Category Soviet Robots in the Solar System

Campaign objectives:

After the three Venus launches failed in late August and early September, Korolev’s team scrambled to prepare for three more launches to Mars in late October and early November. Many measures were taken to enhance the reliability of the fourth stage. There was some pressure to abandon the Mars attempts until the problems with this stage were solved, but Korolev blazed ahead.

The 1962 Mars campaign consisted of two flyby missions and one entry probe. The objectives of the entry probe were to obtain in-situ data on the composition and structure of the atmosphere, and data on surface composition. The objectives of the flyby missions were to examine the interplanetary environment between Earth and Mars, to photograph that planet in several colors, to search for a planetary magnetic field and radiation belt, to search for ozone in the atmosphere, and to search for organic compounds on the surface. A comprehensive payload was prepared for each spacecraft, but apart from the camera and a magnetometer most of the payload was deleted when it was decided instead to install instrumentation to monitor the fourth stage to find out why it was suffering so many failures. These missions then became primarily engineering test flights of the 8K78 fourth stage, with Mars as a secondary objective.

Although the fourth stage failed again on two of the launches, the second of three worked and provided the Soviets with their first spacecraft to Mars. Unfortunately, as in the case of Venera 1 it was immediately clear that Mars 1 had attitude control problems. The inability to perform a midcourse maneuver ruled out the desired close flyby of Mars. On the other hand, communications with Mars 1 were maintained for almost 5 months before it fell silent about half w ay to its target.

Spacecraft:

The 2M V Mars spacecraft were virtually identical to the versions described in detail above for the 1962 Venus missions. Although we have no description of the 300 kg entry probe of the 2M-3 No. l spacecraft we know7 it w7as not designed as a lander but as a simple spherical entry system containing a parachute, radio, and instruments intended for measurements during descent. Surviving impact must have been more a hope than a goal. In fact, since the designers had no idea just how thin the Martian atmosphere is. the entry probe would have crashed into the surface before any useful data could have been returned.

The Mars 1 spacecraft is depicted in Figure 8.4 in a stand. Above the stand is the pressurized compartment containing the scientific instruments for the flyby. Next is the ‘orbital’ compartment. The large port in the front is the star sensor, and to the right of that is the Sun sensor. The gas bottles for the attitude control system are on
the waist separating the two compartments. Topping the spacecraft is the propulsion system. The parabolic high gain antenna is fixed pointing in the opposite direction to the solar panels, and there are hemispherical radiators mounted on the ends of the panels.

Launch mass: 893.5 kg (Mars 1)

1.097 kg (probe version)

305 kg ‘

Payload:

Many of the instruments developed for the 2MV Mars spacecraft were removed in order to accommodate systems to monitor the fourth stage of the launcher. There is no information on how many were actually removed, but the magnetometer and the flyby imaging system are known to have been carried by Mars 1.

The original set of instruments is given in this list.

Carrier spacecraft:

1. Magnetometer to measure the magnetic field

2. Scintillation counters to detect radiation belts and cosmic rays

3. Gas discharge Geiger counters

4. Cherenkov detector

5. Ion traps for electrons, ions and low-energy protons.

6. Radio to detect cosmic waves in the 150 to 1,500 meter band

7. Micrometeoroid detector

Descent I landing capsule:

1. Temperature, pressure and density sensors

2. Chemical gas analyzer

3. Gamma-ray detector system to measure radiation from the surface

4. Mercury level movement detector

Flyby instrument module:

1. Facsimile imaging system to photograph the surface

2. Ultraviolet spectrometer in the camera system for ozone detection

3. Infrared spectrometer to search for organic compounds

These instruments were identical to those built for the Venus mission, except that the Mars infrared spectrometer operated in the 3 to 4 micron C-H band to search for organic compounds and vegetation on the surface of Mars.

Mission description:

Two of the three missions were lost to the new and as yet unreliable fourth stage. The 2MV-4 No.3 Mars flyby was launched on October 24, 1962, but failed to leave parking orbit when the fourth stage turbo pump failed after 17 seconds due either to a foreign particle in the assembly or to the pump overheating after a lubricant leak. The fourth stage and spacecraft broke into five large pieces that re-entered over the course of the next few’ days. The US Ballistic Missile Early Warning System radar in

Alaska, which was at a state of high alert in the midst of the Cuban missile crisis, dc tec ted the debris after launch and was initially concerned that it might represent a Soviet nuclear ICBM attack, but rapid analysis of the debris pattern put this fear to rest.

The rocket carrying the second spacecraft was rolled out to the pad the next day. October 25, at the peak of the missile crisis. Shortly thereafter the firing range was ordered to battle readiness, which required the preparation for launch of the two R-7 combat missiles. One of these was stationed at the launch site where the Mars rocket stood. Stored in a corner of the Assembly and Test Building, it was uncovered and the launch team switched from supporting the Mars launch to preparing the missile. Fortunately, when the order to stand down came on October 27 the Mars rocket had not yet been removed from the launch pad. The 2MV-4 No.4 flyby spacecraft was successfully launched on the optimum date of the window, November 1, and became the first spacecraft to be sent towards Mars. The mission was named Mars 1. Just as in the case of Venera 1, a serious problem was discovered immediately after launch. The pressure in one of the two nitrogen gas containers was dropping rapidly because of a leaking valve. Later analysis showed that manufacturing had allowed debris to foul one of the valves. The outgassing caused the spacecraft to tumble out of control. When the tank drained after several days, ground controllers managed to use the gas in the remaining tank to halt the tumbling, restore the spacecraft to the desired Sun pointing attitude and spin it at 6 revolutions per hour so that the batteries would be continuously recharged from the solar panels. But by then most of the dry nitrogen for the cold gas jets of the attitude control system and for pressurizing the engine was expended. The backup gyro system used for attitude control was not designed for continuous use. Stuck in the backup Sun pointing spin mode, the spacecraft was unable to point its high gain antenna at the Earth or to make a midcourse correction. The Earth link was maintained through the UHF system and the medium-gain semi­directional antennas. Contact was established every 2 days for the first 6 weeks, and then every 5 days thereafter. On March 2. 1963, the signal strength began to decline and communications were lost on March 21, probably due to a final breakdown of the attitude control system at the unprecedented range of 106,760,000 km. The silent spacecraft would have passed Mars at a distance of about 193,000 km on June 19, 1963; the intended flyby distance was between 1.000 and 10.000 km.

The third spacecraft to be launched, 2MV-3 No. l, was stranded when the fourth stage failed to reignite properly. Vibrations in the core stage caused by cavitation in its oxidizer lines had dislodged a fuse and igniter in the fourth stage. Its engine was commanded to shut down after 33 seconds. The Americans detected five pieces of debris whose origins were unclear. The spacecraft is believed to have re-entered on January 19, 1963.

Of the six 2M V spacecraft launched between August and November 1962, four were lost to failures of the fourth stage, one was lost to a failure of both the third and fourth stages. The other one was launched successfully and named Mars 1, but failed in transit. No more 2MV spacecraft were built. The design wras improved to produce the 3MV spacecraft for the next series of Mars and Venus missions in 1964 1965.

In the US, the orbital remains of the 1962 Venus and Mars spacecraft, including

Mars 1, were designated as Sputniks 19 to 24 in order of launch. All the spacecraft stranded in parking orbit re-entered within days.

Results:

No information was obtained on Mars. However, Mars 1 did acquire data during its cruise before it fell silent. The radiation zones around Earth were detected, and the distribution and flux of particles were measured. Л third zone at 80,000 km was detected. The solar wind and magnetic fields were measured in interplanetary space to a farther distance than Venera 1. Л solar wind storm was measured on November 30, 1962. ‘flic intensity of cosmic rays had almost doubled since 1959 due to a less active Sun. The micrometeoroid collision rate decreased with distance from Earth and showed intermittent increases as meteoroid showers were traversed. The Taurid meteor shower w as encountered twice at ranges from 6,000 to 40.000 km, and again at distances from 20 to 40 million km. with a strike rate of one every 2 minutes on average.

