19h 41min, mar 12, 1974 y - Mars 6
Slightly successful descent craft and flyby
The Mars 6 descent craft separated successfully from the main spacecraft and descended through the atmosphere, transmitting 224 seconds of data before abruptly cutting off (either when the retrorockets fired or when it slammed into the ground). Although this was the first data of its kind (from within the Martian atmosphere), most of it was garbled and unusable due to the microchip problem. Mars 6 landed at 23.90°S, 19.42°W.
Added to timeline:
the videos are in the parts of Mars Exploration Rover Spirit...