Microbial Life on Venus Requires a Unique Life Cycle to Overcome Extreme Conditions

Table of Links

Abstract and 1. Introduction and Overview

2. Challenges and Assumptions for Life in the Venusian Clouds
3. A Proposed Cycle for Venusian Aerial Microbial Life
4. Discussion
5. Summary, Acknowledgments, Author Disclosure Statement, Funding Information, and References

5. Summary

Life in the Venusian clouds has long since been a popular if speculative topic. The clouds decks of Venus themselves are often described as conductive to life. We reassessed this notion and reviewed the severe and unique environmental challenges that life in the aerial biosphere of Venus would have to overcome. The challenges include: an extremely acidic environment, far more so than any known environment on Earth; very low water content; and nutrient scarcity.

We also highlighted the assumption that life would have to reside inside protective cloud droplets (sulfuric acid mixed with water), and that any life would have to be photosynthetic to have enough energy for a variety of cellular processes.

The main new point of this work is to present a life cycle concept. Assuming that life must reside inside cloud droplets, we resolve the subsequent conundrum of gravitationally settling droplets reaching hotter, uninhabitable regions by proposing a Venusian life cycle where a critical step is microbes drying out to become spores on reaching the relatively stagnant lower haze layer, which we call a leaky ‘‘depot.’’ The dried out spores would reside there until some of them can be transported back up to the temperate, habitable cloud layers, where they would act as CCN to promote cloud formation, becoming enveloped in cloud droplets to continue the life cycle.

Acknowledgments

The authors thank Joanna Petkowska-Hankel for the preparation of Figs. 1, 4, and 5. They also thank Daniel Koll for useful discussions.

Author Disclosure Statement

No competing financial interests exist.

Funding Information

The authors thank the Change Happens Foundation, the Heising-Simons Foundation, and the MIT Professor Amar G. Bose Research Grant Program for funding. P.G. acknowledges support from the 51 Pegasi b Fellowship funded by the Heising-Simons Foundation.

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