This was the first attempted launch of the giant N1 booster as part of early test operations in the Soviet piloted lunar landing program. N1 development began in 1962 after two years of initial research and development on heavy booster designs. Although the first launch had been originally planned for 1965, a major redesign of the booster in 1964 and financial and organizational difficulties delayed the launch by four years.
The Soviet Communist Party and government officially sanctioned the human lunar landing program in August 1964, more than three years after President John F. Kennedy’s famous speech calling on the United States to land an American on the Moon before the end of the 1960s.
Development of both the N1 rocket and the L3 payload was plagued by many delays. On this first launch, the N1 carried a basic 7K-L1 spacecraft modified for operations in lunar orbit, rather than for circumlunar flight. Known as the 7K-L1S, the spacecraft was equipped with an Engine Orientation Complex (DOK) for attitude control in lunar orbit.
The plan was for the spacecraft to carry out a short mission in lunar orbit during which time it would have tried to photograph the Ye-8 rover on the surface (the rover that had failed to reach orbit just two days earlier).
During the launch of the N1, two first stage engines (of a total of 30 NK-15 engines) shut down, but the remaining 28 engines operated for over a minute despite a growing fire at the base of the rocket. The rocket’s KORD control system effectively shut down all first state engines at T+70 seconds. The booster crashed about 31 miles (50 kilometers) from the launch site and the payload successfully used its launch escape system to descend without problem some 20 to 22 miles (32 to 35 kilometers) from the pad.
Investigators believed that the booster failed when a pipe for measuring fuel pressure broke at T+23.3 seconds, setting in motion a sequence of events that led to a huge fire at T+54.5 seconds in the tail of the first stage. The fire short-circuited the control system and shut down all the engines at T+70 seconds.
Siddiqi, Asif A. Beyond Earth: A Chronicle of Deep Space Exploration, 1958-2016. NASA History Program Office, 2018.