Viking Mars,Now 50 Years Old,Still Needs a Scientific Analysis

Abstract

Gas chromatography-mass spectrometry data from the Viking Mars mission were misinterpreted in 1976 as showing that martian soils contain no organic molecules, and therefore no life, even though the three life detection experiments delivered by Viking all reported life-positive data under the terms of their experimental design. This mistake has been propagated for a half century, including in textbooks and National Aeronautics and Space Administration-endorsed documents, even though it has been known since 2009 that the martian soils contained perchlorate, perchlorate destroys organic materials in ways that might generate the GC-MS results, and Curiosity in 2013 observed such processes in Gale crater on Mars, as have other rovers since. Anomalies in the propagated misinterpretation, including a contradiction between the “strong martian soil oxidant” hypothesis and quantitative results in the carbon assimilation experiment, were “explained away” in 1976, in some cases by invoking results of experiments that had not yet been done. Today, a scientific back-and-forth is long overdue to develop an understanding of what Viking revealed about the possibility of life on the near surface of Mars. Starting this back-and-forth here, we note how the Viking results are compatible with a soil that contains bacterial autotrophs that respire with stored oxygen on Mars (BARSOOM), a lifestyle adapted to its environment, including sparse resources that drive dormancy, scarce atmospheric oxygen, and a cold and briny fluid only intermittently available, perhaps, when the water-ice fogs seen by Viking indicate that the relative humidity exceeds 100%.