Punishing conditions in the clouds of Venus could be home to a DNA-like molecule capable of forming genes in life very different to that on Earth, according to a new study.
Long thought to be hostile to complex organic chemistry because of the absence of water, the clouds of Earth's sister planet are made of droplets of sulphuric acid, chlorine, iron, and other substances.
But research, led by Wrocław University of Science and Technology, shows how peptide nucleic acid (PNA) - a structural cousin of DNA - can survive under lab conditions made to mimic conditions that can occur in Venus' perpetual clouds.
The international team drew on expertise from Cardiff University, Massachusetts Institute of Technology, Worcester Polytechnic Institute and industry collaborators Symeres for the study, which assessed PNA's ability to withstand a 98% sulfuric acid solution at room temperature for a period of two weeks.
Their findings published in Science Advances, add to the evidence that shows that concentrated sulphuric acid can sustain a diverse range of organic chemistry that might be the basis of a form of life different from Earth's.
Lead author, Dr Janusz Jurand Petkowski from Wrocław University of Science and Technology, said: "People think concentrated sulfuric acid destroys all organic molecules and therefore kills all life, but this is not true.
"While many biochemicals, like sugars, are unstable in such an environment, our research to date shows that other chemicals found in living organisms, such as nitrogenous bases, amino acids, and some dipeptides, don't break down."
Here, we've started a new chapter on the potential of sulfuric acid as a solvent for life demonstrating that PNA, a complex molecule, structurally related to DNA, and known to interact specifically with nucleic acids, exhibits remarkable stability in concentrated sulfuric acid at room temperature.
The work builds on findings from mid-2020, where a team of scientists from Imperial College London presented evidence for the presence of phosphine, a toxic gas produced in oxygen-poor environments, on Venus.
In the same year, a group of scientists from Cardiff University shared preliminary results from their research indicating the presence of ammonia on the planet .
Dr William Bains from Cardiff University's School of Physics and Astronomy was part of both studies.
He added: "Both ammonia and phosphine are biomarkers, which means they can indicate the presence of life. But Venus' clouds are utterly hostile to life as we know it on Earth. So our latest study seeks to explore the potential of concentrated sulfuric acid as a solvent that could support the complex chemistry needed for life in these seemingly uninhabitable clouds."
To find that PNA with its similarities to DNA can remain in concentrated sulfuric acid for hours is quite astonishing. It's a new piece of a much larger puzzle in our understanding of how life, albeit very different to ours, is made and where in the universe it might exist.
The findings also offer new ways of understanding the chemistry of sulfuric acid, one of the most widely used industrial chemicals, that may have practical use in the future, according to the team.
Dr Pętkowski added: "Our study shows that PNA is no longer stable in sulphuric acid at temperatures higher than 50°C. So, our future research will focus on creating a genetic polymer - a molecule that can play the role that DNA plays in life on Earth - that is stable in concentrated sulphuric acid over the temperature range of Venus' clouds, between 0°C and 100°C, and not just at room temperature.
"The discoveries so far are therefore only the first step towards finding such a stable polymer."
Their paper, ' Astrobiological Implications of the Stability and Reactivity of Peptide Nucleic Acid (PNA) in Concentrated Sulfuric Acid ' is published in Science Advances.