In late 1968 and early 1969 it became apparent to the Soviet Union that American astronauts might very well reach the Moon before Russian cosmonauts. Anxious to ensure that a Soviet mission was first to return lunar soil to Earth, NPO-Lavochkin hurriedly modified the Ye-8 spacecraft for a sample return mission. The lunar rover variant of this spacecraft was well advanced in design by the end of 1968. and could readily be modified simply by replacing the payload of the lander. Even although it would have scientific merit, the sample return mission had a far greater significance than being just another task for the Ye-8. The robotic sample return mission became the means to upstage Apollo by returning a sample to Earth before the Americans could do so. The fact that these complex spacecraft could be designed and built so readily, and ultimately work so well, is amazing in hindsight. It would seem to be a Russian characteristic to ”just do if to dismiss the hardship, use whatever you have at hand, and fix things up on the fly during and after build.

The modification of the Ye-8 lunar rover spacecraft to the Ye-8-5 for the sample return mission faced daunting problems, not the least of which were mass limitations on the return vehicle, lifting off from the Moon and navigating back to Earth. It was originally believed that the return vehicle would require the same complex avionics as any interplanetary spacecraft, to enable its position to be determined and to make midcourse correction maneuvers. The avionics necessary to meet these requirements far exceeded the available mass. However. D. Ye. Okhotsimskiy, a scientist at the Institute of Applied Mathematics, found a small set of flight trajectories for launches from the surface of the Moon that did not require midcourse corrections. In essence, the large gravitational influence of the Earth at lunar distance could, under certain conditions, assure an Earth return. These trajectories were limited to specific points on the Moon, varying within a general locus with the time of year, and required the lander to set dow n within 10 km of its target and the lunar liftoff for a direct ascent to occur at a precise moment. Accurate knowledge of the lunar gravitation field was also required, but this information had already been determined by the Luna 10, 11. 12 and 14 orbitcr missions.

These passive return trajectories simplified the ascent vehicle enormously. Only a single burn of the ascent vehicle was required. No active navigation was necessary, and no midcourse maneuvers were required. The only problem with a passive return was the very large error ellipse on arrival at Earth, which would make recovering the small capsule impraclically difficult. This problem was solved by using a low-mass meter wave radio beacon on the ascent vehicle so that radio tracking would be able to determine its actual trajectory, supplemented by optical observations from Earth during the latter half of its flight. In addition, the return capsule would have its own radio beacon to assist in recovery operations.

Even with these ingenious solutions, the engineers could not trim the design mass of the Ye-8-5 below 5,880 kg. At that time the most that the Proton-К could send to the Moon was 5,550 kg. However, Babakin managed to cajole the Proton maker into providing sufficient additional mass capability to launch his sample return spacecraft to the Moon. This was accomplished without major changes to the launch vehicle.

Spacecraft;

Lander stage:

The lander stage was essentially the same as designed for the rover mission and its mission profile through to lunar landing was identical. The only differences were the attachment of a surface sampling system and, for the first eight spacecraft, a pair of television cameras for stereo imaging of the sampling site and floodlights for night landings. The rover and ramps were replaced by a toroidal pressurized compartment which held the instruments and avionics for surface operations. The ascent stage was mounted on top, with the entire lander and toroidal compartment acting as its launch pad.

The ascent stage was powered by a silver-zinc 14 amp-hour battery, and the return capsule by a 4.8 amp-hour battery. Lander communications were provided at 922 and 768 MHz, with backups at 115 and 183 MHz. The ascent stage communicated at 101.965 and 183.537 MIIz. The return capsule had beacons at 121.5 and 114.167 MHz for radio tracking.

The sampling system for the Ye-8-5 consisted of an upright 90 cm long boom arm capable of two degrees of freedom, with a drill at its end for surface sampling. Three movements were required to place the drill on the surface through a 100 degree arc of swing, and then another three to transfer the sample to the ascent stage. From the stowed position it first swung itself vertical, then rotated in azimuth to line up on the selected sample site before swinging down onto the surface. A movement in azimuth with the head on the ground might be used to clear a small area to improve drilling. This sequence was reversed to transfer the sample to the return capsule of the ascent stage. Mounted at the end of the boom was a cylindrical container 90 mm diameter and 290 mm long for a hollow rotary/percussion drill. The drill bit had a diameter of 26 mm and was 417 mm long. Its cutter was a crown with sharp teeth. The drill was equipped with different coring mechanisms for hard coring and for loose coring. At a speed of

500 rpm, it required 30 minutes to fill the entire core length of 38 cm. The drill was both insulated and hermetically sealed, and to enable the mechanism to be lubricated using oil vapor it was not opened until just before use. Some parts used a lubricant designed to reduce friction in a vacuum. A standby motor was provided as a contingency to overcome obstacles encountered during drilling. The whole device weighed 13.6 kg.

An improved drill system tvas provided for the Ye-8-5M version, which had a rail mounted deployment mechanism. This drill was capable of penetrating to a depth of

2.5 meters and preserving the stratigraphy, but it could not be articulated to select a sampling site. It used an elevator mechanism rather than the articulated boom arm to transfer the sample to the return capsule.

Ascent stage:

The ascent stage was a smaller, vertically mounted open structure composed of a pressurized cylindrical avionics compartment above three spherical propellant tanks and the rocket engine. This was the same engine as used on the lander, but was not throttled. Four vernier engines were attached outboard of the propellant tanks. There were perpendicular antennas mounted radially at 90 degree intervals near the top of the avionics compartment. The spherical return capsule was held in place on top by deployable straps. Including the return capsule, the ascent stage was 2 meters tall. It weighed 245 kg dry and 520 kg with propellant. The KRD-61 Isayev engine burned nitric acid and UDMH and produced a thrust of 18.8 kN for 53 seconds to impart a velocity of 2.6 to 2.7 km/s, which was enough to escape from the Moon on a direct ascent trajectory.

Return capsule:

The return capsule was a 50 cm sphere covered with ablative material for entry at a speed of about 11 km/s and a peak deceleration load of 315 G. It had three internal sections. The upper section contained the parachutes (a 1.5 square meter drogue and a 10 square meter main) and beacon antennas, the middle section contained the lunar sample, and the base had the heavy equipment including batteries and transmitters.

on entry.

Luna 15 launch mass: 5,667 kg

Luna 16 launch mass: 5,727 kg

Luna 18 launch mass: 5,750 kg

Luna 20 launch mass: 5,750 kg

Lima 23 launch mass: 5,795 kg

Luna 24 launch mass: 5,795 kg

4,800 kg (Luna 24)

1,880 kg

520 kg (515 kg for Luna 23 and 24) 35 kg (34 kg for Luna 23 and 24)

Payload:

1. Stereo panoramic imaging system with lamps (deleted on Luna 23 and 24)

2. Remote arm for sample collection (improved drill on Luna 23 and 24)

3. Radiation detectors

4. Temperature sensor inside capsule

The stereo imaging system had two 300 x 6,000 panoramic scan cameras of the type used on the earlier Yc-6 landers and Lunokhod rovers. Mounted on the lander just below the level of the ascent stage on the same side as the sampling system, they were spaced 50 cm apart, angled at 50 degrees to the vertical, and gave a field of view of 30 degrees. The orientation of the lander was determined by measuring the position of Earth in a panoramic image. Stereo images were taken of the surface between the
two landing legs to select the position to be sampled. They also imaged sampling and drilling operations, For the Luna 23 and 24 sample ret urn missions the earner as and lamps were deleted.

Mission description:

Only six of the eleven spacecraft in this series were launched successfully. Of these, three succeeded in returning lunar samples to Earth.

The first attempt

The first launch (Ye-8-5 No.402) was attempted on June 14, 1969. one month prior to the Apollo 11 launch date, but the Block D failed to ignite for its first burn and the payload re-entered over the Pacific Ocean.

