[5] The coast stage, or bus, carried a magnetometer, plasma traps, cosmic ray and micrometeoroid detectors, and an instrument to study proton and electron fluxes from the Sun.

Mars 6 was launched by a Proton-K carrier rocket with a Blok D upper stage, flying from Baikonur Cosmodrome Site 81/23.

[3] The launch occurred at 17:45:48 UTC on 5 August 1973, with the first three stages placing the spacecraft and upper stage into a low Earth parking orbit before the Blok D fired to propel Mars 6 into heliocentric orbit bound for Mars.

However, at 09:11:05 UTC, with the spacecraft about to fire its retrorockets in preparation for landing, all contact was lost.

Due to a design flaw, a chip aboard the spacecraft had degraded during the mission, and a large amount of the data which had been returned was unusable.