Stability of Nucleic Acid Bases in the Acidic Clouds of Venus Suggests Its Potential To Support Life

Searching for signs of life outside the planet Earth has become one of the motivations in our modern-day space explorations. In the Solar System, the planet Venus is commonly referred to as the twin planet of the Earth because of their size and structure similarities. However, it has also been accepted that this planet cannot host life due to its extremely hot surface temperature. This belief was challenged by an experiment performed by a group of researchers.

(Photo: Wikimedia Commons/ NASA/JPL-Caltech)

Exploring the Habitability of Venus' Clouds

A team of experts discovered that the atmospheric conditions in the Venus clouds could potentially support life. The research team comprises biologists, chemists, and planetary scientists from the Massachusetts Institute of Technology (MIT), Harvard University, Nanoplanet Consulting, and the University of Alberta.

A previous study reveals that the average temperature on the surface of Venus reaches up to 462 degrees Celsius which is too hot to host living organisms. Surprisingly, its atmosphere is much cooler, especially in the clouds, where the temperature is just between 30 to 70 degrees Celsius. This temperature range is an ideal condition to sustain life.

However, these clouds are made up of sulfuric acid, which is even more acidic than any clouds here on Earth. Despite this, scientists are still intrigued about the possibility of nurturing life in such an environment. To verify their conclusion, the team designed experiments to identify the survival rate of RNA and/or DNA bases in this type of atmosphere.

Using an experimental model, the researchers exposed DNA and RNA bases such as cytosine, thymine, adenine, uracil, and guanine to chemical conditions resembling Venusian clouds. A similar setup was done with purine and pyrimidine nucleic acid base cores. Then NMR and UV spectroscopy were used to test the stability of the acid bases.

It was found that the nucleic acid bases showed stability under such extreme conditions and remained that way for two weeks. Therefore, the research team concluded they could behave that way in real clouds on Venus.

Researchers believe that although the result of this study might be shocking to planetary scientists, it could be backed up by many chemists. Oil refinement requires sulfuric acid, which can result in the creation of organic compounds such as aromatic molecules. Based on this analogy, the researchers suggest that as space scientists attempt to look for signs of life in any universe region, they should also expand their search to a planet's atmosphere instead of just analyzing its surface.

Can Venus Support Life Forms?

Venus has been placed in the uninhabitable category of planets for many years because of its hot surface temperature. However, it possesses some properties that made some scientists reconsider this theory.

Venus has temperate cloud layers that are permanent and continuous across the planet. The clouds also stretch vertically extensively at 48 to 60 km above the surface. According to experts, cloud layers contain some of the main requirements for the existence of life. These include a liquid environment, appropriate temperatures for forming covalent bonds, and energy sources.

In principle, the cloud layers in Venus could potentially host systems with the main requirements for life. Even if their chemical structure differs from terrestrial environments, scientists believe that the life forms that can form in Venusian clouds can undergo Darwinian evolution.

The aerial biosphere on Earth supports the concept of life in Venusian clouds. The transient and fragmented nature of Earth's clouds challenges its ability for permanent habitation. In contrast, Venus has a continuous and permanent cover from a vertically extensive cloud system.