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Overview
Zond 1
Zond 1964A
Zond 2
Zond 3
Zond 1967A
Zond 1967B
Zond 4
Zond 1968A
Zond 5
Zond 6
Zond 1969A
Zond L1S-1
Zond L1S-2
Zond 7
Zond 8

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Zond Program
Moon, Venus, Mars ~ 1964-1970

Overview

Zond was a Soviet program that was mainly based on lunar exploration, and it greatly increased our knowledge about Earth's closest neighbor. It also explored other inner solar system planets, including Venus and Mars.

Zond 1

Zond 1 was launched from an Earth-orbiting platform Tyazheliy Sputnik (64-016A) towards Venus. It flew by Venus on July 14, 1964, at a distance of 100,000 km and entered a heliocentric orbit. The mission objectives were space research and testing of onboard systems and units. Communications from the spacecraft failed soon after May 14, 1964.

Zond 1964A

This flight was planned as a lunar flyby. The mission was designed as a technology test of the Zond spacecraft for future Mars missions. The SL-6/A-2-e launcher failed and the spacecraft did not achieve Earth orbit.

Zond 2

Zond 2 was an automatic interplanetary station launched from a Tyazheliy Sputnik (64-078A) in Earth parking orbit towards Mars to test space-borne systems and to carry out scientific investigations. The probe carried a descent craft and the same instruments as the Mars 1 flyby spacecraft: A magnetometer probe, television photographic equipment, a spectroreflectometer, radiation sensors (gas-discharge and scintillation counters), a spectrograph to study ozone absorption bands, and a micrometeoroid instrument. The spacecraft had six experimental low-thrust electrojet plasma ion engines that served as actuators of the attitude control system and could be used instead of the gas engines to maintain orientation. Power was provided by two solar panels.

The craft took a long curving trajectory towards Mars to minimize the relative velocity. The electronic ion engines were successfully tested shortly after launch under real space environment conditions over the period December 8-18, 1964. One of the two solar panels failed so only half the anticipated power was available to the spacecraft. After a mid-course maneuver, communications with the spacecraft were lost in early May of 1965. The spacecraft flew by Mars on August 6, 1965, at a distance of 1500 km and a relative speed of 5.62 km/s.

Zond 3

Zond 3 was launched from a Tyazheliy Sputnik (65-056B) Earth orbiting platform towards the moon and interplanetary space. The spacecraft was equipped with an f106 mm camera and TV system that provided automatic in flight film processing.

On July 20, lunar flyby occurred approximately 33 hours after launch at a closest approach of 9200 km. 25 pictures of very good quality were taken of the lunar far side from distances of 11,570 to 9960 km over a period of 68 minutes. The photos covered 19,000,000 square km of the lunar surface. Photo transmissions by facsimile were returned to Earth from a distance of 2,200,000 km and were retransmitted from a distance of 31,500,000 km (some signals still being transmitted from the distance of the orbit of Mars), thus proving the ability of the communications system. After the lunar flyby, Zond 3 continued space exploration in a heliocentric orbit.

The spacecraft design was similar to Zond 2; in addition to the imaging equipment it carried a magnetometer, ultraviolet (0.25 - 0.35 µm and 0.19 - 0.27 µm) and infrared (3 - 4 µm) spectrographs, radiation sensors (gas-discharge and scintillation counters), a radio telescope and a micrometeoroid instrument. It also had an experimental ion engine.

It is believed that Zond 3 was initially designed as a companion spacecraft to Zond 2 to be launched to Mars during the 1964 launch window. The opportunity to launch was missed, and the spacecraft was launched on a Mars trajectory, although Mars was no longer attainable, as a spacecraft test.

Zond 1967A

This was an unmanned test flight of the Soviet lunar capsule planned for manned flights. The exact intended mission is not known, but may have a flight out to lunar distance (but in the opposite direction from the moon, as was done later for Zond 4) and return. The capsule was similar to the Zond 4 and presumably carried instruments, such as the proton detectors carried by Zond 4, as well.

The SL-12/D-1-e Proton launcher first stage had six engines. The fuel line of one of these engines was blocked after liftoff by a rubber plug which had come loose. This caused the rocket to fall off its intended course 60 seconds after launch. The Zond capsule was lifted away by the escape tower and landed safely. The rocket crashed 65 km downrange.

Zond 1967B

This was an unmanned test flight of the Soviet lunar capsule planned for manned flights. The exact intended mission is not known, but may have a flight out to lunar distance (but in the opposite direction from the moon, as was done later for Zond 4) and return. The capsule was similar to the Zond 4 and presumably carried instruments, such as the proton detectors carried by Zond 4, as well.

One of the four rocket engines on the SL-12/D-1-e Proton second stage failed triggering the emergency system, which included disengagement of the cabin and automatic shutdown of the other engines. The Proton crashed 300 km downrange. The Zond cabin was recovered despite a premature firing of the landing rockets.

Zond 4

Zond 4 was launched to a distance of 300,000 km from Earth. The purpose of the mission was to explore circumterrestrial space and to flight test new systems and equipment. The launch was made in a direction away from the moon in order to avoid complications from lunar gravity.

Zond 4 was similar to the later Zond 5 in design: A cylindrical capsule approximately 4.5 meters in length and 2.2 to 2.72 meters in diameter, with two solar panels attached on opposite sides of the body spanning a total of about 9 meters. The spacecraft carried proton detectors and radio test relays among its instrumentation. This spacecraft was an unmanned test of the capsule and a precursor to manned spacecraft.

