Viking lander biological experiments
NASA astrobiologist Chris McKay has estimated, in fact, that if Phoenix-like levels of perchlorates were present in the Viking samples, the organic content of the Martian soil could have been as high as 0.1% and still would have produced the (false) negative result that the GCMS returned."[7] According to a 2010 NASA press release: "The only organic chemicals identified when the Viking landers heated samples of Martian soil were chloromethane and dichloromethane -- chlorine compounds interpreted at the time as likely contaminants from cleaning fluids."According to a paper authored by a team led by Rafael Navarro-González of the National Autonomous University of Mexico, "those chemicals are exactly what [their] new study found when a little perchlorate -- the surprise finding from Phoenix -- was added to desert soil from Chile containing organics and analyzed in the manner of the Viking tests."[1] Periodically, the instrument sampled the atmosphere of the incubation chamber and used a gas chromatograph to measure the concentrations of several gases, including oxygen, CO2, nitrogen, hydrogen, and methane.[15] A CNN article from 2000 noted that "Though most of his peers concluded otherwise, Levin still holds that the robot tests he coordinated on the 1976 Viking lander indicated the presence of living organisms on Mars."[16] A 2006 astrobiology textbook noted that "With unsterilized Terrestrial samples, though, the addition of more nutrients after the initial incubation would then produce still more radioactive gas as the dormant bacteria sprang into action to consume the new dose of food."[17] The 2011 edition of the same textbook noted that "Albet Yen of the Jet Propulsion Laboratory has shown that, under extremely cold and dry conditions and in a carbon dioxide atmosphere, ultraviolet light (remember: Mars lacks an ozone layer, so the surface is bathed in ultraviolet) can cause carbon dioxide to react with soils to produce various oxidizers, including highly reactive superoxides (salts containing O2−)."[7] In a 2002 paper published by Joseph Miller, he speculates that recorded delays in the system's chemical reactions point to biological activity similar to the circadian rhythm previously observed in terrestrial cyanobacteria.[18] A 2007 paper by Dirk Schulze-Makuch and Joop M. Houtkooper argues that the experiment may have killed potential microbes by supplying them with an excessive amount of water.[21][22] On 12 April 2012, an international team including Levin and Patricia Ann Straat published a peer reviewed paper suggesting the detection of "extant microbial life on Mars", based on mathematical speculation through cluster analysis of the Labeled Release experiments of the 1976 Viking Mission.The general scientific community surmises that the Viking's biological tests remain inconclusive, and can be explained by purely chemical processes.The study's authors found that perchlorate can destroy organics when heated and produce chloromethane and dichloromethane as byproduct, the identical chlorine compounds discovered by both Viking landers when they performed the same tests on Mars.While this study was not specifically designed to match the data from the LR experiment, it was found that hypochlorite could partially explain the control results, including the 160 °C sterilization test.[46][47][48] In 2006, scientist Rafael Navarro demonstrated that the Viking biological experiments likely lacked sensitivity to detect trace amounts of organic compounds.According to Gilbert Levin and Patricia Ann Straat, investigators of the LR experiment, no explanation involving inorganic chemistry as of 2016 is able to give satisfactory explanations of the complete data from the LR experiment, and specifically address the question of what active agent on the soil samples could be adversely affected by heating to approximately 50 °C and destroyed with long-term storage in the dark at 10 °C, as data suggest.[60] That is not a problem for missions which land via an airbag-protected capsule, slowed by parachutes and retrorockets, and dropped from a height that allows rocket exhaust to avoid the surface.The Phoenix Scout lander descended to the surface with retro-rockets, however, their fuel was hydrazine, and the end products of the plume (water, nitrogen, and ammonia) were not found to have affected the soils at the landing site.
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Viking programbiologicalexperimentsViking 1Viking 2biosignatureslife on Marsgas chromatograph — mass spectrometergas chromatographmass spectrometermolecular weightKlaus Biemannorganic moleculesApollo programastrobiologyPhoenix landerperchloratechloromethanedichloromethaneRafael Navarro-GonzálezNational Autonomous University of Mexicochlorinated organicsTrace Gas OrbiterheliumoxygennitrogenhydrogenmethaneGilbert LevinexobiologistsMiller-Ureymetabolizedsuperoxidescircadian rhythmcyanobacteriaDirk Schulze-MakuchBig ThinkPatricia Ann Straatpeer reviewedcluster analysis1976 Viking MissionNorman Horowitzatmospherecarbon monoxidecarbon dioxidecarbon-14radioactiveisotopephotosyntheticbiomasscarbon fixationmetabolismUV lightozone layeroxidantJet Propulsion LaboratoryMarinerVikinghydrogen peroxidetitanium dioxideMars Science LaboratoryExoMarsnomenclatural rankmetabolicJames Lovelockmethane has been discovered in MarsExoMars Trace Gas OrbiterMars Orbiter MissionairbagMars PathfinderMars Exploration RoversPhoenix ScouthydrazineBiological Oxidant and Life DetectionBiosignatureExploration of MarsEuropa Lander (NASA)BibcodeNational GeographicInteractive image mapglobal topography of MarsMartian roverslandersBeagle 2CuriosityDeep Space 2InSightMars 2Mars 3Mars 6Mars Polar Lander ↓OpportunityPerseverancePhoenixRosalind FranklinSchiaparelli EDMSojournerSpiritZhurongViking 2 Viking Mars landersExtraterrestrial lifeShergotty meteoriteNakhla meteoriteMurchison meteoriteAllan Hills 77005Allan Hills 84001Yamato 000593CI1 fossilsCP 1919CTA-102KIC 8462852EPIC 204278916VVV-WIT-07HD 164595 signalSHGb02+14aWow! signalFast radio burstEarliest known life formsPlanetary habitability in the Solar SystemLife on VenusLife on TitanPlanetaryhabitabilityCatalog of Nearby Habitable SystemsCircumstellar habitable zoneEarth analog