A new theoretical kind of extraterrestrial life could survive the harsh acid clouds of Venus, according to MIT researchers.
Despite longstanding conceptions that Venus would be too deadly for even the hardiest of extremophiles, new evidence suggests a rethinking of life from the ground up may be in order. The work was revealed in a recent paper published in the Proceedings of the National Academy of Sciences, which describes how extraterrestrial life could form from peptides to thrive only in such a hostile environment.
Based on recent evidence, it may be time to cast a wider net in the search for extraterrestrial life and look at planets that bear little resemblance to Earth.
The Brutal Venusian Environment
“We really don’t know the full extent of what planet archetypes are out there,” said senior co-author Sara Seager, the Class of 1941 Professor of Planetary Sciences in the Department of Earth, Atmospheric and Planetary Sciences and a professor at MIT’s departments of Physics and of Aeronautics and Astronautics. “We’re seeking exoplanets that might be a true Earth twin, but what if they’re all Venuses? Our findings definitely open up a whole range of possibilities.”
About 30 to 40 miles above Venus’s scorching surface, which reaches temperatures close to 900° F, lies a pocket of milder temperatures that some scientists think may be conducive to life. However, this region’s heavy cloud cover poses its own challenges. Instead of being composed primarily of water, the clouds on Venus are 98% sulfuric acid, which is strong enough to dissolve metals and would kill any known life on Earth.
While traditional astrobiological thinking held that this would be far too extreme for complex biological molecules to hold together, new evidence is overturning that idea. Recent work at MIT suggests that peptides can endure such challenging conditions, maintaining their stability and adopting shapes useful to biological processes.
“If peptides find their way to that cloud layer of concentrated sulfuric acid, they will stay and be stably preserved in that cloud of droplets,” said senior co-author Mei Hong, an MIT professor of chemistry and one of the senior authors of the new study. “And once these macromolecules have a defined three-dimensional structure, they can potentially have a function.”
Seeding Extraterrestrial Life
Following the concept of panspermia, which holds that the building blocks of life are transmitted throughout the universe on meteoroids, asteroids, and comets, the researchers investigated whether any building blocks could survive the Venusian conditions to give rise to extraterrestrial life.
Work began in Seager’s lab in 2020, studying how biological molecules could endure the stress of such an acidic environment. With nuclear magnetic resonance spectroscopy, they analyzed the structures of molecules in sulfuric acid solution. Surprisingly, nucleic acids, lipids, and amino acids all maintained their integrity under acidic conditions.
The next step was to investigate whether peptides could likewise hold their integrity and also assume useful biological shapes. They were surprised to find how resilient the peptides were, holding on for weeks at a time. Ironically, the lack of water in the environment could be a blessing, as without it, the hydrolysis reaction that breaks down peptides cannot occur.
“Without water, an acid that you would consider a harsh solvent suddenly is not as menacing as one might think,” Hong said.
New Concepts in Extraterrestrial Life
Additionally, the sulfuric acid molecules acted as scaffolds, allowing biologically useful shapes to form that otherwise wouldn’t, such as omega loops, which are found in some naturally occurring proteins on Earth but not typically in peptides.
“What hadn’t been known is that peptides can survive so well and have specific three-dimensional shapes in an acidic environment,” Hong explained.
Follow-up work will take these ideas even further, synthesizing a DNA alternative called PNA, made from peptides. Their existing work shows that a single PNA strand is stable in sulfuric acid, but the new research will attempt to recreate DNA’s double-strand structure with peptides. They also plan to investigate whether long peptides can hold omega loops under these acidic conditions.
Based on their results, extraterrestrial life could easily be hiding in environments highly divergent from anything seen on Earth. Continued investigation may reveal that rather than being poisonous, environments like Venus may be the only places certain lifeforms could exist.
Ryan Whalen covers science and technology for The Debrief. He holds an MA in History and a Master of Library and Information Science with a certificate in Data Science. He can be contacted at ryan@thedebrief.org, and follow him on Twitter @mdntwvlf.
In a widely expected move, a committee organized by the Food and Drug Administration (FDA) has voted to endorse removing restrictions on the manufacture of peptides for human use. Thursday's panel meeting saw a sharply divided group recommend lifting limits on four peptides; votes on three additional peptides are scheduled for today. The move comes despite a continuing lack of evidence regarding their safety and effectiveness.
The move had been telegraphed months earlier as peptide enthusiast and Health and Human Services Secretary Robert F. Kennedy Jr. took steps to ensure this outcome.
Like proteins, peptides are composed of amino acids that are chemically linked into a chain. Peptides differ merely by length; they're often 10–20 amino acids long, in contrast to proteins, which can be hundreds or thousands. Some of them, such as insulin, are specifically made by targeted processing of a protein into shorter fragments, and the resulting peptide interacts with receptors that have evolved to send signals to cells based on its levels.
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