The mission failed on 2 September 1988 when a computer malfunction caused the end-of-mission order to be transmitted to the spacecraft.

[3] Phobos was chosen as the target in order to avoid directly competing with previous American missions.

The probe would then rendezvous with Phobos, drop a lander containing scientific equipment from an altitude of 50 meters, and move into a final equatorial orbit above Mars where it would study the Martian surface and atmosphere.

In stage one the probe would investigate the Sun and interplanetary space while traveling from the Earth to Mars.

[7] The optical coronagraph that was part of the Terek experiment and designed to observe the Sun was non-functional from launch.

Same as the case of Mariner 1, a technician unintentionally left out a single hyphen in one of the keyed commands.

By losing its lock on the Sun, the spacecraft could no longer properly orient its solar arrays, thus depleting its batteries.

[10][11] Software instructions to turn off the probe's attitude control, normally a fatal operation, were part of a routine used when testing the spacecraft on the ground.

However, a single-character error in constructing an upload sequence resulted in the command executing, with subsequent loss of the spacecraft.

The investigation concluded with the dismissal of the ground control commander at Yevpatoria and the acknowledgement that the computer system was poorly designed.