Luna 15

The second spacecraft in this series was successfully launched on July 13, 1969, just 3 days before Apollo 11, and the Soviets announced that Luna 15 was to land on the Moon on July 19, one day ahead of the Americans, with the objective of returning something to Earth. At 10:00 UT on July 17 it entered a 240 x 870 km lunar orbit inclined at 126 degrees. ‘This orbit was much higher than intended, so the next day it was trimmed to 94 x 220 km. Another trim a day later yielded an orbit 85 x 221 km. Ideally the orbit should have been near-circular at about 100 km, but the Soviets had underestimated the effect of the lunar in a scons and they were also suffering attitude control problems. Meanwhile. Apollo 11 had arrived and entered an equatorial orbit The drama was palpable. In Russia its nature was clear, but in America the ultimate purpose of Luna 15 was mysterious and opinions ranged from the suspicious to the sublime to the ridiculous. Apollo 8 astronaut Frank Borman, just back from a visit to the Soviet Union, appealed for information and the Academy of Sciences supplied orbit data, operational frequencies, and assurances that Luna 15 would not endanger the Apollo 11 mission.

On July 20. after several more orbit changes, Luna 15 began its descent sequence during its 39th orbit by lowering its perilune to 16 km above the landing site in the Sea of Crises. The intention was to land just 2 hours before Apollo 11 landed further west in the Sea of Tranquility. But when controllers saw the radar data from the first perilune pass they became concerned. The one and only target appeared uneven and potentially dangerous. It must have been with the utmost reluctance and dismay that the decision was taken to postpone the landing to test the radar and perform further observations. As a result of this delay, not only was there now’ no chance of landing ahead of the Americans, the nature of the return trajectory would make it impossible to get a sample back first. All of this w as unknown to an anxious world, wondering wrhat stunt Luna 15 was going to pull in order to upstage Apollo 11. Eighteen hours later, on its 52nd orbit, Luna 15 w*as commanded to land at 15:46:43 UT on July 21. after Armstrong and Aidrin had already walked on the Moon. The descent maneuver failed and. for reasons still to be explained, the transmission ceased 4 minutes after the de-orbit burn started. It erashed at 17 N 60 H, about 800 km east of Tranquility Base. Jodrell Bank flashed notification to the Americans that Luna 15 had impacted at a velocity of 480 m/s just as Apollo 11 ‘s lunar module was preparing to leave the Moon. The Soviets reported that Luna 15 had ’"reached the lunar surface in a preset area" but remained silent on its true mission and there was no propaganda victory.

Campaign objectives:

The 1978 Venus campaign objectives were to repeat the resounding successes of the Venera 9 and 10 landers with new instruments to analyze both the atmosphere and surface. The 1976-77 opportunity was skipped in order to build the new7 apparatus, and a launch in 1978 dictated a much higher arrival velocity at Venus than in 1975. The larger propellant load required for the longer orbit insertion burn was unable to be accommodated together with the mass of the new instruments, so the carrier was downgraded to a flyby role. A positive outcome wras that a flyby spacecraft would remain in view7 of the lander for longer in order to relay data from the surface. Both of the previous landers had still been operating when their orbiters flew7 below their horizons. The new7 lander investigations featured a high resolution color camera and an experiment to drill into the surface. The descent investigations included new7 experiments to study the chemical composition of the atmosphere, the nature of the clouds, and any electrical activity in the atmosphere. The flyby instrumentation was reduced in order to maximize the mass available for the descent and surface science.

Spacecraft:

Although assigned only to a flyby role the Venera 11 and 12 spacecraft were almost identical to their or biter predecessors, but the lander relay was increased to 3 к bits/s per channel. After releasing the entry system 2 days prior to arriving at the planet, Venera 11 (and all later flyby spacecraft) made a deflection maneuver to establish a flyby w7hich would enable it to relay to Earth for longer than w^as possible using an
orbitcr. The spacecraft were identical and the landers had the same configuration as their recent predecessors but the floodlights were deleted and the camera lens cap was redesigned. The complexity and mass of the parachute system was reduced to accommodate more instruments. Only a single supersonic braking parachute was used instead of a sequence of two, and only one main parachute was used instead of a system of three. Some of the instruments were modified and new ones were added, in some cases being installed on the shock absorbing impact ring. All landers from now through to Vega 2 carried a technology experiment consisting of a set of small solar cells arranged around the lander ring.

4,450 kg (Venera 11) 4,461 kg (Venera 12) 2,127 kg 1,600 kg

731 kg

Payload:

Flyby spacecraft:

1. Extreme-ultraviolet (30 to 166 nm) spectrometer (France)

2. Magnetometer

3. Plasma spectrometer

4. Solar wind detectors

5. High energy particle detectors

6. KONUS gamma-ray burst detector

7. SNEG gamma-ray burst detectors (France-USSR)

KONUS was an interplanetary cruise experiment to try and identify the source of mysterious astronomical gamma-ray bursts by having the two spacecraft coordinate with the Prognoz satellite in Earth orbit to triangulate on individual bursts. SNEG was an instrument complementary to KONUS, built in cooperation with the French. And a new French-built extreme-ultraviolet spectrometer covered the spectral lines of atomic hydrogen, helium, oxygen and other elements that it was thought might be present in the exosphere of Venus. The solar wind detector was a hemispherical proton telescope, and the high energy particle experiments used four semiconductor counters, two gas-discharge counters and four scintilla­tion counters.

Lander:

Entry and descent:

1. Scanning spectrophotometer (0.43 to 1.17 microns)

2. Mass spectrometer Гог atmospheric composition

3. Gas chromatograph for atmospheric composition

4. Nephelometer for aerosols of about 1 micron in size

5. X-ray fluorescence spectrometer for elemental composition of aerosols

6. Accelerometers for atmospheric structure from 105 to 70 km

7. Temperature and pressure sensors for 50 km to the surface

8. GROZA radio sensor at 8 to 95 kHz for electrical and acoustic activity

9. Doppler experiment for wind and turbulence

The experiments for determining the light scattering properties of the atmosphere were modified for a higher spectral resolution. The angular scattering nephelometers were deleted because they had satisfactorily measured the particle size and refractive index when carried on the Venera 9 and 10 landers. Instead, only the back scattering nephelometers w ere retained to examine the spatial uniformity of the cloud layers in different regions of the planet. The scanning spectrophotometer was improved for a higher spectral resolution. Every 10 seconds it measured radiation coming from the zenith using a ramp interference filter at a resolution of about 20 nm continuously over the range 430 to IT70 nm, and the angular distribution of radiation (a full 360 degrees) in the vertical plane in the bands 0.4 to 0.6, 0.6 to 0.8, 0.8 to 1.3. and 1.1 to

1.6 microns using a rotating prism mounted on the aerobrake. The temperatures and pressures were measured by a suite of four thermometers and three barometers, flic monopole radio-frequency mass spectrometer of Venera 9 and 10 w as replaced by a Bennett radio-frequency design and the inlet system modified to prevent it becoming clogged by cloud particles which might then contaminate the atmospheric readings. The microscopic leak admitting the atmosphere to the instrument w7as replaced by a piezoelectric valve that would open a relatively large hole for a very short time in order to admit a pulse of atmosphere into a long sample tube which w? ould trap cloud particles. In addition the instrument was not to be operated until the lander wras at about 25 km. well below the aerosols. The apparatus w^as pumped down between atmospheric readings to purge the sample. Two other new atmospheric composition experiments were included. The gas chromatograph used neon to carry atmospheric samples through columns of porous materials and a Penning ionization detector. It had one column 2 meters long that was optimized for water, carbon dioxide and the compounds hydrogen sulfide, carbonyl sulfide, and sulfur dioxide; a second column 2.5 meters long for the volatile gases helium, molecular hydrogen, argon, molecular oxygen, molecular nitrogen, krypton, methane and carbon monoxide; and a third column just 1 meter long specifically for argon. An x-ray fluorescence spectrometer used gamma rays to excite the emission of x-rays from cloud particles collected on a cellulose acetate filter by drawing atmospheric gas through the instrument, thereby measuring the elemental composition of the aerosols.

The GROZA experiment comprised an acoustic detector and an electromagnetic wave detector using loop antennas with four narrow-band receivers at 10, 18, 36 and 80 kHz and a wide-band receiver over the range 8 to 95 kHz. This was to start at an altitude of 60 km and operate down to and on the surfaec. The electromagnetic wave detector was to register radio bursts from lightning and the acoustic signals could be interpreted in terms of thunder, wind speed past the lander during the descent and, while on the ground, perhaps even seismic quakes.

