Campaign objectives:

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

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

Spacecraft launched

First spacecraft:

Cosmos 21 (3MV-1A No.2)

Mission Type:

Mars Spacecraft Test Flight

Country! Builder:


Launch Vehicle:


Launch Date ‘: 7 ime:

November 11, 1963 at 06:23:35 UT (Baikonur)


Stranded in Earth orbit, fourth stage failure.

Second spacecraft:

Zond 2 (3MV-4 No.2)

Mission Type:

Mars Flyby

Conn try і Builder:


Launch Vehicle:


Launch Date; Time:

November 30, 1964 at 13:12 UT (Baikonur)

Mission End:

May 5, 1965

Encoun ter Date/ 7 ime:

August 6, 1965


Lost in transit, communications failure.

Third spacecraft:

Zond 3 (3MV-4 No.3)

Mission Type:

Mars Spacecraft Test

Conn try: Builder:


Launch Vehicle:


Launch Date: Time:

July 18, 1965 at 14:38:00 UT (Baikonur)

Encoun ter Date/ 7 7me:

July 20, 1965 (Moon)

Mission End:

March 3, 1966


Succeeded at Moon, failed to reach Mars distance.

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

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

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

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


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

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


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

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

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

Launch mass: 800 kg (Cosmos 21)

950 kg (Zond 2)

960 kg (Zond 3)


3MV-1A ISo.2:

1. Facsimile imaging system

2. Radiation detector

3. Charged particle detector

4. Magnetometer

5. Micrometeoroid detector

6. Lyman-alpha atomic hydrogen detector

7. Radio telescope

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

1. Facsimile imaging system

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

3. Ultraviolet 190 to 275 nm spectrograph for ozone

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

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

6. Charged particle detector

7. Magnetometer

8. Micrometeoroid detector

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

Mission description:

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

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

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

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


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


Figure 9.7 Lunar far side image from Zond 3.