Lunar Soyuz (Zond), 1967-1970

As early as 1959 the Soviets had a plan for manned circumlunar flights. When the Americans decided in mid-1961 to go to the Moon, Korolev was already designing the Soyuz spacecraft for these missions. It was the same three-module arrangement with w’hich we are all familiar, with a support module containing all the resources required for power, propulsion, communication, navigation and consumables for the cosmonauts, a descent module to carry them aloft and to return them to Earth, and a compartment to provide more room for the cosmonauts on long flights. After the Vostok and Voskhod manned capsules, this system was introduced and remains the reliable Russian system still in use today.

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Figure 5.4 Soyuz 7K-L1 ‘Zond’ circumlunar spacecraft (from Space Travel Encyclope­dia).

The Soyuz 7K-L1 was a version of the 7K-LOK lunar orbital spacecraft modified to perform a circuit! lunar mission. Although the three-stage R-7 used for Soyuz flights in Earth orbit was replaced by the more powerful four-stage Proton, mass limitations meant that the 7K-L1 did not have the ‘orbital’ module and was designed to carry only two cosmonauts. The idea was to fly circumlunar missions with two astronauts using the 7K-L1 as a precursor to performing a lunar landing using the 7K-LOK version of the Soyuz (which would have an orbital module) and the LK lunar lander, all launched by the massive N-l rocket. To prepare for the manned circumlunar missions, several automated flights of the 7K-L1 were conducted, the first two in Earth orbit and then nine others over the years 1967-1970 either to lunar distance or performing actual circumlunar flights. Zond 4 reached lunar distance before returning to Earth, but in a direction away from the Moon in order to simplify navigation, and Zond 5 to 8 each made circumlunar flights. Zond 4 self – destructed on re-entry, Zond 5 had significant but non-fatal problems with on board systems, and Zond 6 crashed on landing only a few weeks before the Apollo 8 mission. Although Zond 7 and Zond 8 were complete successes, the Soviets never used the system for a manned circumlunar flight.