Venus' Mass Spectra Show Signs of Disequilibria in the Middle Clouds

Abstract

Venus' clouds harbor several proposed trace chemical species that suggest the potential for chemistries yet to be discovered. Exemplar trace species include ammonia, oxygen, hydrogen, methane, and ethene, which were detected remotely or in situ (

Iron-sulfur chemistry can explain the ultraviolet absorber in the clouds of Venus

“…These data reveal a wealth of plausible physical and chemical processes that are poorly constrained. These include, but are not limited to, the depletion of sulfur dioxide and water in the clouds ( 6 , 8 ), an unknown ultraviolet (UV) absorber at the top of the clouds ( 1 , 9 ), discrete size distributions of aerosol particles ( 10 ), redox disequilibrium chemistry ( 5 , 11 , 12 ), and the possible presence of a cloud layer (47 to 52 km), tentatively indicated by VEGA-2 x-ray data, where phosphorus is at least as abundant as sulfur ( 13 , 14 ). Of import, current models of atmospheric chemistry on Venus are unable to explain a number of observations, such as the behavior of carbonyl sulfide (OCS) and sulfuric acid (H 2 SO 4 ) vapor below the clouds, the behavior of water vapor and sulfur dioxide (SO 2 ) in and above the clouds, and the lack of O 2 above the clouds [see Bierson and Zhang ( 5 ) for a helpful summary of these four outstanding problems].…”