Launch Date Nov. 10, 1968
Launch Site Baikonur Cosmodrome, Kazakhstan, Russia | Launch Site 1
Destination Earth’s Moon
Type Flyby (Circumlunar)
Status Partial Success
Nation Soviet Union
Alternate Names 1968-101A, 03535

Goals

Fly around the Moon and return to Earth, taking photographs and testing the effect of space travel on a biological payload.

Accomplishments

Zond was the second Soviet spacecraft to fly to the Moon and back. It took pictures of the lunar near and far sides, but crashed on re-entry. Though the picture film was salvaged, the biological payload was lost.

Key Dates

Nov. 10, 1968: Launch
Nov. 14, 1968: Lunar Flyby
Nov. 17, 1968: Return to Earth

In Depth

Zond 6 was the second spacecraft that the Soviets sent around the Moon.

Soon after translunar injection, ground controllers discovered that the vehicle's high-gain antenna had failed to deploy. Given that the main attitude- control sensor was installed on the antenna boom, controllers had to make plans to use a backup sensor for further attitude control.

The spacecraft circled the far side of the Moon at a range of 2,420 kilometers, once again taking black-and-white photographs of the Moon.

During the return flight, temperatures in a hydrogen peroxide tank for the attitude-control thrusters dropped far below acceptable levels. Engineers attempted to heat the tank by direct sunlight, but as they later discovered, such a procedure affected the weak pressurization seal of the main hatch and led to slow decompression of the main capsule.

Despite the failures, Zond 6 successfully carried a fully automated guided reentry into the primary landing zone in Kazakhstan.

A radio altimeter, not designed for work in depressurized spacecraft, issued an incorrect command to jettison the main parachutes. As a result, the spacecraft plummeted to the ground and was destroyed. Although the main biological payload was lost, rescuers salvaged film from the cameras.

Spacecraft

Launch Vehicle: 8K82K + Blok D (Proton-K no. 235-01 / Blok D no. 19)

Spacecraft Mass: about 5,375 kg

Spacecraft Instruments:

  1. biological payload
  2. radiation detectors
  3. imaging system
  4. photo-emulsion camera
  5. micrometeoroid detector

Additional Resources

NSSDC Master Catalog: Zond 6

NSSDC Soviet Lunar Missions

Selected References

Siddiqi, Asif A. Deep Space Chronicle: A Chronology of Deep Space and Planetary Probes 1958-2000, NASA, 2002.

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