Surface:

1. Panoramic two-camera color imaging system

2. Soil drill with x-ray fluorescence spectrometer analysis system

3. Rotating conical soil penetrometer (PrOP-V)

The panoramic camera system had been improved by adding clear, red, green and blue filters for three-color imaging, and by increasing the image quality from 128 x 512 pixels at 6 bit encoding to 252 x 1,024 pixels at 9 bit encoding and 1 bit parity. It was capable of resolving detail as fine as 4 or 5 mm at a range of 1.5 meters. The transmission bandwidth had been increased by a factor of twelve, one reason for this being the Kvant-D upgrade to the Soviet communications facilities; in particular the introduction of 70 meter antennas at Yevpatoria and Ussuriisk. The increase in the transmission rate from the surface of Venus from 256 bits, s to 3,000 bits/s enabled a color panorama to be sent in 14 minutes, as against 30 minutes for a lower resolution black-and-white panorama previously.

The gamma-rav soil analysis instrument inside the Venera 8, 9 and 10 landers was replaced by a superior instrument. A drill mounted on the shock-absorbing impact ring w as to core a sample of the surface and then pass it through a series of pressure – reduction stages to the x-ray fluorescence spectrometer carried inside the lander. The penetrometer was on a deployable arm and reported its results on a dial that was to be read by the cameras.

1ission description:

Venera 11 lander:

Venera 11 was launched on September 9, 1978, and made midcourse corrections on September 16 and December 17. After the entry capsule was released on December 23 the spacecraft made the deflection burn in order to perform a flyby of the planet at the desired relay communications altitude, and on December 25 the entry system hit the atmosphere at 11.2 km/s. After a 1 hour descent the lander touched down at a speed of 7 to 8 m/s on the day-side at 14 S 299 E. It w as 03:24 UT, 11:10 Venus solar time, and the solar zenith angle was 17 degrees. The lander transmitted from the surface for 95 minutes before the relay spacecraft flew over the horizon after 110 minutes, so none of the transmission was lost.

figure 15.3 Venera 11 and Venera 12 encounter design, showing entry capsule targeting followed by flyby vehicle deflection and lander relay communications.

Venera 12 lander:

Venera 12 was launched on September 14, 1978, pursued a faster trajectory with midcourse corrections on September 21 and December 14, and arrived ahead of its partner. It released its entry system on December 19. This entered the atmosphere on December 21 at a velocity of 11.2 km/s. The parachute was jettisoned at 49 km and after a 1 hour descent the lander touched down at about 8 m/s on the day-side at 7°S 294°E. It was 03:30 UT, 11:16 Venus solar lime, and the solar zenith angle was 20 degrees. Unlike Venera 11, it kicked up a cloud of dust that took about 25 seconds to settle. Both landers encountered an unexplained anomaly at an altitude of 25 km, where instrument readings went off-scale and there was an electrical discharge from the vehicle. This lander transmitted from the surface for 110 minutes until the flyby spacecraft passed below the horizon. It is therefore not known when it finally ceased to function.

Venera 11 and 12 flyby spacecraft:

After the deflection maneuver, each spacecraft Hew by Venus at a range of about

35,0 km and relayed the data from its lander to Earth throughout the descent and then during the period of surface activity. The last reports from the flyby spacecraft were in January 1980 for Venera 11 and March 1980 for Venera 12.

Results:

Venera 11 and 12 decent measurements:

The landers inferred atmospheric density from accelerometer data over the altitude range 100 to 65 km and then directly measured atmospheric temperature and pressure from 61 km down to the surface. Opacity was measured from 64 km to the surface, the chemical composition of aerosols from 64 km to 49 km, aerosol scattering from 51 km down to the surface, and thunderstorm activity from 60 km down to the surface. The gas chromatograph analyzed nine atmospheric samples from 42 km to the surface. The new mass spectrometer measured atmospheric composition from 23 km to 1 km. Wind velocities were measured from about 23 km down to the surface, and altitude profiles of horizontal wind speed and direction were obtained from Doppler data.

The spectrophotometer produced the first realistic water vapor profile, identifying water vapor as the second most important greenhouse gas in the atmosphere (after carbon dioxide). The contemporary analysis indicated a profile that decreased from 200 ppm at the cloud base to 20 ppm at the surface, but a re-analysis many years later obtained a better fit for the Venera 11,12 and 14 spectrophotometer data using a constant mixing ratio for water vapor of about 30 ppm from 50 km to the surface. The mass spectrometers on these missions reported values as high as 0.5% at 44 km and 0.1% at 24 km; these are much larger mixing ratios for water vapor than were obtained from the spectrophotometer and other remote spectral measurements from Hanh, and are considered suspect.

The mass spectrometer results from Venera 11 and 12 obtained by the analysis of 176 complete spectra of 22 samples were reported as:

carbon dioxide

molecular nitrogen

argon

neon

krypton with isotopic ratios as follows:

0. 0112 ± 0.0002 1.19 ± 0.07 0.197 ± 0.002

The gas chromatograph made eight measurements betw een 42 km and the surface with the following results:

2.5 + 0.3 %

25 to 100 ppm

40+10 ppm

130 + 35 ppm

28 + 7 ppm (low altitudes)

less than 20 ppm

krypton

hydrogen sulfide carbonyl sulfide

The x-ray fluorescence spectrometer on Venera 12 measured cloud particles from 64 km to 49 km and was then overcome by the high temporal tires. It missed sulfur (< 0.1 mg/m3). but found chlorine (0.43 + 0.06 mg/nri) in cloud particulates. The chlorine was suspected to be a non-volatile compound such as aluminum chloride at the time, but it was not specifically identified. The large amount of chlorine relative to sulfur was incompatible with the theory that the clouds were composed of sulfuric acid droplets, but these anomalous data were corrected by the Venera 14 mission.

Both Venera 11 and 12 detected a large number of electromagnetic pulses in the descent from 32 to 2 km similar to those produced by distant lightning Hashes on Harth. The activity was more intense on Venera 11 than Venera 12, and diminished in intensity towards the surface. No such pulses were detected by Venera 11 after it touched down, but one large burst was noted by Venera 12 while on the surface. The microphones were saturated by aerodynamic noise during the descent and detected no thunder on the surface, but they did pick up sounds issued by the instruments and surface activities.

As with Venera 9 and 10. the light scattering data indicated clouds with a base at an altitude of 47 km, and a much lower loading of aerosols below that. Venera 11 and 12 found the atmosphere to be generally free of aerosols below ^30 km. The nephelometer on Venera 11 measured cloud particles throughout the descent and its results confirmed the uniformity of the cloud layers as reported by Venera 9 and 10. The base cloud layer was located between 51 and 48 km, with a mist below that. The nephelomeler on Venera 12 did nol function correctly. It was confirmed that only about 3 to 6% of the sunlight reaches the surface. Intense Rayleigh scattering in the dense atmosphere gives poor visibility. Above several kilometers altitude the surface must be invisible. At ground level the horizon will be visible, but the detail of the landscape must fade quickly into an orange haze. The Sun is not visible as a disk, merely a uniformly lit hazy sky.

Venera 11 and 12 surface measurements:

The temperature at the Venera 11 landing site was 458 + 5 C and the pressure was 91 + 2 bar. There was no surface imaging because the lens covers would not open. These had been redesigned after the problems w ith one camera on each of Venera 9 and 10, but with disastrous results. The transmit ted pictures were uniformly black. The soil drill collected a sample, but it was not properly delivered to the instrument container and no soil analysis was accomplished.

The temperature at the Venera 12 site was 468 + 5 C and the pressure was 92 + 2 bar. The fact that this suffered exactly the same camera and soil analysis experiment failures as its partner implied a systematic design flaw. Vibrations while descending broke the sample transfer system on the drill and no soil analysis was possible. The soil penetrometers also failed on both landers.

