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dc.contributor.authorSeager, Sara
dc.contributor.authorPetkowski, Janusz J
dc.contributor.authorGao, Peter
dc.contributor.authorBains, William
dc.contributor.authorBryan, Noelle C
dc.contributor.authorRanjan, Sukrit
dc.contributor.authorGreaves, Jane
dc.date.accessioned2021-10-27T20:24:36Z
dc.date.available2021-10-27T20:24:36Z
dc.date.issued2020
dc.identifier.urihttps://hdl.handle.net/1721.1/135680
dc.description.abstractWe revisit the hypothesis that there is life in the Venusian clouds to propose a life cycle that resolves the conundrum of how life can persist aloft for hundreds of millions to billions of years. Most discussions of an aerial biosphere in the Venus atmosphere temperate layers never address whether the life-small microbial-type particles-is free floating or confined to the liquid environment inside cloud droplets. We argue that life must reside inside liquid droplets such that it will be protected from a fatal net loss of liquid to the atmosphere, an unavoidable problem for any free-floating microbial life forms. However, the droplet habitat poses a lifetime limitation: Droplets inexorably grow (over a few months) to large enough sizes that are forced by gravity to settle downward to hotter, uninhabitable layers of the Venusian atmosphere. (Droplet fragmentation-which would reduce particle size-does not occur in Venusian atmosphere conditions.) We propose for the first time that the only way life can survive indefinitely is with a life cycle that involves microbial life drying out as liquid droplets evaporate during settling, with the small desiccated 'spores' halting at, and partially populating, the Venus atmosphere stagnant lower haze layer (33-48 km altitude). We, thus, call the Venusian lower haze layer a 'depot' for desiccated microbial life. The spores eventually return to the cloud layer by upward diffusion caused by mixing induced by gravity waves, act as cloud condensation nuclei, and rehydrate for a continued life cycle. We also review the challenges for life in the extremely harsh conditions of the Venusian atmosphere, refuting the notion that the 'habitable' cloud layer has an analogy in any terrestrial environment.
dc.language.isoen
dc.publisherMary Ann Liebert Inc
dc.relation.isversionof10.1089/AST.2020.2244
dc.rightsCreative Commons Attribution NonCommercial License 4.0
dc.rights.urihttps://creativecommons.org/licenses/by-nc/4.0/
dc.sourceMary Ann Liebert
dc.titleThe Venusian Lower Atmosphere Haze as a Depot for Desiccated Microbial Life: A Proposed Life Cycle for Persistence of the Venusian Aerial Biosphere
dc.typeArticle
dc.contributor.departmentMassachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences
dc.contributor.departmentMassachusetts Institute of Technology. Department of Physics
dc.contributor.departmentMassachusetts Institute of Technology. Department of Aeronautics and Astronautics
dc.relation.journalAstrobiology
dc.eprint.versionFinal published version
dc.type.urihttp://purl.org/eprint/type/JournalArticle
eprint.statushttp://purl.org/eprint/status/PeerReviewed
dc.date.updated2021-09-30T12:15:53Z
dspace.orderedauthorsSeager, S; Petkowski, JJ; Gao, P; Bains, W; Bryan, NC; Ranjan, S; Greaves, J
dspace.date.submission2021-09-30T12:15:55Z
mit.journal.volume21
mit.journal.issue10
mit.licensePUBLISHER_CC
mit.metadata.statusAuthority Work and Publication Information Needed


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