Mars 2M No.522

It also carried a radiometer, a series of spectrometers, and an instrument to detect water vapour in the atmosphere of Mars.

[3] Mars 2M No.522 was launched at 10:33:00 UTC on 2 April 1969 atop a Proton-K 8K78K carrier rocket with a Block D upper stage, flying from Baikonur Cosmodrome Site 81/24.

The remaining engines managed to compensate for about 30 seconds of flight, but the thrust section fire eventually resulted in loss of control.

[6] The engines shut down, and the rocket fell back to Earth and exploded 41 seconds after ignition.

[3] The accident left a deep impression on Soviet military personnel attending the launch and helped spur the development of next-generation ballistic missiles with safer solid propellants.