The surface experiments were an almost total failure on both landers. It is possible
that they suffered rough landings which damaged the instruments that were mounted on the impact ring. The lack of results was very disappointing, hut in typical Soviet fashion this spurred the engineers on to succeed at the next flight opportunity.

Venera 11 and 12 flyby spacecraft:

The ultraviolet spectrometer detected Lyman-alpha emissions from hydrogen atoms and 584 angstrom (He-I) emissions from helium atoms. These provided exospheric temperatures and number densities. Time profiles for 143 gamma-ray bursts were obtained by Venera 11 and 12 and the results triangulated with an identical detector on Prognoz 7 in harth orbit. On Kebruary 13 and March 17, 1980, Venera 12 used its extreme-ultraviolet spectrometer to observe Comet Bradfield.

The Scientific Production Organization NPO-Lavochkin was originally founded in 1937 as the Lavochkin Aircraft Design Bureau, OKB-301, named for its Chief Designer. Lavochkin produced a number distinguished fighter aircraft during WW-11

and then surface-to-air missile designs after the war, producing the first operational system for the defense of Moscow. In 1953 the SAM business was transferred to a new design bureau and OKB-301 pursued ramjet intercontinental cruise missiles as a hedge against problems with ICBM development. But the successful introduction of ICBMs in the late 1950s left OKB-301 without work. Semyon Lavochkin died in 1960 and the organization transferred in 1962 to Chelonrey’s OKB-52. The factory was closed, but reopened in 1965 as NPO-Lavochkin under the steady and capable leadership of Georgi Nikolayevich Babakin specifically to take responsibility for the robotic lunar and planetary spacecraft programs transferred from OKB-1.

The new NPO-Lavochkin realized immediate success using its inheritance from OKB-1 augmented by a history of great skill and experience in aviation technology. Luna 9 soft landed on the Moon’s surface in January 1966, and before the year was over there were three successful lunar orbiters and a second soft lander. The first successful Venus entry probe, Venera 4, followed in 1967. NPO-Lavochkin went on to continue this highly successful series of spacecraft at Venus, a successful series of lunar orbiters, rovers and sample return missions, and the singularly complex and successful Vega missions which delivered landers and balloons to Venus enroute to a flyby of Halley’s comet. LTnfortunately, NPO-Lavochkin had no success at Mars: their campaigns in 1969, 1971, and 1973 were riddled with failures, and worse was to come in 1988 and 1996. Their astronomy missions have met with better success, in particular the Granat and Astron space observatories. Today NPO-Lavochkin is the single engineering center for the production of robotic scientific spacecraft.

Russia built the first interplanetary spacecraft for launch attempts at Mars in 1960 and Venus in 1961. These two sets of spacecraft were similar, but the 1M pair built for Mars and the 1VA pair built for Venus had differences relating to the different thermal conditions expected and the communication differences involved. Each pair was identical. Only one of these spacecraft, Venera 1, survived the launch vehicle and was dispatched towards its target, but contact was lost 7 days later.

TIMELINE: JAN 1963-DEC 1965

Between their success with Luna 3 in October 1959 and the opening of 1963, the Soviets suffered two failed lunar missions, five failed Mars missions, and five failed Venus missions. During those long 39 months, Sergey Korolev’s engineers had been working on a new lunar soft-lander to take advantage of the four-stage version of the R-7. Unfortunately, this new Luna would suffer an even longer and more frustrating series of failures than the Ranger crash-lander being developed by the Americans. In fact, there would be eleven failures over the three years 1963-65 before managing a soft landing, with four of the six launch failures being caused by malfunctions of the fourth stage. Of those that were successfully deployed, Luna 4 to 8, two missed the Moon and the other three crashed onto it. The real objectives of these missions were not revealed at the time. Meanwhile, in 1964-65 the LTS finally had a string of successes with Ranger 7 to 9.

fn parallel, the Soviets were applying the lessons from Venera 1 and Mars 1 in the development of the 3MV planetary spacecraft, basically an improved version of the 2MV, for the planetary launch windows of 1964 and 1965. To gain some experience with the new spacecraft, it was decided in late 1963 to make two interim flight tests, but these spacecraft were lost to launch vehicle failures on November 11, 1963 and February 19, 1964. Undeterred, wrhen the Venus launch window opened the Soviets proceeded to launch spacecraft to Venus on March 27 and April 2, 1964. Only the second spacecraft w? as launched successfully, but because it was immediately clear that on board failures would prevent it from reaching its target it was named Zond 1 instead of being given a Venera designation. A launch to Mars – was accomplished successfully on November 30, but once again the spacecraft was sufficiently crippled that it would not make its target and so it was named Zond 2.

The loss of so much hard work must have been doubly galling with the success of the Mariner 4 flyby of Mars on July 15, 1965. As with Venus, the LTS had somehow reached Mars first! Troubled by the significant problems suffered by Zond 1 and 2, the Soviets decided to conduct another 3MV test flight. Launched on July 18, 1965,

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outside a launch window, Zond. 3 was unable to reach Mars but it could fly the kind of trajectory that would be used by a real mission. The timing of the departure was arranged so that it could test its camera system by photographing the far side of the Moon. It exercised its navigation systems, propulsion system, flight and instrument operations, and returned its pictures. Unfortunately communications were lost before it reached the equivalent of Mars distance, preventing it from demonstrating its deep space capabilities.

The Zond 3 experience paid off on the flights of Venera 2 and Venera 3, both of which were launched later in November 1965, the first equipped to make a flyby and the second with an entry probe. They flew without serious problems and became the first Soviet planetary spacecraft to reach their target. But they added to rheir maker’s woes by both losing communication, Venera 2 just as it arrived and Venera 3 when
seventeen days from its target on a collision trajectory. Neither mission returned any data from Venus.

The years 1964-65 were crucial turning points in the Soviet space program. Since 1959 OKB-1 had been working on a plan to send eosmonauts on circumlunar flights, and had designed the Soyuz system for this objective. It had no plans to land people on the Moon. The Soviets initially saw the US stated intention to land a man on the Moon as mere hyperbole, but by 1964 it had become clear that major resources had been assigned to the program and that the development of the necessary rockets and spacecraft was progressing. Confident that their Soyuz could beat the Americans to a circumlunar mission but reluctant to be upstaged by a lunar landing, the Politburo directed Korolev in August 1964 to proceed with landing cosmonauts on the Moon in addition to performing the circumlunar program. However, in what would prove to be a huge management mistake, the government divided the development work for these programs amongst competing design bureaus without central leadership or responsibility. The space program was reorganized and additional resources applied. To manage all the work, new design bureaus were established and responsibilities distributed. At this point Soviet space policy underwent a fundamental change, and instead of pursuing long standing plans for the conquest of space it began to directly compete with the American program.

The other issue forcing a shake up in the Soviet space program was the long string of robotic lunar and planetary program failures between 1960 and 1965. Thus far. Korolev had been responsible for virtually all types of Soviet spacecraft and now he had been given the further task of overtaking the Americans in the race to the Moon. By his own admission. OKB-1 was overburdened and unable to devote enough time and resources to the robotic missions. In March 1965, on the advice of Keldysh, he asked his friend Georgi Babakin. who headed NPO-Lavochkin, to take over after the current production run of lunar and planetary spacecraft at OKB-1 ran its course. In April, Korolev handed over OKB-l’s plans and knowledge base to Lavochkin. The remaining robotic spacecraft were launched during the rest of the year, ending w ith Luna 8 and Venera 3, while Lavochkin designed modifications and set up to produce new’ spacecraft.

The next three sample return attempts were lost to launcher failures. In September Ye-8-5 No.403 was stranded in parking orbit when the Block D failed to restart. An oxygen fuel valve had stuck open after the first firing and allowed all the oxidizer to escape. It was designated Cosmos 300 by the Soviets, and re-entered after 4 days. In October a programming error caused the Block D to misfire and spacecraft No.404. designated Cosmos 305, re-entered during its first orbit. In February 1970 spacecraft No.405 was lost wdien a pressure sensor command error shut down the second stage after 127 seconds of flight and the vehicle was destroyed. This precipitated a review7 of the Proton launch vehicle, w hich had a miserable record with many more failures than successes in the Ye-8 and lunar Zond series at that time. Changes w ere made as a result of this review, and in August 1970 a successful suborbital diagnostic flight was flown. The following month another sample return attempt was made and, after five successive failures in a period of 15 months, success w’as finally achieved.

