Mission Summary
This spacecraft marked the seventh consecutive Soviet failure to soft-land on the Moon, yet it carried an important change. Launched April 10, 1965, it was the first Ye-6 probe to fly with a redesigned control system meant to end the long run of failures and finally reach the surface.
On earlier missions a single I-100 unit had governed both the Blok L upper stage and the spacecraft, and it had caused most of the breakdowns. For this flight, engineers gave the fourth stage and the spacecraft separate systems. The fix went untested, though: during launch, a nitrogen pipe for the third stage’s liquid oxygen tank lost pressure, preventing the engine from igniting.
The spacecraft broke up over the Pacific without reaching Earth orbit and received no formal designation. Although the attempt failed at launch, the control-system redesign it introduced carried forward to the later Ye-6 probes that at last brought a Soviet craft safely to the lunar surface.
Sources and notes can be found on the Sources page.
