* Zond 6 – 10 November 1968 – Lunar flyby and return to Earth

In addition to astronomical research, it was used to track the Zond 1, Zond 2, Ranger 6 and Ranger 7 space probes, and also Apollo 11.

** Zond 6

Zond 6, a formal member of the Soviet Zond program and unmanned version of Soyuz 7K-L1 manned moon-flyby spacecraft, was launched on a lunar flyby mission from a parent satellite ( 68-101B ) in Earth parking orbit.

Zond 6 flew around the moon on November 14, 1968, at a minimum distance of 2420 km.

Zond 6 landed in an undetermined region of the Soviet Union.

Zond 6 used a relatively uncommon technique called " skip reentry " to shed velocity upon returning to Earth.

This article was originally based on material from NASA ( NSSDC ) information on Zond 6

cs: Zond 6

it: Zond 6

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oc: Zond 6

pt: Zond 6

The flawless recovery of Soyuz 3 left the spacecraft designers with the impression that re-entry and landing systems had been perfected: the crash-landing of the Zond 6 satellite just one month later has been partly attributed to this mistaken sense of security.

Zond 6, Zond 7 and Zond 8 made successful skip entries, although Zond 5 did not.

Aerocapture has not yet been tried on a planetary mission, but the re-entry skip by Zond 6 and Zond 7 upon lunar return were aerocapture maneuvers, since they turned a hyperbolic orbit into an elliptical orbit.

The Zond spacecraft was another derivative, designed to take a crew traveling in a figure-eight orbit around the Earth and the moon but never achieving the degree of safety or political need to be used for such.

The cruise bus of Venera 7 and 8 was similar to that of earlier ones, with the design ascending to the Zond 3 mission.

The existence of a giant far side basin was suspected as early as 1962 based on early probe images ( namely Luna 3 and Zond 3 ), but it was not until the acquisition of global photography by the Lunar Orbiter program in the mid-1960s that geologists recognized its true size.

It was the brainchild of Vladimir Chelomei's design bureau as a foil to Sergei Korolev's N1 booster with the specific intent of sending a two-man Zond craft around the Moon.

Zond ( Зонд ; Russian for " probe ") was the name given to two distinct series of Soviet unmanned space program undertaken from 1964 to 1970.

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.

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.

Zond 3 was a member of the Soviet Zond program sharing designation Zond, while being part of Mars 3MV project.

It was unrelated to Zond spacecraft designed for manned circumlunar mission ( Soyuz 7K-L1 ).

It is believed that Zond 3 was initially designed as a companion spacecraft to Zond 2 to be launched to Mars during the 1964 launch window.

The spacecraft design was similar to Zond 2, in addition to the imaging equipment it carried a magnetometer, ultraviolet ( 0. 25 to 0. 35 micrometre and 0. 19 to 0. 27 micrometre ) and infrared ( 3 to 4 micrometre ) spectrographs, radiation sensors ( gas-discharge and scintillation counters ), a radiotelescope and a micrometeoroid instrument.

This article was originally based on material from NASA ( NSSDC ) information on Zond 3

Zond 5, a formal member of the Soviet Zond program and unmanned version of Soyuz 7K-L1 manned moon-flyby spacecraft, was launched from a Tyazhely Sputnik ( 68-076B ) in Earth parking orbit to make scientific studies during a lunar flyby and to return to Earth.

This article was originally based on material from NASA ( NSSDC ) information on Zond 5

Pulsed plasma thrusters were the first electric thrusters to be deployed in space, used for attitude control on the Soviet probes Zond 2, from parking at Earth orbit to Mars on November 30, 1964, and Zond 3 in 1965.

Zond 3 completed a successful Lunar flyby, taking a number of good quality photographs for its time.

Of all circumlunar Zond craft launches, Zond 7 would have been the first to make a safe flight for a crew had it been manned.

In October 1965 the Soviet government ordered a compromise ; the circumlunar mission would be launched on Chelomei's UR-500 using Korolev's Soyuz spacecraft in place of their own Zond design, aiming for a launch in 1967, the 50th anniversary of the Bolshevik Revolution.

* February 21, 1969 – Vehicle serial number 3L – Zond L1S-1 ( Soyuz 7K-L1S ( Zond-M ) modification of Soyuz 7K-L1 " Zond " spacecraft ) for Moon flybyDue to unexpected high-frequency oscillations in the gas generator, one of the pipes broke apart and a fire started.

* July 3, 1969 – Vehicle serial number 5L – Zond L1S-2 for Moon flybyAt liftoff a loose bolt was ingested into a fuel pump, which failed.

The technique was used by the Zond series of circumlunar spacecraft, which planned for one skip before landing.

The Apollo orbital spacecraft ( command ship ) for the lunar flyby also had two modules ( command and service ) but was five times heavier, carried a crew of three and entered lunar orbit, whereas the L1 ( Zond ) performed a flight around the Moon and came back on a return trajectory.

Planned for 8 December 1968 for priority over the US, a first manned mission of the L1 ( Zond ) was cancelled due to insufficient readiness of the capsule and rocket.

There were also concerns from the Central Intelligence Agency that the Soviet Union was planning their own circumlunar flight for December to upstage the Americans once again ( see Zond program ).