Colloquium: Heterogenous Chemistry in the Clouds of Venus - Toward an Abiotic Baseline
The clouds of Venus are believed to be made of sulfuric acid (H2SO4), water (H2O) and other minor constituents. The nature of those minor constituents remains unknown. Past tentative detections of molecular oxygen (O2), methane (CH4), ethane (C2H6), hydrogen sulfide (H2S), phosphine (PH3) and ammonia (NH3) in the clouds have recently been treated as possible biosignatures, and upcoming missions, such as the Venus Life Finder mission funded by Rocket Lab, will search for these chemical species and others. However, to assign any confidence to claims of life in the clouds of Venus, we need a clear abiotic baseline: a picture of what abiotic processes can produce based on experiments and models. I will talk about two abiotic hypotheses that can provide some context for these anomalous detections within the clouds: that there are hydroxide salts in the clouds and that iron-sulfur chemistry is taking place in the cloud droplets. I will then focus on one particular “life in the clouds” hypothesis, and show that, if these chemical anomalies are signs of life, it is very different from terrestrial life, and its presence would pose a serious challenge for using disequilibrium biosignatures to search for life on other planets. I will conclude by discussing the potential implications for this work for the Venus Life Finder mission and future work that would help place the mission results in a more complete planetary context.
recording: www.youtube.com/watch