![]() "In hindsight, it is possible that approach was too much of a good thing." "Since Earth is a water planet, it seemed reasonable that adding water might coax life to show itself in the extremely dry Martian environment," Schulze-Makuch wrote. (The labeled release, pyrolytic release and gas exchange experiments all involved adding water to the soil.) Too much of a good thing ![]() The general scientific consensus is that the presence of perchlorate and its byproducts can adequately explain the gases detected in the original Viking results, which has essentially "resolved the Viking dilemma," Chris McKay, an astrobiologist at NASA's Ames Research Center in California, told Live Science in an email.īut Schulze-Makuch believes most of the experiments may have produced skewed results because they used too much water. However, the gas exchange experiment, which was deemed the most important of the four, produced a negative result, leading most scientists to eventually conclude that the Viking experiments did not detect Martian life.Īnd in 2007, NASA's Phoenix lander, the successor to the Viking landers, found traces of perchlorate - a chemical that's used in fireworks, road flares and explosives, and naturally occurs inside some rocks - on Mars. (Subsequent landers and rovers have since proved that these organic compounds occur naturally on Mars.) The GCMS also found some traces of chlorinated organic compounds, but at the time, mission scientists believed the compounds were contamination from cleaning products used on Earth. ![]() The labeled release and pyrolytic release experiments produced some results that supported the idea of life on Mars: In both experiments, small changes in the concentrations of some gases hinted that some sort of metabolism was taking place. The results of the Viking experiments were confusing, and have continued to perplex some scientists ever since. Each of the Viking landers - Viking 1 and Viking 2 - carried out four experiments on Mars: the gas chromatograph mass spectrometer (GCMS) experiment, which looked for organic, or carbon-containing, compounds in Martian soil the labeled release experiment, which tested for metabolism by adding radioactively traced nutrients to the soil the pyrolytic release experiment, which tested for carbon fixation by potential photosynthetic organisms and the gas exchange experiment, which tested for metabolism by monitoring how gases that are known to be key to life (such as oxygen, carbon dioxide and nitrogen) changed surrounding isolated soil samples.
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