Phosphine on Venus Cannot Be Explained by Conventional Processes
Name
ast.2020.2352.pdf
Description
Published version
Size
1.31 MB
Format
Adobe PDF
Checksum (MD5)
8e36a001584459db066d78a7e259fce7
Author(s)
Bains, William
Petkowski, Janusz J
Seager, Sara
Ranjan, Sukrit
Sousa-Silva, Clara
Rimmer, Paul B
Zhan, Zhuchang
Greaves, Jane S
Richards, Anita MS
Date Issued
October 1, 2021
Journal
Astrobiology
Publisher
Mary Ann Liebert Inc
Version
Final published version
Abstract
The recent candidate detection of ~1 ppb of phosphine in the middle
atmosphere of Venus is so unexpected that it requires an exhaustive search for
explanations of its origin. Phosphorus-containing species have not been
modelled for Venus' atmosphere before and our work represents the first attempt
to model phosphorus species in the Venusian atmosphere. We thoroughly explore
the potential pathways of formation of phosphine in a Venusian environment,
including in the planet's atmosphere, cloud and haze layers, surface, and
subsurface. We investigate gas reactions, geochemical reactions,
photochemistry, and other non-equilibrium processes. None of these potential
phosphine production pathways are sufficient to explain the presence of ppb
phosphine levels on Venus. If PH3's presence in Venus' atmosphere is confirmed,
it therefore is highly likely to be the result of a process not previously
considered plausible for Venusian conditions. The process could be unknown
geochemistry, photochemistry, or even aerial microbial life, given that on
Earth phosphine is exclusively associated with anthropogenic and biological
sources. The detection of phosphine adds to the complexity of chemical
processes in the Venusian environment and motivates in situ follow up sampling
missions to Venus. Our analysis provides a template for investigation of
phosphine as a biosignature on other worlds.
MIT Department
Massachusetts Institute of Technology. Department of Earth, Atmospheric, and Planetary Sciences
Massachusetts Institute of Technology. Department of Physics
Massachusetts Institute of Technology. Department of Aeronautics and Astronautics
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Persistent DSpace Link
DOI of Published Version
https://doi.org/10.1089/ast.2020.2352
