On The Biomass Required To Produce Phosphine Detected In The Cloud Decks Of Venus

Left panel: potential biomass present in the aerial biosphere (in kg). Right panel: possible biomass density in the biosphere (in mg m−3 ). In both panels, the vertical axis depicts the characteristic temperature (in ◦C) of the temperate layer, while the horizontal axis quantifies the Gibbs free energy (in kJ mol−1 ) for the phosphine pathway. Note the logarithmic scale on the horizontal axis, e.g., the location 2.0 is equivalent to 100 kJ mol−1

The putative detection of phosphine in the atmosphere of Venus at an abundance of ∼20 ppb suggests that this gas is being generated by either indeterminate abiotic pathways or biological processes.

We consider the latter possibility, and explore whether the amount of biomass required to produce the observed flux of phosphine may be reasonable. We find that the typical biomass densities predicted by our simple model are several orders of magnitude lower than the average biomass density of Earth's aerial biosphere.

We briefly discuss how small spacecraft could sample the Venusian cloud decks and search for biomarkers. On account of certain weakly constrained variables as well as the heuristic nature of our model, the results presented herein should be viewed with due caution.

Manasvi Lingam, Abraham Loeb
Comments: 6 pages; 2 figures
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Instrumentation and Methods for Astrophysics (astro-ph.IM)
Cite as: arXiv:2009.07835 [astro-ph.EP] (or arXiv:2009.07835v1 [astro-ph.EP] for this version)
Submission history
From: Manasvi Lingam
[v1] Wed, 16 Sep 2020 17:54:42 UTC (348 KB)

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