A composite image of the planet Venus as seen by the Japanese probe Akatsuki. The clouds of Venus could have environmental conditions conducive to microbial life.
Credit: JAXA

The clouds of Venus may be a depot for life.

New research has looked into the prospect that microbial life could reside inside protective cloud droplets (sulfuric acid mixed with water) hovering high above that hellish world.

The new work is led by Sara Seager in the Department of Earth, Atmospheric, and Planetary Sciences at the Massachusetts Institute of Technology and published in the journal, Astrobiology.

Challenges

The scientific team reassessed 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,” they write.

The main new point of the work is to present a life cycle concept – albeit hypothetical.

Hypothetical life cycle of Venusian microorganisms.
Credit: Sara Seager, et.al

Leaky depot

“Assuming that life must reside inside cloud droplets,” the researchers report, “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 [cloud condensation nuclei are ‘‘cloud seeds,’’ a small solid surface needed for vapor to condense] to promote cloud formation, becoming enveloped in cloud droplets to continue the life cycle.”

“We argue that life, if it exists in Venus’ atmosphere, must reside inside cloud liquid droplets for the majority of its life cycle,” the scientists report.

Go to the paper — “The Venusian Lower Atmosphere Haze as a Depot for Desiccated Microbial Life: A Proposed Life Cycle for Persistence of the Venusian Aerial Biosphere” – at:

https://www.liebertpub.com/doi/full/10.1089/ast.2020.2244

Leave a Reply