were state secrets and unknown outside the closed circle of Soviet secrecy. Launches were not announced, and the Soviets rarely revealed the purpose of their spacecraft except for human missions where this eould not be hidden. This policy hid embarrassing failures, and only when a success could be claimed was its purpose revealed.

The heavily cloaked Soviet robotic exploration program provided mystery and a challenge to the Americans. State secrecy concealed the fact that the Soviet robotic space exploration program was bolder, more innovative, and more tragic than any observers in the West could have imagined at the lime. As eaeh planetary launch window approached, the Americans would get very anxious about what spectacular the Soviets might be planning. The subliminal pressure to outdo the Soviets added to this anxiety, particularly in the first decade of the space race when the USSR always appeared to have the upper hand. Imagine the despair on the American side in the late 1960s if it had been known that the Soviets were planning landings on Mars in 1969 while the US was still conducting flybys. Over the long run, the Soviets were tragically jinxed at Mars, never gaining a true success despite expending enormous effort and resourees on a resolute and more aggressive attack on the planet than was the case in the US. They were the first to launch at Mars in 1960, failed with their next generation spacecraft in the 1960s, fared poorly with their massive grand fleets in 1971 and 1973. fell tragically short with the Phobos missions in 1988, and ended abysmally with Mars-96. Yet many Soviet achievements endure the lunar rovers and sample returns, the Vega missions, and the extensive and very successful in-situ exploration of Venus are all accomplishments that were never equaled by the US.

і’he story of the Soviet lunar and planetary exploration program is a tale of great adventure, excitement, suspense, and tragedy; a tale of courage and the patience to overcome obstacles and failure; a tale of fantastic accomplishment and debilitating loss; a tale of courage and enthusiasm to try the previously impossible. To carry it out they exhibited superb expertise in engineering design and development. They were very innovative in utilizing the technology available to produce engineering systems that accomplished the task. Their rocket engines are testimony to mastery of materials development and propulsion system engineering. Their innovative lunar mission design and return trajectories and their terminal optical navigation scheme for the M-71 and M-73 missions demonstrate excellence in celestial mechanics, navigation, and guidance and control. The automation of the midcourse maneuvers and optical navigation scheme for Mars were applied successfully well before the US even contemplated such complexity a clear demonstration of superior skill in automation and software which unfortunately was to unravel in later missions. The

success of any enterprise is ultimately the result of people, and the Soviet Union had excellent engineers, scientists and managers who faced immense difficulties with the heavy-handed, personality-driven, complex and entangled national system of control and supply, and succeeded thanks to an intense devotion to the space exploration enterprise and a strong sense of competition with America.

The successes of the Soviet robotic exploration program were achieved at a heavy price. The Luna, Venera and Mars programs all endured an enormous number of losses from launch vehicle and spacecraft failures – far more than would have been tolerated in a US program. Soviet persistence in pursuing their goals, particularly in the early years, would have appeared maniacal to an American. During one stretch between 1963 and 1965, the Soviets suffered eleven straight failures in attempting a lunar soft landing. Korolev had to exercise considerable political skill to save his lunar lander program after such a long string of disasters. This w ould have brought dow n an American program w here no such commanding personality existed for the robotic program. The worst string of losses in an American robotic exploration program occurred roughly contemporaneously and was only about half this number. The Americans suffered six straight failures from 1961 to 1964 in their Ranger lunar impact or program. At one time they were very close to terminating both the program and its implementing organization. Thereafter the Americans never tolerated more than an occasional failure in their program, whereas the Soviets tolerated relatively large failure rates as a matter of course.

The poor reliability of Soviet rockets was the primary cause of failures until the mid-1970s, but it was these very same rockets that enabled the Soviet Union to be so bold in executing their program. The Molniya was capable of lifting many times the weight of American rockets. It was produced in quantity, and readily available from the military on short notice and at no apparent cost. This characteristic was essential since the Soviets, in contrast to the Americans, tested their spacecraft by Hying them – resulting in many more attempts to launch Soviet spacecraft than American: 106 versus 51 through 1996. This may have been a consequence of the readier access to Soviet launch vehicles before cost became an issue, but in any case Soviet engineers also lacked discipline in ground testing. They rushed their designs through assembly with insufficient system test time in low quality clean facilities with loose ground test procedures. This showed in the poor performance of their spacecraft in flight. By the end of 1965, they had lost all four of their spacecraft launched to Venus, both of their spacecraft launched to Mars, and five of nine lunar spacecraft. In that same time, they lost an additional 24 of their 39 missions to launch vehicle failures. w7hich w’as not only a very large number in itself but also a huge percentage loss from an American point of view. The situation improved with time, but failures continued to plague the program. The inflight failure rate dropped from over 70% through 1965 to 39% by 1976, and the launch vehicle failure rate dropped from over 60% to 48% over that same period of time. After 1976 the inflight failure rate fell to 10% and the launch vehicle failure rate dropped to 9%.

The absence of strong ground test discipline w as symptomatic of a weakness in systems engineering. The Americans learned their skill in this discipline through the trouble-plagued Ranger lunar program in the early 1960s, and rarely had an inflight failure afterwards. The Soviets were much slower in applying this discipline, and suffered continuing inflight failures. Their problems were exaeerbated by a handicap in electronics technology. Decades after vacuum electronics had become standard in Western spacecraft the Soviets eontinued to fly pressurized spacecraft – in fact, right up to Mars-96. One impetus for continuing this practice was that Soviet rockets were so large that the mass penalty of old electronics was not a major consideration, but another problem was that Soviet industry did not produce vacuum qualified complex electronic systems for its exploration missions. The reliability and operating lifetime of Soviet space avionics systems were a problem throughout the program and were a principal reason why the USSR never attempted a mission to the outer planets. Their Mars spacecraft were for some reason particularly prone to inflight avionics failures from start to finish.

The sad part of the story is the disappearance of Russia from the scene after the fiasco of Mars-96. This has been a great loss of vision, enterprise and expertise in robotic space exploration. The Soviet enterprise was born as part of the Cold War. and seemingly expired with it. After 1991 the Russian space program turned almost exclusively to humans-in-orbit. The Academy of Sciences had a great deal of trouble acquiring funds to keep its robotic space exploration program alive. After Mars-96 failed and government interest in robotic space exploration plummeted, it increased its investment in human spaceflight and partnership with the US in the International Space Station. Now7, after a long hiatus, the Russians are reviving their robotic space exploration program with the Phobos-Grunt mission.

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