Using Mars-like soil taken from Atacama Desert, a study confirms Mars has organics, and Viking found them.
A reanalysis of Mars Viking experiments shows the probes did find
The result was not initially understood due to the strong oxidation effects of a salt in the Mars soil known as perchlorate.
A follow-up study on perchlorate-enhanced soil similar to what’s found on Mars revealed fingerprints of combusted organics.
The Viking 1 Lander, illustrated in this model, touched down on the western slope of Mars’ Chryse Planitia (the Plains of Gold) on July 20, 1976.