Thomas J. Wdowiak is an Athena scientist who takes time out of his busy schedule to show kids how to do fun
science experiments at home. When he isn't teaching at the University of Alabama at Birmingham or training
at the Jet Propulsion Lab in California, he writes for the local newspaper in Birmingham in the "Just for
Kids" section. He goes by "Tommy Test Tubes," a nickname given to him when he was a kid. Now "Tommy Test
Tubes" contributes his experience and knowledge to the Athena web page with a new column. If you have a
question for Tom, click here.
In your article about Venus, you mention the extreme temperatures and concentrated sulphuric acid as reasons why life could not exist there. But there are life forms on Earth that use sulfur for everyday needs and their environment is very hot. Why rule out hot, sulphuric places for life?
The point I was making is that Venus is not Earth, and the most significant difference is the absence of liquid water as in Earth's oceans and hot springs like those in Yellowstone National Park. The high temperatures at the surface of Venus make liquid water impossible according to the laws of chemistry (you might want to read up on the "critical point" of water in this regard). In the clouds of Venus the droplets are concentrated sulphuric acid because water molecules evaporate away leaving just acid. This also occurs in the Earth's atmosphere when sulphurous volcanoes erupt as has happened in recent times in the Philippine Islands, resulting in concentrated acid cloud droplets in the stratosphere. The issue is that liquid water is necessary for life, as we know it, including microbes that use sulfur in high temperature environments.
Also, the highest temperatures at which microbial life exists in deep-sea vents appear, from a very recent investigation, to be about 130 Celsius. This is very "cool" compared to temperatures on Venus. There is also a limitation to how high a temperature at which an organic molecule like a proteins can exist in liquid water anywhere. When liquid water under pressure as in the ocean depths of Earth has a temperature approaching 200 Celsius, water molecules considerably more often breakdown (chemists say "disassociate") into hydrogen ions (H+) and hydroxyl ions (-OH) than at lower temperatures. In effect water under high pressure and temperature becomes a combination of acid and base, which makes it very chemically reactive with organic molecules. Things like proteins are easily "cooked" down to basic building blocks not unlike making soup!
For all these reasons I stand by my assessment that Venus is not the place to look for life being present. On the other hand, if conditions were different there billions of years ago, when the Sun probably shined less brightly and Venus might have been a cooler place, the situation might have been different.
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