Mars 6

Launch date: 05 August 1973
Nation: USSR
Outcome: success/failure

Wikipedia - "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. The spacecraft performed a course correction on 13 August 1973.
Mars 6's lander separated from the flyby bus on 12 March 1974 at an altitude of 48,000 kilometres (30,000 mi) from the surface of Mars. The bus made a flyby with a closest approach of 1,600 kilometres (990 mi). The lander encountered the atmosphere of Mars at 09:05:53 UTC, slowing from 5,600 to 600 metres per second (12,500 to 1,300 mph) as it passed through the upper atmosphere. A parachute was then deployed to further slow the probe's descent, and retrorockets were intended to fire during the last seconds before the probe reached the ground.
The spacecraft returned data for 224 seconds during its descent through the Martian atmosphere. 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.[2]"