Is Life Possible in the Upper Clouds of Venus?

Question of the Week: What are your thoughts on the possibility of life in the clouds of Venus?

My Answer: The atmospheric pressure on Venus’s surface is 93 times greater than the atmospheric pressure on Earth’s surface. Venus’s atmosphere is composed of 96.5% carbon dioxide, 3.5% nitrogen, and trace amounts of sulfur dioxide, sulfuric acid, and hydrogen sulfide. This thick atmosphere of largely carbon dioxide explains why the surface temperature of Venus is 863° Fahrenheit (462° Centigrade), more than hot enough to melt lead. However, somewhere between 50 and 65 km above Venus’s surface, the atmospheric temperature and pressure roughly equal those of Earth’s surface. Consequently, this part of the upper atmosphere of Venus ranks as the most Earth-like environment of any region in the solar system beyond Earth. It is this “Earth-like” quality that has caused some to speculate that life might exist in this part of Venus’ upper atmosphere.

I believe that if astronomers search diligently enough they will find the remains of microbial life 50­–65 km above the surface of Venus. I take this position not because I believe there is a possibility of indigenous life in the upper atmosphere of Venus. Rather, I hold this position because I believe it is inevitable that the remains of Earth life have been transported to Venus’s upper atmosphere by natural means.

There is scientific evidence establishing that diatoms and other microorganisms are wafted up into Earth’s upper stratosphere and beyond 25–100 km above Earth’s surface.¹ From there, passing dust particles will transport a few of these microorganisms to the upper atmosphere of Venus. Another transport route would be large meteoroids bombarding Earth with sufficient force to export Earth rocks and soil into interplanetary space. For example, astronomers have calculated that meteoroids have deposited about 20,000 kg of Earth material on average on every 100 square km of the Moon’s surface.²

I believe that only the remains of Earth life, not viable Earth life, will be found in the upper atmosphere of Venus. Both the transport route from Earth to Venus and the upper atmosphere of Venus are hostile for even the hardiest of Earth’s microbes. Both the transport route and Venus’s upper atmosphere lack the resources to sustain microbial metabolism and offer no protection from deadly solar and cosmic radiation.