Depicted: A cropped "tourism poster" of the planet Venus. Photo Credit: NASA.
An article published in the scientific journal Nature Astronomy suggests that there might be alien microbial life floating in the clouds of Venus. They didn't find life itself, but they found significant quantities of phosphine--a chemical typically created on Earth by microbes breaking down organic matter.
What is Phosphine?
On Earth, phosphine is formed by microbes processing phosphorous-containing organic matter. There are non-biological processes that can create phosphine, but these processes typically require too much energy for them to naturally occur.
However, it is likely that these non-biological processes do happen in the hot, dense cores of Jupiter or Saturn. The intense environments within these planets provide enough energy for phosphine to be made by non-biological means.
But on Venus, scientists are not aware of any non-biological process that could be responsible for creating significant quantities of phosphine. Volcanic activity and lightning strikes could have created phosphine on Venus, but the authors of the Nature Science paper ruled out such non-biological processes as not being able to create the quantity of phosphine that has been detected on Venus. Unless scientists can find a non-biological source of phosphine, it is very possible that the phosphine is created through some biological process.
What are the Microbes Like?
First of all, we don't know whether such microbes exist--only that the phosphine does. However, scientists have made assumptions on what Venusian life might be like, given what we know about Venus's atmosphere.
One possibility is that microbes live in cloud droplets in the temperate part of Venus's atmosphere, until the droplets grow large enough to fall to the hotter lower layers of the atmosphere. The microbes would "dry out" into desiccated spores that turn back into microbes on the way back up.
Have we Thought of Life on Venus Before?
Science fiction writers have long thought about Venus as a planet very much like Earth. But Mariner 2 in the year 1962 and subsequent space probes revealed to us that Venus has surface temperatures that can approach 900°F and a toxic, high-pressure atmosphere that is unlikely to support life as we know it.
However, sections of Venus's upper atmosphere are more temperate. About thirty miles above the surface, Venus's temperature and pressure become very Earth-like while still providing an effective shield against radiation from space. In 1967, Carl Sagan and Harold Morowitz published an analysis suggesting that life is possible in Venus's clouds.
Since the, science-fiction writers have dreamed of humans (or Venusians) inhabiting cities floating in the temperate portion of Venus's atmosphere. The headline photo on this Dark Shift article is a cropped artist's impression of such a cloud city.
Was Venus more temperate in the past?
Many scientists believe that Venus's atmosphere was not always as toxic as it is today. Venus may have had cool temperatures and oceans of liquid water for billions of years until a mysterious event that happened around 750 million years ago--possibly releasing enormous quantities of the carbon dioxide that was trapped in the rocks.
That carbon dioxide and other greenhouse gases were likely responsible for a "runaway greenhouse effect" that heated Venus up to its current hellish temperature. Some worry that Earth could suffer the same fate if we fail to control climate change.
If that happens, maybe we should move to the clouds of Venus and become Venusians ourselves.