Fast Facts: Luna 4

While Luna 4 did not achieve its primary goal of a soft lunar landing, the spacecraft made a close flyby of the Moon and returned new information about radiation in space.


The third Soviet attempt to perform a lunar soft-landing (planned for 19:42:37 UT on April 5, 1963) was the first in which the spacecraft actually left Earth orbit.

During the coast to the Moon, the spacecraft’s Yupiter-M astronavigation system suffered a major failure (probably related to its thermal control system) that left the probe in an incorrect attitude. As a result, Luna 4 was unable to perform its planned mid-course correction.

Although communications were maintained with the spacecraft, it passed by the Moon at a range of 5,300 miles (8,500 kilometers) at 01:24 UT on April 6, 1963 and eventually entered heliocentric orbit from its intermediate barycentric orbit.

Data from the gas discharge counter was compared with data from Mars 1 to provide further clarification to a radiation map of Earth up to lunar distance. The data showed that the intensity of cosmic radiation remained virtually constant up to 0.24 AU from the Earth.


Siddiqi, Asif A. Beyond Earth: A Chronicle of Deep Space Exploration, 1958-2016. NASA History Program Office, 2018.

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