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dc.contributor.authorBains, William
dc.contributor.authorPetkowski, Janusz J
dc.contributor.authorRimmer, Paul B
dc.contributor.authorSeager, Sara
dc.date.accessioned2022-02-04T00:31:10Z
dc.date.available2022-02-04T00:31:10Z
dc.date.issued2021-12-28
dc.identifier.issn0027-8424
dc.identifier.urihttps://www.repository.cam.ac.uk/handle/1810/333627
dc.description.abstractThe atmosphere of Venus remains mysterious, with many outstanding chemical connundra. These include the unexpected presence of ∼10 ppm O2 in the cloud layers, an unknown composition of large particles in the lower cloud layers, and hard to explain measured vertical abundance profiles of SO2 and H2O. We propose a hypothesis for the chemistry in the clouds that largely addresses all of the above anomalies. We include ammonia (NH3), a key component that has been tentatively detected both by the Venera 8 and Pioneer Venus probes. NH3 dissolves in some of the sulfuric acid cloud droplets, effectively neutralizing the acid and trapping dissolved SO2 as ammonium sulfite salts. This trapping of SO2 in the clouds, together with the release of SO2 below the clouds as the droplets settle out to higher temperatures, explains the vertical SO2 abundance anomaly. A consequence of the presence of NH3 is that some Venus cloud droplets must be semisolid ammonium salt slurries, with a pH of ∼1, which matches Earth acidophile environments, rather than concentrated sulfuric acid. The source of NH3 is unknown but could involve biological production; if so, then the most energy-efficient NH3-producing reaction also creates O2, explaining the detection of O2 in the cloud layers. Our model therefore predicts that the clouds are more habitable than previously thought, and may be inhabited. Unlike prior atmospheric models, ours does not require forced chemical constraints to match the data. Our hypothesis, guided by existing observations, can be tested by new Venus in situ measurements.
dc.format.mediumPrint
dc.publisherProceedings of the National Academy of Sciences
dc.rightsAttribution 4.0 International
dc.rights.urihttps://creativecommons.org/licenses/by/4.0/
dc.subjectVenus
dc.subjectastrobiology
dc.subjectatmospheric chemistry
dc.subjectclouds
dc.subjecthabitability
dc.titleProduction of ammonia makes Venusian clouds habitable and explains observed cloud-level chemical anomalies.
dc.typeArticle
dc.publisher.departmentDepartment of Earth Sciences
dc.date.updated2022-02-03T11:01:37Z
prism.endingPagee2110889118
prism.issueIdentifier52
prism.publicationDate2021
prism.publicationNameProc Natl Acad Sci U S A
prism.startingPagee2110889118
prism.volume118
dc.identifier.doi10.17863/CAM.81043
dcterms.dateAccepted2021-11-11
rioxxterms.versionofrecord10.1073/pnas.2110889118
rioxxterms.versionVoR
dc.contributor.orcidPetkowski, Janusz J [0000-0002-1921-4848]
dc.contributor.orcidRimmer, Paul B [0000-0002-7180-081X]
dc.identifier.eissn1091-6490
rioxxterms.typeJournal Article/Review
cam.issuedOnline2021-12-20
cam.depositDate2022-02-03
pubs.licence-identifierapollo-deposit-licence-2-1
pubs.licence-display-nameApollo Repository Deposit Licence Agreement


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Attribution 4.0 International
Except where otherwise noted, this item's licence is described as Attribution 4.0 International