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.

Missions based on the 3MV planetary probe

Main article: 3MV planetary probe

File:Zond Assembly.jpg

Zond with top stage of Proton booster in assembly hangar

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

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

4

External links

• Very detailed information about the Soyuz 7K-L1 used in Zond 4-8
• Detailed 7K-L1 pictures
• Radios in Zond spacecraft
• Exploring the Moon: the Zond Missions