UNITED24 - Make a charitable donation in support of Ukraine!


7K-L1 Zond Program - Western Views

The now inactive Zond program of precursors to manned circumlunar flight began in 1968 (although earlier failures not officially linked to this program are suspected.) After five flights, the program was terminated for reasons still unknown. Speculation as to what happened to this program as well as Soviet plans for manned lunar flight will be discussed later.

The view had long been held that just as the U.S.S.R. was first in Earth orbit, so would they be first to send men around the Moon. The 1965 missions in which Proton payloads were flown using the D class vehicle suggested that a launch vehicle was available to support such a mission. The same common wisdom suggested a Soviet Moon landing by 1972, and this was the estimate President Kennedy hoped to beat with Apollo. A vigorous and successful development of the D-l-e booster might have realized the first of these predictions and provided a stunning celebration of the fiftieth anniversary of the Soviet state in November 1967.

On two occasions in 1967, according to British measurements, the D-l-e was used for flights which attained Earth orbit only. These were on March 10 with Kosmos 146 and on April 8 with Kosmos 154. The flights occurred just one lunar month apart, so possibly were Zond precursors that failed, and if so, may have set back the Soviet timetable. There may have been other, later attempts which were even less successful, as they did not reach Earth orbit. Newsweek magazine claimed that on November 22, 1967 and April 22, 1968 , Zond flights to the Moon were attempted and failed. There are no official statements to prove or disprove that contention.


On March 2, 1968 Zond 4 was launched (14) and it is now judged as a diagnostic engineering test of subsequent Zond flights (which the Russians themselves identified as fully capable of carrying a human crew around the Moon). It wasn't until 1971 that a drawing was released showing the ship to be virtually identical in external appearance to Soyuz, but without the forward work module. The British Royal Aircraft Establishment has estimated its weight at 4,820 kg, with a length of 5.3 meters and diameter of 2.3 meters. This estimate may very well understate the weight which could have been as much as 5,800 kg.

Zond 4 was launched one half lunar month away from the ideal time to launch toward the Moon, and was sent in a direction opposite to the Moon. Using the D-l-e, it was placed in a parking orbit around Earth, and then was fired from its orbital launch platform out to what the Russians called "outlying regions of near Earth space." Presumably it was intended to go out about as far as the Moon's orbit, but would afford a better opportunity for controlled return to Earth without lunar gravity being as operative as during a flight around the Moon itself. Considering the significance of a new program of such magnitude and portent, the failure of the Russians to give any further report on the flight strongly suggests that it was not a success, but there is no evidence in the public domain either way.


On September 14, 1968 , Zond 5 was launched in a similar fashion, but this time on a course to circle the Moon. On September 17 a mid-course correction was performed to bring it to the correct path to swing around the Moon at a distance of 1,950 km. Another correction was later made on approach to the Moon relating to its return to Earth.

The ship was described as consisting of two compartments. One was the recoverable cabin, with its heavy layers of ablation material, parachute packs, scientific instruments, radio communications equipment, heat regulating system and power supply. The other was the service module with two large solar cell panels extending like gull wings, a radio telemetry system, control equipment, orientation and stabilization systems, heat regulation system, chemical batteries, and rocket propulsion systems for course corrections. Optical sensors and radio antennas were also carried externally.

Although the mission was primarily an engineering test, it also carried cameras and a biological payload. The cameras returned for the first time high quality photographs rather than radio facsimile pictures. The biological payload consisted of: turtles; wine flies; meal worms; a spiderwort plant with buds; seeds of wheat, pine and barley; chlorella in various nutrients; lysogenetic bacteria of various types; and other unspecified living matter. Upon recovery, the turtles were active, but had lost about 10 percent of their body weight and had excessive glycogen and iron in their liver tissue as compared with Earth-based controls. In 1971 the Soviets revealed that the barley and pine seeds showed some changes, as expected because of their known sensitivity to radioactivity, but no changes in the other plants were noted.

Seven days after launch, Zond 5 returned to Earth. This was the first return of a spacecraft from a deep space mission (although similar high speed reentries had been simulated by U.S. craft) and it had to hit a reentry corridor between 35 and 48 km above the Earth. If the ship had approached Earth 10 kin lower, it would have been destroyed by overloads of heat and pressure; 24 km higher and it would have skipped out of the atmosphere.

Entering the atmosphere at 10,900 meters per second, it was slowed aerodynamically to 200 meters per second and then deployed a parachute at 7 km altitude. The approach to Earth was over the South Pole, and Zond 5 then made a ballistic reentry, landing in the South Indian Ocean as it headed north at coordinates 32°38/S. by 75°33'E. The capsule had been exposed to heat levels of 13,000°C during reentry.

This was the Russians' first water recovery of a space capsule, and the Soviet account said it was especially difficult because the splashdown occurred at night and the payload had to be "discovered." Recovery was directed by the Academy of Sciences rescue service and the tracking ship Borovichiy which used radio direction finders and searchlights. An oceanography ship, Vasiliy Golovnin, carried the capsule to Bombay where it was transferred to a Soviet AN-12 cargo plane and flown to the U.S.S.R.