Luna 16

Luna 16 was launched at 13:25:53 UT on September 12, 1970. Seventy minutes after entering parking orbit, the Block D reignited and performed the translunar injection burn. After a course correction on September 13. the spacecraft entered a nearly circular 110 x 119 km orbit at 70 degrees inclination on September 17. After gravity data had been acquired in this orbit, two orbital adjustments were made on September 18 and 19, the first into an elliptical orbit wdth its perilune 15.1 km above the landing site and an apolune of 106 km, and the second to adjust the orbit plane to 71 degrees inclination. As the spacecraft approached perilune on September 20. the extra tanks were jettisoned. The engine was ignited at perilune. 05:12 UT, and fired for 270 seconds to cancel the orbital velocity and initiate the free fall. Triggered by the radar altimeter, the engine was restarted at an altitude of 600 meters and velocity of 700 km hr. It was shut down at an altitude of 20 meters and a velocity of 2 m/s. The primary verniers were ignited for the tenninal phase, and cut off at a height of 2 meters, then the spacecraft dropped to impact at about 4.8 m/s. Touchdown occurred at 05:18 UT in the Sea of Fertility at 0.68 S 56.30 H. only 1.5 km from the planned point.

Because Luna 16 touched down 60 hours after local sunset and was not fitted w ith floodlights it did not provide any images. The drill was deployed after an hour, and in 7 minutes of operations it penetrated to a depth of 35 cm before encountering an obstacle. 1 he boom then lifted the core sample from the surface and swung it up to

the return capsule atop the ascent stage, inserting it through an open hatch that then closed. Some soil was lost from the sampler during this operation. At 07:4.1 UT on September 21, after 26 hours and 25 minutes on the Moon, the ascent stage lifted off and escaped at 2.7 krn/s. The lower stage remained on the surface and continued to transmit lunar temperature and radiation data. The ascent stage returned directly to Earth. On September 24, at a distance of 48,000 km, the straps released the return capsule. Four hours later it hit the atmosphere traveling at 11 km/s on a trajectory at 30 degrees to the vertical on a ballistic entry with a peak deceleration of 350 G. At an altitude of 14.5 km the top of the capsule was ejected and the drogue parachute deployed. At 11 km the main chute was unfurled and the beacon antennas deployed. The capsule landed at 03:26 UT on September 24, approximately 80 km southeast of the city of Dzhezkazgan in Kazakhstan.

Luna 16 proved, to contain 101 grams of lunar material. It was a triumph, and the Soviet press made the best of it, hyping the use of robots over manned missions. For the Americans, Luna 16 confirmed what they suspected about Luna 15, that it was a sample return attempt intended to upstage Apollo 11.

Luna 18

The next attempt at sample return was made one year later. Luna 18 was launched on September 2, 1971, made midcourse corrections on the 4th and 6th, and entered a 101 km circular lunar orbit inclined at 35 degrees the following day. After lowering its perilune to 18 km it was commanded to land on September 11, but the signals cut off abruptly at 07:48 UT at an altitude of about 100 meters. The main engine had run out of fuel due to excessive consumption in earlier operations, and the wreckage lies at 3.57°N 56.50°E in rugged highland terrain.

Luna 20

Luna 20 was the second attempt after Luna 18 to obtain a sample from in the lunar highlands. Launched on February 14, 1972, it was tracked by telescopes to compute an accurate trajectory, made a midcourse correction the following day and entered a 100 km circular lunar orbit at 65 degrees on February 18. It lowered its perilune to 21 km the following day. And finally, at 19:19 UT on February 21, it touched down in the Apollonius highlands near the Sea of Fertility at 3.53°N 56.55,:>E, only 1.8 km from where Luna 18 crashed. The Sun was 60 degrees above the horizon. Images of the surface were transmitted prior to the sampling operations. The drill encountered resistance, and had to be paused three times to prevent overheating. It was ultimately able to achieve a depth of only 25 cm. The recovered sample core was transferred to the return capsule.

The ascent stage lifted off at 22:58 UT on February 22, and then upon its return to Earth fell into a strong snow storm. .Although it came down over the Karkingir river 40 km north of Dzhczkazgan, when it landed at 19:19 UT on February 25 it touched down on an island. The ice, wind, and snow presented the recovery team with severe difficulties. It was recovered the following day, and when opened proved to contain only 55 grams of lunar soil.

Luna 23

The first improved Ye-8-5M sample return vehicle, No.410, became Luna 23 with a successful launch on October 28, 1974. After a midcourse correction on October 31, it entered an almost circular 94 x 104 km orbit at 138 degrees on November 2. Upon lowering its perilune to 17 km it was commanded to land on November 6. Although Luna 23 landed on target in the southern part of Sea of Crises at 12.68’N 62.28°E, it did so at 11 m/s and the impact shock wrecked the sample collection apparatus and caused other damage. No samples wjere obtained and the ascent stage was not lired. The lander continued to transmit until contact was lost on November 9.

TIMELINE: 1979-1981

The pace of planetary exploration slowed considerably after 1978, particularly in the US. There were no launches to the Moon or the planets in 1979-80. ft was a striking contrast to the hectic 1960s and 1970s. Tn fact there would be no lunar or planetary launches by the IJS during the eleven years between 1978 (Pioneer Venus) and 1989 (Galileo). Continuing their assault on Venus using the successful Venera spacecraft, the Soviets had the field to themselves. At the next Venus opportunity in 1981 they launched another pair of Venera flyby/’landcrs. Both were successful, and this time produced the first color images of the surface of the planet.

Launch date

1979

No missions

1980

No missions

1981

30 Oct Venera 13 flyby/landcr Success, first color images from surface

4 Nov Venera 14 flyby/lander Success

COLOR PICTURES FROM THE SURFACE OF VENUS: 1981

Campaign objectives:

Venera 11 and 12 had not completed the goals set for them. Whilst the experiments carried out during the descent produced a prodigious amount of information on the

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atmosphere, the surface science was mostly a failure. The Soviets skipped a launch opportunity in order to develop new heat-resistant technologies in order to fix these problems. In 1981 they were ready to try again with better devices and instruments, principally aiming to obtain color images from the surface and to analyze a sample obtained by a drill. The landing sites were chosen in collaboration with US scientists using maps based on the radar imaging experiment perfonned by the Pioneer orbiter in 1978. ~

As flyby spacecraft, Venera 13 and 14 were essentially identical to their immediate predecessors. The major changes for 1981 concerned the lander. In particular, metal teeth were added to the periphery of the impact ring in an effort to reduce the spin and oscillation during the descent and prevent the rough landings experienced by the 1978 missions. The camera lens cover problem was fixed, and the soil sampler was redesigned to alleviate the problem that disabled it on Venera 11 and 12.

Payload

Flyby spacecraft

1. KONUS gamma-ray burst detector

2. SNEG gamma-ray burst detectors (France-USSR)

3. Magnetometer (Austria)

4. High energy particle cosmic ray detector

5. Solar wind detectors

The flyby spacecraft carried a reduced payload to facilitate an increased payload on ihc lander. Updated forms of the cosmic ray experiment and the two gamma-ray investigations were included, and an Austrian magnetometer on a 2 meter boom was attached to one of the solar panels.

