Mission Type: Orbiter
Launch Vehicle: N1 (no. 15005)
Launch Site: NIIP-5 / launch site 110P
Spacecraft Mass: about 6900 kg
Spacecraft Instruments: Unknown
Deep Space Chronicle: A Chronology of Deep Space and Planetary Probes 1958-2000, Monographs in Aerospace History No. 24, by Asif A. Siddiqi
National Space Science Data Center, http://nssdc.gsfc.nasa.gov/
Solar System Log by Andrew Wilson, published 1987 by Jane's Publishing Co. Ltd.
This was the second attempt to launch the giant N1 rocket. As with its predecessor, its payload consisted of a basic 7K-L1 ("Zond") spacecraft equipped with additional instrumentation and an attitude-control block to enable operations in lunar orbit. Moments after launch, the first stage of the booster exploded in a massive inferno that engulfed the entire launch pad and damaged nearby buildings and structures for several kilometers around the area. Amazingly, the payload's launch-escape system operated without fault, and the Zond descent apparatus (or descent module) was recovered safely 2 kilometers from the pad.
An investigation commission traced the cause of the failure to the entry of a foreign object into the oxidizer pump of one of the first-stage engines at T-0.25 seconds. The ensuing explosion started a fire that began to engulf the first stage. The control system shut down all engines except one by T+10.15 seconds. The booster lifted about 200 meters off the pad and then came crashing down in a massive explosion.