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Ye-6/8 Mission to Earth's Moon

Mission Type: Lander
Launch Vehicle: 8K78 (no. R103-26)
Launch Site: NIIP-5 / launch site 1
Spacecraft Mass: About 1,470 kg
Spacecraft Instruments: 1) imaging system and 2) radiation detector
Deep Space Chronicle: A Chronology of Deep Space and Planetary Probes 1958-2000, by Asif A. Siddiqi.

This was the seventh consecutive failure to accomplish a lunar soft-landing by the Soviets. On this mission, engineers redesigned the problematic I-100 guidance system that had caused most of the previous failures.

Previously, the I-100 unit had controlled both the Blok L upper stage and the spacecraft itself. On this mission (and subsequent Lunas), the fourth stage and the Ye-6 spacecraft had separate systems.

Unfortunately, this probe never reached Earth orbit. During the launch, depressurization of a nitrogen pipe for the liquid oxygen tank on the third stage had prevented third-stage engine ignition. The spacecraft broke up over the Pacific without reaching orbit.

Key Dates
10 Apr 1965:  Launch
Status: Unsuccessful
Fast Facts
Ye-6/8 Facts This was the Soviet Union's 31st deep space mission.

Engineers made improvements to a troublesome guidance system on this spacecraft, the seventh attempt at a lunar soft landing.

It is believed depressurization of a nitrogen pipe prevented the third-stage engine from firing and doomed the mission.
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Last Updated: 2 Dec 2010