The atmosphere of Venus is one of the most inhospitable places in the Solar System. With scorching temperatures on the surface and acidic clouds composed of sulfuric acid, it would be unthinkable to imagine any form of life there. However, scientists are rethinking this possibility in light of an intriguing discovery: Xenonucleic Acids (or XNAs), synthetic relatives of DNA, may be able to survive in extreme conditions — including in the upper atmosphere of Venus.
What are XNAs?
DNA and RNA are the fundamental building blocks of life on Earth, but they are not the only possible forms of molecules that carry genetic information. XNAs are artificial variants that replace the sugar (deoxyribose or ribose) in the backbone of DNA/RNA with other chemical components. This small modification results in molecules that are more stable and resistant to extreme environments.
Some of the most studied types of XNAs include:
HNA (hexose nucleic acid)
TNA (threose nucleic acid)
FANA (fluorinated nucleic acid)
LNA (locked nucleic acid)
Why Venus?
Despite its hellish surface, Venus’s upper atmosphere, located between 50 and 60 km above sea level, has less hostile conditions: temperatures between 30ºC and 70ºC and atmospheric pressure similar to that of Earth. Still, the environment is highly acidic, with droplets of sulfuric acid suspended in the clouds.
These conditions would be lethal to most DNA-based life forms, which would degrade quickly. But XNAs, with their alternative chemical structure, can resist acidification, ultraviolet radiation and dehydration much better.
The scientific hypothesis
In 2020, scientists detected phosphine in the atmosphere of Venus — a gas that, on Earth, is normally produced by biological processes. The discovery has reignited the debate over extraterrestrial life on the neighboring planet. If life exists on Venus, it would need a radically different biology than that on Earth.
And that’s where XNAs come in.
Researchers suggest that life forms based on XNAs could theoretically exist—or be created—to study and even survive in the Venusian clouds. They would be perfect candidates for astrobiology experiments in simulated Venusian conditions.
Resistance beyond DNA
Recent studies have shown that XNAs not only retain the ability to store genetic information, but can also replicate and evolve, something essential for any form of life. In addition:
They are more resistant to hydrolysis, meaning they do not break down easily in humid or acidic environments.
They can maintain their functional structure even under high doses of UV radiation, common on Venus.
They have greater chemical flexibility, which allows them to operate in conditions incompatible with DNA.
Biotechnology and future missions
NASA and other space agencies are increasingly interested in extreme bioengineering, including the use of XNAs for living probes, biosensors, and even synthetic life forms that can survive beyond Earth.
Experiments with XNAs in simulated environments on Venus could be part of future space missions, such as:
NASA’s DAVINCI+, which aims to study the composition of the Venusian atmosphere;
ESA’s EnVision, which is scheduled to investigate the planet’s geology and chemistry.
Implications for astrobiology
The existence of molecules like XNAs radically expands our understanding of what can be considered “life.” If life can be based on structures other than DNA and RNA, then the chances of finding life beyond Earth increase significantly.
Furthermore, if we can create synthetic life forms based on XNAs that can survive the Venusian atmosphere, this could revolutionize areas such as:
Planetary exploration
Biotechnology
Regenerative medicine
Molecular computing
Challenges and ethical considerations
Creating synthetic life to explore Venus raises important ethical questions. Should we send lab-grown life forms to other planets? How can we ensure that we do not contaminate alien ecosystems, if they exist?
Modern astrobiology also grapples with dilemmas such as:
What is the universal definition of “life”?
How can we avoid cross-contamination between planets?
What rights would synthetic life forms have?
These questions are at the heart of an emerging debate among scientists, philosophers, and space agencies.
Conclusion
XNAs represent a new chapter in the history of biology and space exploration. Their potential to survive in hostile conditions such as those in the upper atmosphere of Venus could transform both the search for extraterrestrial life and the definition of “life” itself.
If we can imagine — and create — an alternative biology capable of facing the extremes of another planet, we may be closer to finding life beyond Earth… or even getting it there.
