Mission Type: Lander
Launch Vehicle: 8K78 (no. G103-11)
Launch Site: NIIP-5 / launch site 1
Spacecraft Mass: 1,422 kilograms
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/

The third Soviet attempt to perform a lunar soft-landing was the first in which the spacecraft actually left Earth orbit.

During the coast to the Moon, the spacecraft's Yupiter astronavigation system suffered a major failure (probably in its thermal control system) and left the probe in an incorrect attitude. As a result, Luna 4 was unable to perform its planned midcourse correction.

Although communications were maintained with the spacecraft, it passed by the Moon at a range of 8,500 kilometers on 6 April and eventually entered heliocentric orbit (after being in an intermediate barycentric orbit).