Zond 6 was launched with a D-l-e on November 10, 1968 . A total of three orbital corrections were made: the first on November 12, and the other two after passage around the Moon on November 14 at a distance of 2.250 km.

Much of this mission was a repeat of Zond 5. Equipment was carried to study the effects of radiation on living creatures (although no description of the biological payload was given) as well as a photoemulsion chamber to record the paths of cosmic rays and a device to measure the impacts of micrometeorites.

More lunar photographs were taken with a standard aerial camera which had a focal length of 400 mm, frame size of 13 x 18 cm, and a resolution of 50 lines per millimeter. While Zond 3 facsimile pictures could provide 1.2 million data bits per picture, each Zond 6 photograph had 134 million data bits. Some of the views made stereo pictures of the Moon possible, both on the near and far sides. The film itself measured 29 cm wide and 28 meters long.

On November 17, Zond 6 returned to Earth in the same manner as Zond 5 with one important difference. It approached at 11 km per second, used aerodynamic braking to slow to 7.6 km per second, and then the control mechanism on board was used to orient the craft so that it developed considerable lift and skipped outside the atmosphere again. Then it made a second reentry into the atmosphere and by continued operation of its orientation system made a controlled landing in the Soviet Union in the "preset district." This was a very impressive achievement, to travel so many thousands of additional kilometers beyond the point of ballistic reentry.

The Russians explained that the South Pole approach was the only practical one for returning Zond payloads to the Soviet Union , because a direct ballistic approach would bring too heavy an overload for a human crew. The southern approach permits the long double entry, skip return. Academician G. I. Petrov noted, however, that the prolonged reentry increased the effect of heat flow, and added a considerable strain to the structure of the heat protecting system. (15) He also stated that the G load for Zond 5 reached 10 to 16 G's and implied that for Zond 6 it was more like that for Soyuz (3 to 4 G's). This was later reported to be 4 to 7 G's for the first immersion. (16)

The Russians finally made a formal announcement that Zonds 4, 5 and 6 were all aimed at perfecting a manned space ship to go around the Moon. Although all the indications were that Zond 6 performed well, Academician Blagonravov stated that further unmanned tests would be required before men could be sent."(17) (We now know that Zond-6 had in fact crash landed destroying the spacecraft descent module)


The launch of Zond 7 came on August 7, 1969 , with the announced purpose of further engineering tests and more photographs of the Moon's surface. On August 9 a course correction was made so that it circled the Moon on August 11 at a distance of 2,000 km. The craft returned to Earth August 14, in the same manner as Zond 6 and from all outward signs it was quite successful. Only two orbital corrections had been required. Recovery was announced more promptly than for earlier flights.

The only difference between this mission and the others was that it, took color as well as black and white photographs. Sessions of picture taking were held on August 8 for Earth, and on August 11 for the Moon (twice) and the Earth as it set beneath the Moon s horizon. The hope was that color pictures from different angles would reveal differences in the microstructure of lunar material, and that new features of the Earth would be discovered.


The only Zond flight of 1970 and the last in the series was Zond 8 on October 20.

When it was 328,000 km from Earth, the craft was observed by telescope at the Sternberg Astronomical Institute in the Transili Alatau of Central Asia . Photomultiplier tubes made it possible to find its movement against the star background to determine its trajectory very precisely. Similar pictures were taken at other times both by the Institute and the Crimean Astrophysical Observatory.

On October 21, Zond 8 transmitted the first television images of Earth, from a distance of 65,000 km, and these continued for the next two days. On the 24th, after a mid-course correction, the craft passed within 1,100 km of the Moon, and both color and black and white pictures were taken of the surface.

This mission used a quite different approach to Earth upon reentry: over the North Pole instead of the South. This had the advantage that during most of the reentry, Soviet ground stations could control the flight. This also proved to be the second Russian water recovery, with the craft splashing down 725 km southeast of the Chagos Archipelago in the Indian Ocean , probably in a ballistic reentry. This time recovery ships were sufficiently well positioned to see the actual reentry, and although it was again at night, the capsule was quickly picked up by the Taman

It was then transferred to the Semyon Chelyuskin for the trip to Bombay , where it was put aboard a cargo plane for the flight back to the Soviet Union.



14. As detailed in previous sections, Zond 1-3 were planetary probes; Zond 1 to Venus In 1964; Zond 2 to Mars in 1964; and Zond 3 past the Moon (where It took high quality pictures of the far side) and on to Mars.

15. Izvestiya, Moscow , November 19, 1968 , p. 2.

16. Moscow Rural Life, Nov. 24, 1968 , p. 4.

17. Moscow Radio, Dec. 10, 1968 , 1200 GMT.

Join the GlobalSecurity.org mailing list

Page last modified: 09-07-2018 13:25:01 ZULU