Zond program

Zond (Зонд; Russian for "probe") was the name given to two distinct series of Soviet unmanned space program undertaken from 1964 to 1970. The first series based on 3MV planetary probe was intended to gather information about nearby planets. The second series of test spacecraft being a precursor to manned circumlunar loop flights used a stripped-down variant of Soyuz spacecraft, consisting of the service and descent modules, but lacking the orbital module.

File:Zond 3.28.jpg

A shot of the Moon's polar region as seen from Zond 3.

Missions based on the 3MV planetary probe

Main article: 3MV planetary probe

An art potrait of Zond 2 on its planetary mission.

The first three missions were based on the model 3MV planetary probe, intended to explore Venus and Mars. After two failures, Zond 3 was sent on a test mission, photographing the far side of the Moon (only the second spacecraft to do so) and continuing out to the orbit of Mars in order to test telemetry and spacecraft systems.

Circumlunar missions

Circumlunar Zond spacecraft en route to the Moon. Artist's impression

File:Zond Assembly.jpg

Zond with top stage of Proton booster in assembly hangar

File:Proton-Zond2.jpg

Proton 7K-L1 with Zond rollout

Main articles: Soyuz 7K-L1 and Moon Race § Soviet circumlunar loop flights (1967–1970)

The missions 4 through 8 were test flights under for the Soviet Moonshot during the Moon race. The Soyuz 7K-L1 (also mentioned just as L1) spacecraft was used for the moon-aimed missions, stripped down to make it possible to launch around the moon from the Earth. They were launched on the Proton rocket which was just powerful enough to send the Zond on a free-return trajectory around the moon without going into lunar orbit (the same path that Apollo 13 flew in its emergency abort). With minor modification, Zond was capable of carrying two cosmonauts.

In the beginning there were serious reliability problems with both the new Proton rocket and the similar new Soyuz spacecraft, but the test flights pressed ahead with some glitches. Then majority of tests flights from 1967–1970 (Zond 4 to Zond 8) showed problems during re-entry.

Zond spacecraft made only unmanned automatic flights. Four of these suffered malfunctions that would have injured or killed any crew. Instrumentation flown on these missions gathered data on micrometeor flux, solar and cosmic rays, magnetic fields, radio emissions, and solar wind. Many photographs were taken and biological payloads were also flown.

Timetable

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3MV planetary probe based missions

• Zond 1
  • Launched 2 April 1964
  • Communications lost 14 May 1964
  • Venus flyby 14 July 1964
• Zond 2
  • Launched 30 November 1964
  • Communications lost May 1965
  • Mars flyby 6 August 1965
• Zond 3
  • Launched 18 July 1965
  • Lunar Flyby 20 July 1965

Soyuz 7K-L1 test missions

• Cosmos 146
  • Launched 10 March 1967
  • Prototype Soyuz 7K-L1P launched by Proton into planned highly elliptical earth orbit.
• Cosmos 154
  • Launched 8 April 1967
  • Prototype Soyuz 7K-L1P launched by Proton and failed into planned translunar trajectory.
• Zond 1967A
  • Launched 28 September 196