Mars 4

Launch date: 21 July 1971
Nation: USSR
Outcome: failure

Wikipedia - "Mars 4 was launched by a Proton-K carrier rocket, a Blok D upper stage, flying from Baikonur Cosmodrome Site 81/23. The launch occurred at 19:30:59 UTC on 21 July 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 4 into heliocentric orbit bound for Mars.
Shortly after performing a course correction on 30 July 1973, two onboard computers failed, leaving Mars 4 unable to perform manoeuvres. As a result of this, it was unable to enter orbit around Mars. A small amount of data was returned as the probe flew past Mars on 10 February 1974, with a closest approach of 1,844 kilometres (1,146 mi) at 15:34 UTC."