EGU General Assembly 2022
© Author(s) 2022. This work is distributed under
the Creative Commons Attribution 4.0 License.

Metabolic Signatures of an Aerial Biosphere in the Clouds of Venus: A Self-Consistent Photo-Bio-Chemical Model

Sean Jordan1, Oliver Shorttle2,1, and Paul Rimmer2,3,4
Sean Jordan et al.
  • 1Institute of Astronomy, University of Cambridge, Madingley Rd, Cambridge CB3 0HA, United Kingdom
  • 2Department of Earth Sciences, University of Cambridge, Downing St, Cambridge CB2 3EQ, United Kingdom
  • 3Cavendish Laboratory, University of Cambridge, JJ Thomson Ave, Cambridge CB3 0HE, United Kingdom
  • 4MRC Laboratory of Molecular Biology, Francis Crick Ave, Cambridge CB2 0QH, United Kingdom

Life in the clouds of Venus, if present, has been proposed to extract energy from its environment using sulfur-based metabolisms. These metabolisms link life to the chemistry of Venus's atmosphere and thus provide testable predictions of life's presence given current observations. In particular, these hypothetical metabolisms raise the possibility of Venus's enigmatic cloud-layer SO2-depletion being explained by life. We couple each proposed metabolic pathway to a photochemical-kinetics code and self-consistently predict the composition of Venus's atmosphere under the scenario that life produces the observed SO2-depletion. Using this photo-bio-chemical kinetics code, we show that all three metabolisms produce SO2-depletions which violate other observational constraints on Venus's atmospheric chemistry. For each metabolism, we estimate the maximum potential biomass density in the cloud layer before the observational constraints are violated. Our analysis shows that either the observed SO2-depletion is due to a currently unknown metabolism, or there is not a high-mass biosphere in Venus's clouds. 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.

How to cite: Jordan, S., Shorttle, O., and Rimmer, P.: Metabolic Signatures of an Aerial Biosphere in the Clouds of Venus: A Self-Consistent Photo-Bio-Chemical Model, EGU General Assembly 2022, Vienna, Austria, 23–27 May 2022, EGU22-2528,, 2022.