Flyby payload mass: 92 kg Lander

Entry and descent

1. Accelerometers for atmospheric structure (110 down to 63 km) and then lander impact analysis

2. Temperature and pressure sensors

3. Gas chromatograph for atmospheric composition

4. Mass spectrometer for chemical and isotopic composition

5. Hydrometer for water vapor content

6. Nephclomcter for aerosol studies

7. X-ray fluorescence spectrometer for elemental composition of aerosols

8. Spectrophotometer for spectral and angular distribution of solar radiation

9. Ultraviolet photometer 320 to 390 nm

10. GROZA-2 radio for electrical activity and microphone for acoustic and seismic events

11. Doppler experiment for wind and turbulence Surface

1. Panoramic color imaging system with two cameras

2. Drill and surface sampler

3. X-ray fluorescence spectrometer for surface rock elemental composition

4. Rotating conical soil penetrometer (PrOP-V)

5. Chemical oxidation state indicator

Several of the instruments were improved from their Venera 11 and 12 versions, including the camera, drill, spectrophotometer, x-ray spectrometer for aerosols, mass spectrometer and gas chromatograph. The hydrometer humidity sensor and chemical oxidation state indicator were new; the latter being a simple chemical indicator to search for traces of oxygen in the atmosphere. The spectrophotometer measured the full spectrum from 470 to 1,200 nm using a wide-angle sky view and an array of six narrow-angle directional views. The gas chromatograph was equipped with a better detector, could sense more species, and was capable of operating in the cloud layer. l he mass spectrometer was improved to provide 2 to 40 times better mass resolution with 10 to 30 times greater sensitivity. The anomalous krypton reading of the 1978 missions was understood and corrected. The GROZA-2 instrument now; included a modified 10 kHz detector, a new7 detector in the 2 kHz band, and was better able to search for seismic events after touchdown.

The panoramic imaging system was fitted with an improved lens cover. The large increase in bandwidth for the transmission to the flyby relay spacecraft allowed each camera to have clear, red, green, and blue filters. Each camera was to cycle through its 180 degree panoramic image four times, one for each filter, taking almost an hour to complete. To ensure that a color section would be transmitted if the lander lasted only 30 minutes, one camera first scanned a full 180 degrees through the clear filter and then scanned each of three 60 degree sections in turn with red, green and blue filters.

It is a testament to the technology of the Venera landers that so many instruments were mounted outside and hence exposed to the pressure, temperature and corrosive atmosphere of Venus. These included the drill, penetrometer, mass spectrometer, gas chromatograph, hydrometer, aerosol x-ray spectrometer, oxidation state indicator, and the GROZA radio sensors and microphone. The cameras and nephelometer were mounted inside with special housings attached to the pressure vessel to enable them to observe out through windows and prisms. The platinum thermometer and aneroid pressure instrument used external sensors with wires fed through ihe pressure vessel.

The drill sampler was on the base of the lander. The machining of this device had to take account of thermal expansion at 500"C, and the process of drilling, sampling and analysis had to complete within the 30 minute guaranteed lifetime of the lander. A telescoping drill head was to bore into the surface for about 2 minutes, reaching as much as 3 cm into solid rock and coring a 2 cc sample. Information on the speed and

movement of the drilling rig. depth of drill penetration, and magnitude of the current drawn by the elec trie motor while drilling, provided information on the physical and mechanical properties of; the surface. After the few grams of material gained by the drill had been deposited on a tray, this would be moved pyrotechnically through a three-stage airlock to transfer it from the ambient 90 bar pressure to just 0.06 bar in the analysis chamber of the x-ray fluorescence spectrometer, which used plutonium, uranium-235 and iron-55 sources. The gas pumping for this transfer was enabled by a vacuum reservoir on the base of the lander.

The dynamic penetrometer was designed to determine the mechanical properties of the surface material, whether rock or soil. It consisted of a cone-shaped die that could pivot on the end of a lever and fall forward onto the ground. Л sighting device within the field of view of one of the cameras determined the depth of penetration. After penetration, a spring would cause the die to rotate in the soil and the angle of its turn would be displayed on the sighting device. A cable unit was also attached to one end of the die and an electronic unit within the lander could measure electrical resistance.

Lander payload mass: 100 kg

Mission description:

Landers

Venera 13 was launched on October 30, 1981, and made midcourse corrections on November 10 and February 21, 1982. It released its entry capsule on February 27 at a range of 33,000 km from the planet, and this entered the atmosphere on March 1. The accelerometer was turned on at about 100 km altitude and provided data on atmospheric density until parachute deployment. The parachute opened at 62 km and was jettisoned about 9 minutes later at an altitude of; 47 km. The descent instruments were activated just after the parachute opened, and the descent time from parachute opening to landing was just over an hour. The lander hit at 7.5 m/s. bounced once, and came to rest on a fiat, crumbly surface in an elevated hilly landscape at 7.55 :S 303.69 :E. It was 03:57:21 UT, 09:27 Venus solar time, and the solar zenith angle was 36 degrees. The surface transmission lasted 127 minutes.

Venera 14 was launched on November 4, 1981. and required three midcourse corrections to reach Venus. This was because the first one on November 14 w as not executed properly. After a compensating maneuver on November 23, the final trim maneuver was made on February 25. 1982. The entry system was released on March 3, and this entered the atmosphere on March 5. The parachute opened at 62 km and w as jettisoned at 47 km. The lander touched down at about 7.5 m/s on a low lying plain at 13.055 S 310.19’E, 950 km southwest of; its partner. It was 07:00:10 UT, 09:54 Venus solar time, and the solar zenith angle was 35.5 degrees. The surface transmission lasted 57 minutes.

Venera 13 and 14 experienced the same electrical anomaly as had Venera 11 and 12 at 12.5 km altitude. The science sequences worked very well on descent for both

landers and also on the surface. Immediately upon landing, the lens covers popped off and imaging began. A black-and-white contingency image was transmitted first, followed by the color panoramas. The drill experiment was also started immediately after landing and the entire process of drilling, sampling, and analysis took a little over 32 minutes. Venera 13 obtained a 2 cc sample and Venera 14 obtained a 1 cc sample, each from a depth of 3 cm. The Venera 13 penetrometer worked well, but by bad luck on Venera 14 this experiment deployed on top of an ejected lens cover. The microphones picked up aerodynamic noise during the descent, the sounds of the landing, and then the deployment of the lens covers, the drilling noise and sampler pyrotechnics, winds at the site, and other sounds of the lander at work.

Flyby carrier spacecraft:

The flyby carriers each passed Venus at an approximate closest point of approach at

36,0 km and entered heliocentric orbit where they continued to return data on the Sun, including flares. As tests to assist in planning late midcourse maneuvers for the Halley’s comet encounters by the Vega missions, Venera 13 fired its engine on June 10, 1982, and Venera 14 did so on November 14, 1982.

Results:

Venera 13 lander:

Descent measuremen ts:

The microphysical properties reported by the nepheiometers indicted, three distinct layers in the main cloud system: a dense top layer from 60 km (the altitude at which the measurements began) down to 57 km, then a transparent layer from 57 to 50 km, and finally the densest layer from 50 to 48 km. Doppler measurements gave a wind profile. Interestingly, the humidity sensors on both Venera 13 and 14 indicated ten times more water in the atmosphere than was determined spectroscopically in the 46 to 50 km range. The water mixing ratio was determined from several instruments and, despite some conflicting values, it seemed to be greatest in the cloud formation

region between 40 and 60 km with less water above and below the cloud layers. The amount of water vapor at 48 km was estimated at 0.2%. The mass spectrometer was not opened until below the cloud layers to preclude it being clogged by aerosols, and it provided altitude profiles of a number of atmospheric constituents between 26 km and the surface. These findings include a neon isotope ratio slightly higher than for Earth but less than for the Sun, a small krypton mixing ratio significantly less than that measured by the gas chromatograph and by Venera 11 and 12, and an argon-40 mixing ratio about four times lower than for Earth. The gas chromatograph detected some new species including molecular hydrogen, hydrogen sulfide, and carbonyl sulfide. Other species detected included molecular oxygen, water vapor, krypton, and sulfur hexafluoride.

The coronal discharge detectors of the GROZA-2 experiment established that no vehicle discharges were responsible for the very low frequency bursts interpreted as lightning by the Venera 11 and 12 experiments. No lightning or electrical discharges were detected.

