Mission Type: Lander
Launch Vehicle: Modified SS-6 (Sapwood) with 2nd Generation Upper Stage + Escape Stage, 8K78M (no. U103-31)
Launch Site: Tyuratam (Baikonur Cosmodrome), USSR, NIIP-5 / launch site 1
Spacecraft Mass: 1,442 kg
Spacecraft Instruments: 1) imaging system and 2) radiation detector
References:
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.

On this Soviet attempt at a lunar soft-landing, the mission proceeded as planned until the major midcourse correction late on 9 June. Although the main retrorocket engine (the S5.5A) ignited on time, it failed to cut off and continued to fire until propellant supply was exhausted.

An investigation later indicated that the problem had been due to human error; a command had been mistakenly sent to the timer that ordered the main engine to shut down. Although the spacecraft was sent on a completely wrong trajectory, ground controllers put the spacecraft through a series of steps to practice an actual landing, all of which were satisfactorily accomplished.

Luna 6 passed by the Moon late on 11 June at a range of 161,000 kilometers and eventually entered heliocentric orbit. Contact was maintained to a distance of 600,000 kilometers from Earth.