The Viking Mission: implications for life on Mars.
The results of the Viking Biology experiments are best explained by non-biological phenomena: The interaction of the reagents with the materials comprising the regolith. Conditions of water activity, temperature, availability of carbon sources and others in most regions of the planet are too extreme for survival and growth of any known Earth microorganisms. Although the possibility persists that some very unusual form of life is somewhere on that planet the evidence is best interpreted as negative. Even though there is no evidence for current life on Mars, whether or not life ever originated there is not known.
D002244:Carbon; D002625:Chemistry, Organic; D005118:Extraterrestrial Environment; D008401:Gas Chromatography-Mass Spectrometry; D005740:Gases / Q000032:analysis; D055601:Organic Chemistry Phenomena; D013696:Temperature; D014867:Water
D005740:Gases; D014867:Water; D002244:Carbon