Surface measurements:

Venera 13 obtained both black-and-white and the first color panoramic images from the surface of Venus. These show the lander ring base with triangular ‘crown’ points for lander stabilization during the descent, the ejected camera covers, the color test pattern strips, the deployed PrOP-V penetrometer, and the exhaust port of the aerosol x-ray fluorescence instrument on the lander ringjusl to the left of the penetrometer. The landing site appeared to be composed of bedrock outcrops surrounded by dark, fine-grained soil. The Venera 13 and 14 panoramas both showed llat, layered stones with a dark soil between them, and scattered small grains to compose a scene reminiscent of the floor of a terrestrial ocean. The photometers noted dust raised by

the landing, but it quickly settled and the resulting sedimentation was apparent by comparison of sequential images through different filters.

The Venera 13 site showed dark, flat rocks distributed over a darker crumbled soil surfaee with some low, rolling ridges in the background. The cameras returned four panoramas each, one in each filter: clear, red. green and blue; the latter three for the color image. However, precise color balancing was difficult to achieve in processing the filter data because the deployed calibration strips were affected by heat, pressure, and the orange sky. and because the radiometric response of the camera was not well known.

The drill sample analysis indicated a potassium-rich basalt of a type that is rare on Earth. The penetrometer showed the load-bearing capacity of the soil to be similar to heavy clays or compacted dust-like sand. These are both consistent with the surface characteristics derived from stress-strain profiles measured in the mechanics of the landing, which indicated a surface covered by a weak, porous material similar to the properties of weathered basalt. The electrical resistivity of the surface was surprising low. in the semi-conductor range, perhaps due to a thin film of conducting material on insulating soil particles.

The exposed-surface chemical test on both landers for the oxidation state of the Venusian atmosphere seemed to indicate a reducing carbon dioxide-rich atmo­sphere instead of an oxidizing one, but the experiment may have been compromised by the dust disturbed upon landing. Due to the short lifetime on the surface, the GROZA-2 acoustic experiment was designed to detect the micro seismic events that commonly occur at a rate of about one every few’ seconds on Earth. No events were detected by Venera 13, but tw7o such events may have been noted by Venera 14. The Venera 13 microphone recorded the aerodynamic noise of the descent, and on the surface this data gave w ind speeds of 0.3 to 0.6 m/s. Successive pictures through different filters show ed dust being blown off the lander ring. The temperature at the landing site was 465°C and the pressure was 89.5 bar. Only 2.4% of sunlight reached the surface. Some minor changes in illumination were observed, perhaps due to clouds, but the overall impression was of a dead calm, murky atmosphere over a flat volcanic plain.

Venera 14 lander:

Deseent measurements:

The Venera 14 lander conducted the same observations as Venera 13. both during its descent and w hile on the surface, obtaining very similar results. The combined mass spectrometer results were:

the isotopic ratios were:

13/12 carbon 40/36 argon 38/36 argon 20/22 neon

and the combined gas chromatograph results were:

water vapor molecular oxygen molecular hydrogen krypton

hydrogen sulfide carbonyl sulfide sulfur hexafluoride

The x-ray fluorescence instrument measured the composition of the aerosols from 63 to 47 km. It detected both sulfur (1.10 + 0.13 mg/m3) and chlorine (0.16 + 0.04 mg/mJ) and the chlorine abundance was considerably knver than the measurement by Venera 12. This more precisely calibrated instrument measured a sulfur/’chlorine abundance ratio compatible with sulfuric acid aerosols. The aerosols in the region between 6.3 and 47 km were composed principally of sulfur compounds with some chlorine compounds. The abundance ratio of sulfur and chlorine varied with altitude. The highest density aerosols were in the range 56 to 47 km. The x-ray fluorescence instrument of Venera 13 did not operate properly.

Surface measurements:

Unlike Venera 13, the Venera 14 photometers detected no dust raised on landing. It came down on a smooth level plain with flat, layered rocks which had very little soil

between them. The composition of the drill sample indicated a low-potassium basalt similar to that of terrestrial mid-ocean ridges. A lower sulfur content than Venera 13 may well indicate that the Venera 14 site is younger. The surface properties inferred from the dynamics of touchdown indicated a surface similar to the Venera 13 site, but possibly covered with a layer of weaker, porous material. No penetrometer data was obtained from Venera 14 because the instrument swung down onto a jettisoned lens cover. The audio sensor reported two sounds that could have been distant and small seismic events. The temperature at the site was 470=,C and the pressure was 93.5 bar. Hie amount of sunlight reaching the surface was 3.5%.

X-ray fluorescence soil analysis results were:

The surface composition measurements from Venera 8, 9, 10, 13 and 14 at sites around the planet were all consistent with basalts of compositions similar to those on Earth. The great variety of igneous and metamorphic rocks widespread on Earth was not evident, most likely owing to the lack of water on Venus.

Venera 13 and 14 flyby spacecraft:

Both ilybv spacecraft collected data on the solar wind and solar x-ray Hares. They participated in an interplanetary network to triangulate on gamma-ray bursts, in this case detecting about 150 events. Later in the decade, the Vega spacecraft were to use a flyby of Venus to set up an encounter with Halley’s comet, so after leaving Venus behind Venera 13 and 14 fired their engines to rehearse the maneuvers that would be required by those later missions.

Whereas in the US the National Academy of Sciences is an advisory body to the government, the Soviet Academy of Sciences had governmental and implementation roles. It was integral to the Party, and made decisions on the worthiness of proposed space projects, approving those to be undertaken. However, the Ministry of Machine Building allocated the funding for these projects. The President of the Academy, Mstislav Keldysh, was a powerful and highly influential figure in the Soviet space program during his tenure. Before he became President of the *Acadcmy in 1961, he was head of the Institute of Applied Mathematics (TPM) and kept this position until his death in 1978, when IPM was named the Keldysh Institute. It played a major role in space navigation and mission design.

Also unlike in the US, where university laboratories and NASA’s various field centers prepared scientific experiments for planetary missions, in the USSR the research institutes of the Academy of Sciences filled this role. These institutes were established by the Academy, but were funded through MOM. In the early years, the leading player was the Vernadsky Institute, more formally known as the Institute of Geochemistry and Analytical Chemistry. In 1965, at about the same time as Korolev transferred the robotic program to NPO-Lavochkin, the Soviet Academy of Sciences under Keldysh’s initiative established the Institute for Space Research (IKI; Institut Kosmicheskikh Issledovanii), which gradually built up its role in scientific missions, including providing flight instruments, and by the 1970s was a fierce competitor to Vernadsky. With Roald Sagdeev’s appointment as Director in 1973, IKI assumed scientific leadership of deep space missions. After Sagdcev quit in 1988. Vernadsky shared leadership under Valery Barsukov until the latter died in 1992. Today IKI is the leading space science institution. The institutes develop flight instruments and NPO-Lavochkin is responsible for the spacecraft and operations.

After the failures of the 1M and 1VA missions, a new multi-mission spacecraft was designed 1’or missions to Mars and Venus. The 2MV modular spacecraft had a mass of approximately 1,000 kg. The core of the spacecraft was a cylindrical pressurized ‘orbital’ module that had the propulsion module attached at one end and the payload at the other end. The payload could consist of either an entry probe or a pressurized module with instruments for flyby observations. Solar panels, antennas, thermal control devices, navigational sensors and several science instruments were attached to the side of the main module. The communications, attitude control and thermal control systems for the 2MV were greatly improved over the 1M and 1VA, and the same propulsion system was provided for midcourse trajectory corrections.

Four variants were designed. The 2MV-1 and 2MV-2 were Venus models, and the 2MV-3 and 2MV-4 were Mars models. The -1 and -3 versions were equipped with appropriate entry vehicles, and the -2 and -4 carried instruments for a flyby mission. Six spacecraft were launched, three to Venus (two probes and one flyby) in August and September 1962, and three to Mars (two flybys and one probe) in October and November 1962, Unfortunately all but one was lost to launch vehicle failures. The Mars 1 spacecraft launched on November 1, 1962, flew for almost 5 months before communications were lost on March 21, 1963, at what was then regarded as the vast range of 106 million kilometers from Earth. In view7 of this engineering success, the 2MV general design set a long-term precedent for Russian planetary spacecraft, particularly for Venus where this type of spacecraft was used until 1975.