Due to a malfunction, the lander failed to perform a maneuver necessary to enter the Martian atmosphere, missing the planet and remaining in heliocentric orbit along with the coast stage.

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

Mars 7 was launched by a Proton-K carrier rocket with a Blok D upper stage, flying from Baikonur Cosmodrome Site 81/24.

[3] The launch occurred at 17:00:17 UTC on 9 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 7 into heliocentric orbit bound for Mars.

Due to a retrorocket failure, the probe missed the atmosphere of Mars, and, instead of landing, flew past along with the coast stage, with a closest approach of 1,300 km (810 mi).