Zond 4 was launched into Earth parking orbit as part of a Tyazheliy Sputnik (68-013B) station by the SL-12/D-1-e UR-500K Proton launcher. A Block D fourth stage put the probe out to 300,000 km distance. Its return to Earth was supposed to be made by a skip re-entry, but apparently an attitude control error led to the angle of attack being too steep, and the spacecraft entered at high speed over West Africa. Ground control set off the self-destruct mechanism over the Gulf of Guinea at an altitude of 10 km.

Zond 5

Zond 5 was launched from a Tyazheliy Sputnik (68-076B) in Earth parking orbit to make scientific studies during a lunar flyby and to return to Earth. On September 18, 1968, the spacecraft flew around the moon with the closest approach being 1,950 km. High quality photographs of the Earth were taken at a distance of 90,000 km.

A biological payload of turtles, wine flies, meal worms, plants, seeds, bacteria, and other living matter was included in the flight. On September 21, 1968, the reentry capsule entered Earth's atmosphere, braked aerodynamically, and deployed parachutes at 7 km. The capsule splashed down in the Indian Ocean and was successfully recovered, safely returning the biological payload. It was announced that the turtles had lost about 10% of their body weight but remained active and showed no loss of appetite. The spacecraft was planned as a precursor to manned lunar spacecraft.

Zond 6

Zond 6 was launched on a lunar flyby mission from a parent satellite (68-101B) in Earth parking orbit. The spacecraft, which carried scientific probes - including cosmic-ray and micrometeoroid detectors, photography equipment, and a biological payload - was a precursor to manned spaceflight.

Zond 6 flew around the moon on November 14, 1968, at a minimum distance of 2420 km. Photographs of the lunar near and far side were obtained with panchromatic film. Each photo was 12.70 by 17.78 cm. Some of the views allowed for stereo pictures. The photos were taken from distances of approximately 11,000 km and 3300 km. Controlled reentry of the spacecraft occurred on November 17, 1968, and Zond 6 landed in a predetermined region of the Soviet Union.

Zond 1969A

This mission was intended to be similar to the Zond 5 and Zond 6 missions, consisting of a lunar flyby and return to Earth, an unmanned test of the lunar capsule. The craft was presumably equipped with automatic cameras. One of the SL-12/D-1-e stage 2 engines shut down 25 seconds early, causing the emergency system to abort the flight. The escape tower brought the Zond cabin down safely.

Zond L1S-1

This mission was the first test of the powerful N-1 rocket booster (SL-15/N-1). The payload, a Zond capsule with automatic cameras and a dummy lander, was supposed to be put into lunar orbit. The cameras would have been used to record potential landing sites for future manned missions. At 3-7 seconds after liftoff, engines 12 and 24 shut down due to an error in the control system, but the remaining engines automatically compensated. At 25 seconds, the engines were throttled back to minimize vibration during the period of maximum dynamic pressure. At 66 seconds after liftoff at an altitude of about 30 km, the engines throttled up to full power and an oxidizer pipe burst due to the vibration, causing a fire, shorting out wiring, and resulting in the surrounding engines and turbopumps exploding. This caused all remaining first stage engines to shut down and the escape mechanism to fire at 70 seconds, lifting the Zond capsule to safety. The N-1 rocket fell back to Earth and exploded 45 to 50 km downrange, and the Zond capsule landed 32 to 35 km downrange.

Zond L1S-2

This mission was the second test of the powerful N-1 rocket booster (SL-15/N-1). The payload, a Zond capsule with automatic cameras and a dummy lander, was supposed to be put into lunar orbit. The cameras would have been used to record potential landing sites for future manned missions. 5-9 seconds after liftoff at 150 to 200 meters, the engines shut down and the rocket fell back to the launch pad and exploded, destroying the pad. The Zond capsule was thrown clear by the escape tower and landed 1 km away. The accident was apparently caused by a foreign object which was carried through a pipeline into the engine 8 oxygen pump. The object may have been a steel diaphragm from a pulse sensor which broke free or a piece of waste from the oxidizer tank. The oxygen pump exploded, damaging some of the engines and electrical circuitry and triggering automatic shutdown of all rockets just as the N-1 was clearing the launch tower. The N1 crashed back on the launch pad 18 seconds after liftoff, also damaging nearby launch pad 2 and an N1 engineering model stationed there.

Zond 7

Zond 7 was launched towards the moon from a mother spacecraft (69-067B) on a mission of further studies of the moon and circulmunar space, to obtain color photography of Earth and Moon from varying distances, and to flight test the spacecraft systems. Earth photos were obtained on August 9, 1969. On August 11, 1969, the spacecraft flew past the moon at a distance of 1984.6 km and conducted two picture taking sessions. Zond 7 reentered Earth's atmosphere on August 14, 1969, and achieved a soft landing in a region south of present-day Kustanai.

Zond 8

Zond 8 was launched from an Earth-orbiting platform, Tyazheliy Sputnik (70-088B), towards the moon. The announced objectives were investigations of the moon and circumlunar space and testing of onboard systems and units. The spacecraft obtained photographs of Earth on October 21 from a distance of 64,480 km. The spacecraft transmitted flight images of Earth for three days.

Zond 8 flew past the moon on October 24, 1970, at a distance of 1110.4 km and obtained both black and white and color photographs of the lunar surface. Scientific measurements were also obtained during the flight. Zond 8 reentered Earth's atmosphere and splashed down in the Indian Ocean on October 27, 1970.


References

NASA's National Space Science Data Center.