Proposed energy-metabolisms cannot explain the atmospheric chemistry of Venus

Abstract

Life in the clouds of Venus, if present in sufficiently high abundance, must be affecting the atmospheric chemistry. It has been proposed that abundant Venusian life could obtain energy from its environment using three possible sulfur energy-metabolisms. These metabolisms raise the possibility of Venus's enigmatic cloud-layer SO${}_2$-depletion being caused by life. We here couple each proposed energy-metabolism to a photochemical-kinetics code and self-consistently predict the composition of Venus's atmosphere under the scenario that life produces the observed SO${}_2$-depletion. Using this photo-bio-chemical kinetics code, we show that all three metabolisms can produce SO${}_2$-depletions, but do so by violating other observational constraints on Venus's atmospheric chemistry. We calculate the maximum possible biomass density of sulfur-metabolising life in the clouds, before violating observational constraints, to be $\sim 10^{-5}-10^{-3}\mathrm{mg}{\mathrm{m}}^{-3}$. The methods employed are equally applicable to aerial biospheres on Venus-like exoplanets, planets that are optimally poised for atmospheric characterisation in the near future.

Published in Nature Communications

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Cited by in corpus (4)

• Venus' Atmospheric Chemistry and Cloud Characteristics Are Compatible with Venusian Life
• Astrobiological Potential of Venus Atmosphere Chemical Anomalies and Other Unexplained Cloud Properties
• Tracing the Inner Edge of the Habitable Zone with Sulfur Chemistry
• Venus Cloud Research: Progress and Perspectives